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British regional geology East Anglia

Editors J R Lee M A Woods B S P Moorlock

Bibliographical reference: Lee, J R, Woods, M A, And Moorlock, B S P (editors). 2015. British Regional Geology: East Anglia (Fifth edition). (Keyworth, Nottingham: British Geological Survey.)

British Geological Survey

British Regional Geology East Anglia

Fifth Edition Editors J R Lee M A Woods B S P Moorlock

NERC copyright 2015. © NERC 2015 All rights reserved. British Geological Survey, Nottingham 2015. First published 1937.  Second edition 1948.  Third edition 1954.  Fourth edition 1961. ISBN 978 085272 823 9

The grid, where it is used on the figures, is the National Grid taken from Ordnance Survey mapping. Maps and diagrams in this book use topography based on Ordnance Survey maps. © Crown copyright and database rights 2015. Ordnance Survey Licence number 100021290 EUL.

Definitions of stratigraphical units mentioned in the text may be found via the British Geological Survey’s website in the Lexicon of Named Rock Units.

Copyright in materials derived from the British Geological Survey’s work is owned by the Natural Environment Research Council (NERC) and/or the authority that commissioned the work. You may not copy or adapt this publication without first obtaining permission. Contact the BGS Intellectual Property Rights Section, British Geological Survey, Keyworth, e-mail ipr@bgs.ac.uk. You may quote extracts of a reasonable length without prior permission, provided a full acknowledgement is given of the source of the extract.

Your use of any information provided by the British Geological Survey (BGS) is at your own risk. Neither BGS nor the Natural Environment Research Council gives any warranty, condition or representation as to the quality, accuracy or completeness of the information or its suitability for any use or purpose. All implied conditions relating to the quality or suitability of the information, and all liabilities arising from the supply of the information (including any liability arising in negligence) are excluded to the fullest extent permitted by law.

(Front cover) Coastal cliffs at Hunstanton showing the Carstone Formation (base), Hunstanton Chalk Formation (lower middle, red, horizon) and Ferriby Chalk Formation. Photo: ©iStockphoto.com/CaptureLight.

Foreword to the fifth edition

East Anglia’s open, rolling landscapes belie its complex geological foundation, extending back more than 600 million years. Evidence from the deeply buried geology shows that the region originally formed as a group of oceanic volcanic islands in the southern hemisphere, which later became part of the ancient supercontinent of Gondwana. Continental drift propelled the region steadily northwards. At various times during this journey East Anglia has been covered by deep and shallow seas, tropical forests, river deltas, arid deserts, sand seas, arctic tundra and continental-scale ice sheets. The region is particularly famed for its Quaternary geology which forms one of the most important long-term archives of Quaternary environmental change and early human occupation in northern Europe.

The first edition of the Regional Guide was published in 1937, with the fourth and most recent edition, compiled by C P Chatwin, published in 1961. A revision of the East Anglia Regional Guide has been long overdue because fundamental changes have occurred in our understanding of geology, including plate tectonics and climate change, which are of critical importance to the geological story of East Anglia. These paradigm shifts in geological thinking have driven the rewriting of this guide, which highlights the importance of the region from both purely scientific and applied geological research perspectives.

Whilst retaining the methodical aspects of previous editions, the style of the new edition is a narrative of East Anglia’s geological journey through profound environmental upheavals and how they have acted to shape the modern physical landscape. It sets out how these events can be interpreted in the broader perspective of global geological processes and environmental change. Two chapters provide stand-alone overviews of the bedrock and Quaternary geology and provide a contextual framework for more detailed accounts of the geology provided within other chapters. A further chapter explores both modern and historical links between geology and humans – issues such as geodiversity, water and mineral resources, coastline management, geohazards, building stones and energy.

The book thus offers a comprehensive account of the geology of East Anglia and how it has been shaped by global processes. It should prove informative to a wide range of users including those with a general interest, students and professional scientists, planners and engineers.

John N Ludden, PhD Executive Director. British Geological Survey

Acknowledgements

The editors wish to take this opportunity to acknowledge the input and support of many colleagues who have been involved in the work the British Geological Survey (BGS) has undertaken in the region over the past 50 years. In particular we wish to thank Jim Rose for his enthusiasm and energy in helping to drive forward research into many aspects of the Quaternary geology of the region. A number of people have contributed significantly to the preparation of the Regional Guide through the production of figures, plates and photographs and we would like to gratefully acknowledge the highly professional input of Alex Bradley, Keith Henderson, Henry Holbrook, Lesley Oliver, Amanda Hill, Debbie Rayner, Jim Rayner, Simon Ward, Chris Wardle, Paul Witney and Craig Woodward. Anne Dodd (Oxford Archaeology), Emily Beech (Natural History Museum) and Sarah Hammond (Sedgwick Museum) are thanked for allowing us to use specific images and figures within the Guide; Paul Crofts and Gillian Dredge are thanked for their help with copyright issues. We would also like to thank Jim Rose and David Schofield for reviewing individual chapters; and Jonathan Ford, Peter Hopson and Stephen Mathers for their reviews of earlier versions of the complete manuscript. Joanna Thomas is thanked for her guidance and editorial support throughout the production of this guide.

We also wish to acknowledge and show appreciation to the large number of formal and informal contributions various colleagues have made to the work of BGS in East Anglia over the past 50 years: Mark Abbott, Don Aldiss, Peter Allen, Jennifer Allsop, Julian Andrews, Russell Arthurton, Nick Ashton, Tim Atkinson, Peter Balson, Vanessa Banks, René Barendregt, Mark Barron, Mark Bateman, Anthony Benham, Neil Berridge, Stephen Booth, Steve Boreham, Geoffrey Boulton, Stephanie Bricker, David Bridge, Roger Bristow, Helen Burke, Ian Candy, Raymond Casey, John Cornwell, Beris Cox, Frank Cox, John Day, Richard Downing, Richard Ellison, David Entwistle, Paul Fish, Jonathan Ford, Ian Gale, Ramues Gallois, Phillip Gibbard, Douglas Graham, Chris Green, Claire Hallsworth, Peter Harris, Richard Hamblin, Rex Harland, Anna Harrison, Jane Hart, Stephen Hitchens, Peter Hoare, Peter Hobbs, Tim Holt-Wilson, Peter Hopson, Albert Horton, Hugh Ivimey-Cook, Dennis Jeffrey, Holger Kessler, Sarah Kimbell, Robert Lake, Nigel Larkin, Tim Lawson, Melinda Lewis, Stephen Mathers, Richard Merriman, Jeremy Lee, David Millward, Roy Mogdridge, Stewart Molyneux, Richard Monkhouse, Anthony Morigi, Rory Mortimore, Julian Murton, Edmund Nickless, Adrian Palmer, Simon Parfitt, Steven Pawley, Catherine Pennington, Tim Pharoah, Emrys Phillips, Richard Preece, Adrian Read, Helen Reeves, Peter Riches, Jim Riding, Dave Roberts, Nicholas Robins, Jim Rose, Peter Rowe, Christopher Royles, Andreas Scheib, Danielle Schreve, Roy Shephard-Thorn, Elvin Thurston, Alan Smith, Nigel Smith, George Strong, Mike Sumbler, Brian Taylor, David Vaughan-Hirsch, Richard Waller, Martin Warren, Dennis White, Colin Whiteman, Paul Whittlesea, Ian Wilkinson, Chris Wood, Bernard Worssam, Reg Wyatt, John Wymer and Jan Zalasiewicz.

Introduction

J R Lee, M A Woods and B S P Moorlock

East Anglia may not possess the spectacular scenery of other areas of Britain, nevertheless, the subdued topography and the rich agricultural landscape of the region masks a geological record that has, for well over 150 years, courted the attention of amateur and professional geologists alike. To this day, the region continues to be at the forefront of geology with research focusing on records of environmental change spanning the late Mesozoic and Cenozoic, as well as in important aspects of applied geology.

Since the publication of the previous East Anglia Regional Guide in 1961, there have been fundamental advancements in the science of geology and its wider application. Many of these new concepts manifest themselves within the geology of East Anglia, both in terms of how the geology of the region is described but, perhaps more significantly, the broader context and significance of the geology and how it interacts with human interests. We now understand that much of the concealed and surface bedrock geology of the region relates to the formation and subsequent break-up of the Pangaea supercontinent during the Late Palaeozoic and Mesozoic, the opening of the North Sea Basin and the relative emergence of the British landmass. The resulting geology includes several major rock types that are important aquifers and provides mineral resources at both regional and national scales.

Modern scientific appraisal points to the Quaternary Period as being significantly less benign than previously imagined. Rather, it is one of the most dynamic and complex periods of recent earth history characterised by numerous global-scale changes in climate that have acted to drive extensive and cyclical changes in palaeogeography and geological processes. The landscape of Britain has proven to be highly sensitive to Quaternary climate change due principally to its proximity to polar and low latitude weather systems and our maritime geographical position relative to northern Europe. East Anglia possesses a sedimentary archive of environmental change that spans, albeit discontinuously, much of the Quaternary. It is widely acknowledged as one of the most important long-term records of its type in northern Europe, contributing significantly to our understanding of the nature of past climates and environments, early human evolution, and the sensitivity of the landscape to climate change, sea-level change and neotectonics.

Within this new Regional Guide we provide a broad perspective of the geology of East Anglia, encompassing the counties of Norfolk, Suffolk, Cambridgeshire and parts of Lincolnshire and Bedfordshire. The principal aim of the guide is to provide an overview of the geological framework of the region, its earth history context and relevance to the activities and interests of society. With this scope in mind, the guide has been written for the informed reader and whilst some scientific terminology is employed, we attempt to explain it in an accessible manner. The guide has been subdivided into two main parts, the first describes the bedrock evolution of the region, with chapters devoted to the concealed geology, Jurassic, Early Cretaceous, Late Cretaceous and Palaeogene. Part two focuses on different aspects of the Late Pliocene to Holocene geology of East Anglia, and therefore is dominated by the Quaternary Period. Both sections are preceded by overview chapters that show how the regional geology can be understood in a broader framework of tectonic, climatic and palaeogeographical processes. For more detailed information on specific localities and topics, readers are directed to the ‘sheet memoirs’ and other descriptive texts that accompany the published 1:50 000 geological maps; and the scientific literature that is detailed within the Bibliography at the back of the guide.

Throughout the Regional Guide, chronostratigraphical ages are used in accordance with the geological timescale of the International Commission on Stratigraphy (Gradstein, F M, Ogg, J G, Schmitz M, D, and Ogg G, M, (editors). 2012. The Geologic Time Scale 2012. Elsevier B V). By convention, epochs are typically subdivided into Early, Mid and Late, except for the UK Quaternary, where the terms Early, Middle and Late are more commonly used by workers and this nomenclature is adopted here.

Landscape and geology

The low-lying flat expanses of the Fenland bordering The Wash, drained by the rivers Great Ouse and Nene, give way eastwards to higher, gently undulating terrain, cut by easterly draining rivers such as the Stour, Gipping, Deben and Alde in the south, and Waveney, Yare, Wensum and Bure in the north (Figure 1). This topographical contrast is reflective of the bedrock geology, with soft-weathering clays beneath the Fenland passing eastwards into more resistant sandstones and limestones, including the Chalk (Figure 2).

The geological succession of the East Anglia region is shown in (Figure 3) and (Figure 4), and a simplified map showing the distributions of the bedrock units is given in Figure 2. The succession at rockhead comprises Mesozoic and Cenozoic units, ranging from Mid Jurassic to Neogene in age. The Mesozoic succession largely forms parallel bands in an arcuate outcrop trending south-west to north-east in the south of the region to north–south in the north. Strata dips are typically to the south-east and south (Figure 2). In contrast, Cenozoic deposits in the south-east of the region cross the Chalk in a roughly west-south-west to east-north-east orientation; their pattern relates to the broadly east–west orientation of the London Basin further south, into which the Cenozoic succession thickens progressively eastwards into the North Sea area. Most natural exposures of the bedrock geology occur in the western part of the region, or in cliffs along the coast; elsewhere an extensive cover of Quaternary deposits masks the underlying geology.

The geological foundations of East Anglia are ancient ‘basement’ rocks of late Neoproterozoic and Palaeozoic age, cut by deep-seated thrust faults and uplifted during Mid Devonian earth movements. They form a rigid structural block that subsequently became persistently dominated by terrestrial and shallow marine environments in the Mesozoic and Cenozoic. In recent decades our knowledge of these rocks has been greatly enhanced by information from deep boreholes and regional gravity and aeromagnetic data. These data show that later Palaeozoic and early Mesozoic (pre-Jurassic) successions are generally thin and sporadically developed in the subsurface, and largely influenced by the lateral encroachment of contemporaneous deposition occurring in the adjacent southern North Sea Basin.

Persistent periods of higher relative sea level during the later Mesozoic created the extensive areas of Jurassic and Cretaceous rocks that dominate the bedrock geology of East Anglia. Thick, soft-weathering Mid and Late Jurassic mudstones form the wide embayment around The Wash, and predominantly underlie the low-lying Fenland in the north-east of the region. These clays are an important resource for brickmaking around Peterborough, and have also contributed outstanding specimens of Jurassic marine reptiles to museum collections.

Early Cretaceous rocks form thin outcrops running south from The Wash (Figure 2), and although superbly exposed in the multicoloured cliffs at Hunstanton, knowledge of their character elsewhere in the region mainly comes from boreholes and temporary exposures. East Anglia is one of the few parts of the UK where marine conditions persisted across the Jurassic–Cretaceous boundary, and the region has figured prominently in studies of this key interval. Across East Anglia, as elsewhere in the wider Anglo–Paris Basin/North Sea, the Late Cretaceous is synonymous with the Chalk Group. Despite being the most extensive geological unit at rockhead, in East Anglia the Chalk is widely covered by Quaternary strata, so that with the exception of south-east Cambridgeshire, it does not generally form typical downland landscapes. The western margin of the Chalk forms a reasonably well-defined escarpment south of The Wash and also near Newmarket and Cambridge, but is much less well defined in the vicinity of Methwold and Mildenhall, where the Chalk is cut through by the rivers Lark and Little Ouse, and the trend of the Chalk swings round from south-south-east to south-west. Evidence from regional gravity data suggests that this marked change in the structural trend of the Chalk may result from later movement of a fault in much older rocks at depth. In the past, the area where Chalk is at crop was covered by many small pits used for the extraction of agricultural lime for soil improvement, and palaeontological data from these as well as modern quarries and the ancient flint workings at Grimes Graves, has allowed understanding of the age distribution of the Chalk beneath the Quaternary cover.

The understanding of the stratigraphy of Jurassic and Cretaceous units has advanced greatly since the previous edition of this Regional Guide. Partly this is a consequence of civil engineering feasibility studies and works within the region, such as the Wash Water Storage and Ely–Ouse Water Transfer schemes; a pilot study of oil shale occurrences in the Kimmeridge Clay; and investigations at Mundford, in the 1960s, as a potential site for a large proton accelerator. All of these projects have involved the drilling of boreholes to investigate the detailed geological succession. As a result of these initiatives, detailed stratigraphical schemes have been developed for the Ampthill Clay, Kimmeridge Clay and Gault formations. At Mundford, geophysical logs and core from boreholes have allowed more-detailed understanding of variation in the physical character of the Chalk, and drilling of the BGS Trunch Borehole has allowed parts of the Norfolk succession to be related to the Chalk of Lincolnshire and Yorkshire.

The mixed clays and sandstones that form the youngest part of the bedrock succession, belonging to the Palaeogene and Neogene, are mainly found in the south-eastern part of the region, and in the subsurface northwards into Norfolk; their original extent was probably greater, but was subsequently reduced by erosion. Palaeogene deposits represent deposition in a plexus of nonmarine, nearshore and offshore-marine settings, and part of the succession preserves evidence of voluminous igneous activity associated with the opening of the North Atlantic. In places, weathering of the Palaeogene succession has reduced it to a covering of blocks of hard, silica-cemented sandstones (sarsens) scattered over the present-day land surface.

Neogene strata are represented by the two basal formations of the Crag Group. The Crag Group collectively records shallow-marine and coastal sedimentation within the western margins of the North Sea Basin (known locally as the Crag Basin). Deposition occurred during the Pliocene, Early Pleistocene and early Middle Pleistocene prior to the creation of the Straits of Dover; thus the British landmass was joined to mainland Europe at this time.

The Coralline Crag Formation is of early Pliocene age and forms a narrow outcrop between Aldeburgh and Orford on the Suffolk coast and extends offshore to the north-east for several kilometres. Although originally named for its abundant ‘coral’ fauna, the Coralline Crag actually comprises bryozoan-rich calcareous sandstones deposited within a shallow marine environment. Deposition of the overlying Red Crag Formation spans the boundary between the Neogene and Quaternary periods and is of Late Pliocene to earliest Pleistocene age. The Red Crag Formation is composed of cross-bedded sands and mud drapes that record the migration of offshore tidal sand banks, it crops out within the south-east of the Regional Guide area. Overlying shallow-marine and coastal deposits of the Norwich Crag and Wroxham Crag formations were deposited during the Early Pleistocene and early Middle Pleistocene and these crop out and occur buried at depth through eastern Suffolk and Norfolk. The age of the boundary between the two formations is not known with any certainty but it is widely acknowledged that several major unconformities of generally unknown duration occur throughout the sequence. Vertical and lateral facies associations and the existence of distinctive emergent surfaces demonstrate that fluctuations in sea level occurred on numerous occasions during the deposition of the Crag Group. It highlights the sensitive position of eastern East Anglia during the Pliocene to early Middle Pleistocene interval, with even small changes in sea level resulting in significant changes in geography and the position of the coastline. This is highlighted by the complex interdigitation of shallow-marine (Crag Group) sediments and terrestrial deposits that relate to the large preglacial river systems (see below) that drained central and eastern England.

Fluviatile sediments, composed largely of sands and gravels, belong to the Britannia Catchments Group and include two major stratigraphical subdivisions within the Regional Guide area. These correspond to the ancestral Thames (Kesgrave Catchment Subgroup) and Bytham (Bytham Catchments Subgroup) river systems. Sand and gravel deposits form distinctive terrace staircases situated on the flanks of these former river valleys and indicate that uplift occurred in central England during the Early and early Middle Pleistocene.

Variations in the lithology of these fluvial deposits and their marine equivalents reflect temporal changes in catchment extent and the processes operating within the catchments themselves; all occurred against a backdrop of progressive climatic change. It was against this backdrop of massive climatic instability that early humans first occupied the landscape of East Anglia. Archaeological evidence from East Anglia demonstrates that the first human occupation of northern Europe may have occurred as long as 800 000 years ago with humans living in a range of climates that at times were much cooler and warmer than the present day.

The most extensive glaciation to affect Britain during the Quaternary occurred at the beginning of the late Middle Pleistocene, about 450 000 years ago, and is known as the Anglian Glaciation. During its maximum extent, ice covered over two-thirds of the British Isles and resulted in the widespread modification of the preglacial landscape of East Anglia.

Lobes of British Ice Sheet extended across the region from the Pennines to the north-west and the North Sea to the north. However, the precise age of these deposits remains debated and the possibility remains that elements of the ‘Anglian’ sequence of the region could relate to either older or younger glaciations. This glacial advance saw the Chalk escarpment that forms the western bedrock spine of the region lowered, causing it to migrate eastwards and the Fen and Wash basins to be eroded. Upon deglaciation, a new postglacial drainage network developed in East Anglia focused upon the Fen Basin with the establishment of river systems such as the Nene, the Ouse and the Cam with the northward flowing streams established over the relict till sheet. Early humans were not always present in East Anglia following the Anglian Glaciation. Partly, this is because the formation of the Straits of Dover was initiated during the Anglian Glaciation, and during subsequent periods of high global sea level, Britain and East Anglia became isolated from continental Europe restricting the migration of early humans.

In the last Devensian cold stage, evidence from many of the Fenland river systems shows that the landscape of western and northern East Anglia was a cold and barren place.

During the Late Devensian, glacier ice extended southwards into the Southern North Sea Basin, reaching the margins of The Wash and the north-west Norfolk coast, and deposited sediments that form part of the North Sea Coast Glacigenic Subgroup. To the south of this ice limit, East Anglia was arctic tundra with the widespread development of periglacial features and deposition of windblown cover sand. Humans were absent from the region for much of this Late Devensian cold interval but returned as climate improved during the Late Glacial with Britain finally becoming an island about 8000 years ago as sea levels rose rapidly during the current Holocene Interglacial.

Whilst sea-level change and climatic amelioration underpin the geology of the Early Holocene, the past 6000 years have been increasingly dominated by human interaction with the landscape and underlying geology — from woodland clearance to expanding agriculture and the drainage of the Fen, urbanisation, resource extraction and coastal management.

Today, East Anglia is one of the fastest growing regions of the UK, and it is certain that management of its geological resources will continue to play an important part in its future development.

Chapter 1 Bedrock geology of East Anglia: national and global context

M A Woods

The subdued topography of East Anglia, and overwhelming influence of Quaternary deposits on the character of the landscape, belies the fact that the region has a much more ancient geological history. This history tells the geological story of how and when East Anglia was formed, and progressively shaped, during cycles of rock deposition and major tectonic events. Study of the region continues to provide evidence of the wider story of global change that shaped the geological evolution of the British Isles. Figure 5 summarises the key events in the pre-Quaternary geological history of East Anglia.

Neoproterozoic to Silurian: basement evolution

East Anglia, in common with the broad area of England extending to the Solway Firth, is underlain by deformed Precambrian and Early Palaeozoic rocks, forming the concealed Caledonide basement (Figure 6). During the late Precambrian, the basement of England and much of Wales, including East Anglia, formed part of the microcontinental Avalonian Terrane, the western part of which occurs in eastern North America and the eastern part underlies the Low Countries and north-west Germany. Geochemical evidence reveals that the Precambrian plutonic and volcanic rocks that form the terrane are recycled fragments of juvenile crust* and evolved continental crust, and probably include fragments of juvenile oceanic island arcs or plateaux developed during the amalgamation of a supercontinent at about 1.0 Ga. By about 660 Ma, the Avalonian Terrane had accreted onto the margin of the ancient continent of Gondwana, with extensive coeval phases of continental arc magmatism* between 640 and 550 Ma; volcaniclastic* rocks from this episode crop out in the Charnwood Forest area of Leicestershire. A transition to a stable continental platform occurred by approximately 540 Ma, whereupon marginal terranes, including Avalonia, began to break off Gondwana as the Iapetus Ocean opened between Laurentia and Gondwana.

The Iapetus Ocean was probably at least 5000 km wide at its maximum extent, and separated regions that currently include England and most of Wales from the palaeocontinent of Laurentia, which included Scotland (Figure 7a). Little is known about the Iapetus Ocean in relation to East Anglia prior to the Ordovician, although it seems likely that the region bordered a narrow arm of this ocean, known as the Tornquist Ocean. Deep marine sandstones, siltstones and fossiliferous mudstones of Tremadoc (485.4 to 477.7 Ma) and Llanvirn (467.3 to 485.4 Ma) ages occur in the Wyboston and Huntingdon boreholes, and data from deep boreholes and airborne geophysical surveys suggests the widespread occurrence of Ordovician igneous rocks at depth beneath East Anglia (Figure 8). These rocks, and deep thrust faults such as the Glinton Thrust, are thought to reflect convergence of the Avalonian and Baltica terranes, and subduction of the ocean crust that separated them.

Silurian strata are commonly encountered in deep boreholes across the region (Figure 6). The Silurian rocks suggest the presence of an oxygenated, storm-influenced, sand- and mud-dominated outer shelf in the south-west of the region, marginal to a platform area further to the south-west, with more mud-rich sediments deposited in less-well-oxygenated conditions to the north-east (Figure 9a). The closure of the Iapetus Ocean, and concomitant deformation and uplift of the intervening sedimentary succession largely occurred before the end of the Silurian, and was once thought to be responsible for the Acadian Orogeny, deemed to be the cause of the deformation and weak metamorphism recorded in the Silurian rocks. However, evidence now indicates that the Acadian deformation is Early Devonian in age and some 20 million years later than the closure of Iapetus. Acadian deformation is undoubtedly present in the buried Early Palaeozoic rocks in East Anglia, but the clear distinction between Acadian and earlier, possibly Late Ordovician structures developed on the large scale, is problematical. Earlier-formed thrusts are likely to have been reactivated, and evidence has recently emerged for some of these structures influencing the pattern of much later Mesozoic sedimentation.

Late Palaeozoic: emergence of the London– Brabant High

During the Devonian, East Anglia, in common with much of the rest of the UK appears to have been dominated by largely arid terrestrial environments, probably including deltas, alluvial plains and upland landscapes (Figure 9b). Marine conditions were largely restricted to southern England, and in the Late Devonian a shoreline appears to have cut along the southern fringes of East Anglia, with a borehole at Wyboston showing evidence of large plant fragments associated with a sparse fauna of marine microfossils. The Devonian marks the start of a long and persistent phase of nearshore and terrestrial environmental conditions across East Anglia. Whilst the fringes of the region were periodically inundated by marine conditions, it was not until the mid Cretaceous that marine sedimentation became re-established across the whole region.

By the beginning of the Carboniferous, continental drift had moved the British Isles into an equatorial location, on the northern edge of a marine corridor between the two large continental masses of Laurentia (to the north) and Gondwana (to the south) (Figure 7b).

Tropical carbonate reefs, sandstone-dominated deltas and lushly vegetated alluvial plains (coal swamps) were the dominant geological themes for most of the British Isles at this time, with crustal extension creating shallow blocks and deeper basins, and the waxing and waning of high latitude ice sheets driving rapid oscillations of sea level. Little of this directly affected East Anglia, which for most of this period formed part of the London–Brabant High (also known as ‘St George’s Land’), extending from the near continent across central England and on into Wales (Figure 9c, d). However, a phase of early Carboniferous crustal extension influenced the development of the southern North Sea Basin on the margins of East Anglia, and reactivation of the thrusts forming part of the East Anglian basement may also have occurred.

In the early Carboniferous, marine conditions probably occurred just south of the London area, and Carboniferous strata preserved in boreholes at Cambridge and Gayton suggest a location close to the southern margin of the London–Brabant landmass. In the later part of the early Carboniferous, shallow-marine conditions may have extended northwards across Suffolk; contemporaneous deposits at depth in north-east Norfolk include shallow shelf limestones, but if similar deposits existed across Suffolk then they were removed by later erosion. Fluvial-deltaic and lacustrine sandstones, siltstones and mudstones are typical of the later part of the Carboniferous, and are locally present in boreholes in north-east Norfolk.

Progressive convergence of Laurentia and Gondwana during the Carboniferous largely eliminated marine conditions from much of the British Isles, and the East Anglian region now formed a rigid block ahead of an advancing mountain-building front. This period of earth movement, the Variscan Orogeny, brought Laurentia and Gondwana together, creating the supercontinent of Pangaea. The northern edge of thrusting associated with Variscan uplift, the ‘Variscan Front’, runs just to the south of the East Anglian region, but regions further north were affected by broader deformation. Reactivation of older structures is likely to have occurred, probably including basement thrusts beneath East Anglia.

The palaeogeography of the British Isles was radically altered by the Variscan Orogeny and the formation of Pangaea. In the Permian the whole region lay deep within the Pangaean supercontinent. This vast continent spanned the Equator and extended to high northern and southern latitudes (Figure 7c). Britain occupied a position at low latitudes in the northern hemipshere, within an arid climate belt in the path of easterly trade winds. East Anglia is inferred to have largely been covered by a slightly elevated rock desert, with patches of sand and gravel and some areas occupied by sand dunes (Figure 9e), just a small part of a vast desert area that was probably comparable in its scale to the modern-day Sahara. In the early Permian, northerly directed fluvial palaeocurrents carried sandy conglomerates (Rotligendes Group) from eroding uplands to the south, across north Norfolk into the low-lying North Sea Basin. By the late Permian this basin was occupied by the largely land-locked ‘Zechstein Sea’, perhaps up to 200–300 m deep at its maximum development. The shoreline, bordered by arid salt flats ‘sabkhas’, largely skirted around north Norfolk, but encroached into the north-east part. Cycles of evaporation and marine flooding produced the alternating carbonate–evaporite succession of the Zechstein Group. Subsidence across this part of East Anglia and the adjacent East Midlands Shelf was probably largely controlled by thermal relaxation of the lithosphere underlying the Southern North Sea, following an early Permian phase of crustal extension in this region.

Mesozoic: flooding of the London– Brabant High

The Triassic, represented by subsurface occurrences of pebble beds, sandstones, siltstones and mudstones (Figure 6), saw a continuation of the largely arid terrestrial environments that dominated East Anglia and the wider British Isles during the Permian. Near Lakenheath and Soham, where the undifferentiated succession rests unconformably on Palaeozoic rocks, deposition probably occurred by flash floods, in ephemeral streams and playa lakes. A thin covering of these rocks was thought to occur quite widely across the East Anglian region, but some of these occurrences might actually represent Late Devonian or Carboniferous strata.

A greater nearshore and marine influence is suggested for deposition of the Bacton and Haisborough groups (broadly equivalent to the onshore Sherwood Sandstone and Mercia Mudstone groups), which overlie Carboniferous strata in boreholes in north-east Norfolk.

Britain still formed part of Pangaea, but now at a slightly more northerly latitude (15 to 20°) with a monsoonal climate. Tectonically, crustal stresses were beginning to develop that would eventually cause the break-up of Pangaea, the formation of new ocean basins, and the progressive return of marine conditions to the East Anglia region. This process began with a marine transgression, emanating from the south-west, in the Late Triassic. By Rhaetian times this had covered much of central and south-west England, the Southern North Sea, and the fringes of East Anglia. Along the northern and western shores of the London–Brabant High, which still dominated the heart of East Anglia, thin successions of limestones and sandy limestones represent marginal facies of the Penarth Group, heralding the widespread development of marine conditions in the Jurassic.

By the Early Jurassic, a combination of sea-level rise and regional subsidence, related to crustal extension associated with the opening of the Atlantic Ocean, turned Britain into a cluster of islands surrounded by shallow seas. Elevated atmospheric carbon dioxide levels meant that global climate was much warmer than the present day, so despite being only some 10° south of our current latitude, the region enjoyed subtropical conditions. One of the largest islands in this archipelago was the London–Brabant High, extending across much of East Anglia and southwards to the London area and Kent (Figure 9f). Through the Jurassic the extent of this land area waxed and waned in response to the interplay of sea-level change and tectonic uplift or subsidence. The region became progressively more marine influenced through the Early Jurassic; fluctuated between terrestrially and marine-dominated in the Mid Jurassic (Figure 10a); became progressively more marine in the Late Jurassic (Figure 7d, 10b); and finally terrestrially dominated in the latest Jurassic. Consequently the development of Jurassic rocks across the region is very variable; in some cases it is likely that the original extent of geological units has been reduced as a consequence of intra-Jurassic and later Early Cretaceous erosion events. This dynamic marine environment is reflected in the variety of rock types deposited during the Jurassic. There were largely deep-water marine mudstones and clays (Charmouth Mudstone, Whitby Mudstone, Oxford Clay, West Walton, Ampthill Clay and Kimmeridge Clay formations); nearshore, marginal marine and freshwater deposits (Northampton Sand, Grantham, Rutland and Blisworth Clay formations); and high-energy, shallow-marine limestones (Lincolnshire Limestone, Blisworth Limestone, and Cornbrash formations) (Figure 6). Some of these rock types show cyclic features that may be related to regular climatic fluctuations resulting from regular oscillations in the Earth’s orbital parameters (Milankovitch Cycles). In some cases short-lived periods of environmental change gave rise to distinctive rock types, such as the sand-rich Dyrham Formation related to a brief fall in sea level, or the Marlstone Rock and Kellaways Clay, formed during periods of sea-floor anoxia.

In the Mid Jurassic the East Anglia region was influenced by the development of a major upwarp caused by thermal doming associated with volcanic activity in the North Sea Basin (Figure 10a). This doming was probably developed in response to crustal stretching caused by Atlantic rifting, and at times the related regional uplift experienced across East Anglia and adjacent regions acted to mitigate the effects of sea-level rise and promote the development of freshwater and lacustrine conditions. In contrast, Late Jurassic lithospheric extension beneath the North Sea appears to have accelerated subsidence rates across the East Midlands Shelf and adjacent areas during the Kimmeridgian, and this is reflected in the extensive coverage and thickness of the Kimmeridge Clay Formation in the north-west of the East Anglia region.

By the close of the Jurassic, the sea had retreated from much of the British Isles, and the island landmass that had dominated East Anglia for much of the Jurassic now adjoined low-lying river plains to the south and west (Figure 10c). Sediments spanning the boundary between the Jurassic and Cretaceous are rarely preserved in Britain, but the northern fringes of East Anglia are an exception with a succession of ammonite-bearing sandstones (Sandringham Sand Formation), with phosphate horizons recording periodic breaks in sedimentation. Here marine conditions persisted for much of the Early Cretaceous, with the deposition of the Dersingham, Roach and Carstone formations (Figure 6), although the continuity of the succession is broken by erosion events, particularly between the Roach and Carstone. Overall, the story of the Cretaceous is mainly one of progressive global sea-level rise, driven by exceptionally high rates of ocean spreading that influenced mid-ocean-ridge systems and displaced ocean volumes onto adjacent landmasses. Initially a marine corridor extended around the western and southern margins of East Anglia, depositing sandstones (Woburn Sand Formation) that provide evidence of a seaway swept by powerful currents, and towards the end of the Early Cretaceous (Late Albian) the bulk of the region was covered with marine mudstones of the Gault Formation, with coeval limestones of the Hunstanton Formation forming across a shallow-water shoal covering north-west Norfolk (Figure 10d). In the Late Cretaceous, sea levels rose to exceptionally high levels, perhaps 200–300 m above their present values, and East Anglia together with much of north-west Europe was blanketed in fine-grained deposits of Chalk (Figure 6). The tiny nannoplankton that form the Chalk thrived in an exceptionally warm global climate, a consequence of high levels of atmospheric carbon dioxide resulting from mid-Cretaceous volcanic activity. Tectonic influences are generally minor through the Cretaceous, although there is evidence that thrust faults in the Palaeozoic basement continued to respond to changes in the regional stress field and across parts of East Anglia there appears to be a connection between Cretaceous movement of these structures and the style of Chalk sedimentation.

Cenozoic: development of the London Basin

Between the end of the Cretaceous and the deposition of the oldest post-Cretaceous rocks preserved in East Anglia, there is a time gap represented by an erosion surface. This erosion event was triggered by a combination of sea-level fall and regional uplift, conventionally interpreted as a prolonged event spanning the latest Cretaceous and Early Palaeogene, but perhaps actually representing a briefer period within the Mid Paleocene. Although the locus of Cenozoic sedimentation appears to be to the south of the region, towards the London Basin, the original extent of deposition is uncertain, and may have been much greater across East Anglia and adjacent areas of eastern England; the region may have been contiguous with the wider North Sea Basin, with the preserved depositional pattern of Cenozoic rocks a product of later folding.

The oldest Palaeogene sediments in East Anglia, the Ormesby Clay, are deep-water clays, containing ash layers that correlate with the earliest pyroclastic activity in the British Palaeogene Igneous Province. South of a positive relief area in the south of the region, the Ipswich–Felixstowe High, there was a rapid transition into shallower water conditions with the sand-dominated deposition of the Thanet Sand Formation. Later marine transgression (Upnor Formation) and regression (Reading Formation and laterally equivalent Woolwich Formation) is typical of the eustatically* and tectonically influenced cycles in the Palaeogene succession, with environments ranging from shallow-marine shelf to coastal plain. These cycles were driven by patterns of sea-level change and pulses of tectonic uplift and subsidence. Volcanic ash layers in the sediments relate to volcanic activity associated with contemporaneous rifting in the North Atlantic, rifting that in turn is likely to have affected the subsidence pattern in the North Sea Basin and adjacent areas. In the Early Eocene (Figure 10e), more fully developed marine conditions led to the deposition of the Harwich and London Clay formations. The Harwich Formation contains ash beds reflecting a very explosive episode of volcanic activity in the area to the north and north-west of Scotland (Greenland–Faroes vicinity). The London Clay contains fossil evidence, such as crocodiles, fossil seeds and fruits, of a very warm climate — part of a global pattern of warm Eocene climate conditions known as the Eocene Thermal Maximum. This was preceded by a short-lived period of extreme temporary climate warming known as the Paleocene–Eocene Thermal Maximum, which may have been triggered by the release of greenhouse gases from volcanic or deep-ocean sources.

There is no record of Oligocene or Miocene deposits in East Anglia, and the whole of the East Anglian region is inferred to have come under the influence of terrestrial environments at this time. Sea levels fell in the Early Oligocene, perhaps by 70 m, as global climate dramatically cooled and ice sheets became established across eastern Antarctica. In the Miocene, much of southern Britain was influenced by compressive crustal stresses caused by the Alpine Orogeny resulting from the developing collision of Africa with Eurasia, although early phases of uplift probably began in the Eocene. The effects of these were to cause regional uplift and folding across southern Britain — the synclinal structure of the London Basin formed at this time, with its northern edge crossing the southern part of the East Anglia region. Marine conditions were re-established widely across East Anglia in the Pliocene, continuous with the Southern North Sea, and perhaps intermittently connected to the Atlantic based on affinities of the sandy, bioclastic sediments deposited in East Anglia (Coralline Crag) and Western Approaches at this time.

Chapter 2 Concealed geology

N J P Smith and C W Thomas

East Anglia is perhaps most renowned for its Mesozoic and Cenozoic geology (Figure 11). However, buried at depth beneath these strata is a complex and thick sequence of rocks that records not only the birth and early geological history of what we now call East Anglia, but also provides important clues to the region’s subsequent geological and tectonic evolution. These concealed rocks range in age from the Early Palaeozoic through to the early part of the Mesozoic Era (541 to 201 Ma), however, much older basement rocks of lateNeoproterozoic age also probably occur but have yet to be reached by deep boreholes. In parts of southern Britain, direct geological evidence from this part of the stratigraphical column is limited and this is especially the case beneath East Anglia where these rocks typically occur at over 200 m depth. Our understanding of this important part of the East Anglian geological record is therefore based upon deep borehole records, seismic reflection data and airborne survey data (gravity and aeromagnetic data) and on comparison with adjacent areas where rocks of this age crop out. Within this chapter, the current knowledge and interpretation of the concealed bedrock geology beneath East Anglia are outlined.

Precambrian and Early Palaeozoic

Precambrian rocks

During the late Neoproterozoic (about 730 to 541 Ma), the palaeogeography was dominated by a supercontinent, Gondwana, which was situated broadly over the South Pole (Chapter 1; Figure 12a). Located adjacent to the western margin of Gondwana were several microcontinents or terranes* including Laurentia, Siberia, Baltica and Avalonia which today fringe several of the continents bordering the North Atlantic region. Terms such as ‘microcontinent’ and ‘terrane’ do by their very nature conjure images of terrestrial landmasses. However within a tectonic context, they relate to buoyant fragments of crustal material which could form a part of a terrestrial landmass, but could equally form part of the floor of a marine basin. Rocks from these terranes are composed largely of calc-alkaline volcanic (e.g. andesite, dacite) and plutonic (e.g. diorite) igneous rocks that are interpreted to have formed as subduction-related volcanic arcs on or adjacent to the Gondwana continental margin (Figure 12b). Their geochemistry is typically rich in calcium-bearing ferromagnesian minerals (e.g. hornblende, augite) and feldspar which are associated with sedimentary rocks that were laid down contemporaneously within arc-related basins and then recycled magmatically via subduction and melting.

Much of England and Wales, including East Anglia, formed part of the Avalonia microcontinent (Avalonian Terrane) during the late Neoproterozoic. Published studies from elsewhere suggest that the origins of the Avalonian Terrane date back to at least 1.0 Ga, being formed by the amalgamation of recycled fragments of continental crust, oceanic crust and oceanic island arcs. One such crustal fragment is the Midlands Microcraton (or Platform) which underlies the English Midlands extending westwards into south Wales where it is bounded by the Welsh Borderland Fault Zone and to the south by the Variscan Orogenic Front. Outcrops of Avalonian rocks in England occur within the Charnwood Forest area of Leicestershire, near Nuneaton in Warwickshire, and within the Welsh Borders and Malvern Hills. Beneath East Anglia, no basement rocks of comparable age have yet been identified within deep boreholes but are believed to exist at depth due to their presence within adjacent wells located in the Southern North Sea (Well 53/16-1), Glinton and Orton in Cambridgeshire, and Oxendon Hall in Northamptonshire (Figure 13). These wells recovered felsic* ash-flow tuffs* with textures characteristic of ignimbrites* and have uranium-lead (U-Pb) radiometric ages of about 612 and 616 Ma. In the Mountsorrel area of Leicestershire, late Neoproterozoic basement rocks have also been inferred and appear to have been emplaced towards a linear belt of granodiorite intrusions that occur within the hanging wall of the younger Glinton Thrust.

Early Palaeozoic rocks

During the Early Palaeozoic (541 to 419 Ma), the Avalonian Terrane drifted into more midlatitudinal positions within the southern hemisphere. This continental drift reflects the successive opening and closure of several ocean basins (e.g. the Iapetus and Tornquist oceans) and accompanying phases of volcanic arc activity, continental collision and uplift (orogeny) (Chapter 1). Central to our understanding of the palaeogeography and timing of major phases of tectonic plate rearrangement during the Early Palaeozoic are the preserved faunal assemblages. For example, throughout much of the Cambrian and Mid Ordovician, the isolation of the Avalonian Terrane by extensive deep ocean basins is indicated by the development of distinctive endemic faunas. By contrast, at other times, faunal assemblages from the Avalonian Terrane share characteristics with adjacent drowned continental margins and indicate episodes of ocean closure.

Rocks of inferred Cambrian age (Figure 3) have been recorded within a number of wells in the north of the region including around Wisbech and Spalding (Figure 13). They include gently metamorphosed sandstone (quartzite) and finer-grained mudstone (phyllite) that probably represent continental shelf to deeper marine facies. Rocks of Early Ordovician Tremadoc age (485.4 to 477.7 Ma) locally exceed several hundred metres thickness beneath the northern part of the Fen Basin (Figure 13, 14) and have been examined in detail within the Wyboston Borehole in Bedfordshire. They comprise moderately steeply dipping (15 to 40°) deep-marine black sandstone, siltstone and fossiliferous mudstone. The similarity of Avalonian and Gondwanan marine faunas from rocks of this age suggests the close proximity of the two terranes at this time (Figure 15a). In particular, the deep-water sandstone, which is believed to be a turbidite deposit, indicates the proximity of Avalonia to either a continental margin or volcanic island-arc complex.

Mid Ordovician rocks of Llanvirn age (467.3 to 458.4 Ma) have been identified onshore within the Huntingdon and Great Paxton boreholes and within offshore well 47/29A-1 located in The Wash (Figure 13). Marine faunas record a time when the Avalonian Terrane still formed part of a deep-marine basin but was isolated from large continental masses (Figure 15b). The Huntingdon Borehole contains a thick sequence of fossiliferous and bioturbated* siltstone and mudstone. Superimposed upon these sediments are small-scale faults and minor folding which probably relate to submarine gravity slumps and slides.

Deeper-water slope facies are preserved within the Great Paxton Borehole. They include a locally overturned sequence of interbedded sandstone and fossiliferous (graptolites and trilobites) and bioturbated mudstone. Borehole and seismic data show that the sandstone exhibits graded bedding and well-developed channel structures, interpreted as being formed by turbidity currents. By contrast, beds that contain preserved faunas and bioturbation indicate episodes of well-oxygenated sea-bed conditions between turbidity events.

Late Ordovician rocks, correlated with the Caradoc (458.4 to 450 Ma), have been proven within the North Creake Borehole situated to the south-east of Burnham Market (Figure 13). Here, the borehole penetrated recrystallised ash-flow tuff dated by U-Pb dating to 449 ± 13 Ma and is of similar age to other Caradocian calc-alkaline arc rocks recorded in boreholes across the East Midlands, Lincolnshire and northern England. Faunal assemblages from Late Ordovician rocks elsewhere in Wales indicate the close proximity of the Avalonian Terrane to Baltica signifying the closing of the Tornquist Ocean (Figure 15c).

The existence of Silurian strata from beneath the southern and eastern part of East Anglia is well documented in boreholes where they unconformably overlie older rocks (Figure 13, 14). This unconformity is believed to relate to uplift and erosion that occurred during and immediately after the closure of the Tornquist Ocean when the terranes of Avalonian and Baltica accreted (Figure 15d). Faunal evidence also indicates a close association with Laurentian faunas during the Mid Silurian and this signals the closing of the Iapetus Ocean between Baltica–Avalonia and Laurentia (Chapter 1). The Silurian basin beneath East Anglia probably deepened eastwards from a shallow margin located adjacent to the Midlands Microcraton. Key boreholes, including those at Saxthorpe, East Ruston, Weeley, Stowlangtoft, Sutton, Clare, Lakenheath and Soham, display a range of mudstone, sandstone and siltstone deposited in shelf environments. The precise ages of the strata remain somewhat tentative, however, biostratigraphical evidence indicates strata ranging in age from the Llandovery (443.8 to 433.4 Ma), Ludlow (427.4 to 423.6 Ma) and Pridoli (423.6 to 419.2 Ma).

The sedimentology of Silurian strata from these boreholes provides a valuable insight into the spatial and temporal distribution of shallow marine facies. They offer further constraint to the palaeogeography and environments of deposition. Four lithofacies have been recorded and these include (a) laminated mudstone facies deposited in a deep-water, anoxic environment devoid of benthic life; (b) graded mudstone facies produced by waning turbidity or storm currents, associated with variable water depths and oxygenation levels; (c) graded and hummocky cross-stratified sandstone units formed by turbidity and storm-driven currents; (d) ungraded fine sandstone deposited by high-energy (plane-bed) flows associated with turbidity currents. Collectively, these facies associations record basin infilling and shallowing through time and a progression from anoxic outer-shelf conditions (Llandovery and Wenlock) to more oxygenated conditions (Ludlow) and storm-dominated shelf environments during the Pridoli.

Precambrian and Early Palaeozoic deep structure

The Neoproterozoic rocks described within the previous section were formed during the closure of several ancient ocean basins and the accretion of successive oceanic island arcs and continents onto the Gondwana margin. The Avalonian Terrane was subsequently separated from Gondwana during the Early Palaeozoic by rifting and accreted firstly to Baltica, and then with Baltica to Laurentia. These tectonic events produced a complex concealed and still poorly understood geological structure which appears to have been partly reactivated during subsequent phases of tectonism and exerted a major control upon later styles and patterns of sedimentation. Within this section of the chapter we examine key components of the deep structure beneath East Anglia focusing largely upon observations and inferences that can be made from the airbourne aeromagnetic (Figure 16), gravity (Figure 17) and deep seismic datasets.

The aeromagnetic dataset (Figure 16) reveals a distinctive rectilinear pattern of anomalies (Anomalies A to F) that trend roughly north-west to south-east (Anomalies C to F) and a subordinate set trending west-north-west to east-south-east (e.g. Anomalies A, B). The dominant trend in the data is a continuation of the Furness–north Norfolk Magnetic Anomaly (FINMA) which extends from the Lake District, southwards through northern and eastern England, into north Norfolk and reflects a belt of more magnetic crust located at depth.

Beneath East Anglia, this signal is interpreted as indicating the presence of linear belts of suprasubduction volcanic and igneous rocks that accumulated on and within the Precambrian and Early Palaeozoic basement. Deep boreholes that penetrate these anomalies have been drilled at Rempstone, Leicestershire (Anomaly C) and North Creake 1, north Norfolk (Anomaly D) (Figure 16). The first borehole at Rempstone proved the existence of granodiorite plutons that appear to be part of an intrusive complex that extend from Mountsorrel in Leicestershire eastwards to Huntingdon near Cambridge. Meanwhile the North Creake Borehole records a second belt of intrusive calc-alkaline igneous rocks of Caradoc (Late Ordovician) age that continue into southern Lincolnshire. Regional gravity data (Figure 17) also shows a similar arrangement of high density (green) anomalies which are probably controlled by faults that link with larger north-west- to south-east-trending structures. The age and precise origin of these features are speculative. However, the persistent structural trend which can be traced from East Anglia to northern England, coupled with evidence for Early Palaeozoic movement along some of these structures, suggests that they may be of Precambrian age with subsequent reactivation during the Acadian Orogeny. Lower-density basement rocks are also indicated by the blue areas within the airbourne gravity data

(Figure 17) and could indicate the presence of plutonic igneous rocks beneath areas such as north Norfolk, The Wash and south-east Lincolnshire. An alternative explanation for the gravity low around Saxthorpe is the presence of lower-density sedimentary rocks in a small basin of post-Caradoc age. Overall, the gravity and magnetic data, combined with evidence from some deep boreholes, indicates that volcanic and plutonic igneous arc rocks of calc-alkaline composition, and where dated, of Caradoc age (about 458.4 to 450 Ma), occupy a significant volume within mid-crustal levels beneath East Anglia. These rocks are interpreted as having resulted from the subduction of oceanic crust beneath East Anglia as Avalonia and Baltica converged in the Late Ordovician, generating the heat to drive magmatism*.

Seismic reflection data also offer clues to the deep structure within the rocks beneath East Anglia. Of particular significance is the existence of a south-west-dipping seismic reflector* imaged beneath the Dowsing–South Hewett Fault Zone located offshore within the Southern North Sea (Figure 18). This reflector has been interpreted to be the locus of the subduction zone that gave rise to the Ordovician igneous rocks described within the previous paragraph. Other thrusts have also been imaged at mid-crustal depths within the up-thrown block (hanging wall) of this presumed thrust and dip towards the north-east (Figure 18). These structures, which include the Glinton Thrust, are most likely to be back thrusts generated above the subduction zone, and partly displaced marginal Precambrian and Early Palaeozoic successions back onto the Avalonian margin.

Late Palaeozoic

Devonian rocks

The onset of the Devonian Period (Figure 5), marking the beginning of the Late Palaeozoic, coincides with the final closure of the Iapetus Ocean and the relatively gentle collision (called ‘soft docking’) of Baltica with Laurentia (Figure 15e). This resulted in a period of uplift and emergence known as the Acadian Orogeny, with largely continental conditions prevailing across much of southern Britain (Chapter 1). The rocks beneath East Anglia almost certainly bear this orogenic imprint, although no direct evidence has yet been found. Elsewhere in Britain, deformation and magmatism related to the Acadian Orogeny occurred between about 400 and 390 Ma, resulting in the development of extensive folding, cleavage and low-grade metamorphism of rocks in basins fringing the Midland Microcraton. An arc in the deformation around the apex of the relatively undeformed Midlands Microcraton suggested that this relatively buoyant and rigid crust forming the core of the Avalonian crust in central England, possibly acted as a tectonic indenter much like the Cenozoic collision of India into southern Eurasia to form the Himalayan mountains.

There are no known Early Devonian rocks beneath East Anglia although it is possible that they could be preserved locally in structural depressions. It is widely believed that most of the Early Devonian succession was probably eroded as a result of uplift and subaerial weathering. This is marked in the geological record by a distinctive unconformity commonly referred to as the Acadian Unconformity (Figure 13). Younger Devonian strata, of Mid and Late Devonian age, have been observed within the Soham and Wyboston boreholes and were probably deposited in postorogenic extensional basins or by northward transgression of the Rheic Ocean located to the south of the region at this time (Figure 14). A total of 114 m of fossiliferous terrestrial and marine Late Devonian rocks were recovered from the Wyboston Borehole and includes mudstones, grading upwards into siltstones, sandstones, conglomerates and mudstones. This thickness of strata is tentatively considered to have been deposited within an extensional basin which may equate to the gravity low at Little Chilsill, near Cambridge. This can be traced eastwards underneath the Fen Basin where it narrows, possibly as far west as Northampton and south-eastwards beneath Saffron Walden.

Carboniferous rocks

Throughout the Late Devonian and Carboniferous (Figure 5) periods, East Anglia formed part of the London–Brabant High, a ridge of elevated topography located along the eastern margins of the Laurentia continental landmass (Figure 15f). Laurentia straddled the equator at this time although southern Laurentia and what is now East Anglia was still situated in the southern hemisphere (Chapter 1). Britain was subjected to extensive rifting during this time interval with subduction to the south within the Rheic Ocean leading to the development of a series of backarc basins along the margins of the Midlands Microcraton. Rifting produced the distinctive ‘block and basin’ structure that is characteristic of the Carboniferous in Britain although the orientation of these blocks and basins appears to have been influenced by Late Precambrian and Early Palaeozoic structures. Within the region, sedimentation during the Carboniferous was largely restricted to the area now situated offshore from East Anglia, with the southern North Sea Basin forming an east-south-east extension of the Pennine Basin of northern England.

Deep boreholes situated along the north Norfolk coast have confirmed the presence of Carboniferous strata of Tournaisian to Visean age (358.9 to 330.9 Ma) age. The East Ruston Borehole in eastern Norfolk, for example, yields a 114 m-thick sequence of Carboniferous Limestone Supergroup. It includes beds of limestone, dolomite, dolomitic limestone and shale which were deposited in shallow marine and episodically emergent conditions under a tropical climate. The Carboniferous Limestone Supergroup is, however, absent in the Sibsey Borehole situated to the north-west of The Wash, but thickens south-westwards so may be present to the south and west of Hunstanton. No Namurian age (330.9 to 316 Ma) strata have been recorded beneath East Anglia but they have been identified within offshore well 47/29A-1 situated within The Wash, where seismic reflection data shows that they, and the overlying Westphalian (A–C) units, thicken markedly offshore. Onshore boreholes along the north Norfolk coast, including the Somerton 1 Borehole, prove younger Westphalian rocks — probably equivalent to the Warwickshire Group — resting unconformably upon the older Carboniferous Limestone Supergroup deposits. The absence of older Westphalian and Namurian strata below this unconformity is comparable to the Symon Unconformity in the West Midlands–Welsh Borderland. This unconformity formed as the eroded margins of the London–Brabant High became buried during late Carboniferous thermal subsidence. It is also interesting to note that although of generally subdued topography, the shape of the East Anglia coastline, projecting into the North Sea, probably reflects closely the former northern margin of the London–Brabant High during the Carboniferous. To the south of this landmass lower Carboniferous sediments conformably overlie Devonian strata around Cambridge, but no late Carboniferous strata have been found hereabouts or within the foreland basins to the south.

The late Carboniferous and earliest Permian interval coincides with the final reamalgamation of the continental masses of Gondwana with Laurentia to form a new supercontinent called Pangaea. This continental collision produced an episode of uplift and mountain building referred to as the Variscan Orogeny, and evidence for this event can be seen extensively in rocks across modern-day North America and Europe. The main Variscan Front, which separates the main zone of mountain building (i.e. the fold belt) from the foreland area situated to the north, runs approximately east–west through South Wales, southern England and then north-west Europe. East Anglia lay in the foreland area located to the north of the Variscan Front. Crustal shortening caused uplift and folding of the Carboniferous basins along pre-existing fault structures — a process known as basin inversion. Uplift and folding was accompanied by widespread erosion which generated the Variscan Unconformity at the base of the Permian (Figure 19).

Permian rocks

During the Permian (Figure 5), the London–Brabant High continued to dominate the palaeotopography and East Anglia, with contiguous areas to the east and west, is interpreted to have been subaerially exposed land — probably a desert. No early Permian strata occur beneath East Anglia, and later Permian strata are mainly restricted to the area beneath the Fen Basin (Figure 14) and north-east Norfolk, extending offshore into the southern North Sea (Figure 19). The succession forms the western margins of the Permo-Triassic Southern North Sea (Southern Permian) Basin, associated with the rifting of the North Atlantic and continental fragmentation.

Early Mesozoic

Triassic rocks

Throughout the Triassic (Figure 5), most of East Anglia remained emergent (Chapter 1), though low-lying, forming part of the supercontinent of Pangaea. Sedimentation was restricted to the north-west of the region and neighbouring East Midlands overlapping southwards and onlapping the London–Brabant High. The Sherwood Sandstone Group is restricted to the northern part of the region but is well documented from the North and South Creake boreholes. The sedimentology of the deposit is highly variable in character with a basal sandstone unit — the Hewett Sandstone Member, overlain by clean sandstones, commonly interbedded with mudstone. Some boreholes, such as the East Ruston Borehole, show successions of thick mudstone units sandwiched between units of sandstone that are likely to correlate to the lower part of the Sherwood Sandstone Group. In contrast, other boreholes such as Hunstanton 1, proved the presence of a thick sandstone beneath the clean sandstones interbedded with mudstones, and only a thin mudstone unit overlying conglomeratic sandstone at the base. The thickness reaches 185 m at the coast and the isopachs follow approximately the smooth trend of the north Norfolk coast, before cutting obliquely across the east coast.

Isopachs for the overlying Mercia Mudstone Group–Penarth Group reveal an east-south-east trend in the east, and a probable west-south-west trend in the west, progressively overlapping the Sherwood Sandstone Group southwards (Figure 19). Triassic strata are absent from the Lexham and Warboys boreholes limiting the southerly margin of Triassic subcrop, and numerous boreholes to the south also lack Triassic strata. Several boreholes located in a zone stretching from Ellingham in the north-east to Wyboston in the south-west, prove sandy and conglomeratic red beds beneath the Lias Group (Figure 14). These strata have generally been interpreted as Triassic when logged (assuming downhole conformity). However, an alternative interpretation is that these strata could be Late Devonian or early Carboniferous in age, although no palaeontological evidence is available to verify this possibility. Current evidence suggests an area centred between Lexham and Warboys, where Mercia Mudstone Group strata are absent.

Following an earlier Mesozoic phase of extensional faulting that affected basin development in the Southern North Sea and Weald, East Anglia and adjacent regions experienced regional subsidence in response to thermal relaxation of the underlying crust.

A change from an east–west strike in Permian and Triassic strata to a north-east–south-west strike in later Jurassic strata suggests the presence of a disconformity at the base of the Early Jurassic Lias Group (Figure 14). The following chapters give further details of the Lias Group stratigraphy (Chapter 3) and the younger bedrock successions that can be seen at outcrop within the region (Chapters 4 to 6).

Chapter 3 Jurassic: shallow seas and archipelagos

A J M Barron

Geological and palaeo-geographical setting

The break-up of the Pangaea supercontinent that commenced in the Triassic period continued into the Jurassic, and in north-west Europe formed a number of rifted basins, foreshadowing the opening of the North Atlantic. The development of these basins, coupled with global sea-level rise that began at the end of Triassic times led to the progressive extension of marine conditions across the British Isles, where generally shallow seas surrounded an archipelago of land areas with varying relief. This pattern persisted throughout the Jurassic Period (201.3 to 145.0 Ma). Moderate changes in sea level and elevation or subsidence in platform areas led to rapid fluctuations in coastlines and changes in depositional environments. One of the profound influences on these was the plume-related thermal doming centred in the North Sea, the flanks of which extended across much of Britain. Doming commenced during the Toarcian and although the centre continued to rise until the Callovian, differential subsidence of its flanks began during the early uplift stages (Aalenian) and its interaction with changing sea levels is widely seen in the patterns of deposition throughout the Mid Jurassic and into the Late Jurassic (Figure 20). During this time the British Isles lay between 30 and 40 degrees north of the equator and experienced a subtropical climate that was warm and humid with high levels of carbon dioxide and rainfall, leading to intense weathering and run-off in the emergent areas.

Early Jurassic (Lias Group)

East Anglia lay across the northern margin of the stable and long-lived London–Brabant High, which extended into Belgium. Its western part, the London Platform, was emergent for much of the period, having a dominant effect on sedimentation patterns. Much of the region south-east of a line from Cambridge to Thetford and Norwich remained emergent during the Jurassic, with no deposits of this age recorded in deep boreholes. In contrast, the adjacent East Midlands Shelf to the north-west, located on the distal southern flank of the North Sea Dome, underwent rather moderate but generally continuous subsidence, receiving terrigenous input from the surrounding land areas. Consequently the Jurassic succession across all but the extreme north-west of the region shows evidence of condensed deposition, sedimentation in nearshore environments and erosion of strata at many levels (Figure 20).

Within the East Anglia region, the Lias Group is present at rockhead only in a small area of north Bedfordshire, elsewhere being concealed beneath younger bedrock, and it attains its maximum thickness of about 250 m in the extreme north-west (Figure 21).Further north-west, beyond the East Anglia region, accumulation of the Lias Group on the East Midlands Shelf began in latest Triassic (Rhaetian) times, when the fossiliferous marine mudstone and limestone strata of the coeval Blue Lias and Scunthorpe Mudstone formations were deposited (Figure 20; 21). At this time East Anglia was largely emergent, but marine conditions later extended south-eastwards into the region, where the earliest Jurassic strata are Sinemurian (Figure 20). These oldest beds are progressively overstepped by younger Lias Group beds to the south-east, and there are many minor non-sequences within the succession. Coupled with subsequent erosion in late Toarcian times, this overstep has resulted in a pattern of south-east thinning in all the component formations of the group.

The oldest Lias Group strata seen in boreholes comprise grey variably calcareous mudstone with thin fine-grained and bioclastic limestone beds at several levels, totalling a maximum of about 200 m thick in the north-west. These are attributed to the Charmouth Mudstone Formation, as are the 40 and 50 m of grey fossiliferous mudstone and siltstone of Pliensbachian (Figure 20) age proved in the Soham, Lakenheath and Severals House boreholes near Ely. The 100 m or more of grey mudstone proved in north-east Norfolk is not confidently attributed, but most likely belongs to the Charmouth Mudstone and Whitby Mudstone formations. A minor marine regression in mid to late Pliensbachian times led to the accumulation of variably ferruginous, bioturbated micaceous siltstone with subordinate mudstone beds. This is termed the Dyrham Formation and attains a thickness of 5 m in Bedfordshire and near King’s Lynn. It probably passes northwards into mudstone in the extreme north-west of the region and its persistence east is uncertain, although it may be present in the subsurface near Downham Market. Continued shallowing and the establishment of anoxic conditions on the marine shelf, and intense weathering on land, resulted in the deposition of a condensed succession of ferru-ooidal* ironstone up to 3 m thick in the Tydd St Mary Borehole, comprising the Marlstone Rock Formation. It ranges from Pliensbachian to possibly earliest Toarcian in age, at which time global sea-level rise caused resumption of fully marine deposition of the Whitby Mudstone Formation. This is the oldest formation at rockhead in the region, seen near Podington [SP 93 63]. Basal fish- and ammonite-bearing mudstone and limestone beds are followed by a thick succession of poorly fossiliferous grey mudstone. Deposition was interrupted by late Toarcian uplift related to the North Sea thermal doming, which resulted in deep erosion of the Whitby Mudstone succession, such that an original thickness in East Anglia in excess of 60 m was reduced to 20 m or less.

Mid Jurassic (Inferior Oolite And Great Oolite Groups)

In early Aalenian times (Figure 20), a shallow north–south channel was established across the East Midlands Shelf, affecting the western margin of the region. Minor fluctuations in relative sea level through Aalenian, Bajocian and Bathonian (Figure 20) times resulted here in considerable changes in coastline position and environments. These ranged from freshwater through paralic* to shallow marine, and this depositional area received run-off from land areas to the north-west and south-east. Deep weathering on land generated dissolved iron compounds which were precipitated in shallow marine conditions that extended into the extreme west of our region, producing the sandy ferruginous ooidal limestone and mudstone of the Northampton Sand Formation (Inferior Oolite Group; Figure 22). The formation is a marginal facies of the ooidal ironstone beds of the East Midlands, displaying rootlet traces but lacking shells. The Northampton Sand occurs at outcrop near Farndish [SP 92 63] and at depth around Peterborough and Spalding, and reaches 5 m in thickness.

Marine regression in the late Aalenian resulted in coastal, deltaic and nonmarine environments in which pale to dark grey and purplish sand and silt and black clay of the Grantham Formation (formerly the ‘Lower Estuarine Series’) was deposited over a slightly more extensive area. Some beds are well laminated, others unbedded, and slump and load structures are also seen. Up to about 5 m of strata are preserved in the region. The Grantham Formation is overlapped eastward by the Bajocian Lincolnshire Limestone Formation — the youngest unit of the Inferior Oolite Group — deposited in an expanded marine shelf on which carbonate grains including ooids, bioclasts*, peloids* and lime mud accumulated, along with lesser amounts of silicate grains. This was a high-energy environment, and erosion of the substrate, at least at first, reworked quartz sand from the Grantham Formation. Continuing strong current and tidal activity influenced the limestone facies and caused intraformational erosional breaks. Lower and Upper Lincolnshire Limestone members are recognised at outcrop in the East Midlands, separated by one of these breaks, and respectively characterised by predominance of calcilutite, peloidal packstone* and wackestone*, and cross-bedded bioclastic ooidal grainstone* lithologies. The Lincolnshire Limestone thins east from about 15 m at Peterborough, disappearing south of The Wash, but the relative extents of the members are unknown. It is absent in Bedfordshire.

In the latest Bajocian, despite global sea-level rise, doming-related uplift centred in the North Sea led to erosion of the surface of the Lincolnshire Limestone and formation of hollows holding freshwater lakes up to 1 km across in which dark grey mud and paler silt and sand with root traces accumulated. This is the Stamford Member, the lowest unit of the Rutland Formation (formerly ‘Upper Estuarine Series’), at the base of the Great Oolite Group. The member is about 4 to 6 m thick around Peterborough and in Bedfordshire, with an uncertain eastward extension at depth into Norfolk and Cambridgeshire, where it may be represented by 11 m of lignitic siltstone and sandstone in the Soham Borehole. Subsidence of the

East Midlands Shelf in Early Bathonian times was generally at a greater rate than eustatic sea-level fall and the overlying strata that form the remainder of the Great Oolite Group are intercalated shallow marine, brackish and nonmarine facies with many minor or local non-sequences. Nonetheless, deposition of the Great Oolite succession is inferred to have extended much further to the south-east across the London Platform than the Inferior Oolite.

The Great Oolite forms most of the stratal thickness contoured in Figure 22, although it is not well known from boreholes and the relative extents of the formations are very uncertain. Its outcrop is restricted to the valley of the Great Ouse in north Bedfordshire, where it attains its maximum thickness of over 30 m, and the Peterborough area, where it reaches about 21 m in the Crowland 1 Borehole.

The upper part of the Rutland Formation is characterised by a series of sedimentary rhythms each consisting, where complete, of a marine to brackish shelly mudstone and sandstone unit. It passes up into barren delta-top channel mudstone, overlain by greenish grey mudstone with plant debris and root traces, interpreted as a saltmarsh deposit. This ideal sequence may be truncated by erosion, or may include calcareous and shelly beds signifying transient marine incursions, including a shelly limestone unit, the Wellingborough Limestone Member, seen in Bedfordshire. From over 12 m thick near Bedford and about 10 m thick around Spalding and Peterborough, the Rutland Formation, including the Stamford Member, continues eastwards and is about 8 m thick at Tydd St Mary and 12.3 m at Soham.

Erosion of the upper surface of the Rutland Formation was followed by widespread establishment of sheltered fully marine conditions across the East Midlands Shelf in the Mid Bathonian. This is marked by a sharp upward facies change to the Blisworth Limestone Formation, comprising well-bedded peloidal packstone and wackestone with calcareous mudstone beds. In the west, the formation is 14 m thick around Bedford, 3 m thick at Peterborough, and reaches as far east as Tydd St Mary, where it is 2.1 m thick. It may extend into the Wells-next-the-Sea area, but is inferred to fail south-eastwards, probably passing into nearshore facies. In its marine lithologies, the formation has a prolifi but low diversity bivalve–brachiopod fauna including Praeexogyra hebridica (Forbes) (Plate 1i) and Kallirhynchia, indicating moderate current activity. The significant proportion of silicate silt and sand suggests proximity to land.

A relative sea-level fall in Late Bathonian times reduced circulation on the East Midlands Shelf and led to deposition of the dark grey and brown mudstone beds of the Blisworth Clay Formation. Restricted marine shelly faunas occur in the lowest beds of the formation, and the presence of ferruginous nodule beds, rootlets and the bivalve Corbula at higher levels indicates very shallow water, possibly a brackish lagoon or saltmarsh. Marine influence increases south-westwards, with the shelly limestone facies around Bedford being more typical of the Forest Marble Formation of the Cotswolds. The Blisworth Clay is about 4 m thick around Peterborough, thinning eastwards to less than 2 m near King’s Lynn.

A major marine transgression in the latest Bathonian established a shallow, fully marine carbonate shelf environment from Yorkshire to Dorset, across which the Cornbrash Formation was deposited. Lime sand accumulated, consisting mainly of bioclasts (shell and skeletal fragments) with common peloids, forming a stabilised substrate but subject to pervasive bioturbation. Fossils include an abundant infauna* and epifauna* of bivalves, gastropods, echinoids and rhynchonellid and terebratulid brachiopods, the last displaying vertical changes in assemblage that are useful for biozonation*. Periodic minor fluctuations in sea level, some due to local subsidence, led to formation of disconformities, which may be marked by thin lime mudstone layers and intraformational pebbles in the overlying limestone bed. One of the regressions is widespread and coincides with the Bathonian–Callovian stage boundary at about 166.1 Ma. This boundary separates distinctive brachiopod and ammonite faunas in the Cornbrash, and there is a tendency for beds of flaggy sandy limestone to be generally restricted to the upper part, allowing Lower and Upper Cornbrash members to be recognised (Figure 20). Although these subdivisions are not ubiquitous, nor easily distinguished except in exposures or where the fauna permits, both have been recognised around Peterborough where the Cornbrash forms wide plateau outcrops. Further east at depth, the Lower Cornbrash is impersistent. Despite the included hiatuses, the Cornbrash is remarkably constant in thickness throughout the English Midlands (2 to 4 m; locally less than 1 m), and this pattern is seen in East Anglia, where it is inferred to have had the greatest original extent of the Great Oolite formations.

Mid To Late Jurassic (Ancholme Group)

Through Callovian, Oxfordian, Kimmeridgian and into early Tithonian times (about 166 to 150 Ma), marine sedimentation continued across a deepening and widening East Midlands Shelf, albeit with a number of significant interruptions, and the coastline of the London Platform landmass retreated further south-east than at any time previously during the Jurassic (Figure 23). The mudstone-dominated succession deposited throughout this period is termed the Ancholme Group (Figure 20), and reaches 250 m in thickness (Figure 23). It is at rockhead throughout the western third of the region, almost entirely beneath Quaternary glacial, fluvial or marine deposits. Its five component formations are generally very fossiliferous, and include ammonites which are sufficiently numerous and rapidly evolving to permit subdivision of the chronostratigraphical stages into zones, and at some levels, subzones.

In the Early Callovian, the carbonate shelf of the Cornbrash was occluded by deposition of mud under anoxic bottom conditions. Above a thin transitional shell-rich unit, the overlying dark grey, bituminous, laminated silty mudstone beds belong to the Kellaways Clay Member, forming the lower part of the Kellaways Formation (Figure 24). The member contains few benthic fossils, and the moderately common ammonites, which indicate the Herveyi Zone, are generally preserved in pyrite. This mineral is also finely disseminated through the rock and concentrated in the fillings of burrows that are common at some levels. Phosphatic and ferruginous nodules are also present, and the member becomes increasingly silty and sandy upwards — a result of basinward redistribution of older coastal deposits. It passes up into the Kellaways Sand Member, characterised by fine-grained sandstone and sandy siltstone, interbedded with silty mudstone. The sandstone beds are generally poorly indurated, but locally they may be cemented into calcareous sandstone nodules or ‘doggers’. Common belemnites and ammonites confirm the open marine environment, and a more prolific and diverse fauna of gastropods and bivalves (notably Gryphaea dilobotes Duff; Plate 1e), and intense bioturbation at some levels, indicate improved bottom circulation. Fragments of wood are also common, suggesting proximity to land. The Kellaways Formation crops out along the flanks of the Great Ouse and Nene river valleys, is at rockhead beneath Quaternary deposits through Peterborough and Bedford, and is commonly exposed in sumps and trenches in the floors of the nearby Oxford Clay brick pits. Ranges of thicknesses given separately for the Kellaways Clay and Kellaways Sand members are misleading due to the difficulties of placing the boundary consistently in borehole logs; modal thicknesses for the members in the Peterborough area are 2.5 m and 3.0 m respectively. The formation as a whole is 5 to 7 m thick in the west (Spalding to Bedford), thinning east to 3 to 5.5 m at King’s Lynn, and about 1 m at Ely. The location and nature of its south-eastward pinch-out is uncertain, and it is possible that the formation may extend furthest of all the Ancholme Group units.

The top of the Kellaways Formation is taken at the top of the highest bed of sandstone or sandy mudstone and is sharp and conformable. It is overlain by the Oxford Clay Formation (Figure 24), which forms an outcrop or subcrop about 20 km wide across the west of the region. The formation is dominated by grey silicate mudstone deposited in moderately deep marine conditions. In the west it ranges from 63 to more than 70 m thick around Spalding and Peterborough, and a similar thickness occurs at Bedford (65 to 70 m), with a slight thinning (to about 60 m) between these sites possibly reflecting a closer proximity to the London Platform. The influence of this structural feature is inferred south-eastwards at depth, where the Oxford Clay reduces to about 40 m thick in eastern Cambridgeshire and western Norfolk, and detailed logs of boreholes at Soham and Tydd St Mary indicate a condensed succession. The formation is very fossiliferous throughout, the invertebrate fauna including bivalves, gastropods, brachiopods, belemnites, worm tubes, solitary corals and ammonites (Plate 1a to h). Based on a combination of lithological and faunal characteristics, a threefold subdivision of the formation is recognised, comprising the Peterborough, Stewartby, and Weymouth members (formerly the Lower, Middle and Upper Oxford Clay, respectively).

The Peterborough Member is dark brownish grey fissile organic-rich mudstone with dense spreads of compressed ammonites beautifully preserved in iridescent aragonite as ‘plasters’ on bedding planes, alternating with pale to mid grey blocky and finely bioturbated mudstone. Units of bioturbated mudstone increase in proportion upwards, with the lithologies arranged in rhythmic successions that commonly include a shell bed at the top in which the bivalve and ammonite fossils are typically uncrushed and pyritised. The distinctive worm tube Genicularia vertebralis (J de C Sowerby) (Plate 1g) ranges from near the base of the member up to the lower beds of the Stewartby Member, and together with the robust belemnite guards, are found in soils covering the weathered outcrop. The upper boundary of the member is defined somewhat arbitrarily at the top of the highest bed of organic-rich mudstone. Based on this, its thickness is 23 m at Bedford, 16.6 m at Peterborough, 13.9 m near King’s Lynn, and 17.9 m at Soham, with a general eastward-thinning trend. Organic-rich mudstones in the Peterborough Member reflect the primary preservation of organic material under anoxic sea-bed conditions, and its later conversion into a mixture of organic compounds (generally referred to as kerogen) through the process of burial diagenesis*. The presence of these units has greatly favoured the Peterborough Member for brickmaking using the ‘Fletton’ process, developed at the brickworks at Old Fletton, south of Peterborough (see Chapter 14). Over the last 100 years, practically the full thickness of the member has been worked for brick clay around the city in over a dozen large opencast pits, generally 15 to 20 m deep (Figure 23) which are designated its type locality, and in another ten similar pits at Stewartby, in the Marston Vale of Bedfordshire. At least two levels in the member show the development of more calcareous beds: a persistent bed of ammonitiferous septarian* limestone nodules about 0.5 m above the base usually forms the working floor of the pits.

About 10 m above this, a thin but more continuous muddy limestone with an overlying highly fossiliferous mudstone bed forms the persistent marker of the Acutistriatum–Comptoni Bed (Figure 24). The advancing quarry faces have provided unrivalled access to the unweathered mudstone and its rich fauna. This encouraged much careful and diligent collecting, notably by Roland Brinkmann, who at Peterborough in the 1920s undertook an exceptionally detailed study of the faunal succession of the ammonite genus Kosmoceras (Callomon, 1968). As well as the invertebrates, the Peterborough brick pits are famous for their fossils of large marine vertebrates (Figure 25).

The lower part of the overlying Stewartby Member is exposed in the brick pits at Whittlesey, east of Peterborough, and the uppermost beds at Stewartby, its type section, but the unit’s outcrop is otherwise largely concealed by superficial deposits. The pale to mid grey silty mudstone beds of the member are moderately calcareous, nonbituminous and much less fossiliferous than the Peterborough Member. On their own they are unsuited for Fletton brickmaking unless mixed with the organic-rich mudstone. At Bedford the member is 22 m thick; its thickness is 20.6 m east of Peterborough, 22.9 m near King’s Lynn, and 9.1 m at Soham. The fauna-bearing horizons include beds of intact and robust Gryphaea valves (Plate 1d) preserved in calcite, which survive in the soil; units rich in the fragile bivalve Bositra buchii (Roemer) (Plate 1h); and a few beds with uncrushed pyritised ammonites, amongst which kosmoceratids dominate (Callomon, 1968). There are scattered bivalves and belemnites throughout. The fauna and facies indicate an environment with generally improved bottom-water circulation. The lower part of the member is rather monotonous lithologically, but higher up some beds are sufficiently calcareous to be regarded as muddy limestone. The uppermost of these, the Lamberti Limestone, is very shelly, with pyrite-coated bivalves, gastropods and ammonites including the zonal indicator Quenstedtoceras lamberti (Plate 1c) after which it is named. The top of this limestone marks the top of the Stewartby Member and the Callovian–Oxfordian stage boundary, and hence the top of the Mid Jurassic epoch (see Figure 20).

Lithologically the Weymouth Member bears a strong resemblance to the Stewartby Member. The bulk of it is composed of pale grey, blocky-weathering, calcareous mudstone with a shelly fauna preserved in pyrite and calcite. However, subordinate interbedded darker carbonaceous mudstone beds resting on the burrowed tops of the pale mudstone units indicate renewed rhythmicity. The fauna is sparser and ammonites are now dominated by cardioceratids. The member is very poorly exposed in the region, although it was temporarily fully exposed at Millbrook, Bedfordshire, where it proved to be 21.3 m thick. The upper 25 m were formerly seen in the face of the disused Warboys brick pit [TL 308 818], near Ramsey. Together with data from the nearby BGS Warboys Borehole a total thickness for the Weymouth Member of about 30 m can be inferred here. General eastward thinning is caused by condensed sedimentation and widespread erosion of the upper beds beneath an Early to Mid Oxfordian disconformity developed in response to marine regression. The member is 26 m thick east of Peterborough, 19.6 m thick near King’s Lynn and 14.5 m thick at Soham.

Through most of the Oxfordian (see Figure 20) in southern England and Yorkshire, medium- to coarse-grained siliciclastic and carbonate sedimentation took place in shallow to very shallow marine conditions, depositing the Corallian Group. However, in eastern England basin inversion re-established somewhat deeper water adjacent to land on the London Platform, and here silicate and carbonate mud and silt accumulated to form the West Walton Formation (Figure 24). The beds are arranged in cycles of darker grey carbonaceous silty mudstone and paler grey calcareous mudstone with burrowed horizons indicating sedimentation pauses. Layers of muddy fine-grained limestone concretions have developed at some levels and are more numerous in the more proximal southern part of the region. Following research into the bedrock for a proposed Wash Water Storage Scheme, the succession in the type section West Walton Highway Borehole [TF 4913 1316] was divided into sixteen beds on the basis of lithology and fauna, and a number of these have proved to be widely identifiable, as far away as Bedfordshire. The fossil content is similar to that of the Weymouth Member, dominated by cardioceratid ammonites, bivalves, serpulids and foraminifera and a variety of other invertebrates and trace fossils, with plant debris abundant in some beds. The more resistant calcitic shells of the bivalves Lopha, Nanogyra and Gryphaea dilatata (Plate 1b) may be found in the soil on the formation’s outcrop, although across most of the region it is largely concealed beneath Quaternary deposits. The formation thins south-eastwards across the region, from about 10 to 15 m in the Fenland, to less than 10 m in southern Cambridgeshire. Here successions typically of alternating silty limestone and calcareous mudstone with an abundant bivalve fauna are fairly widely developed, occupying all or part of the interval, and are interpreted as nearshore, probably back-reef facies. Variability of the faunal assemblage (in places including serpulids and coral debris) and early uncertainty about the stratigraphical level and lateral continuity of units, led to several local names being applied to variants of the interbedded limestone and mudstone succession, including St Ives Rock and Gamlingay Rock. More recently most of these have been incorporated into the Elsworth Rock Member, which overlies dark grey mudstone with nodular limestone of the Lower Elsworth Member. An unusual development of over 13 m of coralliferous limestone and shelly lime-mudstone at Upware, 15 km north-east of Cambridge, underlies a low ridge 5 km long and up to 1.5 km wide. There, the Dimmock’s Cote Marl Member and Upware Limestone Member are distinguished above the Lower Elsworth Member (Figure 24). The succession is interpreted as forming on a carbonate ramp building northwards, with conditions permitting the development at times of ooid shoals and coral reefs, in both very shallow and deeper water, with colonisation by a rich fauna that, as well as various corals, includes ammonites, echinoids, crinoids, sponges, annelids, rare brachiopods, and a great diversity of bivalves. The preserved area may be similar to the original extent.

Gradual deepening of the sea and south-eastward retreat of the coastline in the late Mid Oxfordian (about 160 Ma) led to the deposition of the Ampthill Clay Formation (Figure 24). Its base is marked by a change up into mudstone that is darker grey, less silty and calcareous and richer in ammonite fossils than the West Walton Formation. The boundary is generally conformable although at Upware higher beds of the Ampthill Clay lap onto the flanks of the mound of the Upware Limestone Member. Across most of the west of the region the formation is consistently between 50 and 55 m thick, showing slight thinning to the south-east and significant reduction in the Ely–Cambridge area (20 to 30 m) due mainly to attenuation in the upper part. Its persistence at depth is uncertain; it extends into north-west Norfolk but is overstepped by Early Cretaceous strata south-eastwards. The Ampthill Clay is absent beneath the Cretaceous Woburn Sands Formation at outcrop in parts of Bedfordshire, although it was formerly well exposed in the nearby Ampthill railway cutting that forms its type section, with 12.6 m later proved in the BGS Ampthill Borehole [TL 0244 3804].

Study of boreholes for The Wash Water Storage Scheme enabled the Ampthill Clay succession to be subdivided into forty-two beds. On the basis of gross lithology the study grouped these into a lower part of alternating slightly silty dark grey mudstone and pale grey calcareous mudstone and a middle part of smooth-textured mudstone. The upper part is characterised by calcareous and silty mudstone beds with several erosion surfaces capped by oyster encrustations and overlain by mudstone with phosphatic pebbles. Disseminated pyrite and layers of cementstone nodules are present as are rare thin beds of bituminous mudstone and of muddy ironstone. The fossil fauna content is exclusively marine with common ammonites dominated by perisphinctid and cardioceratid forms. Bivalves and foraminifera are also abundant, although their low diversity at some levels implies periodically restricted water circulation, and plant fragments, echinoderms, crustaceans and gastropods are also recorded. The soil on the outcrop is heavy grey-brown clay containing scattered thick shells of the oysters Gryphaea dilatata (Plate 1b) and Deltoideum delta.

Around the northern margin of the London Platform, minor uplift and possibly gentle folding in Late Oxfordian times resulted in erosion of the uppermost strata in the region so that the youngest part of the Ancholme Group, the Kimmeridge Clay Formation (Figure 24), rests disconformably on the Ampthill Clay. This sharp junction is also marked by a lithological change from pale grey calcareous mudstone to mid grey silty mudstone with phosphatic nodules, and a transition in the predominant ammonite genera from Amoeboceras and Ringsteadia to Pictonia and Rasenia (Plate 1j). The formation is composed almost entirely of mudstone, ranging from very pale grey to very dark grey largely depending on calcium carbonate content, with brownish grey fissile kerogen-rich mudstone beds (‘oil shales’) at some levels that were briefly and unsuccessfully exploited for hydrocarbons in the early 20th century (see Chapter 14). Pyrite is present in fossils, replacing burrow fills and finely disseminated, and some beds, mainly in the lower part, contain phosphatic pebbles. Silty mudstone, siltstone and muddy limestone beds are present in subordinate amounts. The fauna is more varied than that of the Ampthill Clay, with a great diversity of ammonites and bivalves, plus gastropods, serpulids, brachiopods, echinoderms, fish and reptiles. The ammonites include many rapidly evolving forms, generally preserved in iridescent aragonite and commonly whole but flattened. The informal division into Lower and Upper Kimmeridge Clay is drawn not on the basis of lithology, but at a biostratigraphical zonal boundary (Eudoxus to Autissiodorensis zones) placed at the upward limit of Aulacostephanus and the first appearance of Pectinatites. Water depths fluctuated during Kimmeridge Clay deposition but it is likely that during this time the sea extended further across the London Platform than at any other point in the Jurassic.

Detailed study of borehole cores across the north of the region and into The Wash allowed recognition of important lithological and faunal variations within the Kimmeridge Clay, and defined a succession of forty-nine distinct beds, many identifiable several hundred kilometres away in Dorset. At the same time, it was recognised that the lithologies were organised into a succession of small-scale rhythms between 0.3 and 2.5 m thick. In the lower part of the formation these comprise silty mudstone overlain by dark grey mudstone and pale grey calcareous mudstone. In the middle and upper parts of the formation the basal beds of each rhythm are the oil shale type and tabular or nodular limestone (‘cementstone’) may occur in the upper part of the rhythm.

Where present at rockhead, the Kimmeridge Clay Formation is almost entirely concealed beneath Quaternary deposits and its subcrop is about 20 km wide in the north, tapering southwards to zero in south Cambridgeshire. About 16 m of beds of the middle part of the formation are visible in Roslyn Hole clay pit [TL 555 808] near Ely, a site also known for its sauropod and marine reptile fossils, but there are no other significant exposures in the region. The mudstones weather to a grey to yellowish brown clay subsoil with abundant clear selenite* crystals, and at outcrop form a heavy clay soil commonly containing the small oyster Nanogyra virgula (Defrance) (Plate 1k). The formation thins from about 130 m beneath The Wash, through 100 m at the Norfolk coast (North Wootton Borehole [TF 6439 2457]), 60 m near Wisbech and about 45 m at Ely. Thinning occurs mainly in response to condensed sedimentation (reduced deposition rates) towards the London Platform as reflected by subtle lateral changes in lithology to shallower water facies, and also through erosion of the upper beds in Late Jurassic and Early Cretaceous times. In Norfolk, from the latest Jurassic (Tithonian stage; 146.5 Ma) into the Cretaceous, marine sedimentation resumed, depositing the Sandringham Sand Formation (Chapter 4), but further south the much younger Woburn Sands Formation overlies the unconformity. Beneath this, the Kimmeridge Clay is entirely overstepped southwards, and the formation has the smallest extent across the London–Brabant Platform of the Ancholme Group formations (Figure 20).

Chapter 4 Early Cretaceous

M A Woods

Introduction

At the dawn of the Cretaceous, some 145 million years ago, a combination of global sea-level fall and regional uplift caused much of Britain to become land. Most of the East Anglian area formed part of the London–Brabant High, extending eastwards into Europe (Figure 26). There was widespread erosion of pre-existing Jurassic rocks, in many areas creating a significant unconformity (Late Cimmerian Unconformity). In East Anglia, this erosion removed the upper part of the Kimmeridge Clay Formation. Uplift was triggered by isostatic effects resulting from extension of the lithosphere associated with ocean-floor spreading in the newly opening North Atlantic Ocean to the west of the British Isles. In East Anglia, Early Cretaceous marine environments were restricted to an embayment, at the southern edge of the North Sea Basin, covering parts of north Norfolk, The Wash and Lincolnshire. Here, the thin geological succession reflects slow rates of basin subsidence, in contrast with the situation south of the London–Brabant High, where locally high rates of downfaulting allowed more than 1000 m of mostly nonmarine Early Cretaceous sediments to accumulate in the Weald of Kent and Sussex. Marine conditions extended into the southern North Sea, and occasional southward marine incursions occurred via a lowland corridor to the west of the East Anglia region, briefly interrupting the otherwise fluvial-dominated deposition across southern England.

The position of the Jurassic–Cretaceous boundary remains the subject of debate. Marine regression at the end of the Jurassic led to the development of endemic ammonite faunas across Europe and Russia, making long-range correlations of sedimentary successions problematic. Consequently, different and non-equivalent age and stage nomenclatures are used for the terminal Jurassic and earliest Cretaceous in southern Europe compared to north-west Europe (Figure 27). Although thick and relatively continuous rock successions span the Jurassic–Cretaceous boundary in parts of southern England, these are predominantly nonmarine, and north Norfolk is one of the few places in the UK which preserves any ammonites across the Jurassic–Cretaceous boundary. Because these faunas are most similar to those seen in Russian successions, the UK has traditionally adopted the Ryazanian (Figure as the earliest interval of Cretaceous time. In East Anglia, the base of the Ryazanian is recognised by a remanié fauna* in a nodule bed in the lower part of the Sandringham Sands Formation. However, indirect evidence from southern England and new correlations between the disparate ammonite faunas of the Russian Platform, Crimea and southern Europe, suggest that the boundary might be lower and equivalent to the base of the Cretaceous as defined by the base of the Berriasian (Figure 27) in southern Europe. Consequently, the Jurassic–Cretaceous boundary might actually occur lower down in the Sandringham Sands Formation.

The latest Jurassic and early part of the Cretaceous (pre-Aptian) in East Anglia is represented by a succession of sandstone, clayey sandstone and thin clays, with erosion surfaces and phosphatic pebble beds that record numerous breaks in sedimentation (Figure 27) and (Figure 28). The onshore succession is up to 78 m thick, and best seen in a narrow tract of country bordering the eastern side of The Wash south of Hunstanton. Thick sandy Early Cretaceous deposits also extend offshore into the Southern North Sea, and there is some data from heavy mineral studies to suggest that the succession was derived from the erosion of uplifted Carboniferous sandstone.

Late Jurassic and Early Cretaceous (Ryazanian to Barremian)

At the base of the Norfolk succession is the Sandringham Sands Formation, divided (in ascending stratigraphical order) into the Roxham Member, Runcton Member, Mintlyn Member and Leziate Member (Figure 27). The sediments probably reflect erosion of the topographically higher areas of the London–Brabant High, with the formation cropping out over a relatively limited area in north Norfolk, between Hunstanton in the north, and the River Little Ouse, near Ely, in the south. In the subsurface it extends as far east as South Creake (Figure 26). Most of the primary sedimentary structures have been obliterated by burrowing, but surviving features suggest that at least parts of the formation accumulated as offshore sand bars. The erosional contact with the underlying Kimmeridge Clay Formation is marked by accumulations of black chert (lydite) and phosphate associated with a hard calcareous sandstone. This boundary was long assumed to represent the Jurassic–Cretaceous boundary until the discovery of Late Jurassic ammonite faunas in the Roxham Member, and this unit is likely to be entirely Late Jurassic (Portlandian, (Figure 27)) in age. Some phosphatised fossils from the base of the Roxham Member are derived from the Kimmeridge Clay, but others are remanié Portlandian forms. The thin (3 to 6 m), poorly consolidated, pyritic sands of the Roxham Member equate with the lower part of the Purbeck Limestone Group in southern England; north-westwards they become the basal part of the Spilsby Sandstone Formation in Lincolnshire. The Roxham Member has its type locality at Roxham Farm, near West Dereham (Figure 26), and is commonly deeply weathered at outcrop to loose, brown, grey or green sands. An exception is the basal sandstone, up to 1.5 m thick, which produces a strong feature and spring line at outcrop. It forms a prominent seismic reflector in the subsurface, and even occurs as large rounded boulders in glacial tills. The sandstone is abundantly bioturbated, with Ophiomorpha and Skolithos burrows that extend down into the underlying mudstones of the Kimmeridge Clay, and is by far the most fossiliferous part of the member. The indigenous fauna includes the ammonites Paracraspedites oppressus Casey, P. cf. bifurcatus Swinnerton and P. stenomphaloides Swinnerton. Recently it has been suggested that P. oppressus (the index of the P. oppressus Zone) might actually be the early growth stage of a different ammonite species belonging to the middle Portlandian Titanites anguiformis Zone.

Erosional breaks mark the base and top of the thin (up to 2 m), dark green, clayey, and highly glauconitic sands of the Runcton Member (Figure 27) and (Figure 28). The depositional hiatus separating the Roxham and Runcton members probably contains the Jurassic–Cretaceous boundary as defined by the base of the Berriasian stage. The Runcton Member is a very condensed, strongly bioturbated unit with phosphatic nodule beds, equivalent to the greater part of the Lower Spilsby Sandstone in Lincolnshire. There is a strong colour contrast with the uniformly grey and less clayey Roxham Member below, but the detailed stratigraphy is quite variable because of a complex and changing pattern of sedimentary breaks within the succession. Temporary sections around North Runcton and King’s Lynn have provided the best exposures of the Runcton Member (Figure 26). At West Dereham it is reduced to a single band of rolled phosphatic nodules, and beneath the central part of The Wash the member has been removed by erosion at the base of the overlying Mintlyn Member. The sparse fauna includes derived material from the Subcraspedites (Subcraspedites) preplicomphalus Zone and indigenous specimens of S. (Volgidiscus) lamplughi Spath, the zonal index for the top of the Portlandian as traditionally defined.

The base of the Ryazanian (Figure 27), and the base of the Cretaceous as traditionally interpreted in the UK, is the nodule bed at the base of the Mintlyn Member (Figure 27), containing fragments of indigenous ammonites that compare with Early Ryazanian faunas from elsewhere in north-west Europe and the Russian Platform (Plate 2). It has also been suggested that the marine fauna of the Cinder Bed, in the middle of the Dorset Purbeck Limestone Group, might correlate with the basal nodule bed of the Mintlyn Member, and represent a temporary southward incursion of the marine conditions that existed in north Norfolk and Lincolnshire; this remains debateable. The Mintlyn Member, named for the parish of Mintlyn near Kings Lynn, comprises up to 15 m of glauconitic sands and clayey sands with horizons of clay ironstone and phosphatic nodule beds marking erosion surfaces. Some of the ironstones are bored and phosphatised and probably represent hardgrounds, formed at times of reduced sedimentation rates when sea-floor sediments became cemented into a hard substrate. These beds occur at outcrop between Wolferton and West Dereham (Figure 26), the best section being that seen in 1965 at Mintlyn Wood during the construction of the Kings Lynn Bypass. Fossils from the member include ammonites belonging to the Hectoroceras kochi, Surites (Lynnia) icenii, S. (Bojarkia) stenomphalus and Peregrinoceras albidum zones (Plate 2), bones and teeth of marine reptiles and lignite logs up to 1 m long. As with other units of the Sandringham Sands Formation, the age of the preserved Mintlyn Member varies laterally; near West Dereham, the basal part is characterised by the ammonite Hectoroceras cf. kochi Spath (‘Hectoroceras Beds’), but these beds thin northwards and are absent beneath The Wash and in Lincolnshire. The top of the Mintlyn Member probably contains the Ryazanian–Valanginian boundary (139.4 Ma), based on the presence of the ammonite Paratollia near the top of the succession seen in boreholes drilled in The Wash.

The thickest and youngest part of the Sandringham Sands Formation is represented by the Leziate Member (Figure 27) and (Figure 28). This comprises poorly consolidated, fine-grained, burrow-mottled, cross-bedded sand, up to 30 m thick, which underlie large areas of heathland in north-west Norfolk. The sands are mostly grey or white (Plate 3) and (Plate 4), but locally orange-brown where oxidised iron minerals have not been leached out. Pyrite nodules occur throughout, with locally abundant glauconite* and minor bands of silt and clay. The absence of clay ironstone distinguishes the Leziate Member from the underlying Mintlyn Member. From their 20.4 m at Hunstanton, the Leziate Beds thicken southwards, attaining their maximum thickness in the Leziate–Middleton area; they thin rapidly beneath The Wash, probably reflecting strong lateral variation in their original depositional extent rather than postdepositional erosion. A thin bed of dark green glauconitic clay marks the base of the Leziate Member, seen in boreholes at Gayton and Marham and in old workings at the type locality at Leziate, where the sands were formerly worked for glass manufacture and foundry moulding (Figure 26). In the lower part of the Leziate Beds, pyritised masses of fossilised plant stems and wood may represent sunken mats of vegetation on the sea bed, but apart from the burrowing (cf. Skolithos and Rhizocorallium) and in spite of the good exposure, other fossils are rare. The member is presumed to be Valanginian on the basis of a single ammonite (Polyptychites?) believed to have been derived from the interval.

A return to more argillaceous sedimentation occurred in the Hauterivian (Figure 27), with the deposition of the fine-grained ferruginous sands, silts and clays of the Dersingham Formation (Plate 3). Palaeogeographical reconstructions suggest that shorelines were retreating, and marine conditions were beginning to encroach into the narrow lowland corridor separating the London–Brabant High from the large Welsh and Pennine landmasses that dominated much of central, northern and western England. The sediments display thin interbedding of the different lithologies and arrangement into fining-upward rhythms, and near the type locality of Dersingham, regularly occurring harder ferruginous sandstone beds within the succession weather to produce a series of terrace-like landscape features. There is a broad change in the rock types constituting the formation, from predominantly sandstone in the south to a more clay-rich succession in the north. In a borehole at Hunstanton, the rhythmic succession appears to be more complex, with erosional bases to many of the rhythmic units, and beneath The Wash, the formation passes laterally into the mudstone-rich Tealby Formation, proved in the subsurface in Lincolnshire. The narrow outcrop of the Dersingham Formation extends southwards from Heacham to East Winch (Figure 26), and the formation probably occurs beneath much of north-west Norfolk. There is a sharp lithological contrast with the clean sands of the underlying Leziate Member, and the boundary is easily traced by means of topographical features.

A distinct clay band at the top of the Dersingham Formation also shows northward thickening, forming a 9 m bed at Heacham, and is named the Snettisham Clay Member (Figure 27). In the former brickworks at Heacham, the clay contained fossiliferous clay ironstones near the top and scattered ironstone concretions throughout. Detailed examination of the Snettisham Clay suggests the presence of subtle lithological variations which can be matched with the upper part of the rhythmic Dersingham Formation seen in the Hunstanton Borehole. At Heacham, the basal contact of the Snettisham Clay is associated with a bed of ferruginous sandstone with pebbles and angular clasts of clay, and locally, the member appears to cut down through the underlying succession to rest directly on the top of the Sandringham Sands; both suggest that a period of intraformational erosion predated deposition of the Snettisham Clay.

Fossils are rather sparse in the Dersingham Formation below the Snettisham Clay. Exceptions are the ferruginous sandstones near the base of the formation that contain a rich bivalve fauna, including an acme of Buchia that correlates with a similar acme in the Speeton Clay Formation in Yorkshire. Rare ammonites from this part of the succession include Endemoceras spp., indicating a Hauterivian age. In contrast, the Snettisham Clay has a rich Barremian fauna that includes ammonites, belemnites and crinoids.

The youngest part of the pre-Aptian Early Cretaceous succession has only been seen in boreholes and in temporary excavations on the beach at Hunstanton. A minor erosion surface above the Dersingham Formation is overlain by up to 21.7 m of fine-grained clayey sand with ferruginous ooliths and pebbles of quartz and ironstone. Bands of phosphatic, shelly ironstone nodules also occur. The unit is named the Roach Formation after a lithologically and faunally similar unit in Lincolnshire (Figure 27) and (Figure 28), and like the underlying Dersingham Formation, the different lithological components are arranged into fining-upward rhythms, many seemingly with erosive bases. The succession is thickest and most complete in boreholes beneath The Wash and in Lincolnshire; south of Hunstanton it is either covered by superficial deposits or removed by erosion at the base of the overlying Carstone Formation.

Fossils are concentrated in the ironstone concretions and, although locally numerous, are of low diversity, dominated by the bivalves Corbula isocardiaeformis Harbort, Entolium germanicus (Wollemann), Paranomia laevigata (J de C Sowerby), Parmicorbula striatula (J de C Sowerby) and plant fragments. Ironstone nodules near the top of the succession temporarily exposed on Hunstanton beach contained the ammonite ?Paracrioceras, suggesting a Barremian age (Figure 27).

Aptian and Albian

The beginning of the Aptian (Figure 27) marked the start of fundamental changes in the palaeogeography of the region. Rising sea levels introduced fully marine conditions to southern England for the first time since the Late Jurassic, and a narrow seaway linked with the established marine deposition in northern East Anglia, Lincolnshire and Yorkshire.

This seaway, named the Bedfordshire Straits, became well established following a further transgressive pulse in the Late Aptian (P. nutfieldiensis Zone) (Figure 26), heralding the progressive drowning of the London–Brabant High and the expansion of marine sedimentation across the whole of East Anglia by the Mid Albian.

In contrast to the thick (+100 m) arenaceous deposits of the Lower Greensand that accumulated in the Weald and Wessex basins in southern England, Aptian deposits in the northern part of East Anglia are represented by a few metres of mudstone seen in boreholes beneath The Wash. Two thin mudstone formations are recognised, the Skegness Clay Formation and the Sutterby Marl Formation, separated by a minor unconformity (Figure 27). In north Norfolk, these deposits are cut out by a major unconformity between the Roach and a condensed, coarse-grained, Albian ferruginous sandstone, named the Carstone Formation (Figure 28). However, the survival of derived Aptian fossils in the base of the Carstone suggests that these or analagous marine mudstones were more widely deposited across the East Anglia region. Apart from the Norfolk localities, similar derived Aptian fossils occur at Potton and Upware in Cambridgeshire (Figure 26).

In the offshore succession, the Skegness Clay Formation comprises less than 2 m of grey and brownish grey mudstone, with a sharp, bioturbated but conformable contact with the underlying Roach Formation. The indigenous fauna from the Skegness Clay is highly significant, because it represents an interval of the Early Aptian (Prodeshayesites fissicostatus Zone, Prodeshayesites bodei Subzone) that is preserved nowhere else in Britain, apart from as a derived fauna at the base of younger formations. The junction of the Barremian and Aptian stages is therefore presumed to be the boundary between the Roach and the Skegness Clay.

Paler, yellowish grey, highly calcareous mudstone containing coccolith debris comprise the Sutterby Marl Formation, which is usually only a few metres thick. Minor erosion surfaces occur at the base and near the top of the formation. The former are marked by reworked fossil material and the latter by a silty mudstone horizon. The rich fauna of ammonites, belemnites, bivalves and brachiopods includes material derived from the underlying Skegness Clay and indigenous specimens of the ammonites Colombiceras, Cheloniceras and Dufrenoyia, indicative of the higher part of the Early Aptian and Late Aptian. The bivalves include numerous small oysters and other forms such as Aucellina and Inoceramus that in southern England occur in the coeval Lower Greensand Group.

Further south, in Cambridgeshire and Bedfordshire, up to 120 m of fine, medium and coarse-grained sand, representing the Woburn Sands Formation, infills a basin cut into the underlying Jurassic clay along the alignment of the Bedfordshire Straits. The succession is best seen in quarries further south around Leighton Buzzard (Figure 26) and (Figure 27); (Plate 5)), where it can be informally subdivided into a thick lower interval of fine and medium-grained sandstone, and a thinner upper interval of coarse-grained, poorly sorted sand.

The conspicuous cross-bedding, seen especially in the higher part of the Woburn Sands, is characteristic of sandwaves that form in strongly current-swept seaways; bedding orientation suggests currents predominantly from the north. At other times during deposition of the Woburn Sands, falls in sea level cut regional-scale erosion surfaces, and the environment was more estuarine in nature. Local beds of Fullers Earth in the succession represent resedimented volcanic ash units, derived from the weathering of adjacent land areas and/ or from reworking of marine deposits. The formation is largely contemporaneous with the Sutterby Marl Formation, but at Upware, near Cambridge (Figure 26), there is a thin interval of richly fossiliferous strata with a derived Early Aptian (P. bodei Subzone) fauna dominated by brachiopods and bivalves. The sparse indigenous ammonite fauna probably belongs to the Late Aptian P. nutfieldiensis Subzone (sensu Ruffell and Owen, 1995).

During the later part of the Early Albian (Douvilleiceras mammillatum Superzone), sedimentation rates across the UK slowed, and there was widespread formation of highly condensed and winnowed deposits. In southern England, these are represented by the phosphate-rich ‘Junction Beds’ facies at the top of the Lower Greensand Group. In Bedfordshire, the ‘Junction Beds’ include the Mundays Hill Phosphatic Sandstone Formation and Shenley Limestone Member, the latter capping a succession of silty deposits that were possibly formed on tidal flats or in a shallow lagoon (Figure 27). Globally, this period of reduced sedimentation broadly corresponds to a period of lowered or falling sea level, but there are also shorter-term sea-level oscillations, so that sediment winnowing caused by both marine lowstand and transgression are likely to have influenced the resulting successions.

In East Anglia, this period of condensed sedimentation is represented by the Carstone Formation, a rusty brown and green, pebbly sandstone, rich in ferruginous ooliths (Plate 4) and (Plate 6), which can be divided into lower and upper members by a strongly channelled erosion surface. Although hand specimens of Carstone appear to be pure oolitic ironstone, detailed examination in thin section shows that many of the ooliths are formed by ferruginous overgrowths of sand grains. Cross-bedding and burrowing are common features, but commonly obscured by weathering. Burrowing is particularly common at the base of the formation, where there are also locally developed phosphatic pebble beds containing derived ammonites. The Carstone is thickest at Hunstanton, where about 19 m are seen in a borehole and in the coastal outcrop (Plate 7). Nearby foreshore exposures also allow detailed examination of the formation, which has become strikingly eroded along a rectilinear joint pattern (Plate 6). The Carstone thins southwards into south Norfolk and north Suffolk (1 to 7 m) and north-westwards beneath The Wash (about 6 m); only a thin remnant of the Carstone appears to be present in the Trunch Borehole in north-east Norfolk. The base of the Carstone is a major unconformity which cuts across older Cretaceous formations when traced southwards in north Norfolk (Figure 28). Further south it rests on Jurassic strata, and eventually on Silurian–Devonian basement rocks of the London–Brabant High, as proved in boreholes around Diss and Bury St Edmunds. At the southern margin of the East Anglian region, around Sudbury, the Carstone is absent at depth, and mudstones of the overlying Gault rest on the Palaeozoic basement.

Apart from plant debris and burrows, fossils are rare in the Carstone, and for many years there was uncertainty about the age of the formation. Phosphatised ammonites from the basal beds of the Carstone include derived Early Aptian forms. Indigenous Early Albian brachiopods and ammonites have also been recorded, the latter including Beudanticeras newtoni Casey, Douvilleiceras mammillatum (Schlotheim) and Leymeriella. At West Dereham, the base of the Carstone belongs to the Early Albian Leymeriella regularis Subzone, and the slightly younger D. mammillatum Superzone (Sonneratia (Globosonneratia) perinflataSubzone) occurs at the top of the formation. An even younger age for the top of the Carstone is indicated by the occurrence of Hoplites dentatus Spath at Hunstanton, belonging to the early Mid Albian H. dentatus Zone, Hoplites spathi Subzone, and contemporaneous with the early deposition of the mudstones of the Gault further south.

Sea levels rose during the Mid Albian, completely drowning the London–Brabant High in eastern England to form the London Platform. Not since the Early Palaeozoic had marine deposition extended across the whole of East Anglia. Over much of the region this phase of deposition is predominantly represented by the mudstone of the Gault Formation (Figure 27) and (Figure 28), which forms a narrow outcrop extending southwards from Hunstanton to Cambridge and beyond. Further south, near Dunstable, the Gault passes upwards into a few metres of glauconitic and micaceous siltstones, representing the Upper Greensand Formation. These slightly coarser-grained sediments, derived from uplifted areas in south-west Britain, are contemporaneous with the higher part of the Gault; their deposition advanced progressively eastwards during the Late Albian, perhaps finally halting at the margin of the East Anglia region. The established biozonal scheme for the higher part of the Gault and equivalent Upper Greensand (e.g. Owen, 1984) has recently been revised, as shown on Figure 29.

However, for continuity with previously published data, the established biozonal nomenclature is used herein unless otherwise stated.

The Gault is informally divided into a darker-coloured, lower interval (Lower Gault) and a more calcareous, paler-coloured upper unit (Upper Gault), separated by a widespread erosion surface; minor erosion surfaces, commonly marked by phosphatic nodule beds, occur throughout the formation. In north Norfolk, the distinction between Lower and Upper Gault is slightly less obvious, with the Lower Gault being generally less silty and more calcareous than further south. There is also some hard calcareous mudstone within the Upper Gault: the Barnwell ‘Hard Band’ (lower Callihoplites auritus Subzone) in Cambridgeshire, and the ‘Pentney Limestone’ (middle C. auritus Subzone) and ‘Bilney Limestone’ (lower Mortoniceras (Mortoniceras) rostratumSubzone) in Norfolk, named after localities near Narborough (Figure 26) and (Figure 29). In general, the mudstone of the Gault displays a characteristic rhythmicity, beginning with a burrowed erosion surface and associated phosphatic nodule and pebble horizon, overlain by silty mudstone, passing up through medium grey mudstone and ending in pale grey mudstone. Fossils are common through much of the Gault, especially in the phosphatic nodule beds that are commonly coincident with zonal or subzonal boundaries (Plate 2). As well as ammonites, bivalves, especially Actinoceramus and Aucellina, also show important changes in morphology and occurrence that can be used for correlation. One of the most remarkable and conspicuous of these changes is that from the concentrically ornamented Actinoceramus concentricus (Parkinson) to the strongly radially ribbed Actinoceramus sulcatus (Parkinson) across the Lower–Upper Gault boundary (Figure 29; Plate 2h, i). This boundary, coincident with the base of the M. (M.) inflatum Zone, Dipoloceras cristatum Subzone, represents an erosion event associated with minor uplift, gentle folding and fault reactivation that completely removed the Lower Gault from some parts of the London Platform. Enhanced current winnowing at this time produced a distinctive phosphatic nodule bed, and might also explain the heavy radial ornament developed in A. sulcatus. While the Lower Gault in East Anglia probably accumulated in a few tens of metres of water, a rise in sea level at the beginning of the Late Albian produced deeper conditions for the deposition of the Upper Gault.

In the past, the nodule beds in the Gault were extensively worked for agricultural phosphate, but the demise of this industry dramatically reduced the number of available sections, and most information about the stratigraphy of the Gault in East Anglia has been gained from borehole investigations. Recently, surviving sections in clay pits near Cambridge showed the development of the Hysteroceras varicosum, C. auritus and M. (M.) rostratum subzones in the Upper Gault at Barrington, Barnwell, Milton and Burwell. The Lower Gault (Hoplites dentatus Zone and lower Euhoplites loricatus Zone) have been recorded in a pit near Soham, and there are a few sections in the formation in Norfolk, at Little Ouse (D. cristatum, Hysteroceras orbignyi and H. varicosum Subzone) and Roydon (H. orbignyi and H. varicosum subzones). The sections recorded around Cambridge demonstrate several characteristic features of the Upper Gault succession, including the abundance of the belemnite Neohibolites in the H. varicosum Subzone, and the development of an indurated mudstone (Barnwell ‘Hard band’) containing glauconite and abundant shell fragments of Inoceramus lissa (Seeley) (Figure 29). Through a combination of detailed examination of lithology and the abundant ammonite and bivalve faunas in borehole cores and at limited outcrops, the Gault of East Anglia has been subdivided into 19 distinctive horizons (numbered G1 to G19 in ascending stratigraphical order) that can be correlated across the region. From these correlations, the Lower Gault has been shown to thicken southwards from north Norfolk (1.45 m at Gayton; 3.72 m at Marham) into south Norfolk and Cambridgeshire (7.42 m at Mundford, 5.75 m at Soham), before thinning further south across the London Platform (2.53 m at Four Ashes, north-east of Bury St Edmunds). The correlations demonstrate the influence of the London Platform on sedimentation, causing progressively younger horizons in the Lower Gault to rest on the Palaeozoic basement (Figure 30). Further south, in the Clare Borehole near Sudbury, the Lower Gault is almost entirely absent, with G10, at the top of the Lower Gault, probably forming the base of the formation. By contrast, the Upper Gault, which is generally thicker (about 7.5 to 12.5 m between Gayton and Four Ashes) than the Lower Gault, appears to blanket the London Platform. The most significant change is rapid local thickening of the Upper Gault near Cambridge, which is at least 43 m thick in a borehole at Duxford, and perhaps more than 50 m at Little Chishill, on the border of Essex and Cambridgeshire (Figure 26). This thickening might be influenced by long-established fault lines close to the margin of the London Platform.

In north Norfolk, the Gault dwindles to a few metres of calcareous mudstones (Figure 30), becoming unrecognisable north of Sandringham. At Dersingham, the succession comprises highly calcareous, red, pink and cream-coloured clays with thin limestone bands, and this passes northwards into the Hunstanton Formation, traditionally termed ‘Red Chalk’, with its type locality in the strikingly colour-banded cliffs that border the eastern side of The Wash at Hunstanton (Figure 27) and (Figure 28); (Plate 7). The formation comprises bright red sandy limestone and thin argillaceous limestone horizons (‘marl’) that have a sharp but conformable contact with the underlying Carstone. Burrowed horizons and bored hardgrounds show that there were extensive periods of nondeposition when the sea bed became lithified. Stromatolitic structures have also been described, comprising carbonate-rich laminae formed in periods of rapid sedimentation, alternating with clay-rich laminae, formed by the trapping of clay minerals on an algal mat that grew during phases of reduced sedimentation. At its type locality the Hunstanton Formation is only 1.1 m thick, but this increases slightly beneath The Wash (3.2 m) and in Lincolnshire (5.5 m), and very substantially in Yorkshire (up to 24 m at Speeton).

Historically, the Hunstanton Formation at Hunstanton Cliffs has been subdivided into three limestone intervals, designated C, B and A in ascending stratigraphical order (Figure 27).

The boundaries of these subdivisions are marked by thin, laterally persistant clay-rich horizons within the formation, and by the contrasting facies of adjacent formations. Further north, a more complete succession is developed at Speeton in Yorkshire, where five members are recognised.

Fossils provide the key to the correlation of these sections and demonstrate the frequency and extent of erosional breaks. In north Norfolk, the rich and diverse fauna of the Hunstanton Formation is particularly characterised by the brachiopod Moutonithyris dutempleana (d’Orbigny), the bivalve Inoceramus and the belemnite Neohibolites (Plate 20). Ammonites are relatively rare, but sufficient to allow the biostratigraphical classification of the limestones at Hunstanton. Bed C contains specimens of Hoplites, including Hoplites canavarii Parona and Bonarelli and H. canavariiformis Spath, and belongs to the Mid Albian H. dentatus Zone, H. spathi Subzone. The fauna from the basal part of Bed B (Bed B (base) on Figure 27) belongs to the upper part of the Anahoplites intermedius Subzone (E. loricatus Zone), and shows that the boundary between beds C and B is a small non-sequence that cuts out most of the lower part of the intermedius Subzone. The remainder of Bed B is much younger, belonging to the Late Albian D. cristatum and H. orbignyi subzones (M. (M.) inflatum Zone), demonstrating the presence of a major depositional break. In the cliff section at Hunstanton this erosion event is represented by nodular blocks of limestone that form the bulk of Bed B, associated with the strong radially ribbed bivalve Actinoceramus sulcatus. This is the same erosion event that marks the boundary of the Lower and Upper Gault (see above), but in the condensed section at Hunstanton its effect was more dramatic, removing the greater part of the Mid Albian. Bed A (lower of Figure 27) contains evidence of the H. varicosum and lower C. auritus subzones, including the bivalves Actinoceramus concentricus and Inoceramus lissa, in continuity with Bed B. The highest part of Bed A (upper of Figure 27) contains the bivalve Aucellina and the belemnite Neohibolites praeultimus Spaeth, suggesting assignment to the Stoliczkaia dispar Zone and the presence of a sedimentary break that omits the higher part of the auritus subzone in the Hunstanton section.

In North Norfolk and Lincolnshire, deposition of the Hunstanton Formation occurred on the relatively buoyant East Midlands Shelf, probably in a shallow, current-swept sea, with short periods of sedimentation alternating with longer periods of nondeposition. The southern limit of this sea is defined by the subsurface occurrence of the Hunstanton Formation in Norfolk, which is presumed to underlie most of the area north of a line from Sandringham to Great Yarmouth. The particularly thin succession at Hunstanton may have been deposited on a shoal formed by the locally much thickened Carstone succession beneath (Figure 30). Further north, greater and more continuous subsidence at the margin of the Cleveland Basin resulted in a much thicker Hunstanton Formation.

Chapter 5 Late Cretaceous: greenhouse climate, tropical seas

M A Woods

Introduction

Following the deposition of the Gault and coeval Hunstanton Formation, there was widespread erosion at the end of the Early Cretaceous, producing a disconformity* with overlying Late Cretaceous strata. In East Anglia, as across the rest of England, the Late Cretaceous is synonymous with the Chalk Group. The Chalk is such a distinctive and immediately recognisable rock; that there is nothing else in the geological record resembling it is a clue to the unusual environmental conditions that created it. The Chalk is the end product of global environmental changes that began in the mid Cretaceous with a dramatic escalation of suboceanic volcanic activity that persisted for millions of years. This volcanism caused a gradual build-up of carbon dioxide in the atmosphere, creating a very warm, ‘super-greenhouse’ climate in the Late Cretaceous.

Dramatically increased fluxes of molten rock to mid-ocean ridge systems, driven by enhanced mantle convection, inflated their volumes and caused global sea levels to rise as water was displaced from ocean basins onto marginal land areas. The rapid rise in sea level favoured the population explosion of coccolithophores — the tiny planktonic algal nannofossils whose calcitic skeletons largely constitute the Chalk. Coccolithophores, which are abundant in deep ocean areas today, thrived in the low-nutrient (oligotrophic) marine waters, that spread across the deeply flooded continental margins in the Late Cretaceous. By analogy with modern accumulations, it was long assumed that the Chalk must represent a deep water oceanic deposit. However, the current consensus is that water depths were likely to have been in the range of 200 to 300 m, which is much more compatible with the Chalk’s relatively diverse benthonic macrofossil content, especially comprising brachiopods, bivalves, gastropods, crinoids and echinoids. It has been suggested that the accelerated rise in sea level in the Late Cretaceous altered the circulation pattern across continental shelves, allowing the widespread development of oligotrophic conditions.

High atmospheric carbon dioxide probably also boosted the populations of coccolithophores. Ocean geochemistry in the Late Cretaceous does not appear to have been adversely affected by the concentration of carbon dioxide in the atmosphere, probably because sufficient time had elapsed for the oceans to equilibrate with this new regime.

Consequently, rather than being a threat to the skeletal growth of coccolithophores, high atmospheric carbon dioxide is likely to have boosted it through enhanced photosynthesis, as suggested by modern laboratory experiments. Other experimental data also suggest that the ionic concentration of Cretaceous seawater, particularly the ratio of calcium to magnesium, was especially favourable for the precipitation of calcium carbonate by coccolithophores. However, by the beginning of the Turonian, when deposition of pure white Chalk facies became predominant, palaeotempretaure estimates from isotopic data show the onset of a long-term cooling trend through the remainder of the Late Cretaceous. It is possible that the role of coccolithophores in consuming carbon dioxide, and locking some of this away in deposits of Chalk, ultimately contributed to rebalancing of the Late Cretaceous climate.

Classification and lithology

Traditionally, the Chalk was subdivided into three broad units: Lower Chalk, Middle Chalk and Upper Chalk (Figure 31), with the boundaries marked by hard beds that formed distinctive features in the landscape. Although relatively simple, even this system was sometimes problematic because the key marker beds were not always consistently developed, or were sometimes confused with other horizons of similar character. Additionally, because the traditional scheme covers such large thicknesses of succession, older literature often supplemented this coarse lithostratigraphical classification with biozonal subdivisions, sometimes treated as if they were lithostratigraphical entities.

In the last 25 years there has been a renaissance in Chalk research, and this has led to new classification schemes based on a more detailed understanding of subtle variations in the character of the Chalk. The new classification recognises that the Chalk Group can generally be subdivided into a lower, generally more mud-rich part, named the Grey Chalk Subgroup, and a much thicker interval of generally pure white Chalk, named the White Chalk Subgroup. Within these subgroups a variable number of formations is recognisable, depending on the extent of post-Cretaceous erosion (Figure 31) and (Figure 32). The formations recognised in the Chalk of northern England (‘Northern Province’) are different from those of southern England (‘Southern Province’), reflecting fundamental contrasts in the character of the chalk that result from differences in depositional setting and subsequent depth of burial. Unfortunately, applying either of these classifications to the Chalk of East Anglia is problematic; the Chalk is extensively masked by younger post-Cretaceous strata. It combines elements of both Northern and Southern Province schemes, and contains units that appear to be unique to the area. Consequently, the term ‘Transitional Province’ has generally been applied to the depositional setting extending across the greater part of the East Anglia region (Figure 32). This account uses the most appropriate Chalk formations based on comparison of the East Anglia succession with the classification schemes for the Southern and Northern provinces, although it is acknowledged that in some cases this is problematic.

Apart from the skeletal debris of coccolithophores (coccoliths), chalk comprises a variety of calcareous microfossils, such as foraminifers, ostracods, and calcispheres (calcareous dinoflagellates), and calcareous macrofossils, particularly bryozoans, bivalves and echinoids.

In combination, these form the typical fine-grained, almost pure calcium carbonate limestone that is immediately recognisable as the Chalk. There are few inorganic impurities, such as clay, sand and silt, except in the lower part, which contains up to 30 per cent clay. Clay-rich intervals are traditionally referred to as ‘marls’, and above the basal part of the Chalk, they tend to be limited to thin horizons just a few tens of millimetres thick. Most appear to be detrital in origin, possibly linked to short-lived oscillations of sea level. However, geochemical analysis of some marls has shown that they represent decomposed volcanic ash, presumably sedimented into the Chalk sea from subaerial volcanic eruptions. More conspicuous features of the Chalk are parallel bands of dark flint, mostly forming irregular nodules, but sometimes occurring in sheet-like form or as distinctive vertical columns. Most flints formed whilst the Chalk was still being deposited, at some depth below the contemporary sea bed. In a series of complex chemical reactions, chalk appears to have been simultaneously dissolved and replaced by silica, and many nodular flints are replacements of burrows made by organisms living in the Late Cretaceous sea bed. Most of the silica came from biogenic sources, particularly the dissolved skeletons of siliceous sponges that widely inhabited the Chalk seas. Sometimes thin sheets of flint can be seen either at a low angle to bedding or at a high angle, typically with a hollow core; both are evidence of structural disturbance. The high angle sheets mostly formed on faults and fractures that affected the Chalk after it was deposited, but the lower angle sheet flints have been interpreted as submarine slide planes, and in some cases these can be linked to phases of tectonic disturbance that occurred during the Late Cretaceous.

Although the Chalk is typically regarded as a relatively soft rock, it can also form hard limestone. Whilst some hardening of the Chalk can reflect changes after it was deposited, hard chalk intervals formed by hardgrounds and nodular chalks are the product of processes that were active during deposition, and both are valuable for characterising and interpreting successions. Hardgrounds formed when low sedimentation rates allowed the sea floor to become cemented, and are typically thin, iron stained horizons (about 0.3 to 0.5 m thick) with glauconite and phosphate enrichment. They indicate enhanced activity of marine currents, and are typically associated with transgressions, regressions or proximity to basin margins and submerged massifs. Thick intervals of nodular-textured chalk (tens of metres thick), in which hard, rounded masses of chalk are embedded in a softer chalk matrix, reflect localised cementation of chalk just below the sea bed.

Marls, flints and hardgrounds are all valuable for correlating Chalk successions. Many have wide geographical extent and distinctive characteristics that allow them to be recognised.

Most of these features also have expression in borehole geophysical logs, allowing the Chalk stratigraphy to be traced and modelled in the subsurface (Figure 33). Gross changes in the relative developments of marls, flints, hardgrounds and nodular chalks are the basis of the modern lithostratigraphical classification of the Chalk; they are manifest as changes in Chalk fracturing and weathering style and in landscape featuring, allowing the stratigraphical subdivisions to be geologically mapped.

The Chalk dips gently eastwards beneath much of the East Anglia region. The oldest strata occur along the western margin of the outcrop, between Hunstanton and Cambridge and south-westwards towards Dunstable. The regional dip introduces successively younger units to the succession eastwards, and the youngest Chalk occurs on the Norfolk coast between Sheringham and Overstrand (Figure 32). The maximum recorded thickness (466.5 m) is in a BGS cored borehole at Trunch, near Mundesley in north Norfolk (Figure 34). This is also the most stratigraphically complete onshore Chalk succession in the UK, ranging in age from Cenomanian to Early Maastrichtian (Figure 31). Near Ipswich, in the southern part of the region, where the youngest preserved Chalk is relatively older (Early Campanian, Figure 31), the group is about 250 m thick. However, the pattern of thickness variation across East Anglia is more complex when studied at a higher resolution. For example, the Trunch Borehole actually has a relatively thin Cenomanian succession compared to other parts of East Anglia there are thickness changes related to syndepositional* structural movements along deep-seated faults in the Palaeozoic basement rocks of the region.

Grey Chalk Subgroup: Cenomanian

The lower part of the Chalk, between its basal erosional contact and the erosion surface immediately underlying a clay-rich unit called the Plenus Marls Member, is designated the Grey Chalk Subgroup in both the Southern and Northern Province successions and is of Cenomanian age (Figure 31) and (Figure 32). These erosion surfaces occur across East Anglia, and the Grey Chalk Subgroup can be used for most of the strata formerly classified as Lower Chalk in this region. Across most of southern England, the Grey Chalk Subgroup can be divided into two formations, the West Melbury Marly Chalk Formation, overlain by the Zig Zag Chalk Formation. Although equivalents occur in East Anglia, they are only applicable to some parts of the region particularly south and west of Cambridge and Sudbury, elsewhere the style and development of the chalk generally more closely resembles the Ferriby Chalk Formation, which represents the Grey Chalk Subgroup in the Northern Province. The Ferriby Chalk is typically thinner, harder, and less rhythmic in its sedimentation style, with more numerous condensed horizons and erosive surfaces. The Grey Chalk Subgroup shows pronounced regional thinning northwards across East Anglia, from more than 50 m near Sudbury in the south, to about 10 m in the Trunch Borehole in north-east Norfolk (Figure 34).

Across much of the region, as far north as Marham in western Norfolk, the base of the Grey Chalk Subgroup is marked by the Cambridge Greensand Member. This is a very distinctive, thin (typically less than one metre thick), micaceous, clayey bed with abundant brown and black phosphatic concretions and common glauconite grains (Plate 8). It contains phosphatised Late Albian fossils derived from the erosion of the top of the underlying Gault, as well as indigenous Early Cenomanian taxa belonging to the basal N. carcitanense Subzone of the M. mantelli Zone. The phosphatised Late Albian fossils include ammonites, bivalves (especially Aucellina) and large brachiopods. The Cambridge Greensand is largely restricted to East Anglia; it extends northwards to near Marham in Norfolk, and in the south-west is truncated by a fault or monocline at Barton-le-Clay, near Luton (Figure 32), referred to as the Lilley Bottom Structure. South of this it is generally replaced by the less phosphate-rich Glauconitic Marl Member, which marks the base of the West Melbury Marly Chalk across much of southern England.

The lower part of the Grey Chalk Subgroup equates with the ‘Chalk Marl’ of the traditional classification. Where seen in the southern part of the region, for example near the margin of the Chalk west of Baldock, Royston and Dunstable, it is analogous to the West Melbury Marly Chalk Formation of southern England, with regular alternations of hard, chalky limestones and marls. It has been speculated that these cyclical variations in lithology could reflect global-scale oscillations between warmer and cooler climatic periods driven by changes in the nature of the Earth’s orbit around the sun. Such orbital variations, commonly referred to as Milankovitch Cycles, are known to have exerted strong controls on climate and geological processes both globally and regionally during the later Neogene and Quaternary periods. Near Dunstable, two of the limestones have distinctive suites of fossils and have been informally named the ‘Doolittle Limestone’ and ‘Dixoni Limestone’; the former is characterised by the bivalve Inoceramus ex gr. crippsi Mantell and the ammonites Schloenbachia varians (J Sowerby) and Hypoturrilites tuberculatus (Bosc), and the latter contain common specimens of the bivalve Inoceramus ex gr. virgatus Schlüter and rarer examples of the zonal ammonite Mantelliceras dixoni Spath.

Further east and north, in boreholes near Sudbury and Bury St Edmunds, the basal Chalk Group succession changes, and does not show the typical marl–limestone rhythmicity seen widely across the Southern Province. Instead, above the Cambridge Greensand there are cream-coloured, smooth-textured, chalky limestones, named the Porcellaneous Beds. Northwards, these correlate with an interval of hard Chalk (Paradoxica Bed) that forms the basal marker of the Ferriby Chalk in the Northern Province (Figure 31). The Porcellaneous Beds have a low diversity fauna dominated by the bivalve Aucellina, small brachiopods, occasional poorly preserved heteromorph ammonites, and inoceramid bivalves towards the top.

Above the Porcellaneous Beds the marl–limestone rhythms are less clearly defined, with the development of erosion surfaces and two prominent horizons of shell-rich chalk, named the Inoceramus Beds. These units, locally seen at crop and present in the subcrop succession from north Norfolk to the Sudbury area in the south of the region, contain large pieces of shell belonging to the bivalve Inoceramus (mainly ‘I.’ ex gr. crippsi Mantell) associated with occasional ammonites, particularly Mantelliceras and Schloenbachia (Plate 9f, b). They belong to the higher part of the M. mantelli Zone (Sharpeiceras schlueteri Subzone), and are overlain by beds with Inoceramus virgatus Schlüter, indicating the M. dixoni Zone. The Inoceramus Beds are a feature of Early Cenomanian Northern Province successions.

Traced northwards across East Anglia, the lower part of the Grey Chalk Subgroup becomes thinner and harder. Eventually, at Hunstanton and in the Trunch Borehole in north Norfolk, the succession has all the characteristic features of the lower part of the Ferriby Chalk. The Paradoxica Bed at the base is an intensely hard limestone, named after the network of Thalassinoides paradoxicus (Woodward) burrows that it contains. An erosion surface and pebble bed marks the contact with the underlying Hunstanton Formation, and further erosion surfaces (hardgrounds) and glauconitised chalks occur within the Paradoxica Bed. There is also a rich terebratulid brachiopod fauna, as well as the bivlave Aucellina (Plate 9c) and the belemnite Neohibolites ultimus (d’Orbigny). This fauna demonstrates the correlation with the Porcellaneous Bed seen further south, and provides a link with the Early Cenomanian Aucellina/N. ultimus bioevent* recognised in equivalent successions in Germany. Above the Paradoxica Bed, the Inoceramus beds form two distinctive shell-rich horizons in the Hunstanton cliffs, each underlain by erosion surfaces. Cream-coloured, slightly marly and locally nodular chalks with stylolites, occur above the Inoceramus beds.

Slightly higher in the Grey Chalk Subgroup, a distinctly grey, silty and sandy, highly bioturbated chalk unit is named the Totternhoe Stone. It takes its name from a small village near Dunstable where it is seen in large quarries, and extends across the East Anglia region, forming a marker bed in the Ferriby Chalk in the cliff section at Hunstanton (Plate 7).

It appears to be the product of a short-lived fall and subsequent rise in sea level, and is underlain by a major erosion surface which shows significant local downcutting into the underlying succession (Figure 31). Phosphatised and glauconitised pebbles occur at the base, and the unit contains both derived and indigenous fossils; small brachiopods, bivalves (especially Entolium and Oxytoma) and ammonites indicative of the Acanthoceras rhotomagense Zone and Turrilites costatus Subzone, are characteristic.

The Totternhoe Stone broadly equates with the base of the Zig Zag Chalk Formation in Southern Province successions, and some features of this typically massive-bedded, grey and white, poorly fossiliferous lithology are seen in exposures near Baldock in south-east Cambridgeshire, and southwards from there. Northwards the succession is thinner and harder, and is more comparable with the Ferriby Chalk. Above the Totternhoe Stone the succession comprises hard, off-white, locally nodular chalk, with wisps and thin seams of marl. One of these marl beds is rich in the remains of the oyster Pycnodonte, and is named the Pycnodonte Marl. Locally, in the Dunstable area, the marl rests on a convolute hardground associated with the terebratulid brachiopod Ornatothyris. Immediately above the marl, many boreholes and sections show the presence of a thin bed of very hard, locally gritty and phosphatic chalk, named the Nettleton Stone (Figure 31). Rare ammonites indicate that it belongs to the upper part of the Acanthoceras jukesbrownei Zone, and although the Nettleton Stone is best developed in the Chalk of Lincolnshire and Yorkshire, it extends southwards into central Suffolk, occurring in the Stowlangtoft Borehole near Bury St Edmunds. Further south, Jukes-Browne Bed 7 represents the equivalent of the Pycnodonte Marl and Nettleton Stone. The highest part of the Grey Chalk Subgroup is typically rather massively bedded and featureless, apart from thin marl seams and occasional pyritic nodules. Fossils are rare, mainly comprising oysters and thin-shelled echinoids such as Camerogalerus, Holaster and Tylocidaris. These faunas equate with the Calycoceras guerangeri Zone.

White Chalk Subgroup: Late Cenomanian to Early Maastrichtian

The White Chalk Subgroup encompasses the remainder of the Chalk succession, from the erosion surface immediately below the Plenus Marls to the unconformity delimiting the top of the Chalk Group. With the exception of the Plenus Marls, this thick unit of Chalk was traditionally classified as Middle Chalk and Upper Chalk, with the boundary between these either marked by a feature-forming bed of hard chalk (‘Chalk Rock’), or by a unit of flint-rich chalk (Brandon Flint Member) slightly lower in the succession.

The lower part of this succession (Late Cenomanian to Early Coniacian) shows the greatest influence of the Northern Province, when features of this depositional regime extended southwards across the East Anglia region. Flint fi appears in the Chalk succession in the lower part of the White Chalk Subgroup, and at a relatively lower horizon within the succession than in the Southern Province. The regional northward thinning affecting the Grey Chalk Subgroup across East Anglia, continues into lower parts of the White Chalk Subgroup until the Late Turonian (Figure 31). However, from the Mid Coniacian the succession begins to show greater affinity with the Southern Province. The standard UK biozonation of the White Chalk Subgroup uses a variety of non-ammonite fossil taxa, including bivalves, brachiopods, echinoids, crinoids and belemnites (Figure 31; Plate 9). Ammonites are poorly preserved in chalk facies, but occasional occurrences permit correlation with the internationally recognised ammonite scheme for the Late Cretaceous.

Despite the progress in revising the classification of the Chalk of southern and northern England, there is not yet a consensus for stratigraphical revision of the Chalk of East Anglia. Across most of East Anglia, the Holywell Nodular, New Pit and Lewes Nodular Chalk formations of the Southern Province can be broadly recognised. However, in north Norfolk, where the influence of the Northern Province was strongest until at least the Coniacian, the lower part of the White Chalk Subgroup belongs to the Welton and Burnham Chalk formations. Above this, the Seaford, Newhaven, Culver and Portsdown Chalk formations of the Southern Province are widely developed, although a largely flint-less variety of Newhaven Chalk, named the Blakenham Chalk Member, occurs in the Gipping Valley near Ipswich, and locally elsewhere in the southern part of the region. The youngest parts of the Chalk succession, which are restricted to East Anglia, are informally termed ‘Norwich Chalk’ (Late Campanian) and ‘Trimingham Chalk’ (Early Maastrichtian) (Figure 31) and (Figure 34).

Late Cenomanian to Early Coniacian (about 95 to 88 Ma)

At the base of the White Chalk Subgroup, a thin succession of hard, nodular, bioclastic chalk with thin clay-rich units represents the Holywell Nodular Chalk Formation of the Southern Province, and coeval basal Welton Chalk Formation in the Northern Province, and has a distinct signature on borehole geophysical logs across East Anglia (Figure 33). The basal part of this succession is the Plenus Marls Member, a thin, clay-rich marker bed, typically less than two metres thick in the south of the region near Dunstable, and thinning northwards to just a few centimetres in the Trunch Borehole in north Norfolk (Figure 34). Clay-filled burrows can commonly be seen extending below a well-marked basal erosion surface, cut during a short-lived sea-level fall. Above this there is a succession of intercalated soft, greenish grey marls and paler, harder limestone, up to eight beds in the Southern Province but usually fewer in East Anglia. The marl contains a varied fauna of mainly brachiopods (Concinnithyris, Orbirhynchia) and bivalves (Entolium, Inoceramus, Oxytoma, Pycnodonte), together with the belemnite Praeactinocamax plenus (Blainville), after which the unit is named although it only ranges through part of the succession. Sporadic ammonites demonstrate correlation with the Late Cenomanian M. geslinianum Zone. Although relatively thin across most of East Anglia, the Plenus Marls form an easily identifiable marker on borehole geophysical logs (Figure 33).

In the latest Cenomanian and Early Turonian, sea levels began to rise rapidly, flooding many of the land areas and reducing the influx of clay-rich material. Chalk sedimentation radically expanded across these newly flooded shelf areas, blanketing them with chalk deposits. The start of this process is marked by the highest beds of the Plenus Marls and a thin overlying unit of hard, nodular, bioclastic chalk.

Immediately above the Plenus Marls is a thin bed of hard, white limestone, named the Melbourn Rock after the locality in south-west Cambridgeshire where it was first described (Figure 32). It is locally well exposed in quarries near the western edge of the Chalk outcrop in East Anglia, and forms a strong topographical feature that is valuable for mapping. Although the Melbourn Rock itself is sparsely fossiliferous, the ten or more metres of overlying strata in the south of the region are richly shelly chalk, with abundant remains of inoceramid bivalves in hard, nodular chalk with thin marls. At Steeple Morden in south-west Cambridgeshire, this succession is unusually flint-rich with beds of large nodular flint (e.g. the Morden Flint; Figure 31), a feature that is not typical of the Holywell Nodular Chalk in the Southern Province. Fossils include brachiopods, echinoids and occasional ammonites, and the unit was traditionally assigned to the Orbirhynchia cuvieri Zone based on the local abundance of this rhynchonellid brachiopod. The inoceramid bivalves almost exclusively comprise species of Mytiloides, which defined the updated basal Turonian Mytiloides spp. Zone.

Above the Mytiloides-rich chalks, the succession becomes smoother-textured, comprising firm or moderately hard chalk belonging to the Terebratulina lata Zone. At some levels there are nodular and shell-rich intervals, and horizons of nodular flints appear more consistently in the succession. There is a well-developed succession of thin (up to 10 cm thick) marls, named in ascending stratigraphical order: the Methwold Marl, Pilgrim’s Walk Marl, Mount Ephraim Marl and Twin Marl (Figure 31). The marls have been recorded in old quarries and chalk pits around Thetford and Brandon, and can be recognised as a series of prominent spikes on borehole geophysical logs across most of the region (Figure 33). In East Anglia, these marls are the local named equivalents of widely developed marl horizons in the Southern and Northern provinces, and the names applied to these horizons in these adjacent geographical regions are shown on Figure 31. The general aspect of the succession closely resembles the appearance of the partly coeval New Pit Chalk Formation of the Southern Province, although the higher strata are actually equivalent to the lower part of the Lewes Nodular Chalk (Figure 31), here represented by sparsely nodular chalk. More typical basal Lewes Nodular Chalk, with hard, nodular textures, flints and marl seams, occurs in chalk pits at Kensworth near Luton, and was seen in cuttings during construction of the bypass at Baldock. Near Bury St Edmunds, reactivation of a deep-seated thrust structure during deposition of the succession appears to cause abrupt northward thinning of the lower part of the T. lata Zone, below the Pilgrim’s Walk Marl (Figure 33). This thinning is associated with the development of erosion surfaces overlain by chalk pebbles, and intervals of glauconitised chalk clasts, seen in Ely–Ouse Borehole 2 near Mildenhall, and the Stowlangtoft Borehole near Bury St Edmunds (Figure 32).

In north Norfolk there is further regional thinning of the T. lata Zone succession, and through the development of a more uniformly flinty character it passes laterally into the Welton Chalk Formation. Here, the equivalent marls are identified by their Northern Province names, in ascending stratigraphical order: Grasby Marl, Barton Marl 2, Melton Ross Marl and Lower Deepdale Marl (Figure 31). Fossils mainly comprise inoceramid bivalves, especially Inoceramus cuvieri J Sowerby and I. lamarcki Parkinson, as well as the small zonal index brachiopod T. lata Etheridge.

Above the Twin Marl, a distinctive flint-rich unit appears in the Chalk succession of Suffolk and south Norfolk, associated with the upward development of hard, nodular chalk, more typical of the coeval Lewes Nodular Chalk in the Southern Province and used to map the base of the formation in East Anglia. The flint succession is named the Brandon Flint Member after the sequence described from prehistoric flint mines at Grimes Graves near Brandon (Figure 32). The flints comprise large nodular and tabular forms, and include a well-developed marl seam, named the Grimes Graves Marl. The feature-forming character of the Brandon Flints, and their approximate coincidence with the base of the Plesiocory (Sternotaxis) plana Zone, made them a useful alternative to the Chalk Rock in mapping the base of the traditional Upper Chalk. Across much of East Anglia, the Chalk Rock is a thin, weakly developed hardground. It comprises hard, nodular, iron-stained chalk with glauconitised pebbles, a short distance above the Brandon Flint Member. An exception to this pattern occurs in quarries at Kensworth near Luton, in the south-west of the region, where the succession is more typical of the Chilterns. Here, the Chalk Rock is thicker (0.7 m) and the Brandon Flint Member cannot be recognised. A distinctive fauna of aragonite-shelled molluscs (the ‘Reussianum Fauna’, named after the ammonite Hyphantoceras reussianum (d’Orbigny)) characterises the Chalk Rock, especially ammonites indicative of the Subprionocyclus neptuni Zone of the standard ammonite zonal scheme (Figure 31). In East Anglia, including the Kensworth quarries, the Chalk Rock equates with the highest of a series of hardgrounds (Hitch Wood Hardground) that variably comprise the Chalk Rock where more completely developed in the Chilterns.

The development of tabular flint increases northwards into north Norfolk, where the succession passes into the basal Burnham Chalk Formation (Figure 31). Here, the Brandon Flint Member is represented by the Ravendale Flint, Triple Tabular Flints, North Ormsby Marl and Ludborough Flint. The old railway cutting near Swaffham formerly exposed the Plesiocorys (Sternotaxis) plana Zone with tabular flints characteristic of the Burnham Chalk, and the higher part of this zone in the Trunch Borehole contains other distinctive marker beds of this formation such as the Ulceby Oyster Bed and Ulceby Marl.

Towards the top of the nodular chalk succession is the Top Rock; a locally developed mineralised hardground, similar to the Chalk Rock. It approximates to the Turonian– Coniacian boundary (Figure 31), and in the southern part of the region appears to comprise several merged hardgrounds that represent a condensed equivalent of the lower part of the Micraster cortestudinarium Zone (Figure 31). Typical fossils include sponges, the echinoids Echinocorys and Micraster, and the inoceramid bivalves Mytiloides and Cremnoceramus, some with phosphatic preservation. The higher part of the M. cortestudinarium Zone is poorly exposed across East Anglia, but where locally seen around Bury St Edmunds, it is hard, nodular chalk above the Top Rock, passing upwards into rather featureless, finer-grained flinty chalk.

Mid Coniacian to Early Campanian (about 88 to 80 Ma)

Relatively little is known about the succession encompassing the Mid Coniacian to Early Campanian interval in East Anglia. An old chalk pit near Euston, a few kilometres south of Thetford, exposes Mid to ?Late Coniacian strata, comprising relatively soft, smooth-textured, flinty chalk. Fossils include the inoceramid bivalves Platyceramus and Volviceramus, indicative of the lower part of the Micraster coranguinum Zone (Plate 9j), and the succession resembles the coeval Seaford Chalk Formation of the Southern Province. A semitabular flint in the lower part of the succession probably represents the Seven Sisters Flint, a marker in the lower part of the Seaford Chalk that correlates with the Eppleworth Flint in the Northern Province Burnham Chalk (Figure 31). Beneath the Seven Sisters Flint, borehole geophysical log correlations in the subsurface near Sudbury suggest the presence of the Belle Tout Marls and the underlying Shoreham Marl 2, the latter marking the bases of both the M. coranguinum Zone and Seaford Chalk Formation in Sussex. Sections in the upper (Santonian part) of the M. coranguinum Zone occur at Horringer, south-west of Bury St Edmunds, and at Stowlangtoft Quarry and near Ixworth, to the north-east (Figure 32). The abundant and diverse fauna includes the brachiopod Gibbithyris ellipsoidalis and the echinoids Micraster, Echinocorys and Conulus albogalerus Leske. A conspicuous yellow sponge bed in the Stowlangtoft Quarry succession may equate with the Barrois Sponge Bed that occurs near the top of the Seaford Chalk Formation in the Southern Province succession.

In north Norfolk, contrasts with successions further south become less marked after the mid Coniacian, and from the Santonian onwards the stratigraphy no longer mirrors the Northern Province succession. Whilst flint remains a persistent, though sometimes intermittently developed, feature to the top of the youngest Chalk in East Anglia, the exposed post-Coniacian succession in the Northern Province is characterised by flint-free chalk (Flamborough Chalk Formation; Figure 31), with numerous marl seams. Only for a relatively brief period in the latest Santonian and earliest Campanian is there a marked regional reduction in flint across East Anglia. This chalk, belonging mainly to the Uintacrinus socialis and Marsupites testudinarius zones, is very soft and fine grained and can be seen in the south of the region near Sudbury. In pits and quarries in the Gipping Valley, near Ipswich, this chalk expands to include the Offaster pilula Zone and has been designated the Blakenham Chalk Member (Figure 35; Plate 10). Weakly developed marls in the Ipswich succession suggest affinity with the Newhaven Chalk Formation of the Southern Province. The fauna includes small calyx plates of the zonal index crinoids, together with brachiopods, oysters (especially Pseudoperna boucheroni (Woods non Coquand)), the echinoid C. albogalerus and the belemnite Actinocamax verus Miller. A coarse-grained, shell-rich chalk interval in the lower part of the O. pilula Zone in the Blakenham Member of the Ipswich district, can be matched with coeval bioclastic facies in the Trunch Borehole (300 to 307.35 m depth) in north Norfolk, and with similar coarse-grained chalks (termed Grobkreide facies) at this stratigraphical level in Germany.

The remainder of the Early Campanian succession comprises soft to firm, regularly flinty chalk with locally conspicuous marl seams. The succession seen in an old quarry near Wells-next-the-Sea, on the north Norfolk coast, spans the upper O. pilula and lower G. quadrata zones, and resembles the flinty and marl-bearing Newhaven and Culver Chalk formations of the Southern Province. A conspicuous marl seam (Wells Marl) has previously been correlated with the Old Nore Marl in the higher part of the Newhaven Chalk, but may in fact be younger (Figure 31). Flinty chalk containing the belemnite Belemnitella, analogous to and coeval with the basal Culver Chalk, also occurs near the top of old chalk quarries near Ipswich, above flintless Blakenham Chalk (Figure 35). Some historical accounts of this succession assigned it to the Belemnitella mucronata Zone, but the records of Belemnitella actually represent B. praecursor, from the Hagenowia blackmorei Subzone at the base of the G. quadrata Zone. Little is known about chalk belonging to the higher part of the G. quadrata Zone in East Anglia.

Late Campanian to Early Maastrichtian (80 to 70 Ma)

The youngest part of the Chalk in East Anglia, belonging to the Late Campanian and Early Maastrichtian, is sporadically exposed near Norwich and in the coastal cliffs between Weybourne, Sheringham and Trimingham. The Late Campanian part of the succession, belonging entirely to the Belemnitella mucronata sensu lato (s.l.) Zone, has been informally designated ‘Norwich Chalk’, and divided into five units, comprising in ascending stratigraphical order: pre-Weybourne Chalk, Weybourne Chalk, Catton Sponge Bed, Beeston Chalk and Paramoudra Chalk (Figure 31). Some of these subdivisions are based on faunal changes rather than variation in lithofacies. Most of the succession comprises soft, flinty chalk, but there are also marl seams, beds of hard, nodular chalk and hardgrounds. The lower part of the succession, up to the Weybourne Chalk, is coeval with and lithologically similar to the Portsdown Chalk Formation of the Southern Province.

The pre-Weybourne Chalk is mainly known from former exposures in chalk pits at Eaton and Earlham, near Norwich, and is distinguished by its fauna, especially the small bryozoan Volviflustrellaria taverensis (Brydone) and the echinoid Echinocorys ex gr. conica (Agassiz). However, both fossils are absent from the oldest part of the succession, which belongs to the basal part of the B. mucronata s.l. Zone and is characterised by small Echinocorys, similar to E. subconicula Griffith and Brydone from the basal mucronata s.l. Zone of Hampshire and the Isle of Wight. In some previous accounts, the pre-Weybourne Chalk has been subdivided into Basal Mucronata Chalk, overlain by the Eaton Chalk. A hardground marks the top of the pre-Weybourne Chalk succession.

The stratotype section of the Weybourne Chalk is between Weybourne and Sheringham. The flinty chalk succession, soft with occasional hard chalk in the lower part, shows increasingly common hard and nodular chalk in the middle and upper parts, and is capped by a pair of iron-stained hardgrounds that form the Catton Sponge Bed. The middle part of the section contains abundant oysters (especially Pycnodonte and Hyotissa) and a hardground up to 0.5 m thick. The fauna also includes the brachiopods Magas chitoniformis Schlotheim and Cretirhynchia woodwardi (Davidson), which characterise the youngest chalk exposed in Dorset and the Isle of Wight. The Catton Sponge Bed is an interregional hardground complex characterised by common sponge remains, equivalent to the North Antrim Hardground of the Ulster White Limestone in Northern Ireland, and correlatable with hardgrounds in Belgium and the Netherlands. The widespread development of this hardground reflects a major relative fall in sea level.

Above the Catton Sponge Bed, the Beeston Chalk is characterised by very large flattish flints, up to 1.8 m in diameter and ring-shaped in plan view. The chalk is relatively soft, locally weakly nodular, and contains abundant inoceramid shell fragments. Near the base there are concentrations of belemnites and the straight-shelled ammonite Baculites, and Carneithyris carnea J Sowerby, Cretirhynchia arcuata Pettitt and C. norvicensis Pettitt become the dominant brachiopods. The top of the Beeston Chalk is a major hardground recorded on the foreshore at West Runton, characterised by accumulations of the echinoid Echinocorys and saurian vertebrae.

In Suffolk, boreholes at Sizewell, a few kilometres east of Saxmundham (Figure 32), have proved up to 60 m of Early Campanian Chalk below 80 m of Cenozoic strata. This chalk appears to occur in a downfaulted basin, and corresponds to parts of the pre-Weybourne, Weybourne and lowest Beeston Chalk. The Catton Sponge Bed is represented by a pair of closely spaced glauconitised hardgrounds, above which the chalk contains numerous glauconitised phosphatic clasts, common sponge remains, and the ammonites Baculites and ?Nostoceras (Bostrychoceras).

The youngest Campanian Chalk is represented by the Paramoudra Chalk, seen on the coast between East Runton and Cromer and formerly well exposed in pits and quarries in the Norwich area. It is characterised by vertical columns of cylindrical flints (paramoudras) up to several metres in height that formed around the burrow Bathichnus paramoudrae Bromley, Schulz and Peake (Plate 11). A hardground characterised by the echinoid Echinocorys pyramidata Portlock, and named the Overstrand Pyramidata Hardground, marks the top of the in situ Paramoudra Chalk succession.

The youngest onshore Chalk in England, of Early Maastrichtian age and assigned to the Belemnella lanceolata s.l. Zone, occurs between Overstrand and Trimingham. The succession is represented by a series of chalk rafts enclosed in glacial deposits (Plate 12), and has been informally designated ‘Trimingham Chalk’ (Figure 31). Four subdivisions have been recognised. The lowest, Sidestrand Chalk, is locally nodular, with marls, marl-filled burrows and large nodular and paramoudra-type flints, including a bed of huge cylindrical flint nodules, about a metre in diameter, with chalk-filled holes. One of these chalk rafts contains the contact with the underlying Paramoudra Chalk, here marked by a marl seam (Upper Overstrand Marl) rather than a hardground. The succession is very rich in fossils including the belemnites Belemnitella and Belemnella, the crinoid Austinocrinus, and large echinoids, such as Echinocorys belgica Lambert.

Hard, yellow chalk with erosional hardgrounds, glauconitised pebbles, pyrite masses and abundant sponge remains characterises the Trimingham Sponge Beds Chalk, and above this is the soft, white, flinty, locally oyster-rich chalk of the Little Marl Point Chalk, containing two thin marl bands. The oysters are predominantly Agerostrea lunata (Woods non Nilsson), and the fauna is significantly less diverse than adjacent units. The succession is capped by chalk containing five grey flint bands and a 0.1 m-thick calcarenitic horizon, representing the Beacon Hill Grey Chalk. The highly diverse fauna of this unit includes the brachiopods Neoliothyrina, Cretirhynchia and Magas; the bivalves Lyropecten, Gryphaeostrea and large Pycnodonte, and the echinoids Cardiaster, Echinocorys, and Gauthieria.

Uplift and erosion of the Chalk Group

The time gap present between the youngest preserved Chalk (Early Maastrictian) and oldest Palaeogene deposits (Thanetian) is about 15 million years duration. In the past it was thought that during much of this interval uplift and erosion of the Chalk Group occurred. However, evidence now suggests that Chalk deposition may have intermittently persisted across onshore Britain into the Late Maastrichtian and Danian, although no trace of these deposits now remains. On this basis, the total period of erosion that affected the Chalk is probably closer to 3 million years. Initial erosion was probably caused by a major sea-level fall, associated with uplift and tilting during the Early Paleocene, with a more significant regional uplift event terminating Danian chalk deposition in the mid Paleocene (early Selandian). Erosion of the Chalk also seems to have been facilitated by gentle folding during uplift.

Chapter 6 Palaeogene

D T Aldiss

Introduction

The North Atlantic Ocean continued to open during Palaeogene (66.0 to 23.0 Ma) times. Crustal extension, at first extending west of Greenland, was accompanied by uplift across much of the British Isles, with tilting towards the south-east. This resulted in a period of erosion that removed some of the younger Chalk Group strata in East Anglia including the inferred Paleocene chalks (see Chapter 5). Uplift led to the formation of a series of Palaeogene sedimentary basins across the United Kingdom with common reactivation of depositional centres, including the intracontinental North Sea Basin, that were previously active during the Mesozoic (Figure 36). This phase of widespread uplift ceased during the Early Eocene, at about the time when oceanic crust began to form between Europe and Greenland, and was followed by regional subsidence and marine transgression.

The southern part of the North Sea Basin extended south-westwards and was, at times, connected with Palaeogene basins in the English Channel and Western Approaches (Figure 36). Parts of the succession deposited during the Paleocene (66.0 to 56.0 Ma) and Eocene (56.0 to 33.9 Ma) are now found onshore in the Hampshire and London ‘basins’, and in East Anglia. In these areas, subsidence was relatively slow and was punctuated by phases of uplift. Eustatic changes in sea level superimposed on this tectonic activity led to a series of marine transgressions and regressions. The local sedimentary sequence is consequently interrupted by a series of unconformities and hiatuses.

Also during this period, there was considerable igneous activity at a number of centres, both in the north-west of Britain, forming the British Palaeogene Igneous Province (BPIP) (Figure 36), and between Norway and Greenland. There were two major phases of intrusion and lava extrusion, the first spanning much of the Paleocene, chiefly between 62 and 59 Ma, and the second mainly during the Eocene, between about 56 and 53 Ma. Ash deposits from two phases of pyroclastic eruption of somewhat shorter duration are found extensively in the Palaeogene sequences of the North Sea area, including those of East Anglia. The earlier phase, during the Late Paleocene, marks eruptions in both the BPIP and in the Faroes– Greenland area. By contrast activity during the later phase, at various times during the latest Paleocene and Early Eocene, originated mainly or entirely in the Faroes–Greenland area.

Palaeogene sequences are confined to the east of the East Anglia region, where they are largely covered by the Crag Group or by younger Quaternary deposits, or both (Figure 37). As indicated by Figure 36, their previous westwards extent was probably much greater.

Borehole records show that in parts of Norfolk and of northern Suffolk, the buried Palaeogene deposits form a north-west-facing escarpment. The only significant natural exposures of the Palaeogene within this region are in the south-east, in the banks of the rivers Stour and Orwell and in coastal cliffs and foreshores. The most northerly occurrence at rockhead is near Aldeburgh. Elsewhere, detailed understanding of the local Palaeogene sequence is derived from a rather small number of borehole records (Figure 37) or from offshore seismic reflection surveys. The maximum estimated thickness of the Palaeogene in the region is 115 m, immediately offshore from Great Yarmouth.

The Palaeogene in East Anglia comprises Late Paleocene and Early Eocene deposits (Figure 38), mainly of marine origin. Units of the Montrose Group and of the Harwich Formation tend to thin southwards over a poorly defined structural axis in southern Suffolk, known as the Ipswich–Felixstowe High (Figure 37), then thicken again into the London Basin, to the south of the region. The Lambeth Group, by contrast, appears to pinch out northwards on the northern flank of this structure. The Ipswich–Felixstowe High is aligned with the north-west-trending, deeply buried, Glinton Thrust (Chapter 2) although, unlike that fault zone, it has no obvious expression in the regional gravity or magnetic fields. Nevertheless, geophysical lineaments suggest that the subcrop extent of the Palaeogene could be partly controlled by north-west-trending faults (Figure 37), following the dominant structural fabric of the deep basement (Chapter 2). Faults of this orientation also occur in the Palaeogene offshore (Figure 36).

The distribution and thickness of the younger (Pliocene to early Middle Pleistocene) Crag Group is partly controlled by north-east-trending faults (Figure 37), forming two or more asymmetric grabens in which the south-easterly side is steep and the north-westerly side is gentle. These structural trends continue into the North Sea to the north and east, and into the London Basin to the south and south-west, so it is likely that the distribution, thickness and, possibly, facies of the Palaeogene is similarly controlled by faults of this orientation. Possible control of thickness variation in the Crag Group by faulting, or by differential erosion, is discussed in Chapter 8.

Ignoring the effects of faulting, the regional dip of the Palaeogene strata is less than 1° to the east, except in the south-east of the region, where the similarly extremely gentle dip is towards the south-east. This change in orientation, which occurs in the region of the Ipswich– Felixstowe High, is accompanied by Palaeogene rocks overstepping the eroded surface of tilted Chalk Group strata, cutting across several of the higher biozones.

The Palaeogene also saw a number of marked variations in global sea level, during which each cycle of sea-level rise and fall is associated with the deposition of an individual sedimentary sequence. Towards the margins of the depositional basins, the sequences are separated from each other by an unconformity, or a non-sequence. Three major composite unconformity-bounded sequences are represented in the Palaeogene of East Anglia, continuing into south-east England (Figure 38). These display marked contrasts in depositional facies, ranging from paralic to open-marine shelf, reflecting the differing proximity of the marine shoreline and differences in water depth arising in differing tectonic settings, and each is assigned to a separate stratigraphical group. Each major sequence is itself made up of smaller-scale depositional sequences, with less-marked contrasts in sedimentary facies association, reflected by the subdivision of the three groups into smaller stratigraphical units (represented by formations and members). Erosional surfaces mark many of the intervals between the stratigraphical units. In some cases these surfaces are penetrated by the burrows of bottom-dwelling fauna, overlain by beds of flint cobbles or pebbles, some with notable concentrations of fossils, including sharks’ teeth.

Lithostratigraphy

The Montrose Group was originally defined to encompass offshore formations in the North Sea Basin but now has been extended to include the partial lateral equivalents onshore, namely the Thanet Formation (in the south-east of the region, and to the south) and the Ormesby Clay Member of the Lista Formation. The Ormesby Clay is a relatively deep-water marine deposit mostly comprising variably glauconitic clay or silty clay, some calcareous. The basal part is glauconitic sandy silt, with a thin cobble and gravel bed, commonly less than 20 cm thick, at the bottom, resting unconformably on the Late Cretaceous Chalk Group. Three thin ash layers, derived from the BPIP, occur in the silty clays of the lower part, which marks the earliest of four cycles of marine transgression and regression recorded by the Ormesby Clay. Above this, a bed of reddish brown clay or silty clay in the second cycle provides a distinctive stratigraphical marker. Like the first, the third cycle is marked by greyish brown silty clay with some ash layers, and the fourth by waxy glauconitic clay with a bed of altered volcanic ash near the base. The Ormesby Clay decreases in thickness southwards from a recorded maximum of 27 m, in part through the overstep of the beds of the first cycle. Between Ipswich and Sizewell, approximately across the Ipswich–Felixstowe High, the upper parts of the Ormesby Clay pass laterally southwards into the more proximal marine facies of the Thanet Formation.

The Thanet Formation is less than 2 m thick in places on the Ipswich–Felixstowe High but thickens southwards into its main occurrence in the eastern part of the London Basin, where it mostly ranges in composition from fine-grained sand to silt and silty clay. Mudstone is present in the lower part of the formation in north-east Essex, for example at Bradwell, indicating the start of the lateral northwards transition into the Ormesby Clay Member. However, in parts of south-east Suffolk, the highest part of the formation comprises up to 4 m of glauconitic medium- to coarse-grained sand. The formation is glauconitic but, in the East Anglia region, varies in colour from grey to pale brown, green and pink. The heavy mineral content of the sand suggests a Scottish provenance, in contrast to that of the overlying Upnor Formation, but similar to that of most of the younger Palaeogene formations. A thin bed of coarse gravel and cobbles, commonly with green-stained flint nodules, (known as the ‘Bullhead Bed’) is generally present at the base, and rests unconformably on the Chalk. Dispersed and degraded volcanic ash occurs at least locally in the Thanet Formation.

In much of south-east Suffolk, and presumably also elsewhere in the region, the upper parts of the Thanet Formation and of the Ormesby Clay were eroded prior to deposition of the Lambeth Group. In Suffolk, the Lambeth Group comprises the basal Upnor Formation and the overlying Reading Formation, with elements of the Woolwich Formation in places, but the distribution of these units is very poorly known in East Anglia as a whole. The Lambeth Group apparently reaches as much as 23 m in thickness at Lowestoft but elsewhere is much less, and apparently pinches out in Norfolk between the Hales and the Ormesby boreholes (Figure 39).

The nature of the Upnor Formation varies across the region. In the south-west of the outcrop, around Sudbury for example, it typically comprises the cross-bedded glauconitic sands, some clayey, that are commonly found in the London Basin to the south. Further north-east, in the Hales Borehole, Norfolk, it is apparently represented by a few metres of pale brown silt, silty clay and sandy silt with rare thin sand layers in places. Its base is probably erosional, with sediment-filled burrows extending down into the Ormesby Clay or Thanet Formation. The Upnor Formation represents proximal marine sedimentation in predominantly high energy, partly tidally influenced environments. In contrast to that of the Thanet Formation, the heavy mineral content of the sands suggests a provenance from the south.

The Woolwich Formation represents a variety of clay-dominated marginal marine facies, with occasional freshwater incursions. It is probably represented in the Halesworth Borehole (Figure 37) and (Figure 39) by lenticularly interbedded and interlaminated silty clay and medium-grained sand (4.3 m thick), passing up into 0.45 m of shelly sand and thin lignitic layers alternating with greyish brown clay.

In East Anglia, as in the London Basin, the Reading Formation consists mainly of clay and silty clay, either grey or reddish brown, or colour-mottled in browns, oranges, greens and greys, with some beds of laminated silt, brown sand or of gravel. It reaches as much as 12 m in the Harwich area but apparently decreases northwards. Scattered over the southern part of Suffolk, as in some other parts of south-east England, are angular blocks of very hard silica-cemented sandstone called sarsens or greywethers. Their distribution and their mineral constitution make it evident that they were derived from the sands of the Reading Formation. The Reading Formation is considered to have been deposited mainly in various fluvial environments within a coastal floodplain, but it is possible that some of the Reading Formation sediments, like those of the Woolwich Formation, originated in estuarine or other marginal marine environments.

The third major unconformity-bounded sequence represented in the local Palaeogene succession is the Thames Group, comprising the Harwich Formation overlain by the London Clay Formation, and representing sedimentation in marine conditions of continental shelf seas.

The Harwich Formation attains 33.6 m in the Ormesby Borehole, in east Norfolk, but is more typically between 15 and 20 m in thickness. In this region it comprises mainly clayey silt or silty clay, with many layers of basaltic volcanic ash, which are typically between 10 and 80 mm in thickness, although they are generally somewhat reworked and bioturbated. Up to 87 ash layers were noted in the Ormesby Borehole. These ash deposits arose from volcanism during the early opening of the North Atlantic Ocean between Greenland and north-west Europe.

In East Anglia and north-eastern Essex, the lower part of the Harwich Formation is assigned to the Orwell Member. Locally around Ipswich, this commences in glauconitic fine-grained sands with well-rounded flint gravel and faunal debris at the base, sometimes known as the Suffolk Pebble Bed. Elsewhere it comprises bioturbated tuffaceous silty sands, sandy clayey silts and sandy silty clays, with shell fragments and discontinuous laminae of dark grey-black clay. The upper part of the member is characterised by tuffaceous sandy silt with laminae of fine-grained sand. The Orwell Member is typically about 5 m in thickness but locally is as much as 14 m. The upper part of the Harwich Formation in this area belongs to the Wrabness Member.

This comprises tuffaceous clayey silt and silty clay, with both disseminated ash and numerous distinct ash layers (Plate 13), and with glauconitic sandy clayey silt at the base, overlain with apparent disconformity by a thin layer (about 1.7 m) of bioturbated fine-grained silty sand with clay interbeds. Layers of concretionary argillaceous limestone occur at several levels, including the regionally extensive Harwich Stone Band near the base of the Wrabness Member, which is about 0.25 m thick and which includes a central ash bed. This forms a useful marker horizon in exposures, boreholes and in offshore seismic reflection surveys. The Wrabness Member is up to about 24 m thick. Coastal sections in the Wrabness Member at Walton-on-the-Naze, just to the south of the region, have yielded an extensive assemblage of fossil bird bones.

In the south-west of the Palaeogene outcrop in this region, the Harwich Formation is represented by the Oldhaven Member, here comprising micaceous, glauconitic silty fine-grained sand that contains small flint pebbles and lignite fragments (Figure 39). At Bures, about 10 km south-east of Sudbury, it is about 8.5 m thick. The nature and position of the eastwards transition from the Oldhaven Member to the Wrabness and Orwell members is not known.

In the East Anglia region, only the lower part of the London Clay Formation, the Walton Member, is present. This is largely confined to the area around Ipswich and eastwards to the coast, where up to 25 m are present (Figure 39). It is made up of silty clay and clayey silt, interbedded with very fine-grained sandy silty clay with sporadic layers of volcanic ash. It is micaceous, commonly with lignitic debris and pyrite, but is generally not glauconitic nor calcareous. There is usually a thin basal glauconitic sandy and gravelly bed, or a layer of dispersed well-rounded gravel, that rests disconformably on the Harwich Formation.

Regionally in East Anglia and the London Basin, the London Clay contains a varied marine fossil fauna, with rare occurrences of freshwater or brackish molluscs, and of other groups (Plate 14). There is also a significant macroflora, including disseminated lignite, representing plant debris carried out to sea. Vertebrate fossils include the remains of fish, reptiles, and birds. Fossils found in the London Clay Formation indicate a subtropical climate.

Changes in global climate leading to eustatic falls in sea level during the Oligocene, followed by extensive tectonic movements in southern England during the Late Oligocene and Miocene, linked to the Alpine Orogeny, suggest that East Anglia was probably a terrestrial area of nondeposition during these epochs. Marine conditions returned to the region during the late Pliocene, as discussed in the next chapter.

Chapter 7 Overview of Late Neogene to Quaternary geology

J R Lee

Introduction

The Late Neogene to Quaternary Period spans the past five million years of recent Earth history and its climatic and environmental legacy has had a profound effect upon the geology and landscape of East Anglia. The region contains one of the most complete records for the late Neogene to Quaternary within north-western Europe rivalled only by sequences in the Netherlands, Germany and the Eastern European plain. Evidence for long-term environmental change is found within an extensive geological record that identifies episodes of marine deposition, lowland river activity, lowland glaciation and periglaciation. The record carries diverse sedimentological, floral and faunal evidence of significant climate changes, sea-level change and soil development together with an ever-growing understanding of early human evolution and landscape occupation. Of particular significance is the fact that East Anglia contains several internationally important archaeological sites that push back the earliest human occupation of northern Europe possibly as far back as 0.8 Ma. Because of the volume and complexity of the Late Neogene to Quaternary succession in East Anglia, it has been necessary to subdivide the superficial sequence into several individual chapters, Chapters 8 to 13, which detail the geological, palaeontological and archaeological evidence. The purpose of this chapter is to provide an overview and context to the Quaternary of East Anglia by examining the drivers of environmental change, its signature within the geological record and wider regional significance.

Drivers of Quaternary change

Climate

Throughout the Cenozoic, global climate has cooled progressively, from the greenhouse climates of the Paleocene–Eocene Thermal Maxima (56 Ma) through to the first appearance of ice caps in Britain and Scandinavia at the beginning of the Quaternary. Long-term evidence for Quaternary climate change and a global climate-driven stratigraphy is provided by the marine isotope record. This record highlights variations over time of the heavy (18O) and light (16O) oxygen isotope concentrations found in the calcareous shells of small marine organisms called foraminifera. The relative abundance of these two oxygen isotopes is controlled by a temperature-dependent fractionation with temporal variations offering scientists a crude relative proxy of temperature and global ice volume. The oxygen isotope curve (Figure 40) shows that global climate and ice volume have oscillated markedly throughout the past five million years. During the Quaternary Period, each major climatic oscillation has been assigned to a marine isotope stage (often referred to as ‘MIS’) with cold stages or glacials being even-numbered and temperate stages or interglacials being odd-numbered. Several MIS have formally designated terrestrial stage names, for example the Anglian (MIS 12) and Hoxnian (MIS 11); however, the majority of numbered MIS are either unnamed or correlations with particular onshore geology remains tentative. Individual cold stages including the Anglian (MIS 12) and Late Devensian (MIS 2), are characterised by enhanced 18O concentrations (relative to lighter 16O), higher global ice volume and lower sea levels. By contrast, temperate stages including the Hoxnian (MIS 11) and Ipswichian (MIS 5e) are enriched in the lighter 16O with lower 18O concentrations, lower global ice volumes and higher sea levels.

Examination of the marine isotope curve shows a remarkable consistency in the frequency and magnitude of these climatic changes. Prior to 1.2 Ma, major climate oscillations occurred approximately every 40 000 years with smaller oscillations, occurring roughly every 20 000 years. Between 1.2 and 0.6 Ma — a time interval referred to as the ‘Mid

Pleistocene Transition’ — a distinctive change in the magnitude, duration and frequency of climatic changes occurred, with the progressive amplification of higher magnitude climatic cycles occurring every 100 000 years. Following the Mid Pleistocene Transition global climate has, on a long-term scale, been driven by these 100 000 years cycles. Collectively, the periodicity of these climatic cycles correspond to known and predictable changes in the shape of the Earth’s orbit around the sun called Milankovitch cycles and occur with a crude periodicity of 100 000, 41 000 and 21 000 years (Figure 41). Milankovitch cycles are important because partly, they control the amount of solar radiation or heat that the Earth receives, and its temporal and spatial distribution over the Earth’s surface. This in turn, controls the intensity and energy of many atmospheric, oceanic and terrestrial systems. However, it is important to recognise that whilst Milankovitch cycles play a vital role in driving environmental change during the Late Neogene to Quaternary, their occurrence is not restricted to this time interval. Indeed, Milankovitch-scale cyclicity has been identified within much older parts of the geological record, for example, the Carboniferous.

At a more regional scale, a major regulator of Britain’s climate is the North Atlantic Current. This oceanic–atmospheric current is a continuation of the Gulf Stream and forms part of a much larger global oceanic–atmospheric conveyor that transfers heat and moisture around the planet. Its warming effect ensures that the Polar Front currently lies to the north of Britain and that we have a more temperate climate than parts of Canada and Russia that occupy similar latitudes. However, the latitudinal position of the Polar Front has, in part driven by the switching off of the North Atlantic Current, migrated across or to the south of Britain for long periods during the Quaternary leading to the establishment of arctic conditions and ice ages.

Tectonics

East Anglia forms part of the western margins of the North Sea Basin which is a failed rift associated with the opening of the North Atlantic during the Triassic to Cretaceous. Within the Quaternary, parts of the North Sea Basin have continued to subside. The marginal area of East Anglia has in consequence been subjected to differential uplift, subsidence and probable tilting. Prior to about 0.45 Ma, net uplift occurred within the central and western parts of the region with either stable or subsiding areas over eastern Norfolk and Suffolk forming a basinal area known as the ‘Crag Basin’ — a part of the early Southern North Sea Basin. This basin was frequently inundated by marine conditions during the Quaternary with thickest onshore accumulations of the Crag Group occurring in the Lowestoft area where subsidence of some 65 m relative to current OD occurred. The total differential uplift/ subsidence rate between the base of the Red Crag Formation at Lowestoft and along the western uplifted margins of the basin at Stansted in neighbouring Essex, is about 170 m.

There was an average rate of 7 mm per thousand years from the onset of the Red Crag Formation (Late Pliocene) to the beginning of the late Middle Pleistocene Anglian Glaciation (a period of about 2.4 million years). Fluvial deposition was already established in the west and south-west of the region contemporaneous with marine deposition within the Crag Basin. It should be noted that average rates can be misleading as uplift and subsidence rates are rarely continuous. This is demonstrated in the area of south Norfolk, where the geometric relationships between the different formations of the Crag Group indicate two distinct phases of uplift separating a phase of subsidence. Relative uplift and subsidence over the Early and early Middle Pleistocene is also an important factor in the evolution of several major preglacial river systems that drained the region as it acted to drive the long-term development of river terrace sequences (Chapter 9).

The beginning of the Anglian cold stage about 0.48 Ma coincides with a fundamental change in the tectonic regime of East Anglia. From the late Middle Pleistocene to the present day, negligible subsidence has occurred within the area of the Crag Basin in East Anglia. This implies, tentatively, that a major component of Early and early Middle Pleistocene subsidence within the Crag Basin was driven by crustal loading caused by thickening of the sediment pile. Interestingly, when sedimentation within the Crag Basin ceased following the Anglian Glaciation, large-scale subsidence appears also to have stopped. Central and western parts of East Anglia have continued to uplift throughout the late Middle Pleistocene to Holocene. Evidence for this is indicated by the development of younger river terrace sequences associated with many of the region’s major extant river systems and their tributaries. However, rates of uplift over this time interval are difficult to quantify due to the general absence of suitably dated material. Late Middle Pleistocene marine deposits of the Nar Valley Formation, which crop out within the Nar Valley in west Norfolk, offer a possible exception. These deposits occur at a maximum elevation of +24 m and their MIS 9 age (about 0.39 Ma) indicates an average uplift rate of 6.0 mm per hundred years. The focus of uplift is considered to be located to the west within Central England and specifically the Pennines and Peak District. An alternative view is that uplift may in part be driven by glacial excavation of the Wash and Fen Basin and lowering of the Chalk escarpment during the Anglian Glaciation which is estimated to have eroded over 550 km3 of bedrock. The effects of isostatic rebound during Middle and Late Pleistocene glaciations are also poorly understood, although it is considered that isostatic readjustments in this region following the Late Devensian Glaciation have ceased.

Quaternary stratigraphical frameworks

Relative stratigraphical frameworks

Establishing a robust relative ordering and geometric understanding of the geological units is a fundamental component of any stratigraphical framework. Pollen assemblage biostratigraphy has underpinned much of our stratigraphical understanding of the Early and Middle Pleistocene of East Anglia over the past 50 years. It is based on the principal that stratigraphically distinctive pollen assemblages develop during specific climatic events — both cold and temperate. These enable the characterisation of pollen/vegetational signatures for the events which are then ordered based on the geometric relationship of the host sediments to one another. Many of the familiar terms used to define British stages, for example Ludhamian, Pastonian and Hoxnian, are underpinned by this approach and are centred upon stratotype localities in East Anglia. Despite its widespread acceptance and utilisation as a stratigraphical approach, pollen assemblage biostratigraphy has many limitations — not least the limited preservation and fragmented occurrence of organic sediments within dominantly clastic sedimentary sequences. Furthermore, this approach places a limited value upon pollen variability as a function of vegetational change within a natural landscape, nor does it factor into consideration the dynamics and style of sedimentation of the host sediment. For example, there are problems with pollen reworking and the often very limited period of sediment deposition. In summary, whilst pollen assemblage biostratigraphy has made an outstanding contribution to Quaternary stratigraphy, its inherent problems do limit its application.

Many biostratigraphers now focus on the first and last appearance datum of particular taxa and faunal assemblages utilising a range of different proxies including marine and terrestrial molluscs, small and large mammals, and insects. In East Anglia, this has proved particularly effective in identifying as many as six different temperate events within the early Middle Pleistocene ‘Cromerian Complex’ and in distinguishing between the MIS 11 and 9 interglacials. However, like all stratigraphical approaches, the technique does possess its limitations. Most significantly, the approach is empirical therefore interpretations may be subject to review and change following new discoveries. Accurate identification of taxa can also be complicated, especially with molluscs and small mammals, where fossil specimens (e.g. teeth) from juvenile forms may be similar to other taxa. Recent developments with the amino-acid racemisation (AAR) technique have proven particularly successful in further constraining molluscan faunas.

Whilst biostratigraphy has contributed a wealth of valuable information and continues to do so, a major constraining factor is the limited preservation and availability of stratigraphical evidence. Other stratigraphical techniques, principally lithostratigraphy and morphostratigraphy, generally form more laterally persistent stratigraphical building blocks. They are thus are integral to any stratigraphical framework derived from geological mapping. Lithostratigraphy is a widely employed stratigraphical tool within the Quaternary. However, lithostratigraphy has limitations consequent upon the internal complexity and fragmentary nature of many Quaternary deposits. This is perhaps most clearly demonstrated within glacigenic successions that reflect both unusually complex spatial associations (allostratigraphy) and tectonic structure (kinetostratigraphy) and a hybridised approach in constructing a stratigraphical framework is typically required. Morphostratigraphy is also an important methodological component and applicable at various scales. At a local scale, morphological features such as concave and convex slope breaks can provide valuable information regarding the underlying geology. At a larger scale, the cross-cutting and geometric relationship of landforms or features within the landscape, enable a relative framework for their order of development to be constructed. Of particular significance to East Anglia are river terrace aggradations associated with large lowland river catchments. Progressive long-term tilting and headwater uplift of these catchments, coupled with shorter-term changes in base level and climate, drive temporal patterns of fluvial aggradation and incision enabling terrace bodies of different elevations and age to be delineated. When used in tandem with biostratigraphy and geochronology, it has proved highly successful in enabling the age of river terrace successions to be established. Several different modelled approaches have been employed to reconcile the evidence from the terrace archive with long-term patterns of fluvial behaviour. A climatic approach to long-term river terrace development that links phases of incision and aggradation to large-scale orbital forcing has been utilised for several rivers in southern Britain — for instance the Thames and Trent (Chapter 9). However, it is also evident that this approach may not be applicable to many of the post-Anglian river systems of East Anglia and the Fen Basin, where more local- and regional-scale factors may be more significant.

Geochronology

Any geological framework is ultimately dependent upon the presence of datum points that have been reliably dated by absolute dating techniques (geochronology). A range of different Quaternary dating techniques have been employed within East Anglia, however, their effectiveness is limited by the effective age range of the techniques and the availability of suitable materials for dating. Conventional radiocarbon (14C) and accelerator mass spectrometry (AMS) radiocarbon dating are widely used for dating deposits of Holocene and Late Devensian age but generally have variable or limited accuracy and precision beyond 40 ka. For effective age ranges that extend back into the late Middle Pleistocene many scientists employ optically stimulated luminescence (OSL), electron spin resonance (ESR) or uranium-series (U-series) dating although large quantities of dates are required to provide confidence. Similarly, amino acid racemisation (AAR) dating of molluscs has proved highly successful back to the late Middle Pleistocene, but currently, doesn’t possess sufficient precision to resolve older stratigraphical problems. Cosmogenic dating has the potential to be highly relevant and important in dating Quaternary deposits in East Anglia, but its application is currently limited because the burial history of suitable materials is difficult to constrain.

Early and Early Middle Pleistocene landscapes

Palaeogeography and geological processes

Palaeogeography and geological processes within East Anglia and southern Britain were dominated by global-scale climate forcing and neotectonics during the Pliocene and Early to early Middle Pleistocene. The relative significance of each fluctuated over this time interval as the global climate signal intensified. This is especially the case during the ‘Middle Pleistocene Transition’ and the gradual switch to 100 ka climate forcing because geological processes (i.e. weathering, sea-level change and sediment budgets) became more amplified under eccentricity-forced climates.

A notable difference between the Pliocene to early Middle Pleistocene palaeogeography of the region and that of modern times is the morphology of the pre-Anglian North Sea Basin. This is also widely referred to during this time interval as the Crag Basin and was previously an epicontinental marine embayment (Figure 42a). At this time, the Straits of Dover, which now link the Southern North Sea to the English Channel, did not exist, the two being separated by a continuous chalk ridge joining Britain to France. The Crag Basin was gradually infilled by extensive prograding delta sediments deposited by rivers that drained southern Britain (Kesgrave Thames, Bytham and Ancaster rivers), the Scandinavian Shield (Baltic ‘Eridanos’ river) and continental Europe (proto Rhine and Meuse rivers). Despite the shallow bathymetry and the numerous sea-level fluctuations, shallow-marine conditions probably prevailed for much of the offshore and marginal areas (i.e. the Crag Basin in eastern East Anglia) of the basin during much of the Pliocene and earliest Pleistocene.

In East Anglia, the late Pliocene and earliest Pleistocene time interval corresponds to the sedimentation of the Coralline Crag, Red Crag and Norwich Crag formations of the Crag Group. The large-scale absence of emergence, could imply that subsidence rates within the Crag Basin either matched or exceeded basin infill driven by sediment input from the European river systems. During the remainder of the mid Early to early Middle Pleistocene, eastern East Anglia formed a low-lying coastal plain at the western margins of this basin where even small changes in sea level resulted in extensive changes in palaeogeography and the importance of shallow marine and terrestrial processes. This is represented by the complex interdigitation of younger shallow marine and coastal deposits of the Crag Group (Norwich and Wroxham Crag formations), fluviatile sediments (Kesgrave and Bytham Catchments subgroups; Cromer Forest-bed Formation) and palaeosols.

The Crag Group of shallow-marine deposits is subdivided into four formations within East Anglia. The lower two formations, the Coralline Crag and Red Crag formations, were deposited during the Pliocene to earliest Pleistocene but are included within the Late Neogene to Quaternary section of the regional guide because of their stratigraphical and palaeogeographical affinity to the younger Norwich Crag and Wroxham Crag formations. They were deposited under climates dominated by the 21 ka precession orbital cycles. Whilst this climate forcing drove numerous small changes in sea level, terrestrial land surfaces were largely stable implying low catchment sediment budgets. Both the Coralline and Red Crag formations record shallow-marine and tidal patterns of sedimentation. The Red Crag Formation, records sedimentation associated with both transgressive and regressive sea-level cycles.

Resting unconformably upon the Red Crag Formation is the Early Pleistocene Norwich Crag Formation. It comprises various tidal-flat, beach and coastal deposits that form several transgressive and regressive sediment packages. The basal facies is the Chillesford Sand Member which records a major Early Pleistocene marine transgression dominated by sandy intertidal and estuarine sedimentation. The change to clay-dominated sedimentation, represented by the Chillesford Clay Member, records a switch to a low-energy depositional environment. The Westleton Beds, by contrast, record shoreface gravel banks aligned along a north-east-trending coastline. Other clay deposits, including the Easton Bavents Clay, record sedimentation within an intertidal or sublittoral environment under subarctic conditions and have been correlated with the ‘Baventian’ cold stage or the Dutch Tiglian C4C stage based upon first-appearance biostratigraphical evidence. However, the temporal significance of this marine regression is not clear. One suggestion is that this sequence could record an exceptionally well-preserved single cold-stage lowering of sea level, however, such preservation is very rare and it is perhaps more likely to represent a longer-term climatic trend and sea-level fall.

Deposition of the Norwich Crag Formation occurred under a dominant 41 ka (obliquity) climatic cyclicity representing a subtle but significant intensification in the background climatic regime. It records a predominantly fine-grained (clay, silt, sand) style of sedimentation with limited longshore sediment transport but frequent changes in sea level. The recognition of both emergent surfaces and terrestrial conditions during the deposition of the Norwich Crag Formation imply that sedimentation rates had increased relative to subsidence within the Crag Basin reflecting more dynamic terrestrial processes (e.g. hillslope processes) and higher sediment budgets. Clast lithologies and derived palynomorphs from the Norwich Crag Formation show that the Early Pleistocene rivers draining across East Anglia into central and western Britain were relatively low-energy systems that transported mainly fine-grained sediment as suspended load. However, the catchment of the Kesgrave Thames was considerably bigger than that of the modern system. For instance, the presence of Silurian acritarchs within the Chillesford Clay Member demonstrates that the headwaters of the river were located within the Welsh Borders.

The Wroxham Crag Formation equates to a marked increase in the proportion of far-travelled and coarser-grained lithologies being transported into the Crag Basin by the adjacent river systems. It spans part of the Early Pleistocene and the entire early Middle Pleistocene including the Mid-Pleistocene Transition. Therefore deposition occurred during the continued dominance of low- to moderate-magnitude 41 ka obliquity climate forcing, and the progressive intensification of the high-magnitude 100 ka eccentricity climate signal from 1.2 Ma. The onset of deposition of the Wroxham Crag Formation has been suggested to be equivalent to the Baventian cold stage (about 1.8 Ma, MIS 68), but this is somewhat tenuous due to ambiguities surrounding the correct identification of the first appearance of the marine bivalve Macoma balthica within the basal member of the formation. Deposits of the Wroxham Crag Formation record numerous eustatic changes and their common interdigitation with fluviatile deposits and palaeosol sequences illustrate the palaeogeographical sensitivity of the region to even small eustatic change. Facies within the Wroxham Crag Formation mainly relate to coastal environments and include beach deposits, subtidal sand and gravel bars, estuarine and tidal-flat deposits. The progressive introduction of far-travelled and coarser-grained lithologies into the Wroxham Crag Formation indicates both more energetic coastal processes and an increasing efficiency of the adjacent river systems to recycle coarse far-travelled materials more rapidly and as bedload. This is reflected by the steady increase in far-travelled clasts such as vein quartz and quartzite (Triassic, Midlands) and various types of chert from the Kesgrave Thames, Bytham and Ancaster rivers within the Wroxham Crag Formation succession.

Terrestrially, extensive river terrace aggradations developed in association with both the Kesgrave Thames and Bytham river systems in the region. Sudbury Formation terrace aggradations of the Kesgrave Thames span the middle and later parts of the Early Pleistocene. During this time interval the Kesgrave Thames was the biggest lowland river system of southern Britain and its headwaters lay beyond the Cotswold escarpment in the Welsh borders (Figure 42b). Terrace aggradations, of which five have been delineated, appear to have accumulated over multiple cold and warm stages. Evidence for long-term landscape stability is provided by the presence of a temperate palaeosol called the Valley Farm Soil, which has been recognised extensively throughout southern East Anglia during this time period. Collectively, evidence indicates a long-term tectonic control on terrace formation with stable land surfaces and low-energy river systems transporting low sediment yields of predominantly fine-grained sediment. By contrast, the younger Colchester Formation terrace aggradations (four) formed during the latest Early and early Middle Pleistocene ‘Cromerian Complex’ between about 0.8 to 0.45 Ma. Individual aggradations have been attributed to different cold stages implying a 100 ka-eccentricity climate-forcing influence on their formation. Their western extent is constrained by the Cotswold escarpment pointing to a far-smaller Kesgrave Thames river catchment and the establishment of the Bytham as the dominant fluvial system of southern Britain (Figure 42d). This indicates a fundamental shift in the pattern of drainage and is believed by some to have occurred at about 0.9 Ma (MIS 20). The cause of this drainage shift remains poorly understood, but either headwater capture by the Bytham River or lowland glaciation that extended to the Cotswolds have been identified as possible mechanisms. Several Bytham terrace aggradations have been recognised extending discontinuously downstream from the West and East Midlands into East Anglia although the precise number remains speculative.

An apparent feature of both the Colchester and Ingham Sand and Gravel formations is the development of possible single cold-stage aggradations and the increased content of far-travelled gravel lithologies. Far-travelled clasts were derived from the headwaters of both the Kesgrave Thames and Bytham and efficiently recycled throughout the catchments and into adjacent estuaries and coastal areas (the How Hill and Mundesley members of the Wroxham Crag Formation). It implies a highly dynamic landscape with marked cold– warm stage differences in weathering, hill-slope processes, sediment budgets and seasonal peak discharges driven by 100 ka eccentricity-forced climates. Cold stages appear to be characterised by reduced vegetation, with increased weathering and slope processes generating greater sediment budgets, and the increased seasonal efficiency of river systems for transporting coarse bedload down-catchment. Widespread active-layer processes and freeze-thaw are important drivers of the enhanced weathering rates. Evidence for permafrost during several of the ‘Cromerian Complex’ cold stages comprises the Barham Soil which occurs throughout the Bytham and Kesgrave Thames sequences and is related to emergent surfaces within the Wroxham Crag Formation. Temperate climates, by comparison, resulted in increased vegetation cover and corresponding reductions in weathering, catchment sediment budgets, fluvial efficiency and seasonal peak discharges. Temperate fluvial deposits equate to the Cromer Forest-bed Formation (Ancaster River) and various unnamed deposits within the Ingham Sand and Gravel Formation (Bytham River). Currently six possible biostratigraphically distinct temperate events have been recognised during the ‘Cromerian Complex’ (MIS 21 to 13) in southern Britain.

Palaeoclimates

Very little detail is known about palaeoclimates in East Anglia prior to 1.2 Ma. However, a growing body of research highlights the significance of glaciation within Britain at this time. Previously, only limited evidence for glaciation existed but new information reveals that several highland areas of Britain, Ireland and adjacent Scandinavia may have possessed ice caps with glaciers occasionally extending into adjacent lowland and marine areas. Rare erratics of unknown origin have been reported from basal beds within both the Coralline and Reg Crag formations and it has been speculated that these may be derived from ice rafting. However, the prevailing climate during the deposition of these units was either warmer (Coralline Crag Formation) or only slightly cooler (Red Crag Formation) than present day which does not lend support to a glacial origin. The most compelling evidence occurs within offshore sequences in the North Sea and Porcupine Basin. Within the Northern North Sea, iceberg scour marks identified within 3D seismic data are tentatively attributed to the Baventian cold stage (MIS 68; 1.8 Ma) which correlates in East Anglia with an episode of subarctic conditions recognised within the Easton Bavents Clay and possibly the Chillesford Clay Member (Norwich Crag Formation). Cores from the Porcupine Basin, located to the south-west of Ireland, contain 16 separate layers of ice-rafted detritus deposited from icebergs that calved from marine-terminating glacier margins between 2.6 and 1.7 Ma. It provides the first evidence for the long-term existence of glaciers within mid-latitude areas adjacent to the North Atlantic under obliquity-forced climates. Critically, it highlights the extreme sensitivity of the British landmass to climatic cooling and the relative ease with which ice volume can build-up in highland areas. Sporadic existence of an ice cap in highland mid Wales during this broad time interval is relevant to East Anglia with Welsh erratics probably fed into the headwaters of the Kesgrave Thames within ice floes. Erratics occur in association with four separate terrace aggradations of the Sudbury Formation in Suffolk and neighbouring Essex between approximately 1.8 and 1.2 Ma.

The onset of the Mid-Pleistocene Transition at 1.2 Ma records a progressive up-scaling in climatic intensity (Figure 40). Ice sheets within Eurasia responded rapidly with the first known shelf-edge expansion of the Fennoscandinavian Ice Sheet — the Fedje Glaciation — and widespread occurrence of ice within the Baltic region at around 1.1 Ma which is believed to have overridden and destroyed the ancient ‘Baltic River’ (Figure 42a). The British–Irish Ice Sheet also shows a strong response with offshore evidence showing several expansions of ice into the Northern North Sea Basin from eastern Scotland during the ‘Cromerian Complex’. The expansion of Welsh ice as far as the Cotswold Hills is often cited as a possible mechanism for the major reorganisation of drainage that occurred in southern Britain at about 0.9 Ma (Figure 42d). East Anglia also contains direct evidence for cold-climate intensification and indirect evidence for glaciation. Cold-climate palaeosols are widely superimposed upon fluviatile deposits of the Kesgrave Thames and Bytham rivers and emergent surfaces within the Wroxham Crag Formation. They contain structures including involutions, ice wedge casts and patterned ground indicative of active-layer processes associated with permafrost development. Ice wedge casts are particularly significant as they are believed to only form when the mean annual air temperature is -6°C or below. Previously, it was thought that just one such palaeosol existed, the Barham Soil, and this developed in response to climatic deterioration during the Early Anglian. However, it is now evident that at least three older cold-climate soil horizons exist including two that occur earlier during the ‘Cromerian Complex’ and one that is of late Early Pleistocene age. Lithological evidence from coastal sediments of the Wroxham Crag Formation in north-east Suffolk and eastern Norfolk point to the activity of glaciers adjacent to, and within, the current area of the North Sea.

Sediments show a significant increase in the abundance of unstable heavy mineral varieties relative to older Crag Group sediments. These include assemblages of amphibole, pyroxene and epidote and suggest enhanced erosion, possibly by glaciers, of greenschist facies metamorphic terrains such as those of the Southern Uplands and Highlands of Scotland and western Norway. Discrete erratic lags, comprising cobbles and boulders from northern Britain and Norway, also occur and are interpreted as having been transported into the Crag Basin by icebergs derived from glaciers that calved into the North Sea.

There is now a growing understanding of the temperate environments that occurred during the late Early and early Middle Pleistocene especially within the context of early humans and the landscapes that they occupied. This time interval includes the ‘Cromerian Complex’ which, as currently defined, spans the interval from MIS 21 to 13 (about 0.9 to 0.48 Ma). It therefore includes five separate interglacial stages recognised within the marine isotope record (MIS 21, 19, 17, 15 and 13) with the Bruhnes–Matuyama (B–M) palaeomagnetic boundary occurring during MIS 19 (0.78 Ma) (Figure 40). To date, six different temperate events have been recognised in Britain based upon biostratigraphical (faunal) evidence.

However, they all postdate the B–M boundary raising the likelihood that several may correspond to climatic variability at a sub-isotope-stage scale — assigning specific ages to them is therefore problematic. Palaeoclimatic reconstructions have been built around the sedimentology of the host deposits, soils and carbonate composition (shells and calcrete), bulk floral assemblages and key floral and faunal indicators that possess constrained environmental tolerances. Collectively, they paint a complex climatic picture with some interglacials being cooler than the present day, others possessing a similar climate and others much warmer than the present day. Of particular significance are deposits at Pakefield and Happisburgh because they accumulated under different temperate climates and contain the earliest-known archaeological evidence in northern Europe. At Pakefield near Lowestoft, evidence for human occupation has been discovered within a thin channel fill called the ‘Rootlet Bed’. The deposit was laid down within a meander cut-off that formed on the Bytham River floodplain close to its estuary during either MIS 17 or later during MIS 19 but prior to the B–M boundary. Environmental proxies including soil calcrete, pollen, plant macrofossils, coleoptera (beetles), ostracods, vertebrates and molluscs demonstrate a marshy floodplain with reed beds, alder car and open grassland with deciduous (Quercus–Ulmus–Tilea) woodland developed on the valley sides. Sediments contain a number of exotic thermophile species indicative of warmer summers, such as aquatic plants Salvinia natans (floating fern) and Trapa natans (water chestnut), and milder winters including Hedera (Ivy) and Ilex (Holly) together with Hippopotamus. Coleopteran assemblages also reveal a much warmer climate with warmer mean summer temperatures (18°C and 24°C) and mean winter temperatures between -6 and 4°C, whilst soil calcretes depict a semi-arid ‘Mediterranean-type’ climate with a strong seasonal moisture deficit. In contrast, at Happisburgh in north-east Norfolk, preserved hominin footprints, the oldest known outside of Africa, and archaeology have been found within slightly older deposits that may date back to between about 0.78 and 1.0 Ma. Sediments were deposited on the floodplain of a large tidal river situated adjacent to a coastal salt-marsh. Extensive open heathland and grassland is indicated by pollen evidence with adjacent coniferous woodland dominated by Pinus (pine) and Picea (spruce). Coleopteran assemblages indicate mean summer temperatures (16 to 18°C) that were similar to East Anglia today, but with mean winter temperatures of between 0°C and -3°C that were significantly cooler. Collectively, the palaeoecological evidence from Happisburgh Site 3 demonstrates a significantly cooler and more northern climate than that of Pakefield, with the site located on the fringes of the northern ‘boreal’ forests — a good modern analogue would be southern Finland. Critically, this demonstrates the existence of markedly different temperate climates during the ‘Cromerian Complex’, and also reveals a degree of cultural and behavioural adaptability by early humans to survive within marginal environments.

Late Middle Pleistocene landscapes

Palaeogeography and geology

The Anglian Glaciation of the late Middle Pleistocene corresponds to the first shelf-edge expansion and most extensive glaciation by the British–Irish Ice Sheet during the Quaternary with over two-thirds of the British landmass covered by ice (Figure 43a). On the basis of the marine isotope record, it is widely believed that northern hemisphere ice volume was greater during the Anglian than any other Quaternary glaciation with widespread ice cover across North America and Eurasia including neighbouring Scandinavia. Correlation of the Anglian Glaciation with the Elsterian Glaciation of continental Europe has been argued by many although the age of the latter within Germany and the Netherlands is somewhat ambiguous.

Within southern Britain and East Anglia, the Anglian Glaciation records a fundamental resetting of the preglacial landscape. The Bytham River was overridden and destroyed by ice that eroded the Wash and Fen basins, whilst the lower reaches of the Thames were diverted further southwards to a course similar to its modern route. Following deglaciation, drainage became re-established and in East Anglia centred upon the Fen Basin. However, whilst the geomorphological impact of the glaciation is well known, considerable debate has centred upon the specific dynamics of the glaciation and particularly the possibility that parts of the ‘Anglian’ glacial sequences in the region may relate to older (e.g. MIS 16) and/or younger (e.g. MIS 10, 6) glaciations. These controversies have stimulated considerable debate and a range of opinions which are summarised in Chapter 10. Ultimately, these views serve to highlight the fact that the geological record can be interpreted in several contrasting ways using different stratigraphical approaches and techniques. Central to the debate, however, are the challenges of applying robust geochronology to a Middle Pleistocene record. This has proved problematic owing to the limited availability of suitable materials to date and the ages of the deposits themselves which lie at or beyond the effective limits of most dating techniques.

Despite debates surrounding the age of the ‘Anglian’ glacial sequence in East Anglia, the processes and dynamics reflected by these deposits are becoming increasingly understood with many recent studies highlighting their role as important analogues of modern glacial processes occurring in places such as Greenland. It is widely believed that East Anglia was glaciated by lobes of British ice sourced from the Pennines to the west and the North Sea and northern Britain to the north (Figure 43a). The glacial sequences of East Anglia reflect the complex interaction of these two ice lobes and several different phases of ice advance. Critically, the previously long-held belief that Norwegian ice extended into north-east Norfolk is not supported by lithological evidence nor regional models of ice flow for the Fennoscandinavian Ice Sheet in the North Sea Basin. The westernmost extent of Scandinavian ice in the North Sea is therefore not known with any confidence. However, many scientists believe that it coalesced with British ice and meltwaters formed an extensive glacial lake within the Southern North Sea (Figure 43a). This lake basin was impounded to the south by the Chalk ridge that linked Britain with Europe. Breaching of the ridge led to the initial incision of the Straits of Dover although final palaeogeographical severance of Britain and Europe during periods of high global sea level is widely believed to have occurred much later during the Ipswichian (MIS 5e). Further discussion can be found in Chapter 10.

The timing and extent of post-Anglian and pre-Devensian glaciations within the Fen Basin and adjacent Midlands is also a controversial topic. Several workers have argued for an incursion of ice into the northern margins of the Fens during the late Saalian (MIS 6) – the so-called ‘Tottenhill Glaciation’, with some re-interpreting pre-Anglian Bytham river deposits within the eastern Fen margin as glacial outwash relating to this glaciation. Other scientists consider the ‘Tottenhill Glaciation’ to equate to a slightly older glaciation that occurred during MIS 8 and is possibly equivalent to a postulated glacier incursion into the Trent catchment.

Either way, the post-Anglian glacial history of the Fen Basin remains an enigmatic topic with, at present, a lack of robust geochronology and unequivocal geological or geomorphological evidence.

Whilst the glacial history of the Fens remains poorly constrained the history of post-Anglian fluvial systems within the basin is increasingly understood. The existence of rivers within the Fen Basin reflects the fundamental change in regional topography and drainage that resulted from the Anglian Glaciation with the main depositional centre shifting westwards from the Crag Basin to the Fen Basin. Several major river systems occupy the Fen Basin including the Welland, Nene, Great Ouse and major tributaries such as the Cam, Little Ouse and the Nar, and all possess extensive river terrace deposits. However, unlike the Trent and Thames catchments which drain to the north and south of the East Anglia region, individual terrace aggradations cannot easily be delineated into regular 100 ka eccentricity-driven cycles. Instead, individual terraces are commonly separated by only several metres with the consequence that terraces of different age overlap or specific terraces may not be present having presumably been reworked and eroded — for this reason, terrace sequences have a degree of asymmetry about them. During MIS 11 (Hoxnian) and MIS 9, marine conditions prevailed within the Fen Basin resulting in the deposition of the Woodston Member (Nene Valley Formation) and the Nar Clay Formation respectively. However, estimating sea level during these interglacial stages is problematic because the post-Anglian uplift history of the East Anglia, and particularly the Fens, remains unknown.

Palaeoclimates

The late Middle Pleistocene landscape of East Anglia and southern Britain was subjected to at least seven major oscillations in climate (Figure 40). Cold climate processes have had the most obvious effects upon the landscape of the region.

Palaeoecological evidence from organic deposits, plus the youngest elements of the Barham Soil formed during the Early Anglian (MIS 12) demonstrate the widespread development of arctic tundra, permafrost and active layer processes prior to the inundation of the region by ice sheets during Britain’s most extensive glaciation. Arctic soil structures relating to at least one additional post-Anglian late Middle Pleistocene cold stage are also evident within the Breckland area of west Suffolk. Severe arctic climates were not just experienced in Britain but elsewhere throughout northern Europe with the glacial stage recognised from the marine isotope record as exhibiting the highest northern hemisphere ice volume compared to other Quaternary stages. During the succeeding late Middle Pleistocene cold stages (MIS 10, 8 and 6), other parts of northern Europe were glaciated by the Fennoscandinavian Ice Sheet. Whilst there is some offshore evidence from the UK continental margin for the existence of ice sheets in northern Britain during this time interval, the extent, timing and consequences of lowland glaciation is ambiguous and currently the subject of much debate.

Evidence for warm climates is well preserved within East Anglia with three late Middle and Late Pleistocene interglacials that correspond to MIS 11, 9 and 7. These are now well constrained across southern Britain by mammalian biostratigraphy, and increasingly by AAR and other forms of geochronology. The Hoxnian Interglacial (MIS 11), equivalent to the Holsteinian Stage of north-western Europe, is particularly well represented within East Anglia and postdiversion terrace sequences of the River Thames in neighbouring Essex. Hoxnian sites in the region include Hoxne, the stratotype locality for the interglacial stage, Sidestrand, West Stow, Elveden and Barnham. These sites typically developed as postglacial lacustrine fi within Anglian-age kettleholes or as small lowland streams or rivers superimposed upon former subglacial tunnel valleys. Palaeoecological and isotopic data suggest that the climate warmed rapidly at the beginning of the Hoxnian and was probably slightly warmer and wetter than present day at its climatic optima. A notable feature is the existence of ‘Rhenish’ (Rhine) faunas within the classic Thames localities of Swanscombe and Clacton, south of this region, which indicate an apparent palaeogeographical link at times during the Hoxnian with continental Europe. Several Hoxnian sites in the region possess important archaeological evidence demonstrating the existence of early humans in the post-Anglian landscape. For example, the archaeological site at West Stow, near Bury St Edmunds, contains evidence for the controlled use of fire with finds of several hearths. At nearby Barnham, the archaeological evidence is difficult to interpret because two separate technologies have been found within the same horizon. Firstly, at one site just cores, flakes and flake tools (previously defined as ‘Clactonian’ technology) have been discovered, whereas at the second site, a handaxe and debris from handaxe manufacture have been recovered. Whether these finds relate to peoples co-existing with different technologies or simply different activity areas is unclear at present.

Detailed palaeoclimatic evidence for other late Middle and Late Pleistocene interglacial stages in East Anglia is more limited. MIS 9-age freshwater and marine deposits have been recognised at Tottenhill in the Nar Valley and constrained by AAR and U-Series dating. The Nar Valley Freshwater Beds record the climatic amelioration at the beginning of MIS 9 with the overlying marine deposits recording a later marine inundation of the Fen margin probably around the climatic optimum. Relative sea level is, however, difficult to constrain because the maximum elevation of marine deposits (+24 m) is far in excess of the maximum known Middle or Late Pleistocene sea level suggesting that the area has been subsequently uplifted. No definitive archaeology can be attributed to MIS 9.

Late Pleistocene and Holocene landscapes

Palaeogeography and geology

The Late Pleistocene and Holocene spans the time interval from 0.125 Ma to the present day including the Ipswichian — the ‘Last Interglacial’ (MIS 5e), the Devensian (MIS 4 to 2) glacial stage and the current Holocene temperate stage (MIS 1). The Ipswichian interglacial is characterised by dominantly terrestrial fluviatile sedimentation with the development of low-energy styles of floodplain sedimentation within many of the region’s river systems including those within the Fen Basin. Determining the position of the coastline around East Anglia is more problematic as no definitive Ipswichian coastal deposits have been identified.

The Devensian (MIS 4 to 2) represents the last major cold stage to affect Britain with a major expansion of glaciers into central and eastern Britain during the Late Devensian Dimlington Stadial (MIS 2) (Figure 43b). Global sea levels during the peak of this period may have been well in excess of 100 m below present sea levels so the area of the Southern North Sea was ‘dry’ forming an extensive lowland area called ‘Doggerland’ which linked Britain to continental Europe. Archaeological evidence demonstrates the presence of early humans within ‘Doggerland’ and East Anglia only sporadically during the Devensian with the first known colonisation by Neanderthals in the late Middle Palaeolithic about 60 ka. Humans were, however, largely absent from East Anglia for notable parts of the Devensian especially during the extreme cold conditions that prevailed between 26 and 14 ka. During much of the Devensian, the landscape in East Anglia and much of southern Britain had limited vegetation cover and was dominated by cold climate processes such as freeze-thaw weathering, permafrost and active-layer development, and aeolian and hillslope mass-movement phenomena. These surface processes coupled with the prevailing background climate led to a dramatic increase in catchment sediment budgets leading to the deposition of coarse-grained braidplain deposits associated with high seasonal-flow regimes with subsequent downcutting forming small terrace aggradations. Extensive fluviatile deposits of this age are widely developed within most catchments in the region, for example the Nene (Nene Valley Formation) and Cam (Cam Valley Formation), which at the time drained into ‘Doggerland’.

East Anglia lay at the maximum southernmost extent of the eastern/North Sea sector of the Last British–Irish Ice Sheet during the Dimlington Stadial (Figure 43b). Deposits relating to this glaciation fringe the Wash margins and the north-west and north Norfolk coastline and form the Holderness Glacigenic Formation. The major till facies of the Holderness Glacigenic Formation is the Holkham Till Member and it has been correlated with equivalent till facies to the west of the Wash in Lincolnshire and further to the north in East Yorkshire. The precise timing of ice incursion into East Anglia is unknown, however, the ice sheet is considered to have reached its maximum spatial extent around 27 ka. The ice sheet was confluent with the Fennoscandinavian Ice Sheet in the Northern North Sea until about 25 ka when it gradually began to decay. Collapse of all ‘marine’ areas of the ice sheet occurred by 17 ka with widespread withdrawal of ice margins towards their highland accumulation areas by 15 ka. Several workers have suggested the existence of a proglacial ‘Lake Fenland’, which formed part of more extensive ice-marginal drainage system that includes lake basins within the Humber and Vale of Pickering. However, unequivocal evidence for such a lake basin in the Fens has proved elusive. Beyond the ice margin, much of East Anglia formed barren arctic tundra and was extensively affected by periglacial processes. Evidence for periglacial conditions is particularly well preserved within the Breckland area, the evidence includes patterned ground, involutions, pingos and palsas. At Thompson Common near Thetford over 40 pingos* and palsas* occur on the modern floodplain of a tributary of the River Wissey and form the theme of a popular walk called ‘The Great Eastern Pingo Trail’. Aeolian processes also dominated the Late Devensian landscape with the cyclic deposition and reworking of a variably thick sequence of windblown sand (coversand) and silt (loess) across the Breckland, west and north Norfolk and the lower Waveney Valley. Collectively they form part of an extensive ‘European Coversand Sheet’ that developed in nonglaciated areas across western and central Europe.

Rapid and sustained climatic warming marked the end of the Late Devensian and continued through into the early Holocene that commenced at 11.7 ka. Associated with this climatic amelioration was the progressive submergence of ‘Doggerland’ (Figure 44) during a rapid rise in global sea level. ‘Doggerland’ was largely submerged by about 8.5 ka with the marine incursion probably reaching the modern tidal embayments of the Wash–Fen basins (Chapter 11). Final submergence of the ‘Dogger Hills’, a small hilly area of ‘Doggerland’ occurred by about 7 ka.

Vegetation became quickly established with the development of thick woodland across much of East Anglia. The reduction of sediment budgets and catchment gradients caused a marked decrease in the energy of the major river systems with a progressive switch to low-energy floodplain styles of sedimentation. The increased population and activity of humans during the Mesolithic resulted in a marked change in the landscape of East Anglia and the transition from hunter-gatherers to cultivation and forest clearance. From as long ago as 4.5 ka, forest clearance and more recently overgrazing and modern agricultural practices within the Breckland have acted to destabilise the land surface causing the episodic reactivation of the Devensian coversand sheet and ‘sand blow’ events. Humans have interacted with the landscape in other ways such as drainage modification, land reclamation (e.g. Fens) and resource extraction (e.g. water, peat, sand and gravel). But it is perhaps the process of urbanisation and installation of infrastructure (e.g. transport and utility networks) that has had the most marked change on palaeogeography and geology by creating a new form of ‘anthropogenic geology’ (Anthropocene).

Palaeoclimates

The Ipswichian is well constrained both climatically and biostratigraphically and is equivalent to the Eemian Interglacial of continental Europe (Figure 40). The region includes the Ipswichian stratotype at Bobbitshole, near Ipswich, and numerous well-studied fluvial sites including Fenstanton, situated to the north-west of Cambridge, and Wretton near Downham Market. Of particular significance is the presence within the region of tropical or subtropical faunas including Hippopotamus amphibus (hippopotamus) and Emys orbicularis (European pond tortoise) which suggest average summer temperatures significantly warmer than the present day. This climatic interpretation is supported by pollen records which show the overlap of Carpinus (hornbeam) with other thermophilus species. However, no locality within the region exhibits a complete climatic record of the Ipswichian which has to be pieced-together from several sites. Global sea levels during the interglacial have been estimated as being some 4 to 6 m higher than present although the position of the Ipswichian coastline is difficult to establish. Previously, raised beach deposits at Morston in north Norfolk were attributed to the Ipswichian but new OSL dating of the deposits suggests that they probably relate to the preceding MIS 7 interglacial. There is a complete absence of archaeology from the Ipswichian in Britain, and indeed with the adjacent cold stages of MIS 6 and MIS 4, represents a gap in the archaeological record of 120 000 years. It has been suggested that this absence may be due to a combination of inhospitable climates during low sea levels (cold stages) and high sea levels during the Ipswichian which separated Britain from mainland Europe.

The Devensian, equivalent to the Weichselian of continental Europe, represents the last cold stage within the Quaternary. East Anglia for the most part appears to have been dominated by cold, arid continental climates; however, these conditions appear to have been punctuated occasionally by slightly warmer intervals known as interstadials. During the Early Devensian (MIS 4), palaeotemperature determinations derived from coleopteran assemblages suggest that average temperatures of the coldest month were well below -20°C with peak summer temperatures approaching 9°C. Similar climates have been reconstructed for the Late Devensian ‘Dimlington Stadial’ (MIS 2) with widespread occurrences of periglacial phenomenon such as involutions, ice wedge casts, pingos, palsas and coversand indicating the presence of frozen ground or permafrost. Indeed, it appears that throughout much of the Early and Late Devensian, humans (Neanderthals) were absent from Britain owing to the extreme climates. Evidence from Lynford, west Norfolk, provides the earliest known human presence in Britain during the Devensian and a brief period of human occupation between about 60 to 43 ka. This time interval corresponds to a significant Mid Devensian (MIS 3) interstadial with evidence showing that the Lynford archaeological site was developed on the swampy margins of the River Wissey with floras and faunas demonstrating a cold, treeless landscape. Average winter and summer temperatures reconstructed from coleopteran assemblages from several localities in East Anglia and the London area show a less extreme climate and a marked seasonality with average summer temperatures of between 16°C and 17°C and average winter temperatures of -4°C to -10°C.

The transition between the Late Devensian glacial maximum (the ‘Last Glacial Maximum’ or LGM) at about 27 ka and the Holocene is characterised by a gradual amelioration of climate (‘Termination 1’) and includes a period between about 16 and 10 ka commonly referred to as the ‘Late Glacial Interstadial’ (Figure 45). It accompanies the widespread collapse of the major European ice sheets and the rapid withdrawal of ice margins into highland accumulation areas. Recent studies of ice cores from Greenland provide a near-annual record of climate for the Termination 1–Holocene transition. They indicate the transition was not smooth and was punctuated by several abrupt cooling and warming events (Figure 45). Abrupt cooling, known as Heinrich Events, relate to massive influxes of cold freshwater into the North Atlantic during the catastrophic melting and collapse of the Laurentide Ice Sheet in eastern north America. The introduction of cold freshwater into the North Atlantic led to the shutting-down of the North Atlantic Current plunging Greenland and north-western Europe back into glaciation. The last Heinrich Event, H0, led to a cold event called the Younger Dryas (Loch Lomond) Stadial which lasted nearly 1000 years (Figure 45). It resulted in the temporary reactivation of periglacial processes in the Brecks and the re-advance of small glaciers in highland areas of Britain. Human occupation was once again interrupted during a short return (about 1 ka) to cold conditions associated with the Younger Dryas Stadial but humans returned by about 11.9 ka.

The climate rapidly warmed during the Holocene with optimum conditions reached during the Holocene Climatic Optimum (HCO) between about 9 and 6 ka (Figure 45). However, Holocene climates have not been stable but have consistently oscillated and this continues to the present day. For example, the climate of Southern Britain has been affected by a number of sharp, short-lived climatic deteriorations such as the 8.2 ka event, although the effect of these upon the geology and landscape of East Anglia is unclear. Since the Industrial Revolution, global climate has warmed markedly with many scientists indicating a link between greenhouse gas emissions and global warming. Recent research suggests that the Earth’s surface has warmed by around 0.5°C since the 1970s. Average global temperatures are estimated to rise between 1.1 and 6.4°C above the 1990 level by the end of the 21st century and this could cause sea levels in the North Sea to rise by as much as 0.3 to 0.5 m by the latter part of the century depending upon various greenhouse gas emission scenarios. Climatically it is estimated that this global temperature rise will result in marked changes in seasonality and weather patterns. The future effects of global warming, changing weather and sea-level change are highly relevant to East Anglia as they potentially have major implications for how humans interact with the landscape and underlying geology, and in turn, economic growth, sustainable development and resource management.

Chapter 8 Late Pliocene and Pleistocene marine deposits

S J Mathers and R J O Hamblin

Introduction

Since at least the Pliocene, East Anglia has been located along the western margin of the southern North Sea Basin. Prior to the late Middle Pleistocene, this southern part, commonly referred to as the Crag Basin, was a relatively shallow-water, tidally dominated, marine embayment. The emergent parts of East Anglia formed a low-lying coastal plain drained by several major river systems that together with river systems draining the Low Countries fed a large, prograding delta in the southern North Sea (Chapter 7). Progressive subsidence, partially driven by crustal loading of this large sediment wedge, combined with frequent climate-driven sea-level (eustatic) change meant that the palaeogeography of East Anglia was subject to rapid changes. During periods of emergence, terrestrial conditions prevailed resulting in the deposition of river-terrace sequences and palaeosols (Chapter 9), whist during marine transgression, the sequences of shallow-marine clastic sediments described in this chapter were deposited.

During the Anglian Glaciation (0.45 Ma; MIS 12) drainage from confluent British and Scandinavian ice sheets apparently led to the development of an extensive glacial lake within the central North Sea. Catastrophic drainage of this lake led to the initial incision of the Straits of Dover and linked the southern North Sea with the English Channel although this link was probably restricted until the Ipswichian (0.125 Ma; MIS 5e) (Chapter 7). Following the Anglian, East Anglia lay largely beyond the limits of all but the highest sea-level highstands with marine conditions restricted to the major river estuaries and embayments such as the Wash. Within this chapter we examine the distribution, context and significance of the East Anglian marine deposits both before and after the Anglian Glaciation.

Pre-Anglian marine deposits

Shallow marine deposits that span the interval from the early Pliocene through to the Early Pleistocene and the onset of the Anglian Glaciation collectively form sediments of the Crag Group. However, evidence of marine conditions in the region reaches back into the Miocene provided by the evidence of older marine faunas contained in phosphatic concretions (locally known as box-stones) found within the basal lag deposits of the older Crag Group deposits in Suffolk. These provide evidence of phosphogenic episodes and notably contain teeth of the Miocene giant shark Carcharocles megalodon. The Crag Group deposits comprise calcarenites and shelly sands passing upwards into fine micaceous sands with lenticular bodies of silt and clay and localised gravel-rich facies.

An overall pattern of the preservation of progressively shallower-water marginal deposits is apparent. Macro- and microfossils together with trace fossils (bioturbation) are common throughout the Crag Group and provide detailed biostratigraphical control as well as palaeoenvironmental and palaeoclimatic information.

In the past, many divisions of the Crag Group have been proposed, but as lithostratigraphical units, many have not stood the test of time. Currently, four distinct lithostratigraphical divisions of the Crag Group are recognised, however, it is important to note that the overall sequence is not continuous but punctuated by multiple unconformities and non-sequences representing hiatuses in sedimentation commonly of considerable duration.

The oldest formations comprise the Coralline Crag and Red Crag formations and have been recorded from the many shallow pits in southern Suffolk. The formations are respectively Early Pliocene and Late Pliocene to earliest Pleistocene in age (Figure 46), however they are included here within this chapter because they both show considerable palaeogeographical and stratigraphical affinity to the overlying ‘Quaternary system’. These older Crag Group deposits are overlain in southern Suffolk by well-sorted fine sands of the Norwich Crag Formation which are of Early Pleistocene age. These Norwich Crag deposits, extending northwards into northern Suffolk and Norfolk, locally contain lenticular silt–clay bodies and gravel-rich facies. These sediments are unconformably overlain by the Wroxham Crag Formation which was deposited during the late Early Pleistocene and early Middle Pleistocene and comprises the youngest of the four Crag Group formations. Much of the Crag Group within the region has a limited surface outcrop expressed as shallow pit excavations or cliff sections, more commonly these sediments lie beneath younger Quaternary deposits.

Structure of the Crag Basin

Competing theories exist to explain the preserved distribution of the Crag Group sediments in East Anglia (Figure 47). Two main features are apparent, the base of the Crag deposits falls eastwards towards the southern North Sea Basin and in mid and south Suffolk the distribution of the deposits appears to be controlled by north-east aligned ridges and basins.

The elevation of the base of the Red Crag Formation to the west of the East Anglia region reaches +90 m around Stansted Mountfitchett in Essex, and is reported in an outlier at about +130 m at Rothamsted in Hertfordshire. The base of the deposit with a similar lithology and fauna also lies below -65 m around Lowestoft (Figure 47). In the southern North Sea east of East Anglia the base of the Quaternary falls to below -500 m and locally over 600 m of Quaternary sediments are preserved.

This range of elevations far exceed those possible by relatively short-term glacioeustatic control and indicates substantial differential crustal movement across East Anglia with significant uplift in the inland areas and subsidence around the coast and offshore. Regional tilting is entirely consistent with the long-established overall pattern of uplift in western Britain and subsidence in the North Sea Basin. This progressive tilting is also supported by the pattern of eastwards drainage into the North Sea that has dominated most of southern Britain since at least the Pliocene and episodes of this fluvial history are extensively described in this account (Chapter 9).

Superimposed on this broad regional pattern are the well-defined ridges and basins in mid Suffolk that include the Stowmarket–Stradbroke Basin (Figure 47). The elevation of the base of the Crag deposits can vary abruptly by at least 30 to 40 m between the basin lows and the adjacent intervening ridges where the Crag sediments have sometimes been completely eroded. The marked linear nature of these basins, their apparently steep margins and local gravity anomalies have all been proposed to support a fault-controlled tectonic origin.

Alternatively, some workers have pointed to the possibility of tidal scour or perhaps even fluvial action in large estuaries to explain the observed distribution. Supporting evidence for this view includes the fact that the basins are parallel to the strike of the Chalk bedrock and could result from the preferential erosion of softer units within it.

Lithostratigraphy

The Coralline Crag Formation is the oldest unit within the Crag Group (Figure 46). Its principal form is as a north-north-east-aligned buried ridge between Aldeburgh and Orford in south Suffolk where it rests unconformably upon the London Clay Formation (Figure 48a). The similarity in size and shape of this buried ridge and modern tidal sand ridges in the North Sea have led several authors to suggest the main body of the Coralline Crag is a preserved tidal sand ridge. Farther south-west outliers occur around Ramsholt, adjacent to the River Deben, and at Tattingstone, south of Ipswich. The deposit reaches in excess of 20 m thickness along the axis of the buried ridge and thins towards the flanks. The Coralline Crag contains a rich and diverse fauna and a selection of typical Coralline Crag macrofossils are depicted in Plate 15 (e, h–l, n–q). Detailed sedimentological and palaeontological studies of borehole cores and exposures in old pits and river cliffs have enabled division into three facies of member status.

The oldest and most extensive unit is the Ramsholt Member. Up to 7.5 m thick, it forms outliers at Tattingstone, Ramsholt Cliff and the nearby Rockall Wood exposure, and from the main part of the Coralline Crag. It comprises a basal phosphate-rich gravel lag deposited during a marine transgression overlain unconformably by aragonitic, shelly, mud-rich sands. These show extensive bioturbation indicating slow rates of sedimentation and relatively weak bottom currents with a foraminiferal assemblage indicating water depths of up to 50 m. A well-preserved molluscan fauna is present due to limited dissolution of aragonitic shells together with a restricted cacitic bryozoan fauna dominated by Metarabdotus monilifera and Cellaria sp. Correlation of these faunas with other records from the North Sea Basin suggests that deposition occurred during the Early Pliocene before about 3.4 Ma and the ‘mid Pliocene’ warm interval. The precise climatic signal is however, more equivocal, with different micro- and macrofossil assemblages indicating a range of climatic conditions from cool temperate through to much warmer temperate and Mediterranean-type climates. The Sudbourne and Aldeburgh members unconformably overlie the Ramsholt Member along the main buried ridge.

The Sudbourne Member is up to 15 m thick and overlies the Ramsholt Member throughout most of the main mass of the Coralline Crag. It comprises a series of slightly muddy cross-stratified calcarenites (Plate 16a,) and generally becomes finer grained towards the south-west. These deposits record the migration of large tidal sand waves towards the south-west, burrows and bioturbation are rarely preserved suggesting a high, but slightly fluctuating, sedimentation rate. Faunal remains of molluscs and bryozoans are highly abraded suggesting that they are reworked from other deposits. In the Orford area the highly porous Sudbourne Member is commonly lithified with a calcitic cement.

The Aldeburgh Member comprises up to 14.5 m of shelly carbonate sands and is only present within the northern part of the distribution of the Coralline Crag Formation around Aldeburgh. The deposits comprises a low-angle, cross-stratified medium sand that coarsens upwards, with abundant burrows and silt drapes indicating low but gently fluctuating sedimentation rates. In the lower parts of this unit molluscs dominate but in the upper part an abundant and diverse bryozoan fauna is preserved.

The evidence suggests that the upper parts of Aldeburgh Member interdigitate with the former perhaps forming upcurrent in quiet, deeper water and acting as source of skeletal material for the higher-energy Sudbourne Member (Figure 48b).

The Red Crag Formation (Figure 46) crops out in southern Suffolk where it has been extensively studied in shallow pit exposures and in coastal cliffs and is also encountered at depth in boreholes in the deeper parts of the Crag Basin throughout the region. The stratotype of the Red Crag Formation is defined as the interval between 6.82 m and 26.00 m within the Wantisden Hall Borehole east of Woodbridge (Figure 47). In this area, the formation rests unconformably upon the London Clay Formation and locally in the Orford–Aldeburgh area it is banked against the buried ridge formed by the Coralline Crag Formation. Farther north and east in the region it oversteps onto older Palaeogene deposits and the Chalk Group. The lithology of the Red Crag Formation comprises heavily iron-stained medium- to coarse-grained, relatively poorly sorted shelly sands and sands. The Red Crag Formation is composed of planar and trough cross-bedded sands with occasional mud drapes and bioturbated horizons and these record the migration of large tidal sandwaves. Where preserved below the water table, and hence un-oxidised, the sands retain their original dark green colour owing to the reduced iron and high glauconite content. Near, and at, the surface they are oxidised to yellow or reddish brown, with ferruginous concretions (iron pan) and are commonly decalcified. At the base of the deposit there is commonly a gravel lag deposit composed of phosphatic nodules and rounded flint together with more exotic lithologies; this lag is reworked from older Neogene deposits and the London Clay Formation. The sands are locally very shelly (Plate 16b), and the most common fossils are bivalves and gastropods, but these are commonly heavily abraded.

Common fossils recorded include bivalves Astarte obliquata (J Sowerby); Cardium parkinsoni (J Sowerby), Glycymeris glycymeris (Linnaeus) and Spisula arcuata (J Sowerby), gastropods Hinia granulata (J Sowerby), Natica multipunctata (S V Wood), Neptunea contraria (Linnaeus), and Nucella tetragona (J Sowerby); and the echinoderm Echinocyamus pusillus (Müller). A selection of some typical Red Crag fossils are shown in Plate 15 (a–d,f–g, m).

To the north of Aldeburgh, borehole cores enable the Red Crag Formation to be divided into two members and record a progressive shallowing of marine conditions (Figure 49). The lower unit, the Sizewell Member comprises up to 13 m of medium- and coarse-grained, moderately to poorly sorted, grey-green, glauconitic sands interbedded with thin beds of finely laminated clay, silt and fine sand. The member is interpreted as being deposited in a subtidal environment. These sediments are normally magnetised and the micropaleontology is distinctive enabling a Late Pliocene Pre-Ludhamian age to be established. The overlying Thorpeness Member is 20 m to 30 m thick, and comprises two coarsening-upward cycles of fine- to coarse-grained cross-bedded sands with thin beds of silty clay, rip-up clasts of silty clay and rare phosphate pebbles. Large cross-stratified sets up to 5 m thick imply water depths of up to 25 m with a dominant flood tidal component encompassing bars and ridges prograding towards the south-west. These are interpreted as large-scale subtidal sand ridges and bars or regressive cycles. These deposits are at least in part reversely magnetised and correlation with the Ludhamian Stage has been tentatively suggested.

Farther north, the Red Crag Formation is present at depth in the deeper parts of the Crag Basin. It has been studied in detail in boreholes at Stradbroke, Ludham and Ormesby. At Stradbroke, the lower parts (-15 m to -39.4 m) of the Red Crag Formation exhibit a normal magnetic polarity attributed to the Gauss Chron (about 3.86 to 2.58 Ma), with pollen biostratigraphy enabling the age to be correlated with the Pre-Ludhamian, so the deposits appear to be contemporaneous with the Sizewell Member of the Aldeburgh–Sizewell area. They are overlain, apparently conformably, by some 45 m of ‘Ludhamian’ deposits. The strata differ from the type section, however, comprising green and grey sands, coarse-grained and shelly below, becoming finer and less shelly upwards, locally with cemented sandstone beds, claystone nodules, and beds of dark blue and grey silt and clay up to 9.9 m thick. These are believed to be of sublittoral origin and may correlate with the Thorpeness Member.

The Ludham Borehole contains about 70 m of Red and Norwich Crag deposits and the lower parts of the sequence are identified as Ludhamian in age, so Pre-Ludhamian deposits are apparently absent. This Red Crag sequence may also correlate with the Thorpeness Member farther south.

In the Ormesby Borehole (Figure 50), a thinner sequence of the Red Crag Formation occurs between -45.73 m and -70.43 m depth and consists of shelly bioturbated sand and clay (Unit 1) overlain by rippled, flaser-bedded and lenticular-bedded sand, silt and clay (Unit 2). These units record a change from subtidal to muddy tidal-flat sedimentation forming a regressive sequence that is lithologically dissimilar and hence difficult to correlate with the other studied cores.

Offshore, pollen of Thurnian type (Ludhamian) is found in the Westkapelle Ground Formation. These deposits also exhibit a reversed magnetic polarity, probably associated with the earliest parts of the younger Matuyama Chron (about 2.58 to 0.78 Ma). These parts of the formation are similar to the Thorpeness Member onshore and the Ludhamian Stage deposits. However foraminifera from the formation indicate an upwards decrease in water depth and increase in energy levels, as found in the complete Red Crag Formation sequence between Aldeburgh and Sizewell. Thus, the Westkapelle Ground Formation may correlate with most of the Red Crag Formation onshore, with the major seismic reflection surface at the base correlating with the base of the Red Crag Formation.

The Norwich Crag Formation (Figure 46) represents a thin but widespread sheet of tidal flat and coastal sediments, formed in shallow-water marginal marine environments. It occurs widely throughout the southern parts of the Crag Basin in Suffolk and southern Norfolk. The Norwich Crag Formation has a strongly unconformable base which records a major Early Pleistocene marine transgression (about ‘Antian/Bramertonian’ age). The formation oversteps to rests upon the Chalk Group in the vicinity of Norwich. Farther south it overlies the Coralline Crag Formation around Aldeburgh and Orford, and the Red Crag Formation across most of the remaining parts of its distribution. Based largely on studies in coastal southern Suffolk, the Norwich Crag Formation may be broadly divided into intertidal to subtidal sands (Chillesford Sand Member), overlain by intertidal silty clays (Chillesford Clay Member and Easton Bavents Clay) together with shoreface and nearshore wave-dominated gravel deposits referred to as the Westleton Beds. In north-east Norfolk the Sidestrand Member, composed of tidal marine sands and gravels, is differentiated. However, its exact relationship to other components is uncertain.

The Chillesford Sand Member is well developed in southern Suffolk (Figure 49). It comprises a widespread sheet of well-sorted, fine- to medium-grained micaceous sands up to 15 m thick. Preserved macrofossils are generally absent. Sedimentary structures include horizontal bedding, ripple marks, flaser bedding, thin clay drapes, small trough cross-sets up to 0.3 m thick, vertical burrows, channel scours and mud cracks. These structures indicate bidirectional currents and locally rapid deposition within an intertidal environment such as tidal flats or an estuary. The Chillesford Sand Member extends inland to Elsenham in Essex beyond the limit of the region, and northwards into coarser, shelly, glauconitic sands that are more typical of a transition to shallow marine sedimentation. Farther north at Bramerton, the Norwich Crag Formation comprises a series of probable temperate–cool cycles and several fining-upwards sequences comprising shell and gravel beds and bioturbated silts and clays. They are interpreted as forming part of regressive sequence with sedimentation taking place within a tidal environment. Based on pollen and mollusc stratigraphy, they are widely believed to be of Antian or Bramertonian age, which are correlated with the Tiglian C3 substage of The Netherlands.

The Chillesford Clay Member, with a type locality at Chillesford Brickyard east of Woodbridge, is an elongate body of silty clay up to 5 m thick and extending across an area of about 50 km2 from Aldeburgh south-west to Butley. The clays are generally unfossiliferous, grey in colour, with weakly defined silt and clay laminae and occasional thin beds of sand. Indigenous pollen grains identified are largely non-arboreal and indicate a climatic deterioration from a cool oceanic to a cold climate, while foraminifera indicate a decline from temperate to cool. Studies of derived microfossils from the Sudbourne Borehole revealed a range of species within the Chillesford Clay Member. Of particular significance is the presence of Silurian acritarchs from the Welsh borders which were likely to have been transported into the Crag Basin by the Kesgrave Thames river. This, combined with a paucity of contemporary marine microfossils, demonstrates that the clays were not deposited within an open marine environment, but more probably within tide-dominated estuaries or lagoons.

The Chillesford Clay Member does not extend northward beyond Aldeburgh, but similar clays, including the Easton Bavents Clay, crop out on the coast between Easton Bavents, Covehithe and Benacre Ness where they are interbedded with sands and gravels, which commonly cap them and truncate them laterally. These clays are also grey in colour, and locally very silty, containing lenticular bedding, scattered silt and sand laminae, and occasional beds of fine-grained sand with clay laminae. Ripple-drift cross-lamination, plant remains and horizons of mud cracks are evident at both localities indicating high intertidal or estuarine deposition, whilst foraminifera and molluscs from other clay beds indicate sublittoral to intertidal conditions. The clays pass laterally and vertically into gravel layers or into sands characterised by trough cross-bedding and ripple-drift cross-lamination, flaser bedding and small-scale channelling, gravel trains and mud drapes. Thicknesses of these clay units vary markedly. For example, a 2 m-thick clay bed can be traced within the base of the cliffs between Covehithe and Benacre Ness, whilst borehole records between Beccles and Lowestoft, prove up to 5.8 m of stiff greenish grey silts and silty clays containing wispy stringers and irregular lenses of fine-grained white sand. Taken together, these strata indicate variable shallow marine to intertidal and supratidal environments in a shifting complex of muddy lagoons and gravelly beach bars, not dissimilar from that part of the coast today.

Pollen assemblages, foraminifera and molluscs indicate that the clays accumulated under a very cold climate. This cold period is correlated with the Baventian cold stage after its Easton Bavents stratotype. It occurred at about 1.8 Ma and is considered to be equivalent to the Tiglian C4C of the Netherlands. Deposits of similar age have been interpreted from the Ormesby Borehole north-west of Great Yarmouth where they rest on the Red Crag Formation. They lie between 27.50 and 45.73 m depth and comprise rippled and cross-bedded sands with thin beds of lenticular bedded silt and massive clay characteristic of sandy tidal-flat sedimentation (Figure 50, Unit 3).

Studies of microfossils from the Easton Bavents Clay at the type site and similar clays at Thorrington yielded significant proportions of far-travelled species. These included reworked Carboniferous (Dinantian to Namurian) spores and Jurassic (Pliensbachian to Late Jurassic) miospores and dinoflagellate cysts, with progressively smaller quantities of locally derived Cretaceous, Palaeogene and Neogene species, and very few indigenous marine species. The Carboniferous spores and Jurassic miospores are considered to have been derived from the Pennines and East Midlands respectively, and transported into the Crag Basin by the Bytham River. In a similar scenario to the Chillesford Clay Member, the paucity of indigenous marine species coupled with high quantities of far-travelled microfossils point to restricted marine conditions and probably estuarine (Bytham) conditions. Analysis of heavy minerals showed high percentages of garnet (up to 30.0 per cent) and zircon (up to 41.5 per cent). These appear to be residual heavy minerals within the Crag Group implying gentle reworking and deposition of sands within the Crag Basin. However, studies of provenance-sensitive heavy mineral ratios (apatite : tourmaline, rutile : zircon, monazite : zircon, chrome spinel : zircon and garnet : zircon) and geochemical studies of detrital garnets reveal their primary source was probably from Palaeogene bedrock to the west. This implies input principally from the Kesgrave Thames that crossed these strata, but more fundamentally, a comparatively low energy river system that transported fine materials as suspended load.

Around Southwold, Halesworth and Dunwich the upper parts of the Norwich Crag Formation contain bodies of highly sorted flint gravel commonly referred to as the Westleton Beds (Figure 51). Typically, they comprise well-sorted pebble and cobble sized clasts of well-rounded, high-sphericity, chatter-marked flint with occasional clasts of vein quartz and yellow quartzite. Fossils, including marine molluscs and whale vertebrae have also been found within these deposits. Three distinct facies of the Westleton Beds are evident:

  1. Planar cross-bedded gravels (Figure 51a), organised in sets up to 10 m thick, inclined towards the south and east at angles up to 10° (Plate 16c).
  2. Horizontally bedded sands with deeply incised gravel-filled channels
  3. Regularly spaced broad channels infills 10 to 15 m wide and up to 2 m deep rimmed with gravel and filled by sands (Figure 51b). Collectively, these facies are interpreted as a complex of wave-dominated shoreface and nearshore gravels (Figure 52) possibly formed during a eustatic fall in sea level. The coastline appears to have been orientated broadly north-east to south-west at the time, based on the inclination of the large shoreface gravel foresets (Figure 51).

The constituent lithologies of the Westleton Beds gravel also provide discrete clues as to the systems contributing sediment into this part of the Crag Basin. The dominant lithology (>90 per cent) is the very well-rounded and chatter-marked flints that closely resemble clasts from gravels and pebble beds found in the Palaeogene strata of south-east England. Whilst ultimately derived from the Chalk Group, they could easily have been reworked into the Westleton Beds from a secondary Palaeogene source. Some 6 to 10 per cent of the flint pebbles are ‘spicular flints’ and these are derived from the Welton and Burnham formations of the Lincolnshire Chalk. Other lithologies include vein quartz and quartzite (up to 4 per cent) from the Triassic Kidderminster Formation of the English Midlands and ‘Rhaxella chert’ from the Corallian (Jurassic) of Yorkshire. Their presence within the Westleton Beds is, however, problematic because other evidence suggests that the rivers of the region were generally unable to transport coarse bedload over long distances. So the likely explanation is that gravel has undergone multiple phases of coastal and fluvial reworking since the Palaeogene with its presence within the Westleton Beds reflecting a final phase of recycling during ‘Norwich Crag times’. Taken in connection with the estuarine Easton Bavents Clay with which the Westleton Beds appear closely associated, the clay would interpreted as being deposited in a shifting complex of muddy lagoons and estuaries protected to seaward by the shoreface gravel barriers and spits. A modern analogue would be the beach gravels forming nearby at Orford Ness with the clays representing the protected marsh deposits between Aldeburgh and Boyton (see also Chapter 11).

In north-east Norfolk, a further facies of the Norwich Crag Formation called the Sidestrand Member is evident where it rests unconformably upon the relatively stable Chalk bedrock platform. This deposit crops out between Weybourne and Beeston and then discontinuously as far south as Trimingham where it is overlain by younger Crag deposits. Farther south, the deposit is now obscured by modern beach material. At Weybourne, the deposit comprises well-rounded flints and quartzose gravel sheets, cross-bedding with clay drapes, and fining- and coarsening-up sequences of rippled sands and clay laminae. The deposit is interpreted as tidal and produced by a single marine transgression. Beds containing marine bivalves, including Macoma balthica, are common, along with mammal bones presumably reworked (locally) including the mammoth Mammutus meridionalis and the deer Alces gallicus. Vole teeth demonstrate the presence of Mimomys pliocaenicus, M. blanci, M. reidi, M. (Borsodia) newtoni and M. pitymyoides. At Marl Point, Trimingham, and Overstrand, allochthonous Sidestrand Member deposits can be seen resting upon the Chalk Group within a series of spectacular glacitectonic rafts (Chapter 10). The Sidestrand Member is the oldest unit of the ‘Crag Group’ seen at crop in north Norfolk, an interpretation supported by a reversed palaeomagnetic signature from Weybourne which suggests deposition during part of the Matuyama Chron between about 2.58 to 0.78 Ma, but correlation with other Norwich Crag deposits in the southern parts of the region is uncertain.

Offshore, dinoflagellate cyst and pollen assemblages resembling those of the Antian (Chillesford Sand Member) are recorded from the Smith’s Knoll Formation whilst a molluscan fauna similar to that of the Baventian/Pre-Pastonian was recovered from the Crane Formation indicating an Early Pleistocene age.

The Wroxham Crag Formation represents the fourth and youngest division of the Crag Group (Figure 46) and forms a relatively thin sheet of tidal-flat and coastal sediments that extends from Thorington and Covehithe in Suffolk, northwards to Weybourne on the north Norfolk coast. It represents a new subdivision of the ‘Crag Group’ and is lithologically distinctive owing to its relatively higher proportion (over 10 per cent) of far-travelled lithologies (Figure 53). Previously, these deposits were recognised as being of fluvial origin based upon their lithological similarity to the Kesgrave and Bytham catchment subgroups. However, surveying has subsequently proven considerably more restricted sediment tracts for both river systems with sedimentary evidence demonstrating that much of this material in Norfolk and northern Suffolk is of shallow marine and coastal origin. The Wroxham Crag Formation therefore includes all marine deposits in northern East Anglia formed after the introduction of significant quantities of far-travelled quartz and quartzite into the basin from rivers draining central and eastern England. This records a significant increase in the dynamics of these river systems, and their increased ability to transport a coarse-grained bedload from their headwaters in Central England to their estuaries within East Anglia. The Wroxham Crag Formation comprises interbedded gravels, sands, silts and clays, deposited in beach, estuarine and tidal-flat environments (Plate 16d).

In the coastal Norfolk–Suffolk borders, the Wroxham Crag Formation formed as the upper part of the Crag sequence in the main deep parts of the Crag Basin. Here two facies of the Wroxham Crag Formation may be recognised, the Dobb’s Plantation and How Hill members (Figure 46), these can be distinguished by their clasts and heavy mineralogy. The Dobb’s Plantation Member has been recognised across south Norfolk and northern Suffolk within boreholes and observed within sections. It typically comprises flint-rich sands and gravels with 10 to 15 per cent of far-travelled lithologies including white or colourless vein quartz and quartzite, and minor but persistent quantities of Carboniferous chert and Rhaxella chert. Dominant non-opaque heavy minerals include garnet, zircon and varying proportions of epidote. These are largely residual minerals within this part of the Crag sequence implying reworking of pre-existing materials rather than fresh inputs of large quantities of far-travelled material. Together, heavy minerals and clast lithologies may be linked to input from the catchment of the Bytham River system but indicate an increased ability of the river system to recycle coarse-grade materials from its headwaters to its estuary. However, the dominance of residual Crag Basin heavy minerals in the Dobb’s Plantation Member still indicates that the river systems were predominantly transporting suspended load and hadn’t the energy or efficiency shown by later fluvial systems associated with the How Hill Member deposits.

Exposures of the Dobb’s Plantation Member are mainly restricted to pit sections, many of which are now disused. At several sites, including Reydon, Thorington and Holton to the south-west of Lowestoft, Norton Subcourse to the north of Bungay and Dobb’s’ Plantation near Wroxham, sands and gravels of the Dobb’s Plantation Member unconformably overlie the older Westleton Beds. The Dobb’s Plantation Member is also tentatively interpreted as being present in the upper horizons of the Ormesby Borehole (27.50 to 14.36 m depth) where rippled and flaser-bedded sands with occasional flint and quartzose pebbly horizons are evident (Figure 50, Unit 4). These facies probably record sedimentation within a sand-dominated tidal flat.

The How Hill Member overlies the Dobb’s’ Plantation Member across much of north-east Suffolk and south-east Norfolk within the main part of the Crag Basin, and has been recorded within numerous boreholes in the Waveney valley and Broadlands areas. Exposures are currently limited to a discontinuous coastal section between Covehithe, Pakefield and Hopton. Lithologically, the How Hill Member is highly distinctive containing much higher proportions (up to 30 per cent) of far-travelled lithologies than the underlying Dobb’s’ Plantation Member. These include red-brown vein quartz and quartzite (15 to 22 per cent) derived from the Triassic conglomerates of the West Midlands, these were probably transported via the Kesgrave Thames and Bytham river systems. Greensand chert (0.3 to 2.1 per cent) from the Weald and Welsh acid volcanics (trace) point to sediment input from the Kesgrave Thames, whilst Carboniferous chert (8 and 5 per cent) and Spilsby Sandstone (0.2 to 1.2 per cent) indicate a more northern provenance associated with the Bytham River. Rhaxella chert (0.1 to 0.6 per cent) from the Howardian Hills of north-east Yorkshire indicates input from a third and most northerly river, the Ancaster River. Together these lithologies demonstrate significant bedload input to the Crag Basin from the three major river systems that drain across the East Anglia region, and an increased energy and efficiency of these rivers in recycling sediment throughout their catchments. A small, yet distinctive, lithological component of the How Hill Member is the persistent presence of trace quantities of lithologies from northern Britain including schist, granite, granodiorite, greywacke and basalt. This appears to be mirrored by increased proportions of fresh non-opaque heavy minerals grains of generally chemically unstable varieties including types of amphibole and pyroxene. The consistent presence of these lithologies is believed to coincide with the widespread erosion of crystalline bedrock areas of northern Britain perhaps by glaciers.

The type site of the How Hill Member is at How Hill near Ludham, here the deposit rests on the Chalk Group and comprises interbedded sands and gravels, silty sands and occasional silty clay lenses and clay drapes. The depositional cross-sets in the sands indicate bidirectional palaeocurrents aligned north-north-west to south-south-east, indicating the migration of small sand bars by tidal currents parallel to the contemporary coastline. At How Hill, and also at sites such as Salhouse to the north-east of Norwich, the far-travelled component of the clast assemblages contains a predominance of lithologies derived from the northern rivers such as the Bytham and Ancaster rather than the Thames (e.g. Carboniferous and Rhaxella chert).

Farther north in north-east Norfolk, the Wroxham Crag Formation was deposited on a gentle eastwards-dipping chalk platform that crops out broadly at low-tide level between West Runton and Mundesley. Deposits of the Wroxham Crag Formation that lie on this platform belong to the Mundesley Member. Previously, they formed part of the Cromer Forest-bed Formation together with fluviatile and underlying marine sediments now assigned to the Norwich Crag Formation. However, many researchers now employ the Cromer Forest-bed Formation term just in relation to the early Middle Pleistocene fluviatile sediments. At its Mundesley stratotype, the member comprises about 2.5 m of tidally laminated clays and sands and shoreface sands and gravels. They include the previously named Yoldia (Leda) Myalis Bed (which also occurs at West Runton) and gravelly sand with Mya truncata (a bivalve with a subtidal habit) in life position. They are overlain by glacitectonised beds of sand, gravel and silt. Farther to the north-west, between Trimingham and Sidestrand and also between East and West Runton, their sedimentology includes fine sands with ripple cross-sets and plane beds, coarse sand and gravel forming large-scale, commonly tangential, cross-bedded units, flaser bedding, clay and silt drapes over ripple laminations, and interbedded organic units (Figure 54). The association of flat-bed, ripple and subaquatic dune bedforms and flaser bedding, and the bimodal current directions, indicates shallow marine or estuarine tidal environments, with the palaeocurrents indicating tidal directions of flow controlled by a coastline aligned roughly north–south. Occasional horizons of brecciated silt and clay, interpreted as tempestite deposits, indicate the presence of storms (Plate 16d) whilst the presence of intraformational ice-wedge casts and frost cracks demonstrate the existence of emergent surfaces during cold conditions.

A further distinctive feature of the Mundesley Member is the presence at sites such as Overstrand, East Runton and West Runton, of horizons rich in oversized erratic cobbles and boulders. Erratics include schist, dolerite, amphibolite, greywacke and granite from northern England and eastern Scotland, and rhomb porphyry from Oslofjord in southern Norway. They are believed to have been transported within icebergs that calved from ice sheets in northern Britain and Scandinavian and became grounded within the shallow margins of the Crag Basin. Crude age determinations using palaeomagnetism combined with rodent and mollusc biostratigraphy and clast lithologies suggests that the majority of these sediments are broadly equivalent in age to the How Hill Member and span the late Early and early Middle Pleistocene.

Lithologically, the Mundesley Member in north-east Norfolk shows broad similarities to the Dobb’s Plantation and How Hill members from farther south in the Crag Basin. However, its lithology appears to be much more variable with anywhere between 10 and 50 per cent far-travelled non-flint pebble lithologies. At Trimingham and Sidestrand, the Wroxham Crag Formation is dominated by angular flint (47.9 to 68.7 per cent) reflecting erosion and incorporation of materials directly from the Chalk Group. Significant quantities of quartzite and vein quartz (21.3 to 38.8 per cent) are also present, many of which possess a brilliant white colouration diagnostic of derivation from the Carboniferous gritstones or Pliocene Brassington Formation of the southern Pennines. This implies bedload input into the northern part of the Crag Basin by the Ancaster River, an interpretation further supported by the presence of distinctive lithologies that crop out in the Ancaster catchment such as Rhaxella chert from north-east Yorkshire and soft Lias Group limestone from the northern East Midlands. Input from the more southern river systems, the Bytham and Kesgrave Thames, cannot be discounted due to the persistent presence of indicator lithologies. However, the common absence of Spilsby Sandstone from the majority of sites in north-east Norfolk indicates that the contribution of bedload from the Bytham River into the northern parts of the Crag Basin was minimal.

There is a lack of faunal evidence to correlate the Wroxham Crag Formation with the North Sea sequence, but since the Winterton Shoal Formation oversteps the Smith’s Knoll and Crane formations, it is likely that the Winterton Shoal Formation correlates with at least the lower part of the Wroxham Crag Formation.

Post-Anglian marine deposits

Following the Anglian Glaciation, only patchy evidence exists for marine conditions within East Anglia prior to the Holocene. Post-Anglian marine deposits collectively form part of the British Coastal Deposits Group. Minor marine deposits that have limited spatial extent have been included within fl                                      formations with which they are typically associated. These are principally restricted to major estuarine areas including the Fen and Wash basins, plus wave-cut platforms around the modern coastline and appear to span at least two separate late Middle Pleistocene interglacial events plus the Last Interglacial (Ipswichian; MIS 5e). Uncertainty arises, however, with respect to the altitude of these ancient sea levels relative to modern sea level because the post-Anglian tectonic history of the region is not clearly understood.

Late Middle Pleistocene

The first post-Anglian interglacial is the Hoxnian Interglacial (MIS 11) and this occurred between about 0.424 Ma and 0.374 Ma. At Orton Waterville, to the south of Peterborough, marine sediments called the Woodston Member have been recognised and these form part of the Nene Valley Formation (Chapter 9). They occur beneath river terrace gravels equivalent to the third terrace of the River Nene and comprise fossiliferous silts and sands that interdigitate with beds of sand and gravel. They possess a diverse flora and fauna which indicate a proximal estuary with water depths typically between 11 and 14 m, with an adjacent large slow-moving river, marshland, meadows and closed forest. Palaoeclimate indicators demonstrate that the climate was slightly warmer than today with the presence of the small vole Microtus subterraneus indicative of a Hoxnian age.

Farther to the north in west Norfolk, the Nar Clay Formation occurs extensively where it has been recorded within boreholes and a number of now-disused brick pits (Figure 55). Marine deposits, the ‘Nar Valley clays’, overlie freshwater beds (‘Nar Valley Freshwater Bed’) that belong to the same formation, and in turn the Oadby Till Member of the Wolston Glacigenic Formation. The Nar Valley clays consist of fine brownish grey laminated silt, clay and silty clay with a base marked by a distinctive shell bed composed mainly of the giant oyster Ostrea edulis, together with a wide range of other bivalves and gastropods that are similar to those encountered within the modern Humber and Thames estuaries. The base of the ‘Nar Valley clay’ rises from west to east where it overlaps the underlying Pleistocene deposits up to an elevation of +24 m OD in the vicinity of Narford, near Swaffham. Ostracods within the clay suggest generally shallow water depths of up to 3 m but species indicative of water depths up to 20 m are also evident. Together, the base of the clay and their faunas indicate a maximum sea level between 24 and 27 m above modern sea level assuming no subsequent uplift or subsidence. U-Series and amino-acid geochronology suggest that the age of these marine deposits is MIS 9.

Raised beach deposits of Late Middle Pleistocene age occur at two localities in East Anglia. The most famous of these is the Morston Raised Beach located on the north Norfolk coast between Morston and Stiffkey (Plate 16f). Here, approximately 2.3 m of rounded flint beach cobbles of the Morston Formation rest unconformably upon the chalky Weybourne Town Till Member, and are overlain in turn, by the Late Pleistocene Holkham Till Member. At the base of the Morston Formation, finely laminated muds contain pollen which indicates interglacial climate conditions. The age of the Morston Raised Beach was widely attributed to the Last Interglacial or Ipswichian principally because its altitudinal range of up to +5 m OD lies within the known Ipswichian sea-level range, and also because it is overlain by Devensian till. However, recent OSL dating of the deposit demonstrates that it is older and probably dates back to the MIS 7–6 transition about 0.19 Ma. Raised beach deposits have also been recognised at Hunstanton, the Hunstanton Raised Beach, and similarly, occur at elevations upto +5 m OD and are overlain by the Devensian Holkham Till Member. No geochronology has been undertaken on these beach deposits although it is possible that they are of similar age to those at Morston.

Late Pleistocene

Marine conditions and the position of the coastline during the Last Interglacial or Ipswichian (MIS 5e), about 0.125 Ma, are difficult to reconcile. As previously established, raised beach deposits at Morston are now believed to relate to an earlier interglacial sea-level highstand. Several lines of evidence, however, indicate an Ipswichian coastline located within the Fen Basin. Here, the March Gravel Member (Fenland Formation) (Chapter 9) crops out around Ely, Wimblington and March. The deposit contains a marine molluscan fauna including Cerastoderma, and at Town End, March, it appears banked-up against a low cliff-line cut into Middle Pleistocene till. At Somersham, southern Cambridgeshire, unnamed organic deposits of Ipswichian age contain a distinctive brackish and marine pollen flora.

Chapter 9 Pleistocene fluvial deposits and soils

J Rose

Introduction

Rivers and soils have played an important role in shaping the landscape of East Anglia and provide a critical insight into cold- and warm-climate geological processes that operated across the region through the Pleistocene. In this chapter we examine the fluvial deposits of East Anglia relative to their stratigraphy and in the broader context of drainage development across southern and central Britain. An important event within this story is the Middle Pleistocene Anglian Glaciation which effectively reset the landscape thus separating a relict preglacial drainage network from the progressive development of the postglacial drainage network. Both the preglacial and postglacial drainage networks are therefore examined individually with important soil units that are superimposed upon the former also outlined. Fluviatile interglacial deposits are introduced here but examined within the context of Quaternary vertebrates (Chapter 12).

Preglacial fluvial deposits

Introduction

East Anglia contains the key evidence for our understanding of the preglacial landscape of Britain, and the findings from preglacial river systems are of international importance for our understanding of human prehistory and environmental change. The East Anglia region was crossed by two major river systems during the Early and early Middle Pleistocene, namely the Kesgrave Thames and Bytham rivers (Figure 56). These extended eastwards across central and eastern England draining into the southern embayment of the North Sea (‘Crag Basin’) in the vicinity of Ipswich and Lowestoft respectively. Deposits corresponding to these river systems collectively form the Dunwich Group, this has been subdivided into the Kesgrave Catchment Subgroup (Kesgrave Thames) and Bytham Catchments Subgroup (Bytham River) comprising individual terrace aggradations (Figure 57). In north Norfolk there is tentative evidence for a third, more northern river, referred to as the Ancaster River. This river system may have been a preglacial precursor to the modern River Trent, and is believed to have flowed eastwards from the East Midlands, through Lincolnshire into the present offshore area north of Norfolk. Fluvial deposits possibly relating to this river system crop out along the north Norfolk coast and are assigned to the Cromer Forest-bed Formation. Previously this stratigraphical term has encompassed organic fluvial deposits of the Bytham River but this practice is not followed in this account.

All of these deposits have a distribution that is determined by the position of the ancestral coastline which changed due to oscillating global and regional sea levels and neotectonic subsidence and uplift. Typically they are preserved within basins, and have been subjected to contemporaneous erosion, reworking and phases of nondeposition. Where the river deposits have formed a stable, low relief land surface, distinctive palaeosol sequences have developed and been preserved. These ancient soils contain a detailed record of prevailing environmental conditions during their formation. With the first lowland glaciations to reach East Anglia, these deposits were eroded by the base of the glacier and typically, over much of the region, they no longer exist. Occasionally, these deposits are buried beneath glacial sediments with negligible evidence of glacial erosion, so that the original landscape and soils are preserved. It is these sites that preserve the most important evidence for the earliest humans in northern Europe, extending back to nearly one million years before present.

Stratigraphy

The Kesgrave Catchment Subgroup comprises quartzose-rich sands and gravels that occur throughout south and eastern Suffolk and extend south-westwards into Essex and beyond (Figure 58). Previously, it was thought that these sands and gravels were outwash deposited by Anglian-age glacial meltwater streams but it has since been demonstrated that they were laid down by an extensive preglacial Kesgrave Thames. At its maximum extent, this river system once flowed from North Wales, through the Midlands and the Vale of St Albans and into southern East Anglia. It was also thought that the preglacial quartzose-rich deposits that occur within eastern Norfolk also related to the Kesgrave Thames. However, subsequent work has demonstrated that these quartzose-rich deposits are actually shallow marine in origin and are thus part of the Wroxham Crag Formation (Chapter 8).

Throughout the southern part of the region, Kesgrave Catchment Subgroup deposits occur overlying the Red and Norwich Crag formations of the Crag Group and beneath glacial deposits. They consist of cross-bedded sand and sand and gravel with foresets inclined towards the north-east. Their sedimentology demonstrates that they were formed by a large, braided river with tracts more than 10 km wide. Intraformational ice-wedge casts indicate formation under periglacial conditions, and suggest that the very high discharges needed to transport such a large body of sediment were derived from high discharges associated with the seasonal melt of snow and ice within the catchment.

The Kesgrave Catchment Subgroup can be divided into two formations on the basis of their lithological content, elevation and geographical distribution with further subdivisions enabling the recognition of individual river-terrace aggradations (Figure 57). The older, higher formation is known as the Sudbury Formation (Plate 17a) and is located in central Suffolk and north Essex. It possesses a moderate percentage of quartz and quartzite lithologies (20 to 30 per cent) and the persistent presence of rocks from Wales such as acid volcanic and low-grade metamorphic rocks. These latter rocks are commonly angular in form suggesting that they have been transported along the river in floe ice during the spring flood, rather than rolled along the river channel as part of the bedload. Typically, sediments of the Sudbury Formation are heavily weathered and eroded and have a whitish colour. The elevation of the Sudbury Formation terraces is such that they would have extended above the lowest col of the Cotswold Hills with headwaters of the river reaching westwards into mid and north Wales (Figure 59).

By contrast, the younger and lower elevation Colchester Formation has a lower percentage of quartz and quartzite, typically in the range of 15 to 20 per cent, and is located south and east of the Sudbury Formation in the southern part of the region (Figure 52) and (Figure 53).

This formation forms steeper, narrower and more sinuous aggradation tracks indicative of lower flow regimes than in the Sudbury Formation. The elevation of the Colchester Formation indicates that the terraces did not extend beyond the lowest col of the Cotswold escarpment suggesting a major reduction in the extent of the catchment of the Kesgrave Thames (Figure 59). What caused the reduction in size of the Kesgrave Thames catchment is unclear although several mechanisms have been suggested including headwater capture by an adjacent river system (e.g. the Bytham), or denudation of the headwaters by glaciation. Sediments of the Colchester Formation are characterised by a brownish colour and have less-well-developed palaeosols on the surface. Welsh volcanic rocks are still found within some terrace levels of this formation, despite the fact that the catchment is thought to have been isolated from this source and this is attributed to glaciation into the Cotswolds region during fluvial deposition. The late preglacial course of the Kesgrave Thames through southern Suffolk and northern Essex persisted until the Anglian Glaciation. The river’s route was then diverted farther southwards, to its modern course by ice blockage, valley impounding and drainage reversal in the Vale of St Albans.

At a number of sites, organic material has been recorded within the Kesgrave Catchment Subgroup (Figure 58). Typically the organic material forms small beds within the sand and gravel and is represented by reworked fragments of a cold climate flora incorporated within an aggrading terrace system. However at some sites there are beds of organic material that represent temperate climate conditions. These have an entirely different significance and reflect deposition within smaller, probably single-thread channels, when the less-powerful temperate-climate rivers were flowing across existing sediments. The main reason why these temperate climate deposits are rare, despite the abundance of temperate climate biomass, is that the river was cutting down during the transition to the next cold stage so their preservation potential is low.

Deposits relating to the Bytham Catchments Subgroup correspond in East Anglia to the Ingham Sand and Gravel Formation and have been subdivided into terrace members based upon lithology and elevation. Several different terrace schemes have been published, for example Figure 60, however, the precise number of terraces and their ages remain somewhat equivocal. This is largely due to the fact that the long-term uplift and eustatic history of the lower reaches of the Bytham River are complex and currently not fully understood. The Ingham Sand and Gravel Formation is composed of quartzose-rich (over 25 per cent) sands and gravels (Plate 17b) which contain elevated quantities of metastable heavy minerals like staurolite, tourmaline and rutile, plus unstable mineral species such as collophane derived from Mesozoic strata of the West and East Midlands. Commonly the sand is a pinkish colour reminiscent of the Triassic sands of the English Midlands from which they were derived.

Ingham Sand and Gravel Formation deposits have been identified bordering the eastern margins of the Fen Basin between Kings Lynn and Mildenhall within the middle reaches of the valley system. Typically, they occur as thin discontinuous spreads of sand and gravel that rest unconformably upon Chalk Group deposits, but also as thicker, more substantial accumulations that have locally been quarried (e.g. Shouldham Thorpe, Feltwell, Lakenheath). From Mildenhall, the lower reaches of this ancient river system occur as an eastward-sloping valley incised mainly into Chalk Group and Crag Group sediments and extends eastwards to where it intersects the modern coastline in the vicinity of Lowestoft. The maximum width of the valley is about 10 km, with a maximum depth of approximately 50 m, although in places, the base of the original river valley has been heavily incised and overdeepened as a subglacial tunnel valley during the Anglian Glaciation and the fluvial deposits destroyed (Chapter 10).

The Ingham Sand and Gravel Formation comprises extensive and mappable spreads that occur both within and on the flanks of the modern Little Ouse and Waveney river valleys. Many now-disused quarries, such as those at Fakenham Magna, Knettishall and Kirby Cane were opened to exploit the gravel, but have also offered excellent opportunities to study the lithology and sedimentology of the gravel. Between Beccles and the modern coast, in the southern part of the Broads, Bytham river deposits have been identified at depth within boreholes. Sedimentary structures within the Ingham Sand and Gravel Formation consist of low and steep-angle cross-bedding in both the sands and gravels, and horizontal and cross-bedded sands, and this is typical of a braided river system. Where depositional foresets occur, the palaeocurrent direction is towards the south and east in the middle and lower reaches of the valley system respectively.

Throughout East Anglia, the Ingham Sand and Gravel Formation is predominantly buried beneath glacial deposits although in some locations, such as throughout the area of the Fen Basin or around Mildenhall, they are absent due to glacial erosion. The elevated quartzose content, common to both the Ingham Sand and Gravel Formation and the Kesgrave Catchment Subgroup deposits results from erosion of Triassic deposits and earlier Palaeozoic rocks in the upper reaches of the river in the West Midlands. However, the Ingham Sand and Gravel Formation differs from the Kesgrave Catchment Subgroup in containing more Carboniferous chert from the Pennines, glauconitic Spilsby Sandstone from south Lincolnshire, and Jurassic ironstones and oolitic limestones from Lincolnshire. Very occasionally there are igneous and metamorphic rocks from Leicestershire.

The Ingham Sand and Gravel Formation contains intraformational ice wedge casts indicating that it formed, like the Kesgrave Catchment Subgroup, by spring flood discharges in a periglacial climate, and that aggradation occurred because more sediment was being eroded and transported from the upper reaches of the catchment than could be transported through the system. The Ingham Sand and Gravel Formation also contains occurrences of cold climate deposits and thin beds of temperate climate materials. Some sites like High Lodge near Mildenhall, Suffolk and Norton Subcourse in south Norfolk include fine-grained materials that are rich in organic remains showing that there was abundant biomass and that climate was broadly similar to the present day. At other sites, such as Pakefield near Lowestoft, organic muds indicate climatic conditions much warmer than the present and the proximity of the Bytham River to its contemporary coastline. During these temperate climates, the Bytham River operated largely as a single-thread channel with overbank floodplain sedimentation. The relative scarcity of these deposits is also due to the fact that incision was dominant during the temperate climate stages and survival was rare.

As with the Kesgrave Thames River system, deposits of the Bytham River are arranged into a series of different terrace aggradations (Figure 60). Older aggradations occur high on the valley flanks and are heavily weathered with a deep palaeosol developed on their surface (where the upper part of the unit has not been removed by glacial erosion). Younger aggradations occur at progressively lower elevations within the river valley, but are much less weathered and indeed contain chalk clasts and chalky sand in localities where the Bytham River had locally eroded chalk bedrock. The precise number of terrace aggradations is speculative with a number of different models proposing 3, 5 and 6 major aggradations.

Differences between these models equate to the role played by palaeosols as markers for aggradation surfaces, plus the possibility of differential rates of relative subsidence within the lower reaches of the valley. Despite these discrepancies, it is widely accepted that the lowest river terrace aggradation is associated with the Anglian Glaciation because in south

Lincolnshire, river-sourced proglacial lake deposits grade into glacially sourced lake deposits. The glacier that dammed the proglacial lake deposited the Lowestoft Glacigenic Formation across much of central and southern East Anglia.

The Cromer Forest-bed Formation crops out discontinuously in coastal sections in north-east Norfolk between Happisburgh and Sheringham and has also been recorded inland in boreholes. The term here is used to define a range of fluvial and estuarine deposits that relate to local rivers and the possible occurrence of a more northern river called the Ancaster River that drained Jurassic, Triassic and Carboniferous strata in the region of the northern Midlands, southern Pennines and Lincolnshire. The course of this northern river, is believed to have breached the Chalk escarpment through the Ancaster Gap in Lincolnshire. However, evidence for the existence of this river is provided by Jurassic and Carboniferous palynomorphs and trace inclusions of lithologies such as Rhaxella chert and Lias limestone within fluvial sediments and adjacent estuarine facies. Deposits of the Cromer Forest-bed Formation comprise sands and muds containing variable amounts of organic material arranged within a succession of discontinuous and sometimes cross-cutting channel structures. Sedimentological, geochemical (isotopes) and palynological evidence suggests that individual channels may have only been active for comparatively short periods of time (tens to hundreds of years) before abandonment and this is typical of active floodplain processes. Detailed analysis of pollen, coleoptera, molluscs and mammal faunas reveals that the deposits accumulated under a range of temperate and cold climates during the late Early and early Middle Pleistocene. The precise age of individual channel deposits has proved difficult to reconcile because the general age of these deposits lies beyond the effective range of most geochronological techniques. However a broad framework for these deposits has been established and continually refined based principally upon molluscan and vertebrate faunas (Chapter 12). The stratotype for the Cromer Forest-bed Formation is at West Runton. The site is particularly famous for the discovery during the 1990s of a near complete skeleton of a Mammuthus trogontherii (steppe mammoth) as described in Chapter 11. Other sites, such as Happisburgh are famous for archaeology that demonstrates the early human occupation of the region (Chapter 13).

Palaeosols

Palaeosols of Early and early Middle Pleistocene age are preserved throughout northern, eastern and southern East Anglia. They have been recognised in association from both the terrace surfaces of the Kesgrave Thames and Bytham rivers where they can represent long hiatuses in sedimentation. To a lesser extent, palaeosols have also been identified as discrete horizons within the shallow marine Crag Group of sediments (Chapter 8), where they indicate much shorter-term emergent surfaces.

Arguably, the most extensive studies of palaeosols have been undertaken in relation to the terraces of the Kesgrave Thames and Bytham River. They are preserved because these terraces had low relief surfaces and were not markedly degraded by gravitationally driven surface processes such as creep, hillwash and mass-movement. Terraces with palaeosols also survive below glacial deposits because in some areas the glaciers moved across the region without causing significant erosion. The palaeosols are of two types and commonly occur superimposed within composite soil profiles as the predominantly temperate climate Valley Farm Soil and the arctic climate Barham Soil. A third and hitherto unnamed warm temperate climate carbonate soil facies has also been recognised.

The Valley Farm Soil occurs widely throughout neighbouring northern Essex, passing into Suffolk within the area of Alderby, Sudbury and Ipswich, where the soil has been recorded within boreholes, quarries and trial pits (Plate 17c). Within the region, the soil is largely buried beneath Anglian glacial deposits and has commonly been glacitectonised — for example at Great Blakenham by the overriding Lowestoft Till ice sheet. To the south of Ipswich, beyond the maximum limit of Anglian ice, where the Valley Farm Soil has not been buried beneath glacial deposits, structures corresponding to this ancient soil can commonly be observed within modern soil profiles.

The Valley Farm Soil is a well-developed soil in which there has been substantial chemical weathering, breakdown of weatherable minerals to residual clay, and remobilisation of iron, clay and silicate minerals to form distinctive illuvial and eluvial horizons. Typically the soil is a distinctive reddish brown colour (Munsell Color hue 5YR) which is due to the iron mineral haematite. Haematite is formed by soil processes and requires seasonal wetting and drying with summer temperatures warmer than present in Britain, and more akin to Mediterranean or warmer regions. The Valley Farm Soil also shows grey mottling within the red matrix and this is due to chemical reduction of the iron minerals along fissures within the soil at times when the soil was saturated indicating fluctuating water tables. Detailed studies of the Valley Farm Soil show that it can be a very complex soil having been formed in a number of warm temperate climate episodes and physically disturbed by active layer processes in a number of cold (permafrost) climate episodes. Thus a section of Valley Farm Soil on a terrace of the Kesgrave Catchment Subgroup or the Ingham Sand and Gravel Formation may reflect a million or more years of weathering and soil formation and a stable land surface.

At Pakefield near Lowestoft, a different and as yet unnamed warm climate palaeosol has been recognised, developed upon alluvial overbank deposits of the Bytham Catchments Subgroup. Here, the abundance of calcium carbonate in the sediment and a slightly more seasonally arid climate has resulted in seasonal dissolution of the calcium carbonate, evaporation, and the subsequent precipitation of the calcium carbonate as carbonate ‘race’ nodules. This process is typical of greater seasonality and evaporation than exists in Britain at the present day, or during the time of formation of the Valley Farm Soil and is typical of drier parts of today’s Mediterranean region. The climatic inference is supported by the study of the stable isotopes of oxygen and carbon in the nodules that possess ratios similar to soils from the Mediterranean.

By contrast, the Barham Soil is an arctic soil. It is widely recognised throughout Suffolk where it has been developed on the terrace sequences of the Kesgrave Thames and Bytham rivers. It has also been widely developed on the Wroxham Crag Formation shallow marine deposits in north Norfolk at localities such as Trimingham and West Runton (Chapter 8). The arctic soil is characterised by such features as ice wedge casts, patterned ground (Plate 17d), sand wedges, frost cracks, involutions, and microscale features such as fractured clay skins, fractured grains, and clay concentrations (formed at the permafrost surface) and is also associated with loess and coversand sediments. All of these features are typical of permafrost or an active surface layer that melts and freezes seasonally. Frequently these features overprint the older Valley Farm Soil and lie directly beneath till indicating that they represent the last evidence of surface processes before the land was overridden by ice. Usually the Barham Soil is of early Anglian age, but a growing body of evidence suggests that the arctic soil may also have formed in earlier cold episodes.

Long-term preglacial controls on river catchment development

The distribution of river terraces within the Kesgrave–Thames and Bytham systems has been shown to be largely the product of erosion-driven uplift with net aggradation in the cold episodes and net incision in the temperate periods. The rationale behind this concept is that during cold climates high energy, physical, mass-movement processes such as solifluction and gelifluction, remove materials from the hill slopes to the river channels, and powerful peak discharges transport these materials to form aggradations in the lower parts of Catchment.

During temperate climates, high-energy physical processes are absent, river regimes are moderated and sediment is locked on the catchment slopes by vegetation. Therefore, river energy is not principally utilised in sediment transport, but is available to erode the river channel. With the net loss of material from the upper parts of the catchment during cold episodes, erosional isostasy causes uplift (but more slowly than the rate of river aggradation) and the temperate climate erosion results in net incision of the channel and erosion of existing river-terrace deposits. In this way, river-terrace aggradations can provide a record of uplift.

In the present-day upper Thames area, uplift was about 100 m during the formation of the Kesgrave Catchment Subgroup, about 75 m in the middle Thames and about 30 m in the lower Thames. Within the present-day middle part of the Bytham river catchment there has been about 50 m uplift over roughly the same period of time. The amounts of uplift result in differential amounts of erosion along river catchments with the greatest amount of material removed from the middle and upper parts of river catchments, and lower erosion and hence less uplift in the lower parts. In the adjacent marine Crag Basin there is net subsidence and deposition has taken place.

Chronology of pre-Anglian river deposits

River-terrace deposits provide a unique record of long-term Quaternary environmental change, but estimating their age has proved problematic. Initially the Kesgrave Catchment Subgroup was linked, on the basis of lithostratigraphy and biostratigraphy, to shallow marine Crag deposits at Easton Bavents in north-east Suffolk, and in turn with deposits of comparable age within the Netherlands. Subsequently, it has been shown that this stratigraphical interpretation is no longer valid. To some extent this problem has been addressed by palaeomagnetism which is applicable at a global scale and can differentiate between sediments that exhibit a normal or reversed polarity (e.g. Bruhnes/Matuyama magnetic reversal at 0.781 Ma). Unfortunately within Britain, very few sites are suitable for this type of analysis because of the type of magnetic minerals contained within the sediments. Use of rodent and molluscan biostratigraphy has also been widely used to correlate with the continental sequences using, for instance, the evolutionary change in water voles from Mimomys savini to Arvicola t. cantiana at around Marine Isotope Stage (MIS) 15/14. But this is based on the assumption that the change was synchronous throughout Europe which is ecologically somewhat tenuous. Dating of this evolutionary change in type areas of central and eastern Europe is far from robust with several different age interpretations existing within the literature. The result is that biostratigraphy gives an indication of relative age, but is in need of independent verification. In general, absolute geochronological methods such as radiometric dating have limited applicability during the Early and early Middle Pleistocene because the age is at or beyond the effective age range of many techniques. Recent developments in the amino acid racemisation (AAR) technique offer a possible way forward and long-term solution for assigning chronology to the early Middle Pleistocene. Currently, AAR can recognise two distinctive temporal subdivisions of the early Middle Pleistocene based upon the amino acid composition of opercula from the freshwater gastropod Bithynia. These subdivisions comprise an older sediment grouping where Bithyniaopercula yield higher quantities of protein degradation and are associated with M. savini faunas, and younger sediments, where Bithyniafaunas posses lower protein degradation and contain the vole Arvicola. This technique has proved highly successful in delineating the relative ages of early Middle Pleistocene interglacial sites in Britain.

An alternative approach has been to apply a very low resolution geomorphological method based on synchronising patterns of river-terrace aggradation and incision, with global-scale climate forcing (Figure 61). This model, which has been applied to a number of large lowland river systems in Europe, argues that the main phases of river downcutting (Phase 1) and floodplain accretion (Phase 3) occur under warm and interglacial climates respectively. By contrast, terrace aggradation (Phases 5 and 6) occurs under cold climates which are characterised by high sediment budgets and elevated seasonal peak discharges. Long-term patterns of terrace aggradation and incision are therefore within this model tuned to the 100 000 year eccentricity-forcing of global climate (Chapter 7).

This has been validated for the last about 0.45 Ma in the Lower Thames region using a number of geochronometric methods linked to mammal and molluscan assemblage biostratigraphy. It should in principal, be applicable back approximately one million years from when eccentricity-forcing became the dominant driver of environmental change. Using this model, and linking the aggradations to the results of an uplift model, the Kesgrave Catchment Subgroup has been attributed to the period between MIS 65 at about 1.80 Ma and early MIS 12 at about 0.45 Ma when the Anglian Glaciation significantly changed the geomorphology of Britain (Figure 57). More specifically, using this same method, the change from the Sudbury to the Colchester formations occurred around MIS 20 which is about 0.8 Ma. Using this same scheme, combined with normal magnetisation of the sediments, the age of the archaeology at Pakefield is around 0.75 Ma. The age of the archaeology at High Lodge is early MIS 13 around 0.5 Ma. The archaeology at Warren Hill and Hengrave, both of which include derived artefacts in the Bytham Catchments Subgroup are older than 0.56 Ma and 0.75 Ma respectively, being in potentially higher and older Bytham river terraces.

Post-Anglian fluvial deposits

Introduction

The Middle Pleistocene Anglian Glaciation was one of the most significant events that shaped the evolution of landscape and drainage during the Pleistocene. The Ancaster and Bytham rivers were overridden and destroyed by ice with much of the terrain that formed the lower middle reaches of the Bytham catchment eroded to form the present-day Fen and Wash basins. Further south, the lower reaches of the Thames were diverted southwards to broadly their current position. The resulting post-Anglian drainage systems of the region are much smaller than those of pre-Anglian times and focus largely upon the Fen Basin with the two largest river catchments — the Nene and Great Ouse, draining northwards into the Wash. The post-Anglian evolutions of these rivers are, however, difficult to reconstruct due to uncertainties surrounding the timing and nature of post-Anglian and pre-Devensian glaciations of the Fen Basin. Rivers to the east including the Stour, Wensum, Waveney and Gipping, and their location, like several of the tributaries of the Great Ouse, are in part superimposed on glacial drainage routes many incorporating stretches of former tunnel valleys.

The postglacial fluvial successions of the region reveal a complexity not recognised in neighbouring catchments such as the Trent and Thames where long-term patterns of river development appear to be controlled at glacial–interglacial scales. This is indicated by the polygenetic nature of terrace development and the fact that different numbers of terraces exist within different catchments. The Devensian terraces of the Nene and Great Ouse, in particular, show a much more dynamic and sensitive link between fluvial processes, vegetation cover, slope run-off and climate change. Within this section, we examine the stratigraphy and significance of several of the region’s river systems focusing on those that contribute to the geological understanding of the region.

Stratigraphy and chronology

All of the post-Anglian fluvial deposits within the region belong to the Britannia Catchments Group and are subdivided into formations associated with individual river systems. The River Nene and River Welland are two of the principal drainage systems of the western Fen Basin. The Welland lies beyond the western limit of the region and is therefore not described here. The River Nene is the tenth longest river in England draining a catchment of some 1600 km2. Terrace deposits belonging to the Nene Valley Formation occur widely throughout the Peterborough district extending upstream into neighbouring Northamptonshire, and downstream beneath Holocene deposits of the Fens to the Wash. Three river-terrace aggradations have been recognised – the Orton Longueville Member (Terrace 3) which occurs downstream of Aldwincle in Northamptonshire, and two lower terraces that extend farther upstream corresponding to the Grendon Member (Terrace 2) and the Ecton Member (Terrace 1) (Figure 62). The Woodston Member at Orton Longueville near Peterborough contains fluviatile and marine (Chapter 8) sediments that underlie Terrace 3 and probably dates to MIS 11 based upon the presence of the vole Microtus subterraneous which is last recorded from MIS 11. The March Gravel Member occurs at a similar elevation to Terrace 2 although their precise correlation remains a contentious issue (Chapter 8) – they are believed to be of MIS 9 or 7 age, indicating that the terrace is probably of either MIS 10 or 8 age. Terrace 1 sediments at Pod Hole near Peterborough, reveal highly sensitive responses of the Nene to sediment supply, discharge and the prevailing cold periglacial climate. During the Early Devensian, fine-grained sediments were deposited within an anastomosing channel system suggesting a vegetated river valley, with moderate run-off and seasonal discharges driven by snow-melt. The switch to the aggradation of sand and gravel braidplains implies a more intense periglacial regime and reduced vegetation density. This acted to drive greater rates of run-off, sediment availability and discharge within the Nene.

The Great Ouse is the fourth longest river in England extending from Wappenham in neighbouring Northamptonshire through Bedford and the eastern Fen Basin before entering the Wash at King’s Lynn. Between Huntingdon and Sandy in Cambridgeshire, the river is superimposed upon a tunnel valley that contains chalky diamicton and glaciolacustrine sands, silts and clays. Deposits of the Great Ouse belong to the Ouse Valley Formation. The precise course of the lower reaches of the Great Ouse during the late Middle and Late Pleistocene remains poorly understood. This is because definitive deposits downstream of Huntingdon have not yet been encountered. One explanation is that the Great Ouse may have followed a similar route to the modern course and drained directly into the Wash. Alternatively, its course may have been bedrock controlled, constrained by the Chalk escarpment with an outlet through Breckland. Three separate river terraces have been recognised with the Great Ouse catchment (Figure 62). These are composed of flint-richsands and gravels and are called the Biddenham Member (Terrace 3), Stoke Goldington Member (Terrace 2) and Felmersham Member (Terrace 1). Terrace 3 is believed to correspond to MIS 10 to 8 based upon finds of Clactonian-, Acheulian- and Levallois-style Palaeolithic tools. Terrace 2 at Fenstanton near Huntingdon includes a lens of organic material called the Woolpack Farm Member. It contains a temperate mammalian, molluscan and coleopteran fauna equivalent to the Ipswichian (MIS 5e) indicating that underlying and overlying sands and gravels may correspond to MIS 6? and MIS 4 respectively. Terrace 1 forms a distinctive morphological feature within the upper reaches of the Great Ouse but becomes indistinguishable from Terrace 2 within its mid reaches.

Boreholes reveal that gravels extend beneath the modern Holocene alluvium and are probably of Middle to Late Devensian age (MIS 3 to 2).

Several major tributaries feed into the Great Ouse including the Lark, Little Ouse, Cam and Wissey. Each of these modern river valleys are superimposed in part upon an overdeepened subglacial tunnel valley excavated by glacial meltwaters. The River Cam extends northwards from Royston and Saffron Walden through Cambridge before joining the Great Ouse to the south of Ely. Fluvial deposits of the Cam belong to the Cam Valley Formation with five separate river terrace aggradations defined (Figure 62). Within neighbouring northern Essex, the Cam occupies a tunnel valley that contains till and glaciolacustrine deposits attributed to the Anglian Glaciation (MIS 12). Glaciolacustrine deposits grade upwards into an organic deposit, the North Hall Member, which contains pollen attributed to the Hoxnian (MIS 11). High-level sands and gravels that crop out to the north-west of Cambridge form the fifth (Observatory Member) and fourth (Huntingdon Road Member) terraces with amino-acid dating of shells suggesting MIS 10/9 and MIS 8/7 ages respectively. The third terrace, comprising the Impington and Arbury members, forms a distinctive morphological feature and contains organic muds which have been dated to MIS 7 and MIS 5e (Ipswichian) based on amino-acid dating, indicating that the terrace spans both MIS 6 and the Late Devensian (MIS 4). Terrace 2 equates to the Sidgwick Avenue Member and also forms a pronounced morphological feature within the Cam Valley with coleopteran assemblages and radiocarbon dating indicating a Middle Devensian (MIS 3) age. The youngest (first) terrace, the Barnwell Station Member, is the lowest terrace aggradation within the Cam and extends beneath the Holocene alluvium. It is assigned to the Late Devensian (MIS 2) based on radiocarbon dating and contains a full glacial flora and fauna.

The River Lark is an east-bank tributary of the Great Ouse extending from near Bury St Edmunds to Littleport. Deposits of the Lark belong to the Lark Valley Formation with five separate Middle and Late Pleistocene river terrace aggradations composed of sand and gravel having been recognised. Organic sediments — the Sicklesmere Member, which overlie Anglian till and indicate an extensively forested landscape are tentatively correlated with the Hoxnian (MIS 11) interglacial.

The Nar Valley Formation comprises several distinctive terrace aggradations formed during the Middle and Late Pleistocene by fluvial sedimentation associated with the River Nar. The valley of the Nar, like many others within and bordering the Fens, is superimposed upon a subglacial tunnel valley. The tunnel valley contains chalky diamicton and glaciolacustrine deposits that grade upwards into the Nar Valley Freshwater Beds and the Nar Clay Formation. These latter deposits correspond to the transition from glacial to freshwater to marine conditions during a progression from glacial to interglacial climate. Several researchers have suggested that this sequence corresponds to the Anglian–Hoxnian (MIS 12 to 11) transition based upon pollen biostratigraphy and the occurrence of marine deposits at similar elevations in the Peterborough area. However, U-Series and amino-acid dating of the Nar Clay Formation suggests that they are MIS 9 implying that the glacial and freshwater deposits are late MIS 10 to early MIS 9 age. Four separate terrace aggradations have been recognised, with the top terrace believed to be stratigraphically equivalent to glacial outwash (Tottenhill Sand and Gravel Member) and the basal terrace at Marham (MIS 2?) dissected by Holocene channel fills and Fen alluvium.

The post-Anglian evolution of the Fen Basin and its major rivers the Nene, Great Ouse and neighbouring Welland remains controversial. Central to the debate is the precise number, timing and nature of glaciations that affected the Fen Basin between the Anglian and Devensian and their affects on drainage evolution. Various scenarios have been presented for glacial incursion(s) into the Fen Basin during the late Middle Pleistocene corresponding to either MIS 10 and particularly 8 and 6. Unambiguous geological evidence for glaciation south of the Wash and Fen margin is lacking and many inferred stratigraphical correlations are not currently constrained by geochronology. Equally, the post-Anglian uplift/subsidence history of the Fen Basin is poorly understood and this severely limits the use of elevations related to former lake levels and river terraces. Until both of these can be better constrained, the debate will remain somewhat speculative.

Several other important river valleys exist within the region. The River Waveney extends eastwards from near Redgrave, through Bungay and Beccles and joins the River Yare in the area of the Norfolk Broads. The Waveney Valley Formation consists of three terrace aggradations called the Homersfield Member (Terrace 3), Broome Member (Terrace 2) and Shotfield (Floodplain) Member (Terrace 1). The Homersfield Member is correlated with the late Anglian, because at Flixton, sand and gravel are interbedded with chalky clays interpreted as flow tills and the existence of the terrace in the region of Homerfield appears to be an outwash terrace with an ice contact slope at the western end, including ice-contact structures. Several important interglacial sites containing fluviatile or lacustrine organic silt and clay occur within the Waveney Valley including the famous site of Hoxne. This is the stratotype for the Hoxnian interglacial in Britain and contains a 15 m thick sediment sequence — the Hoxne Member, of fluviatile sediments, peat and lacustrine clay overlying the Lowestoft Till Member. A MIS 11 age for the Hoxne Member is based upon a range indicators including sedimentary continuity with the underlying Anglian sequence, biostratigraphy and geochronology (AAR, ESR, U-Series). Important river terrace deposits have also been recognised within the Stour and Gipping–Orwell river valleys although formal terrace schemes have not yet been developed for either. Terrace deposits within the Gipping–Orwell are of particular significance because of the occurrence of interglacial deposits at sites such as Bobbitshole and Stoke.

Chapter 10 Pleistocene glacial and periglacial geology

J R Lee, M D Bateman and S Hitchens

Introduction

This chapter explores the profound effect of Pleistocene ice ages on the landscape and geology of East Anglia. The region was glaciated extensively about 0.45 Ma (the Anglian Glaciation) with the northern part of East Anglia lying at the southernmost extent of at least two subsequent expansions of ice into the North Sea Basin (Figure 63a). Much of the landscape that we see today in East Anglia is a direct legacy of these ice ages. Ice sheets caused widespread erosion and redistribution of sediment across the region and resulted in the large-scale modification of drainage, destroying some ancient river systems and diverting others. Areas in East Anglia that lay beyond the limits of glaciation did not escape the effects of these ice ages with the landscape affected by repeated cycles of freezing and thawing. Today, areas of frozen ground or permafrost occur in parts of Arctic Canada and northern Eurasia including Siberia and act as analogues for this earlier climate in East Anglia. The extensive record of ice age climates is one of the most important cold climate archives in northern Europe and provides a detailed insight into the interaction of ice sheets and permafrost within the landscape. As a consequence, the record of glaciation and periglacial environments has been studied by geologists for well over 150 years with many different and contrasting views on how the sequence should be interpreted. The intensely deformed glacial deposits of the north Norfolk coast have attracted particular attention and continue to play a leading role in the understanding of processes that occur at the margins and beneath ice sheets.

Here, we review the present understanding of ice ages in East Anglia, examining the stratigraphy and chronology of the glacial deposits, the nature of the glacial environments and the periglacial conditions that operated beyond the ice limits and under cold climatic conditions.

Stratigraphy

Middle Pleistocene glacial deposits

During the late Middle Pleistocene, East Anglia was glaciated on least two occasions during the Anglian (0.45 Ma; MIS 12) and ‘Tottenhill’ (0.16 Ma; MIS 6) glaciations. The first and most extensive of these glaciations, the Anglian, resulted in the widespread modification of the preglacial landscape throughout much of the region. In central, southern and western parts of East Anglia, thick sequences of chalky diamicton, the Lowestoft, Oadby and Marly Drift tills, were widely believed to have been deposited by Pennine and North Sea lobes of the British Ice Sheet. In north-east Norfolk, a thick sequence of sandy diamictons, the ‘Cromer Tills’ or ‘North Sea Drift Formation’, were previously thought to have been laid down contemporaneously by a lobe of Fennoscandian ice that reached across the North Sea from Norway (Figure 63a).

Whilst this model has proved popular for many years, new geological evidence raises several questions concerning its validity. These questions relate to: (i) the stratigraphical framework of the major geological units; (ii) the Scandinavian origin of glacial deposits in north Norfolk; (iii) the age of the glacial deposits and the possibility that some glacial deposits may relate to older and/or younger glaciations. Of particular importance is the existence of a robust, underpinning relative stratigraphical framework. However, in East Anglia it has proved largely impossible to transfer the existing lithostratigraphy away from stratotype localities into adjacent local and regional areas. This is a due to previous mapping scales, but more critically, the inherent problems in applying pure lithostratigraphy to glaciated terrains which are partly tectonic in origin and exhibit a high lithofacies variability.

Consequently, although lithofacies have proved an important stratigraphical tool at a local level, examining the nature and geometry of major bounding surfaces has enabled the construction of a more effective and reliable regional-scale mappable stratigraphy. This approach draws together elements of allostratigraphy, tectonostratigraphy, lithostratigraphy and morphostratigraphy and has evolved markedly over the past 15 years (Figure 63b).

Collectively, all pre-Devensian glacigenic deposits in southern Britain are now assigned to the Albion Glacigenic Group (Figure 66) with subdivision into further mappable assemblages. The Happisburgh Glacigenic Formation is the basal glacigenic formation in East Anglia and relates to the earliest glacial incursion into the region. The formation occurs extensively throughout north-east Norfolk extending southwards into the Waveney Valley and westwards as far as Euston near Thetford. Commonly the formation is buried beneath younger glacial deposits with outcrops restricted to valley sides or areas where erosion has removed overlying deposits. Typically, deposits overlie sands and gravels of the Wroxham Crag Formation but within the ancient Bytham River valley they interdigitate with river terrace deposits of the Ingham Sand and Gravel Formation (Figure 64a, b). Two major diamicton units occur within the formation and record at least two advances of ice into the region from the north. They can be mapped extensively and crop out discontinuously in coastal sections between Corton and West Runton. The basal diamicton, the Happisburgh Till Member, is a dark grey matrix-supported subglacial till rich in flint, shell and chalk clasts. The upper surface of the till is characterised by a series of morainic-type landforms and crevasse-squeeze ridges formed during ice-marginal wastage. The upper diamicton, the Corton Till Member, comprises a massive to highly stratified brown sandy diamicton (Plate 18a) laid down both subglacially by grounded ice (massive facies) and as a series of subaqueous debris flows deposited adjacent to an ice margin that terminated within a basin. Formerly, this deposit was called the Norwich Brickearth but recent work has shown that this term actually applies to a soil profile superimposed upon any sandy diamicton in north-east Norfolk and is not stratigraphically significant. To the west of Diss, the equivalent to this till is the Starston Till Member, with its occurrence generally limited to the buried Bytham River valley. Separating the Happisburgh and Corton tills is a variable sequence of glaciolacustrine silts, clays and deltaic sands (Plate 18b) that record proglacial sedimentation when the ice margin had temporarily retreated to the north of the region.

Outwash deposits relating to the Corton and Starston tills occur extensively throughout southern Norfolk and northern Suffolk where they overlie both tills, occupy broad channels incised through them, or rest unconformably upon preglacial Crag Group deposits where tills are abscent (Plate 18c, f). The Banham Member has been recognised in boreholes and at outcrop within the area of Banham and Kenninghall near Diss. It is composed of a stratified complex of diamicton, sand, gravel, silt and clay and records a period of ice-marginal sedimentation within a lacustrine basin. Coarse-grained ice-proximal glaciofluvial facies (the Leet Hill and Coney Weston Sand and Gravel members) and finer-grained sandy distal outwash facies (the Corton Sand Member) occur extensively throughout central East Anglia. Sedimentologically, the Corton Sand Member is composed of stratified fine sands that form three fining-up cycles. They were deposited within glaciofluvial and glaciolacustrine environments with the high sphericity of individual sand grains plus the persistent presence of far-travelled chalk grains implying that aeolian reworking was also a significant process. Intraformational ice-wedge casts, frost cracks and involutions demonstrate the ephemeral nature of the land surfaces and the development of permafrost* and active-layer* processes. It is believed that these outwash deposits were laid down as parts of the ice margin responsible for depositing the Corton and Starston Till members decayed and retreated northwards (Figure 65). Outwash drainage initially followed the lower course of the Bytham River valley eastwards, but downstream blocking by ice caused drainage to be diverted southwards. Boreholes within the Gorleston–Raveningham–Corton area support this interpretation. Here the Corton Sand Member contains up to three successive 10 m-thick fining-up cycles that grade upwards from sands and occasional gravels, into sands with occasional silts and clays. It implies a succession of sediment pulses emanating from the ice margin that progressively caused the pre-existing relief to be infilled, culminating in drainage being diverted southwards unconstrained by topography.

The base of the Lowestoft Glacigenic Formation is characterised by a regionally extensive angular bounding surface. At Leet Hill Quarry, Kirby Cane, a rhizogenic calcrete horizon occurs just beneath the degraded upper surface of the Corton Sand Member. Detailed examination of the calcrete shows that it formed during a climatic amelioration under reduced aridity and in the absence of permafrost. It suggests the presence of a significant hiatus and climatic amelioration between the deposition of the Happisburgh and Lowestoft Glacigenic formations. Other evidence for this hiatus includes the presence of shallow marine deposits at Pakefield and Chapel Hill, Norwich; the existence of intervening ‘Valley Farm’ type temperate palaeosols at Fakenham Magna and Culford, the latter also being associated with an archaeological horizon; and delineation of the glacigenic deposits by several phases of terrace aggradation and incision within the Bytham River valley.

Diamicton units within the Wolston and Lowestoft Glacigenic formations form part of an extensive sheet that can be traced eastwards across the English Midlands and East Anglia. The variable composition of this sheet reflects the successive erosion and incorporation of successive Mesozoic bedrock strata as Pennine ice crossed central and eastern England from west to east. Within Bedfordshire and parts of Cambridgeshire and Hertfordshire the basal diamicton of the Wolston Glacigenic Formation is a newly defined subglacial till called the Bozeat Till Member. Previously, it has been classified as a ‘chalk-free Lias-rich diamicton’ and a facies of the Oadby Till Member, but subsequent investigations have shown it to be a distinctive and mappable unit. It consists of a dark bluish grey, silty clay matrix-supported chalk-free diamicton rich in Jurassic limestone, ironstone with occasional vein quartz, quartzite, Triassic mudstone and sandstone, Carboniferous limestone and coal. It crops out around Yardley Hastings and Haversham, but elsewhere, including the Fen Basin, is buried beneath younger glacial and Holocene deposits but is proven within boreholes. The diamicton thickens westwards into neighbouring Northamptonshire, passing laterally into the Thrussington Till Member in the West Midlands and has been recognised as far east as Hitchin. To the east the Bozeat Till Member passes into the Lowestoft Till Member of the Lowestoft Glacigenic Formation which crops out extensively in south Norfolk, Suffolk and neighbouring Essex, (Plate 18c). The Lowestoft Till Member possesses a locally variable lithology reflecting the incorporation of different substrate lithologies including the Chalk Group, London Clay Formation and Kimmeridge Clay Formation. Across much of its distribution the diamicton is a subglacial till, however, localised debris flow facies (‘flow till’) are common especially in ice-marginal localities and tunnel valleys. An example of such a facies is the Pleasure Gardens Till Member and associated glaciolacustrine deposits (Oulton Clay Member) at Corton (Plate 18e). The ice that deposited the Lowestoft Till Member excavated the Fen Basin and lowered the Chalk escarpment between Swaffham and Newmarket by as much as 80 m, causing its position to migrate eastwards. In southern East Anglia, the diamicton is commonly 10 to 25 m thick, but can locally exceed 40 m. It forms a series of distinctive plateaus across the district, but can also be found at lower elevations within numerous drift-filled channels.

The Lowestoft Till Member is largely absent from the Thetford, Brandon and Swaffham area and is commonly present only within depressions and scours in the Chalk bedrock surface implying that this was a zone of net subglacial erosion beneath the ice sheet. Localised tracts of chalky and flint-rich glaciofluvial outwash occur throughout southern East Anglia where they form thin cappings to hills and valley-flank delta and fan systems relating to deglaciation.

Within north-east Norfolk, the lateral equivalent to the Lowestoft Till Member is the Walcott Till Member which is a pale to dark grey, silty, matrix-supported diamicton rich in chalk and flint (Plate 18d). It was deposited subglacially by grounded North Sea ice that entered the region from the north, and crops out on the Norfolk coast between Happisburgh and Cromer and inland towards North Walsham.

Common features in East Anglia are overdeepened drift-filled channels called tunnel valleys and many of these are related to the ice advance that deposited the Lowestoft Glacigenic Formation. Their existence in East Anglia has been documented for well over a hundred years but the first systematic attempt at mapping their distribution was only published in the early 1970s (Figure 63a). They occur as single, narrow, keel-shaped incisions or complex channels networks, commonly with steep valley terminae, that have been infilled by thick sequences of sand and gravel, diamicton and glaciolacustrine silts and clays that locally can exceed 70 m thickness. Tunnel valleys are produced by the erosive action of meltwater flowing beneath the ice under elevated hydraulic gradients and often utilising pre-existing channels or bedrock joints and fractures. Many tunnel valleys exhibit no obvious surface expression within the modern landscape because they became infilled by glacial sediments when active discharge through them ceased. Within East Anglia, one of the most extensive tunnel valleys occurs within the buried valley of the preglacial Bytham River between Fakenham Magna and Diss, which has been overdeepened by meltwater erosion (Figure 67). Tunnel valleys exist beneath the floodplains of some of the region’s major river valleys including the Yare and Cam, and are particularly well developed in the lower reaches of the Gipping Valley between Great Blakenham and Ipswich Docks.

Overlying the Lowestoft Glacigenic Formation in north-east Norfolk is the Sheringham Cliffs Glacigenic Formation. It crops out widely across north Norfolk between Bacton Green, Dereham and Swafham forming a highly variable succession of glaciolacustrine marls, sands and rhythmically bedded silts and clays. Two distinctive diamictons are evident within the formation — a lower sandy diamicton called the Bacton Green Till Member, and an upper chalky diamicton called the Weybourne Town Till Member. The Bacton Green Till Member can be observed in coastal sections between Bacton Green and Sheringham and comprises a highly consolidated brown sandy diamicton (subglacial facies) and a highly stratified complex composed of beds of greyish brown sandy diamicton, sand and clay (waterlain facies) (Plate 18g). They were deposited during an advance of ice into north Norfolk from the area of the North Sea to the north and north-west.

The upper diamicton corresponds to the highly calcareous Weybourne Town Till Member. Previously referred to as the ‘Marly Drift’. The deposit possesses a variable and heterogeneous lithology reflecting differential incorporation of substrate lithologies including crushed chalk, reworked sand and pre-existing diamicton. Recent studies on the microfossil content of the diamicton confirm thoughts from earlier structural studies that the deposit is actually diachronous. It comprises an older facies rich in Carboniferous and Kimmeridgian palynomorphs derived from the west, and a younger and less-extensive facies, part of the superseding Briton’s Lane Formation, with a North Sea palynomorph signature derived from the north. The spatial extent of both facies has proved difficult to determine by mapping because their bulk appearance is identical. However, the western-derived facies appears to crop out widely across western and central Norfolk thinning progressively eastwards where it occurs only discontinuously. In north Norfolk, the deposit crops out only sporadically, however, evidence for the west to east ice advance that deposited it is preserved in the form a glacitectonic mélange superimposed upon the underlying sediment pile. Historically, this deformed glacitectonite* has been called the ‘Contorted Drift’ and reaches upto 30 m thickness in coastal sections between Bacton Green and Weybourne. At West Runton, coastal sections reveal a complex east to west structural transition between proglacial to ice-marginal to subglacial styles of deformation associated with the westwards retreat of the ice margin (Figure 68). Subglacial facies of the mélange exhibit a range of deformation structures produced by the progressive mixing of pre-existing diamicton and outwash units and the development of secondary folds, faults and fractures (Plate 19a–d). The style and geometry of these structures reveal that their generation was driven by temporal and spatial changes in water content within the subglacial bed. This variably caused the subglacial bed to lock up (dry) or deform (wet) leading to a ‘stick-slip’ control on ice sheet motion.

Within Bedfordshire and Cambridgeshire, the uppermost diamicton unit corresponds to the Oadby Till Member of the Wolston Glacigenic Formation. It occurs as a thick unit, up to 27 m thick, whose base descends gradually from +80 to 90 m OD in the vicinity of Bedford and Biggleswade to around +40 m OD at Maddingley near Cambridge. Within the Fen Basin, the diamicton forms several outliers including those at Downham, Ely and Littleport, and is also proven in boreholes from a number of tunnel valleys including those beneath the River Cam. Lithologically, the diamicton possesses a silty, sandy clay matrix with abundant clasts of chalk, flint, Jurassic limestone and ironstone, Carboniferous limestone and sandstone, vein quartz and quartzite. It has far-travelled erratic clasts including Whin Sill dolerite, schist and gneiss from northern Britain. It was deposited by British North Sea ice that eroded the Chalk escarpment in the vicinity of the Wash and extended south and westwards across the Jurassic and Triassic mudstones of western East Anglia and the Midlands as a fast-flowing piedmont-type lobe. Precise correlation of the Oadby Till Member with deposits in north Norfolk is problematic, because unlike the Thrussington–Bozeat–Lowestoft Till members that form a regionally extensive sheet, stratigraphical continuity with northern East Anglia is broken by the Chalk escarpment in west Norfolk (Figure 63b). Logically, lateral equivalents in north Norfolk should be North Sea derived with either the Bacton Green Till Member (Sheringham Cliffs Formation) or the Briton’s Lane Formation being obvious candidates. Some studies have recently advocated the correlation between the Oadby and Bacton Green Till members, however, this is not supported by glacitectonic evidence from north-east Norfolk. Instead, this evidence demonstrates that the Bacton Green Till Member was laid down and subsequently overridden by eastwards-flowing Pennine ice which deposited the Bozeat and Lowestoft Till members in the west of the regional guide area. Deposition of the Oadby Till Member therefore postdates this event with the removal of Pennine ice from the region required before North Sea ice entered the region. Correlation with the Briton’s Lane Formation in north-east Norfolk is the simplest interpretation (Figure 63b).

The youngest Middle Pleistocene glacigenic formation in northern East Anglia is the Briton’s Lane Glacigenic Formation. The dominant facies of the formation are outwash sands and gravels but discontinuous thrust-bound slices of chalk-rich diamicton occur along the north Norfolk coast. This diamicton, indistinguishable in the field from the Weybourne Town Till Member, contains Cretaceous microfossils derived from the north and north-west. Sands and gravels attain thicknesses of up to 40 m in the vicinity of Beeston Regis and Cromer where they form high ground (up to 100 m) within the ‘Cromer Ridge’. Sands and gravels thin southwards towards Norwich and Fakenham where they form heavily dissected sheets that drape and infill the pre-existing topography. Pebbles in the gravels are dominated by highly spherical flints and are often referred to as ‘cannon shot’. Erratics are common and include lithologies from northern Britain and southern Norway such as greywacke, dolerite, basalt, granodiorite, granite, Old Red Sandstone, gneiss, amphibolite and rhomb porphyry.

The ‘Cromer Ridge’ has previously been interpreted as a composite push moraine formed at the southernmost limit of a southerly directed ice advance from the North Sea. New landform and structural evidence paints a more complex picture with the main ‘Cromer Ridge’ representing an ice marginal still stand. The recognition of small moraine ridges to the south of the ‘Cromer Ridge’ suggests that the maximum ice limit lay further to the south. Detailed examination of glacitectonic structures and landforms reveal a rapid ice advance followed by a multistage pattern of ice-marginal retreat with phases of active retreat* punctuated by glacier surges, stillstands, slow advances and mass-wastage (Figure 69). Retreat of ice from the Glaven valley led to the generation of two successively lower-elevation outwash plains known as the Kelling and Salthouse sandurs and associated ice-contact landforms including the Blakeney Esker, and several kame terraces and kame gravel mounds (Figure 69). Also attributed to this southerly directed advance are the spectacular Chalk bedrock rafts that crop out in the foreshore and cliffs at Marl Point (Trimingham), Overstrand, East Runton, West Runton and Sheringham (Plate 19d and e). They represent largely intact blocks of frozen bedrock and preglacial sand and gravel, ranging upto several hundred metres in length, which have been ripped up and transported for several hundred metres at the snout of the ice sheet before being dumped.

Further to the west at Tottenhill in the Nar Valley, a further unrelated facies of the Britons’ Lane Formation is present — the Tottenhill Sand and Gravel Member (Figure 63b). This deposit comprises a sequence of chaotic to cross-bedded sand and gravel that contains frost wedges and involutions within the lower horizons, passing upwards into better-sorted, cross-bedded gravel. It is interpreted as representing cold-climate fluvial and deltaic sedimentation situated close to an ice margin located to the north. Further research has suggested that these deposits could be equivalent to sediments which have been interpreted by others as being of preglacial Bytham River origin. The alternative view is that these deposits could have been laid down within a large glaciolacustrine basin that occupied the Fens and drained eastwards along the modern course of the Little Ouse and Waveney into the North Sea.

Age and configuration of Middle Pleistocene glaciations

Recent research undertaken in East Anglia has, as previously detailed, led to a notable revision of the relative stratigraphical classification of glacial deposits in the region. Of particular significance is the enhanced understanding of the three-dimensional geometry of the major stratigraphical building blocks and their relationship to other glacial and nonglacial successions in East Anglia and adjoining areas. Developing from this has been the possibility that glacial deposits previously attributed to the ‘Anglian Glaciation’ (MIS 12) may, in reality, have been deposited during several additional older and younger glacial events.

The conventional interpretation of the Anglian Glaciation is that East Anglia was glaciated by coexisting Pennine, British North Sea and Fennoscandian lobes of ice with the age constrained by interglacial sediments of ‘Cromerian Complex’ and Hoxnian age that underlie and overlie the glacial sequence respectively (Figure 70a). Evidence for a later ‘Tottenhill’ (MIS 6) glaciation within this model relates to the deposition of the Tottenhill Sand and Gravel Member located within the southern margins of the Wash Basin at Tottenhill.

More recently, it has been suggested that this model can potentially be delineated into additional older and younger Middle Pleistocene glaciations (Figure 70b). Deposits that may relate to the older of these glaciations, the MIS 16 ‘Happisburgh Glaciation’, include the Happisburgh Glacigenic Formation. Critical evidence consists of reworked clasts of the Corton Till Member and glacially derived heavy minerals identified within Bytham River terrace deposits at Leet Hill Quarry, Kirby Cane. Correlation of these deposits with the third terrace would, if correct, indicate that they are separated from the first Anglian terrace by an intervening second terrace and two phases of fluvial downcutting. Application of a climate-forced model for river terrace aggradation and incision would thus place the second terrace within MIS 14, the two episodes of terrace incision as MIS 13 and 15, and the third terrace and ‘Happisburgh Glaciation’ as MIS 16. This interpretation has proved controversial for two principal reasons. Firstly, some geologists have challenged the interpretation of the Bytham river terrace sequence, instead arguing for a less complex terrace succession with the reworked till clasts and glacially derived heavy mineral occurring within the youngest Anglian terrace. Secondly, palaeontological and amino-acid evidence from organic sediments that occur beneath the Happisburgh Till Member in north-east Norfolk contain faunas that appear to preclude a MIS 16 age. Instead, this evidence suggests that the organic deposits, and by default the Happisburgh Glacigenic Formation, must be considerably younger and probably Anglian (MIS 12) in age. Critical evidence includes the presence of faunal assemblages that include the vole Arvicola t. cantiana, a species widely believed to have evolved from Mimomys savini much later during the ‘Cromerian Complex’. Amino acid age determinations from molluscs also indicate considerably younger ‘Cromerian Complex’ ages. Evaluating all of the evidence surrounding the age of the ‘Happisburgh Glaciation’ highlights several contradictions that occur between different types of geological evidence and these are difficult to fully resolve in the absence of reliable geochronology. However, what should not be overlooked is that taken at face value, a distinctive body of evidence exists for a notable hiatus between the deposition of the Happisburgh and Lowestoft Glacigenic formations.

Evidence, whilst fragmented, includes: (a) a regionally extensive erosive episode and subsequent restabilisation of the land surface with the development of palaeosols (including calcrete) in a nonperiglacial environment; (b) catchment-scale base-level readjustments within the Bytham River; (c) deposition of nonglacial, shallow-marine coastal sediments. The temporal and climatic significance of this interval is speculative but at the very least, cessation and later re-establishment of arid periglacial conditions are indicated.

Other glaciations are also recognised within the multiglaciation model including the largest glaciation — the Anglian Glaciation (MIS 12). This glaciation equates to the deposition of the Walcott Till Member in north-east Norfolk by North Sea ice, and the Bozeat and Lowestoft Till members by Pennine ice (Figure 70b). Its minimum age is constrained by the geochronology of Hoxnian-age (MIS 11) organic sediments at Hoxne that overlie the Lowestoft Till Member and by correlation with terrace sequences within the River Thames.

The Sheringham Cliffs Formation, including the Bacton Green Till and Weybourne Town Till members in north Norfolk, have previously been interpreted as possible lateral equivalents to the Oadby Till Member (Wolston Formation) of Cambridgeshire and Bedfordshire and assigned to a later ‘Oadby Glaciation’ (Figure 70b). An MIS 10 age has been interpreted due to the existence of a sedimentological continuum of the Oadby Till Member with overlying interglacial deposits in the Nar valley that have been dated to MIS 9 by AAR and U-Series dating. Additionally, geological mapping within the Thame and Upper Thames river catchments indicate that the Oadby Till Member passes laterally into MIS 10 terrace deposits. However, as stated previously within this chapter, the correlation of the Oadby Till Member with the Sheringham Cliffs Formation of north-east Norfolk is not supported by glacitectonic evidence nor the till stratigraphy in the western part of the region. In addition, the glacial sequence in north Norfolk is capped by deposits that have been dated by OSL dating to MIS 12 and further constrained by an organic kettle-fill of Hoxnian (MIS 11) age.

The extent and precise timing of the late Middle Pleistocene ‘Tottenhill Glaciation’ is somewhat ambiguous. Many consider the deposition of the Tottenhill Sand and Gravel Member at Tottenhill, west Norfolk, to have occurred during MIS 6 and represent an incursion of ice into the margins of the Wash. However, some workers have speculated that the glaciation was more extensive in East Anglia or the Midlands and may have occurred earlier (Figure 70b). In north Norfolk, it has been suggested that the ‘Cromer Ridge’ and Britons Lane Formation are equivalent to the Tottenhill Sand and Gravel Member and thus part of the ‘Tottenhill Glaciation’. Evidence for the MIS 6 age of these features includes the fresh appearance of Scandinavian erratics which suggest a possible correlation with tills widely assumed to be of this age in East Yorkshire and County Durham. Additionally, it has been argued that the relatively fresh morphology of the ‘Cromer Ridge’ moraine is more akin to Saalian-age (MIS 6) moraines in the Netherlands with older Anglian landforms likely to be more heavily degraded. Whilst a logical conclusion to draw, it has also been argued that the morphology of the Cromer Ridge is unrelated to age but instead reflects specific glacitectonic processes that occurred during a temporary ice-marginal stillstand. A post-Anglian age for the Briton’s Lane Formation also disagrees with OSL dating evidence, which places the sands and gravels within MIS 12, plus the occurrence of Hoxnian-age (MIS 11) organic sediments that occupy a kettlehole within the Britons Lane Formation at Sidestrand. Suggestions that that the ‘Tottenhill Glaciation’ may have occurred prior to MIS 6 relate to the possible glacial disruption of the Trent, Welland and Nene river systems and the deposition of the Wragby Till in Lincolnshire. Evidence from the Trent catchment hints at a MIS 8 age for the glaciations although tracing this into the Fen Basin and Tottenhill is equivocal.

An alternative model, presented within Figure 70c, recognises that the Happisburgh Glacigenic Formation may have been deposited during a glacial advance that preceded the main Anglian Glaciation (MIS 12). Within this model, the Lowestoft, Wolston and Sheringham Cliffs formations plus the Briton’s Lane Formation (excluding the Tottenhill Sand and Gravel Member) were deposited by oscillating Pennine and North Sea ice lobes during the Anglian Glaciation. Here, the Britons Lane Formation is tentatively correlated with Oadby Till Member of the Wolston Glacigenic Formation based upon their common North Sea provenance and association with ‘surge-style’ ice sheet behaviour. The later ‘Tottenhill Glaciation’ is also recognised but could correspond to either a MIS 6 or MIS 8 glaciation.

The various debates and models outlined above continue to be evaluated and re-assessed as new evidence comes to light. Ultimately they serve as a timely reminder of the contrasting ways in which geological evidence can be interpreted and the different philosophical and practical approaches to stratigraphy and stratigraphical correlation. Resolution of these issues requires the widespread application of geochronology although this is problematic due to the limited availability of sediments suitable for dating in the region and the current effective age ranges of the dating techniques.

Late Pleistocene glacial deposits

During the Late Pleistocene, East Anglia was glaciated just once during an event known as the Late Devensian Glaciation or Dimlington Stadial (26.0 to 14.7 ka). This glaciation was considerably smaller and briefer than the Middle Pleistocene Anglian Glaciation; however, with global sea levels up to 140 m lower than present-day, marine basins such as the North Sea became dry land and were inundated by ice. The Late Devensian glaciation is particularly significant because geological evidence is relatively well preserved and age constrained by geochronology. This enables increasingly sophisticated models for the growth and collapse of the last British–Irish Ice Sheet to be constructed, which in turn, provide important insights into the behaviour of modern ice masses in places like Greenland and Antarctica.

The Late Devensian geological record of northern East Anglia provides an important component of this story as it contains tills and outwash deposits that relate to the southernmost extent of the North Sea lobe of the British–Irish Ice Sheet within the North Sea basin.

Devensian-age glacial deposits crop out around the coastal margins of north and north-west Norfolk between Cley, Hunstanton and King’s Lynn where they typically occur at low elevations along the northern flanks of a series of low Chalk bedrock hills (Figure 71).

Glacial stratigraphy

All onshore Devensian-age glacial deposits occurring down the east coast of England belong to the North Sea Coast Glacigenic Subgroup (Figure 66) and have been further subdivided into various mappable formations and members. In East Anglia, Late Devensian glacial deposits were previously classified as part of the ‘Hunstanton Formation’, but more recently, have been reassigned to the Holderness Glacigenic Formation where they correlate with tills and outwash deposits extending through Lincolnshire and Holderness, East Yorkshire.

In north and north-west Norfolk, three members of the Holderness Glacigenic Formation occur. The Holkham Till Member is a reddish-brown matrix-supported clayey diamicton and previously called the ‘Hunstanton Till’ or ‘Hessle Till’ and forms distinctive reddish-brown soils where it crops out at the surface. The till varies in thickness between 1 and 10 m and occurs at elevations of upto +33 m OD on the flanks of Chalk hills that rise southwards and eastwards from the coast. The Holkham Till has also been recognised in boreholes within several northward flowing river valleys such as the Stiffkey, together with thick sequences of glaciolacustrine clays, silts and sands. These indicate that ice flowing out of the North Sea Basin impounded against an area of higher Chalk relief with small lobes extending southward locally. These blocked drainage along pre-existing valleys forming a series of ice-dammed lakes.

Compositionally, the Holkham Till Member can be readily distinguished from Middle Pleistocene diamictons by its comparatively clast-rich nature which can account for up to 12 per cent of the particle size distribution. Up to 95 per cent of the total clast content is dominated by flint, chalk, vein quartz and quartzite. However, the till is equally distinctive due to its relatively common (up to 20 per cent) and diverse far-travelled erratic content, although it is currently unclear whether this reflects its primary provenance or secondary reworking of pre-existing deposits. Erratics include sedimentary rocks derived from Palaeozoic and Mesozoic bedrock strata from eastern England, and crystalline igneous and metamorphic rocks from north-east England, and central and eastern Scotland. Lithologies include Early Cretaceous glauconitic sandstone (Carstone), Jurassic sandstone, limestone and mudstone, Permo-Triassic red and green sandstone, and Carboniferous Millstone Grit. Crystalline erratics include dolerite, various basic, intermediate and acid porphyry, alkali feldspar granite, phyllite, greywacke, chlorite schist, garnet mica schist and migmatite. Generally the Holkham Till Member is widely believed to have been deposited subglacially, but around Ringstead in north-west Norfolk, the till possesses a structure and weak stratification that has been interpreted as a flow till*produced by subaerial slumping.

A second diamicton facies of the Holderness Glacigenic Formation has also been recognised locally where it forms thin caps to some of the Chalk bedrock hills that rise gently southwards from the Holocene coastal plain. The Red Lion Till Member is exposed in a now-disused quarry section in the Red Lion public house car park in Stiffkey. It consists of a 4 m-thick reddish brown to yellowish brown matrix- and clast-supported diamicton rich in chalk and probably reflects a highly localised facies of the Holkham Till Member.

The Ringstead Sand and Gravel Member occurs discontinuously along the lower flanks of the small Chalk hills that rise southwards from the north Norfolk coastline, and within several dissecting valleys. The thickness of the deposit is generally less that 3 m and comprises sheets of sand and gravel, clast-supported gravel with occasional lenses of sand, and beds of finer mud. Gravels are dominated by flint and chalk lithologies, but also contain common crystalline clasts from northern Britain. The deposits were laid down as glaciofluvial outwash, with sedimentation occurring as a series of proglacial braidplains formed by sheet and channelised flow. At several sites between Hunstanton and Heacham the sands and gravels form a series of subtle ice-contact landforms. At Hunstanton Park, sands and gravels form part of a sinuous esker — the Hunstanton Esker that records a former subglacial to englacial ice-walled drainage conduit. Outwash drainage flowed eastwards into the Ringstead valley at Ringstead forming an impounded glacial lake basin marked by a number of kame terraces. Excavations through these terraces reveal a succession of climbing ripples and draped lamination indicating high but fluctuating rates of sedimentation. As ice retreated from the valley, catastrophic drainage of the lake basin incised a deep gorge called the Ringstead Downs Channel. Further to the east, a series of coast-parallel gravel ridges at Holkham, Stiffkey and Morston possibly reflect the development of small thrust-tip moraines within late Middle Pleistocene outwash by Late Devensian ice. Continued ice wastage and withdrawal of the ice margin from north-west Norfolk led to the dumping of gravel mounds (kames) around Hunstanton, Heacham and Wolferton.

Offshore, the Holkham Till Member of the Holderness Glacigenic Formation is equivalent to the Bolders Bank Formation. It occurs as isolated patches within The Wash but as a more extensive sheet, up to 25 m thick, further to the north across Burnham Flats and Docking Shoal although it is commonly buried beneath Holocene sand waves. It is composed of a reddish brown to greyish brown, highly consolidated, matrix-supported diamicton that possesses a distinctive sandy stratification and soft-sediment deformation structures. The base of the diamicton is marked by a high-amplitude planar to gently undulating seismic reflector. A second facies recognised offshore is the Botney Cut Formation which partly infills several ‘deeps’, such as Silver Pit, that radiate southwards to the margins of the diamicton sheet. The formation comprises lower beds of ‘Bolders Bank’ style diamicton, sands and gravels plus laminated silts and clays and records glaciolacustrine and glaciofluvial sedimentation during deglaciation.

Periglacial phenomena

On multiple occasions throughout the Quaternary Period, periglacial* conditions prevailed in East Anglia. Typically this occurred when ice sheets failed to cover all or part of the region or climatic conditions were cold but either of too short duration or insufficiently cold for glaciers to develop. In the open low-relief landscape of East Anglia, permafrost would have developed extensively impeding groundwater. Involutions, thermal contraction crack networks, patterned ground, palsas and pingos would have developed on the ground surface or in the underlying active layer. Some of the features may be of thermokarst origin formed during climatic amelioration at the end of periglacial periods when permafrost melted. Much of the evidence for Middle Pleistocene periglacial periods has either been eroded away by subsequent glaciation or by re-activation of features during subsequent periglacial periods. Where evidence for earlier periglacial conditions exists it is fragmentary and buried. For example cryoturbation, ice-wedge casts and cold-climate aeolian sediment are commonly found in association with the Barham Soil and relate to an early Anglian (MIS 12) and earlier periglacial phases (Chapters 7 and 9). At Hoxne, overlying the interglacial deposits are post-MIS 11 ice-wedge casts, whilst involutions thought also to be of post MIS 11 age are evident at Beeches Pit near West Stowe (Plate 20a).

The most recent period when periglacial conditions prevailed in East Anglia was during the Devensian and whilst many features may have been initiated early on within this period, the relict features preserved in the sedimentary record probably reflect the final phase during the Late Devensian. At this time, with an ice sheet lying adjacent to the northern fringes of the region, a large thermal gradient would have existed across East Anglia leading to the development of a range of periglacial phenomena. Coastal sections in north Norfolk plus sections in quarries across the region, especially within the river valleys of the Nene and Great Ouse, commonly show involuted horizons beneath the modern soil horizons.

Patterned ground is a particularly common feature of the Breckland landscape (Figure 72a), covering over 2500 km2, and known locally as ‘Breckland Stripes’ (Plate 20b–f). Previously misidentified as medieval plough and enclosure patterns they are in fact relict periglacial features with modern-day equivalents to be found in, for example, Alaska. They form polygons on flat ground around 7 to 10 m in diameter but with increasing slope gradients, are formed into stripes (Figure 72b). The Breckland polygons and stripes, although similar in appearance on the surface to ice wedges, are mostly found only on areas of the Late Cretaceous Chalk and areas covered by chalky diamicton. Polygons and stripes are produced by frost heave and cyclic freeze-thaw within the periglacial active layer which act to remobilise and differentially sort clastic materials. During the development of these features, overlying wind-blown coversand is thought to have been incorporated giving rise to distinctive contrasts between the sand in the stripe/polygon and intervening chalky substrate. This contrast can be seen in the soils on bare fields as well as vegetation patterns. Postdepositionally, concentration of subsurface water within the features has caused solution of the underlying frost-shattered chalk creating both irregularities and/or rounded bases to the features (Plate 20d). Related types of patterned ground are the larger scale thermal contraction networks. These are formed by sand-filled wedge casts formed when thermal contraction in winter opened vertical cracks in frozen sediments into which water seeped and froze or into which coversand fell. Sand-filled ice wedges are most commonly located along the Fen margins and around Wretton in the Brecklands. Modern agricultural practices such as ploughing and destoning often destroy the surface expression of patterned ground and stripes, however, these features persist at depth.

Cold climate aeolian or wind-blown sediment occurs extensively across the region and is thought to have in part been derived from winds deflating finer sediment from Devensian outwash from the Fens. Within west Norfolk and the Brecks, aeolian sediments take the form of discontinuous sheets of coversand which vary between 0.5 and 2 m thickness (Figure 72a). Elsewhere much of the original coversand is now surficially absent having been either incorporated into underlying patterned ground or subsumed into present-day soils. Whilst dunes are largely absent or very indistinct on coversands, its wind-blown origin is attributed to it being well sorted (reflecting the winnowing effect), its presence both on topographical highs and lows, and because it contains wind-polished clasts called ventifacts and dreikanter. Coversands are known to have formed between around 21 to 11 ka and form an extensive sheet of sands from central Europe in the east through to France and the UK in the west of which the East Anglian coversand forms just a fragment. Thermoluminescence (TL) dating of coversands incorporated into a stripe at Grimes Graves, Brandon, indicates Late Devensian coversand deposition around 14.5 ka. Infrared stimulated luminescence (IRSL) dating of deposits at Leziate, west Norfolk, returned ages around 12.8 ka which could indicate that coversand deposition was also occurring during the Young Dryas/Greenland Stadial 1. Locally, coversand has been reworked into a series of inland dune fields and these are described within the Holocene chapter (Chapter 11). Elsewhere across parts of north Norfolk, Broadland and southern Suffolk aeolian sediments comprise a variable thick layer of loessic (silt) material (also referred to as brickearth) which forms a thin veneer draping many of the valley flanks. Traditionally, the distribution of aeolian deposits has been mapped using soil augering, particle size and mineralogical studies of soils. An alternative approach, which is particularly useful in areas where only a residual aeolian signal may exist, is through the study of concentrations of the Hafnium (Hf) and Zirconium (Zr) content of soils. Elevated levels of these geochemical elements are particularly diagnostic of aeolian sediments (Figure 73).

Periglacial landforms are also widely evident in East Anglia. Pingos form by the expulsion of sediment porewater by rising permafrost which results in the growth of an ice core and corresponding doming of the ground surface. Water (porewater) can be derived from normally water-bearing sediments such as drained lakes or river channels (hydrostatic or open system pingos) or by groundwater charging from an aquifer situated beneath or within the permafrost (hydraulic or closed-system pingos). Upon melting of the permafrost and ice cores, pingos collapse leaving a distinctive rampart structure around their margins. Excellent examples of pingos that display this morphology can be observed at East Walton Common and Gayton Common in west Norfolk. In present-day periglacial areas, palsas typically form in poorly drained wetland environments (e.g. marshes and valley bottoms). They form where discontinuous permafrost develops within peat-rich sediments causing the surface to dome.

Upon decay, caving and slippage at the base of the landforms cause them to collapse, commonly leading to the development of small ponds and lake basins. An area of extensive palsas development can be observed at Thompson Common and Stow Bedon Common, where over a hundred small rounded ponds and lakes occupy the valley bottom of a tributary of the River Wissey (Plate 21; Figure 72a). Thermokarst thaw lakes, near-circular depressions formed through the melting of ice-rich permafrost, also exist in Cambridgeshire where they are cut into frost-susceptible Jurassic and Cretaceous clays or in silt-rich bedrock. These are distinct from the meres found within the Breckland region of Norfolk of which Hockham Mere, situated to the north-east of Thetford, is the largest being 0.4 km wide and 11.5 m deep. Meres, whilst also being small circular or oval lakes, have very steeply sloping sides and are attributed to solution of the Late Cretaceous Chalk during glacial and/or periglacial conditions. Water levels in these meres reflect a response to Chalk groundwater levels rather than rainfall.

Chapter 11 Holocene

S J Booth, M D Bateman, S Hitchens and P S Balson

Introduction

The Holocene Epoch (Marine Isotope Stage (MIS 1) comprises present postglacial times; it forms the second of two epochs within the Quaternary — the other being the Pleistocene, which has been discussed in the previous chapters. It follows the last glacial stage (MIS 2) known in Britain as the Late Devensian. During the maximum extent of ice sheets during this glacial stage, between about 27.0 and 14.7 ka, global sea levels were up to 130 m lower than present exposing vast areas of sea floor on the continental shelf. The North Sea Basin was largely dry land, and was invaded by the British and Scandinavian ice sheets which coalesced within the northern part of the basin until about 25 ka. As these ice sheets progressively decayed, an area of land was revealed known to archaeologists as Doggerland; this extended eastwards from Britain across the North Sea towards Denmark, Germany and the Netherlands. Doggerland was an area of low-lying topography dominated by inland lakes, marshes and lowland rivers with a small ‘upland’ area known as the Dogger Hills located within the modern offshore area of the Dogger Bank (Figure 74). Drainage within Doggerland appears to have been dominated by rivers that drained northwards towards the deeper parts of the North Sea Basin. These include those whose upper reaches drained East Anglia, including the Great Ouse, which probably extended northwards via the present offshore area beyond The Wash and Inner Silver Pit. The landscape of Doggerland possessed a rich flora and fauna which supported early Mesolithic (10.0 to 6.5 ka) humans as the climatic conditions became more favourable. Global sea levels steadily rose as the Eurasian and North American ice sheets melted and Doggerland became largely submerged by 8.5 ka (Figure 74)b and (Figure 75). The maximum Holocene sea level was reached between 3.0 and 4.0 ka. The Holocene story of East Anglia is associated with the rising postglacial sea level and the adjustment of river catchments and landscape to both warming climates and increasingly, the influence of humans.

For the purposes of description, the Holocene geology is divided into several categories based on the dominant sedimentary processes and form. These include large coastal embayments, together with tide- and wave-dominated coastal sediments, fluviatile deposits and aeolian sediments (Figure 76).

Large coastal embayments

The Wash– Fenland Basin

The Wash–Fenland Basin is contiguous with the coastal plain of Lincolnshire that extends southwards from the Humber Estuary. It has an area of 3400 km2 and widens out to its greatest extent, about 50 km, south of the modern Wash shoreline (Figure 77). The natural tidal incursion extends into the lower reaches of the Great Ouse, the Nene, Welland and Witham rivers but its limit is controlled in modern times by sluices.

Modern Fenland has a landscape profoundly modified by human activities through the drainage and reclamation of intertidal flats, salt marshes and fen. For instance, during the Roman period, the site of the modern market town of Wisbech, 18 km inland, lay on the coastline indicating the extent of land reclamation that has occurred since. Nowadays, large artificial embankments separate the reclaimed coastal plain of the Fenland from the Wash and the North Sea. Large areas, especially in southern Fenland, now lie below sea level, with extreme lows of -2 to -3 m OD, forming some of the lowest-lying and most-valuable agricultural land in the United Kingdom. The lowering of the ground surface is due to a combination of artificial drainage causing sediment compaction and peat wastage.

Present-day sedimentation and processes provide a good proxy of conditions throughout the Holocene. Fluvial and marine sedimentation has occurred in response to sea-level change with natural marine, estuarine and fluvial processes becoming progressively curtailed or modified as a consequence of land reclamation and farming practices over the past 2000 years. In general, the sediments are characterised by cycles of marine and freshwater flooding, during which zones of sedimentation migrated across the basin. It has resulted in a complex lateral and vertical sediment facies variability comprising alternations of clastic sediments (mud and sand deposited on intertidal flats, intermingling with mud, sand and gravel from rivers) and freshwater peat. The Wash–Fenland sediments have a broad, threefold subdivision.

Seaward areas are dominated by tide-dominated coastal sediments. These grade ‘landward’ through estuarine into fluvial sediments. Fringing the basin are large expanses of freshwater peat associated locally with pockets of lacustrine marl (Figure 77). Historically, a number of stratigraphical classifications have been adopted for these Wash–Fenland sequences and these employ stratigraphical terms such as the Barroway Drove Beds and the Nordelph Peat (Figure 78). However, delineating these deposits and in particular the individual units has proven problematic without detailed borehole evidence, stratigraphy, radiocarbon dating and palaeontological data. The current stratigraphical nomenclature groups all the Holocene deposits within the Fenland Basin into the Fenland Formation with division into major sand facies (the Holbeach Member) and mud–peat facies (the Guyhirn Member). Four separate peat horizons are evident within the Guyhirn Member and these correspond to horizons previously referred to as the ‘lower peat’, ‘middle peat’, ‘lower Nordelph peat’ and an ‘upper Nordelph peat’ which interdigitate with a lacustrine shelly marl called the Whittlesea Member. Calibrated radiocarbon ages for the basal ‘lower peat’ of around 8.5 ka demonstrate freshwater marsh conditions to the north-west of Wisbech at this time.

Former watercourses and old tidal creek systems form a network of sinuous features across the Fenland. As a result of dewatering caused by artificial drainage, the surrounding finer overbank sediments have been differentially compacted. As a result, the less compressible silt and sand infill of these channels now forms upstanding meandering ridges up to a metre above the surrounding areas. These ridges are known locally as ‘roddons’. Three separate generations of roddons have been identified that formed between approximately 6.0 and 2.0 ka and these features are particularly well developed between Peterborough, Thorney and Guyhirn (Plate 22). In the southern Fenland a series of mounds capped by Quaternary gravels (at March-Wimblington, Chatteris and Ely) interrupt the Fenland rising up to elevations of 36 m OD. During most of the Holocene this group of ‘islands’ divided the southern Fenland into two separate embayments.

The Broads

The Broads are a network of mainly navigable rivers and lakes in south-east Norfolk and north-east Suffolk (Figure 79) occupying a former large Holocene embayment and marshland that has also been artificially drained and extensively modified by man. Although the terms Norfolk Broads and Suffolk Broads are used to identify specific areas within this area, the term ‘Norfolk Broads’ or ‘Broadland’ is frequently mistakenly used to encompass the whole interconnected water network.

Many of the Broads are flooded medieval peat workings (‘turburrys’) although some natural water bodies are also present. Together they comprise an area of some 303 km2 with 63 distinct water bodies mostly less than 4 m deep and ranging in size from small pools to large expanses of water such Hickling Broad, Barton Broad and Breydon Water. The water bodies are unevenly distributed, being more abundant in the northern half of the Broads (connected by the rivers Bure, Thurne and Ant) than in central and southern part (connected by the rivers Yare, Waveney, Chet and Wensum). Individual broads form part of the modified river system, or are more commonly situated to one side and connected to the river by artificial channels or dykes.

The infilling and eventual burial of the post-Devensian landscape in this area started as sea levels rose and the English Channel and North Sea became connected (around 8 ka).

At this time, the present area of Great Yarmouth occupied the now buried Yare Valley was bordered on its northern and southern flanks by ‘upland’ areas. Marine inundation of the Yare Valley resulted in the deposition of a thick (22 m) sequence of sediments comprising the clay and peat layers that form the Breydon Formation (Figure 80). Generally, accumulation of the ‘Basal’, ‘Middle’ and ‘Upper Peat’ beds occurred when the valley was occupied by freshwater or brackish marshes, whereas the intervening ‘Lower’ and ‘Upper Clay’ beds record episodes of marine incursion and tidal-flat sedimentation. Therefore cycles of sedimentation are indicated by the Breydon Formation. It has been speculated that the initial transgression and deposition of the ‘Lower Clay’ probably occurred at between 8.0 and 7.0 ka. A temporary switch to terrestrial conditions coincided with the accumulation of a ‘Middle Peat’ at about 4.7 ka, and relates to the initial development of a kilometre-long coastal barrier that underlies Great Yarmouth. This barrier comprises sand and gravel (the North Denes Formation) capped by aeolian sand, and forms a wedge-shape prism banked unconformably against an eastwards-facing, inclined erosion surface within the Breydon Formation. The return to tidal flat sedimentation marked by the onset of the ‘Upper Clay’ is believed to have occurred at approximately 2.2 ka. Brackish marine conditions then persisted until at least the 13th century. This is supported by records of local salt workings in the Domesday Book of 1086 AD. Growth of the coastal barrier, coupled with natural and artificial drainage of Breydon Water ultimately led to the final cessation of tidal flat sedimentation. The ‘Upper Peat’, which was deposited during this phase, was extracted during the 13th and 14th centuries, but episodic flooding of these workings or ‘turburrys’ during storm and tidal surges led to their transformation into fisheries and then into the ‘broads’ during the 16th century. In response to these episodic marine inundations, a network of embankments (the ‘Breydon Wall’) was installed by the 17th century, with drainage of the marshes affected by wind-driven pumps.

Tide-dominated coastal sediments

Back-barrier marshes are a striking feature of the East Anglia coastline and are developed extensively along the north Norfolk and eastern Suffolk coastlines. They possess a consistent geology and morphology, a generalised model showing their setting, morphology and relationship to other Holocene sediments is shown in Figure 81. Extensive tracts of silts, clays and peat have accumulated in many of these long-lived tidal, brackish and freshwater back-barrier marshes as they are protected from wave action and the open sea by the coarser sand and gravel deposits forming barriers, spits and shoreface deposits.

Extensive tracts of these deposits occur along the north Norfolk coast protected by classic coastal spit landforms such as Blakeney Point (Plate 23) and they are also abundant in eastern Suffolk and include Benacre, Covehithe and Easton Broads, Westwood and Dingle Marshes, Minsmere, and the extensive marshes behind Orford Ness (Plate 24) fl      the River Alde–Ore between Aldeburgh and Hollesley. Between these major marshland areas, the intervening coastline in north-east Norfolk and Suffolk is usually dominated by cliffs.

Within the marshland behind Blakeney Point there are number of distinctive coast-parallel ridges that, as they restrict direct tidal inundation, commonly mark the boundary between upper and lower marsh environments. These are low dune ridges about 1.5 m high, up to10 m wide, and may extend laterally for up to 3 km although they are dissected in places by major tidal channels. The origin of these ridges is unclear. One possibility is that the ridges are entirely aeolian, although it has also been demonstrated that the dune ridges may have formed around pre-existing gravel layers. These ridges overlie the marshland sediments and are known locally as ‘meals’ or ‘meols’. Examples include the ‘Morston Meals’ and the ‘Stiffkey Meals’ and they are believed to be between about 700 and 900 years old.

In several areas studies have involved the drilling of boreholes to investigate the evolution of these marshland areas. Sedimentation invariably commences with a basal peat layer at elevations between -10 and -15 m OD yielding calibrated radiocarbon dates in the 7.5 to 6.5 ka range and the sequences reveal patterns of alternating peat layers and silt–clay deposits similar to those described above from the Breydon Formation. The preservation of thick aggrading sequences of fine-grained and organic Holocene deposits in many marshland areas attest to the longevity of the coastal barriers and spits that sheltered these depositional environments.

Extensive areas of marshland are also found flanking several of the major rivers of the region including the Blyth, Deben and Gipping–Orwell. Here, despite the action of longshore drift, the rivers have managed to retain fairly straight lower courses out into the North Sea with the development of inter- and supratidal marshes on both banks.

Wave-dominated coastal sediments

Except within the Wash embayment, almost the entire coast of East Anglia has beaches composed of shoreface sand and gravel deposits attesting to the strong wave action experienced along this whole coastline. These take varied forms, for example, narrow shingle beaches are commonly found at the foot of many of the region’s stretches of cliffline and their erosion can act as important sources of sediment for the shoreface and nearshore deposits.

Beaches comprise variable amounts of sand, pebbly sand and gravel depending on the prevailing strength of the offshore winds and wave action, plus the proximity and nature of source material such as that from cliffs backing the beach. Given that much of the material is locally sourced from preglacial or glacial deposits, the shingle generally comprises well-rounded gravel-sized (10 to 15 mm diameter) clasts of flint and subordinate quartz and quartzite, with a matrix of medium-grained sand.

Beach morphology is controlled by a range of local variables that change temporally and spatially and include sediment supply, tidal regime, storminess and wave climate. Typically, beaches form a trapezoidal wedge with a base that dips gently seawards but when erosion occurs, the wedge narrows with the upper beach profile steepening markedly.

These coarse-grained beach sediments are very mobile and subject to the gradual effects of longshore drift and radical redistribution during large storm events. Over time, barrier ridges and spits develop by longshore drift leading to the protection of expanses of low-energy freshwater, brackish and tidal marshland. The barriers and spits tend to migrate landward over these back-barrier marsh areas due to progressive washover of the sediments during storm conditions.

In Norfolk west of Sheringham the longshore drift movement is predominantly westwards along the north Norfolk coast and into the The Wash, whereas to the east of Sheringham, longshore movement is eastwards and then southwards around the coast extending south past Orford Ness as far as Landguard Point guarding the Orwell Estuary at Felixstowe.

The north Norfolk coast to the west of Weybourne is distinctive because of the apparent straightness of the coastline and the presence of a number of coast-parallel storm beach or gravel-dominated ridges, spits and barrier islands. A classic example of an offshore barrier island is Scolt Head Island near Brancaster (Plate 25). Further to the east, Blakeney Point is an excellent example of a coastal spit which comprises a shingle bank ranging from 20 to 200 m wide and 9 to 10 m high, containing an estimated 235 million cubic metres of rounded flint cobbles (Plate 23). One issue that has puzzled geologists is the origin and source of the sediment that forms the spit. The feature is entirely postglacial and it is believed that glacial sediments probably formed the original source for the landform. The shape of the spit and the occurrence of a number of landward-curved shingle banks are related to earlier positions of the end of the spit and imply a westwards growth of the spit. Westwards, nearshore and longshore drift along this part of the Norfolk coastline would suggest that the sediment was derived from between Weybourne and Sheringham. However, whilst flint cobbles do occur within the cliff sections here they are not present in sufficient quantity to be the primary source. Equally, a source to the east of Blakeney does not fully account for the predominance of sand at the distal end of the spit. It has been suggested that the most likely source of sand lies beyond the western end of the spit. A study of aerial photos, taken over 40 years, indicates that sand bars move eastwards across the main tidal channel at Blakeney ultimately merging into the distal end of the spit. Thus, storm events from the north and north-west rather than longshore drift, together with a sediment source from the west rather than from the east, provide an alternative mechanism for extending the spit and may account for the landward-curved banks, as noted above. The source of the flint cobbles remains unclear although it is possible that they could be reworked from older Pleistocene beach or glacial outwash gravels located offshore.

Historical maps also provide valuable data for the evolution of Blakeney Point. A map dating to 1586 indicates that it was much shorter indicating an average extension of 5 m per year since 1586. This rate is far lower than estimates made from more recent historical maps which suggest average spit growth between 1886 and 1904 of 86.3 m per year, and 45.7 m per year during the period 1904 to 1925. There is also considerable evidence to show that the shingle ridge has moved, and is moving, landward. From 1649 to 1924, the ridge was recorded as moving landward at 1 m per year, and this migration is reportedly continuing. By reference to old maps, it is clear that the shingle bar has overridden parts of the marshland, such as Weybourne Marsh at the eastern end of the marsh/shingle complex and is close to overwhelming several small isolated hillocks locally called ‘eyes’ (e.g. Blakeney Eye, Cley Eye, Little Eye and Gramborough Hill) that occur on the seaward margins of the marshland.

Farther south, Orford Ness has also been extensively studied via old maps, regular monitoring of morphology over the last 50 years and by the drilling of boreholes. Orford Ness is a large cuspate mass of shingle formed at the point where the north–south coastline of Suffolk turns onto a north-east to south-west orientation (Plate 24). At the northern end, the River Alde reaches within 50 m of the sea at Aldeburgh before being deflected 15 km southwards as the River Ore to flow past Orford reaching its mouth at Hollesley. Historical cartographical evidence and monitoring in recent years suggest the spit controlling the position of the river mouth may be subject to cyclical growth and destruction. The shingle deposits are known to be at least 15 m thick under Orford Ness and rapidly interdigitate landward with the fine-grained marsh sediments that record evidence of aggradation over the last 8000 years. Their preservation suggests protection from the open sea over a long period. The pebble-grade material within the shingle is composed of 90 to 95 per cent flint with the balance consisting of other resistant siliceous lithologies such as quartzite, quartz and chert. A possible source for the material, bearing in mind the prevailing sediment transport direction, is considered to be the Westleton Beds.

Alluvial tracts

Occurrences of alluvium are mapped throughout the region particularly in the middle and upper reaches of rivers and throughout their tributary valleys. Importantly, the alluvial tracts in their natural state form floodplains that would have been liable to flooding during high river discharge. Most rivers are now constrained behind artificial embankments and rarely flood their surrounding floodplains. Given these characteristics, alluvial tracts tend to be used mainly for summer grazing and silage making; where building development has occurred this creates a flood risk due to surface sealing.

The alluvial sediments comprise mainly unconsolidated layers of sand and silt but include material ranging from organic muds through to coarse gravel derived from local sources.Commonly the sequence includes a thin basal lag gravel and fines upward — a characteristic of low-energy meandering rivers. These alluvial sediments are interbedded with peat and interdigitate downstream with tidal intertidal and estuarine deposits. Locally, alluvial sediments merge with lacustrine muds accumulating in expanses of ponded water. Upstream, in narrow tributary valleys, the alluvium is commonly interbedded with slope deposits including recent head deposits the accumulation of which is enhanced by woodland and vegetation clearance by man and regular ploughing.

Aeolian deposits

Pre-Holocene cold climate aeolian or wind-blown sediment, known as coversand and coverloam, occurs reasonably extensively across the Breckland region and northern Norfolk (Figure 76; Chapter 10). Throughout the Holocene, the coversands have been episodically reworked by the wind; and have been, and continue to be, blown off the dry fields during high winds especially after ploughing. In places the coversand sheets have been reworked into small dune fields such as the ones found at Icklingham and Wangford Warren near Brandon (Plate 26) where the sands can commonly reach thicknesses of 6 m. Across much of the Breckland, sand has been progressively incorporated into soils resulting in the agriculturally unproductive Breckland soils and spreads of extensive heathland.

The widespread nature of this sand movement has rendered the landscape unstable and dune migration events have been referred to locally as ‘sand floods’. Coversand reworking, based on sand found in a core from Hockham Mere, has occurred since at least 12.6 ka. Elsewhere flint artefacts of Mesolithic age (10.0 to 6.5 ka) have been found within reworked dunes at Lakenheath and a Roman period (1.9 to 1.5 ka) settlement was discovered buried beneath blown sand near to Cavenham Mere. At West Stow, a sand-flood event is known to have encroached on the medieval settlement and buried the associated ridge and furrow fields. The earliest documented sand-flood event occurred in the 11th century. Later floods have also been recorded during the 13th and 17th centuries — the former associated with the Little Ice Age. In 1668 Thomas Wright likened the Breckland area to the ‘...deserts of Libya...’ and described the 40-year-long sand-flood which engulfed the village of Santon (‘Sandtown’) Downham to a depth of at least 2.75 m. Nearby at Wangford Warren five phases of sand deposition have been dated with OSL and radiocarbon dating to around 6.5 ka, 1.6 to 1.1 ka, 0.5 ka, 0.4 to 0.3 ka and 0.2 to 0.03 ka with a stable period of fen-peat accumulation and mature soil development between 2.1 and 1.8 ka. Wind-blown reworking has not just been confined to Breckland but has been reported from west Norfolk where the Leziate sand sheet was reworked into the Ling Common Drift sands around 1.5 ka. Earlier instability may relate to extensive forest clearance which took place after 4.5 ka whereas more recent periods appear to be related to animal grazing. In the Brecklands during the 15th and 16th centuries, the sheep population rapidly expanded as did the numbers of commercial rabbit warrens supplying the lucrative London markets with meat and fur. The latter peaked in the mid 18th century with areas of commercial rabbit warrens extending across some 61 km2 of the Brecklands. This led to overgrazing, reducing vegetation cover to the bare loose sandy soil leaving it prone to deflation when climatic conditions were drier or stormier.

Deflation of dry beach and coastal sand-grade sediments also leads to the accumulation of blown sand as coastal dunefields. Older stabilised examples are commonly vegetated with marram grass whilst others have been stabilised by man’s construction activities. Blown sand commonly occurs capping structures such as spits at Great Yarmouth, Lowestoft and Blakeney and in behind-beach spreads overlying marsh deposits and older Quaternary sediments such as at Winterton-on-Sea where up to 7 m of sand is present.

Chapter 12 Quaternary mammals

D C Schreve

East Anglia is arguably the single most significant region in England for documenting the evolution of the British mammalian fauna and, in particular, its response to the changing climatic and environmental conditions of the Pleistocene (Chapter 7). This richly fossiliferous region has been favoured by a combination of environmental and historical factors including the presence of calcareous groundwater aiding preservation of bones and teeth and the absence of widespread destruction by glacial processes since the late Middle Pleistocene.

In addition there has been a diversity of different depositional contexts and a long history of fossil collection particularly by amateur enthusiasts. This has led to the accumulation of a substantial archive of mammalian remains for study. In the light of recently developed biostratigraphical frameworks combined with improved palaeoecological methodologies, it is now possible to construct a detailed history of the mammal fauna in this most important region. The locations of key sites referred to in the text are shown in Figure 82.

Early to Early Middle Pleistocene

Early Pleistocene sites with mammalian remains are rare in Britain but notable assemblages have been recorded since the 1820s from sand and gravel deposits of the marine Crag Group (Chapter 8). These include deposits of the Norwich Crag Formation at sites such as Bramerton and Thorpe near Norwich, and Aldringham-cum-Thorpe, Sizewell and Easton Bavents in Suffolk. The British Early Pleistocene succession is, however, highly fragmented with a number of recognised hiatuses and unconformities. Understanding the age of the various faunas and geological units within this part of the geological record is therefore highly problematic and so far primarily achieved by stratigraphical correlation with more complete sequences in mainland Europe such as the Netherlands, Germany and Russia. Much of the British material is unfortunately unstratified but all is broadly of Antian–Bramertonian age (about 2 Ma, equivalent to the TC3 substage of the Tegelen Clay of the Dutch Early Pleistocene). In addition to aquatic animals such as whales and seals, these shallow-water marine deposits have yielded an important and remarkable terrestrial mammal collection, presumably the remains of carcasses entering the sea via the estuaries of local rivers. These include the most primitive small mammal assemblage known from the British Isles, represented by species such as the water voles Mimomys pliocaenicus, M. reidi, M. newtoni, M. rex and M. altenburgensis (Figure 83) and an extinct hare-like animal Hypolagus brachygnathus. Typical species within the large mammal assemblage are the gomphothere mastodon Anancus arvernensis, the mammoth Mammuthus meridionalis, the zebrine horse Equus stenonis, extinct comb-antlered deer (Eucladoceros falconeri) and gazelle (Gazella spp.). There are also unique British records of a clawless otter, Enhydra reevei and a large European cheetah Acinonyx pardinensis.

Younger faunas attributed to a cool climatic phase with open vegetation, commonly referred to as the Pre-Pastonian ‘A’ substage, have been recorded from deposits of the Norwich Crag Formation at localities in north Norfolk such as West Runton, East Runton, Sidestrand and Weybourne. These are characterised by more advanced representatives of Mimomys pliocaenicus, M. reidi and M. newtoni than occurred in Antian–Bramertonian levels, with the addition of M. pitymyoides, M. tigliensis, Myodes sp. (bank vole) and the desmans (snouted moles) Desmana thermalis and Galemys kormosi. Correlation with the Dutch sequence suggests age equivalence of these faunas with those of the late Tiglian, specifically the second half of TC4c (1.9 to 1.8 Ma) , which exhibits a normal magnetic polarity. Along the north Norfolk coast, shelly deposits are unconformably overlain by beds of pebbly clay conglomerate from which substantial numbers of large mammal remains, chiefly of elephant (Mammuthus meridionalis) (Figure 84) and deer (the comb-antlered deer Eucladoceros teguliensis and the smaller Pseudodama rhenanus), have been recovered. These deposits are of reversed magnetic polarity and correspond to an interval commonly called the Pastonian (equivalent to TC5 to 6, 1.8 to 1.7 Ma) . However, the occurrence of three additional deer species at East Runton, including two comb-antlered deer (E. tetraceros and E. sedgwicki) and the ancestral elk Cervalces gallicus (all of which are absent from Tegelen) is unusual when compared to other continental European assemblages of this age. The presence of additional deer species implies that the East Runton material may span temporal episodes not preserved elsewhere and that there may thus be an admixture of either older (Pre-Pastonian) or younger (Beestonian) material (or both). Some stratigraphical information can be gleaned from the examination of the size variation in the molars of M. meridionalis, with smaller teeth occurring in the Pre-Pastonian and Pastonian levels and larger, less mineralised teeth in higher (possibly Beestonian) strata. An upper age limit of these faunas is provided by an apparent absence of the vole genus Microtus (Allophaiomys), which appears in the Netherlands during the equivalent cold-climate period, the Eburonian. However, although it is clear that there are significant unconformities during the Beestonian cold period and later succession (possibly covering at least one million years), Allophaiomys may yet be discovered in Britain when suitable fine-grained deposits are located.

The early Middle Pleistocene is represented in East Anglia by richly fossiliferous alluvial deposits associated with the Ancaster River (Chapter 9), the Cromer Forest-bed Formation, that crop out in north Norfolk and by similar deposits relating to the Bytham River in Suffolk. Most of the large mammal remains collected over the past two hundred years have been eroded out of the deposits and have been found loose on the beach or on the foreshore. Although the stratigraphical provenance of many specimens is therefore uncertain, important collections of in situ vertebrate material have been obtained from localities such as Pakefield– Kessingland, the West Runton Freshwater Bed and Sidestrand. In the UK, mammalian and molluscan biostratigraphy, in conjunction with other palaeoclimatic evidence, has suggested the presence of as many as six discrete temperate episodes within the British ‘Cromerian Complex’ sequence. The type Cromerian interglacial at West Runton in Norfolk is now recognised to be just one of these temperate episodes, possibly the equivalent of the Dutch Cromerian II (Westerhoven). All British Cromerian Complex interglacials are normally polarised and postdate the earliest Dutch Cromerian I at Waardenberg. A key feature enabling separation of the different ‘Cromerian Complex’ sites is the evolutionary stage of the water vole present therein. The four oldest faunal groupings (including West Runton) are characterised by the presence of Mimomys savini, an archaic form with rooted teeth (Plate 27a), whereas the two youngest groupings are typified by the occurrence of its descendent, Arvicola terrestris cantiana, which has unrooted teeth (Figure 85; Plate 27b). The two youngest groups may be further divided on the basis of the evolutionary stage observed in the narrow-skulled vole lineage, with the replacement of Microtus gregaloides by its descendant Microtus gregalis.

Of the four faunal groupings with Mimomys (Figure 85), the oldest is considered to be Pakefield (Suffolk), a site that has yielded some of the oldest evidence of human occupation in Britain around 0.7 Ma. As well as M. savini, remains of another water vole, M. pusillus, have been recovered from a sandy gravel with shells (the ‘Unio bed’). Despite prolific collecting at other ‘Cromerian Complex’ sites over many decades and the prevalence of suitable palaeoenvironmental conditions, the Pakefield M. pusillus is the only known record from Britain. In Europe, this species is present from the Early Pleistocene to its latest occurrence in the early Middle Pleistocene Ilynian Complex in Russia. The Ilynian Complex is overlain by the Don Till, commonly correlated with MIS 16, consequently suggesting a minimum age for the Pakefield ‘Unio bed’ of MIS 17. The implication of the microtine rodent evidence at Pakefield is that all younger early Middle Pleistocene sites (including the West Runton type site) that lack M. pusillus, should be accommodated within MIS 15 and 13.

These stages contain numerous short-lived substage warm episodes, to which these sites might convincingly be related. The Pakefield mammalian assemblage also contains a rare record of an extinct shrew Macroneomys brachygnathus, and beavers Castor fiber and Trogontherium cuvieri, together with an impressive collection of large mammals, including the sabre-toothed cat Homotherium sp. (Figure 86), lion (Panthera leo), the steppe mammoth (Mammuthus trogontherii) and three species of giant deer (Megaloceros verticornis, M. savini and M. dawkinsi). In addition to M. dawkinsi, two thermophilous species are present at Pakefield that have never been found at West Runton, the hippopotamus (Hippopotamus sp.) and straight-tusked elephant (Palaeoloxodon antiquus). These taxa imply a difference in age between the two sites, a suggestion that is upheld by the presence of southern warm-loving plants and beetles and evidence for higher summer temperatures than at present (18 to 23°C) at Pakefield. West Runton has a very rich vertebrate and invertebrate assemblage but lacks these thermophilous elements and has no evidence for temperatures warmer than today. The site is arguably best known for the discovery, in the mid 1990s, of a spectacular and virtually complete skeleton of Mammuthus trogontherii (Figure 87). Both sites reflect the presence of a meandering river with adjacent marshes, reeds and alder trees, with oak woodland and dry grassland nearby. The youngest Cromerian Complex sites in East Anglia are represented by deposits at Sidestrand and Ostend, which have yielded exclusively the younger morphotype, Arvicola terrestris cantiana with continuously growing molars. These localities are likely to be of approximately the same age as the early Middle Pleistocene site of High Lodge in Suffolk, deposited by the now-extinct Bytham River, which once drained the English Midlands prior to its obliteration by the Anglian ice sheet.

Late Middle Pleistocene

As with the majority of pre-Devensian (last glaciation) cold stages, little is known of the mammalian fauna and palaeoenvironments of the Anglian Glaciation (MIS 12) in East Anglia (Chapter 10). Although it has previously been suggested that cold-climate fluvial deposits of the River Waveney at Homersfield in Suffolk might date from this period and preserve the oldest evidence of woolly mammoth (Mammuthus primigenius), woolly rhinoceros (Coelodonta antiquitatis) and giant deer (Megaloceros giganteus) in Britain, it is likely that these sediments in fact represent a younger episode of cold-climate conditions. Better evidence of Anglian-age mammals comes from Mundesley on the north Norfolk coast, where a crushed skeleton of a ground squirrel (Spermophilus sp.) was found in the freshwater ‘Arctic Bed’ silts below the Walcott Till Member, in association with pollen indicative of cold and open conditions. In addition, a single well-dated record of red deer (Cervus elaphus) comes from the surface of Anglian Lowestoft Till at Hoxne, in Suffolk, also found in association with a herb-dominated flora and the presence of sea buckthorn (Hippophaë) scrub. Although fossils associated with Anglian deposits are uncommon, it is clear that the glaciation caused extensive turnover in the mammalian assemblage, with the extinction (and subsequent replacement by new species) of a number of small mammals, carnivores, rhinoceroses and deer.

Following the Anglian Glaciation, deposits containing mammalian material were deposited in kettleholes and river channels. The Hoxnian Interglacial (MIS 11; 0.424 to 0.374 Ma) is represented by a wealth of sites in East Anglia, including the site of Hoxne itself, the stratotype of the Hoxnian interglacial. At Hoxne, well-studied interglacial deposits occupy a depression in the Lowestoft Till, either formed in a kettlehole or a poorly drained ground moraine swale, immediately following the decay of the Anglian ice. The dating of the site has been underpinned by litho- and biostratigraphy, by AAR and by electron-spin resonance. The sediments preserve a series of lacustrine muds, overlain by peaty, detrital deposits, further lacustrine sediments representing the final infilling of the lake, and ultimately by fluvial deposits. Only the earliest lacustrine deposits are likely to represent the interglacial proper, with subsequent temperate-climate deposits reflecting later interstadials within MIS 11.

Evidence of a climatic deterioration, in the form of Arctic plants and beetles, is also present within the sequence.

Mammalian remains from the early interglacial deposits are sparse, comprising only straight-tusked elephant and the extinct beaver-like rodent Trogontherium cuvieri. The pollen spectra from these levels record a sharp rise in arboreal pollen with the onset of temperate-climate conditions, leading to an expansion of temperate woodland, signalled by a rise in oak (Quercus) and other thermophilous trees, such as alder (Alnus), lime (Tilia), elm (Ulmus), ash (Fraxinus) and holly (Ilex). More humid conditions are subsequently suggested by the development of alder forest, after which a high nonarboreal pollen (NAP) phase has been noted. The unusual NAP phase has equally been observed in contemporary pollen profile from infi         lake basins in Suffolk, such as St Cross, South Elmham and Athelington but has not been found in the estuarine deposits of Woodston in Cambridgeshire, also attributed to MIS 11 on the basis of its mammalian assemblage. This deforestation has variously been ascribed to regional forest fi (possibly initiated through human agency) or to climatic factors. At the end of this subzone, the fi indications of climatic deterioration are observed in the pollen record, with the appearance of silver fi (Abies) and hornbeam (Carpinus). The beetle assemblage indicates the progressive silting-up of the lake and the creation of more marshy habitats and piles of decaying vegetation. The presence of tall, reedy vegetation and lush water meadows at the water’s edge is indicated by beetle species such as Notaris bimaculatus and Donacia semicuprea, although much of the grass and sedge appears to have been affected by smut fungus, as attested to by the presence of large numbers of Phalacrus caricis, the larvae of which feed on the spores. The disease is thought to have been of massive proportions, thereby rendering the local grazing unpalatable or indeed poisonous at this time.

The upper part of the sequence at Hoxne is initially characterised by renewed lacustrine sedimentation and pollen indicating much more open conditions, commonly referred to as ‘oceanic heath’ or park tundra, although some temperate trees are still present. However, plant macrofossil remains, including dwarf birch (Betula nana) and dwarf willow (Salix herbacea) and Arctic beetles indicate climatic deterioration. The fluvial deposits that cap the sequence contain a rich mammalian assemblage. Temperate taxa (fallow deer, Dama dama, roe deer, Capreolus capreolus, macaque monkey, Macaca sylvanus and Eurasian beaver, Castor fiber) are still present but species characteristic of open grassland, such as horse, become dominant.

The Hoxne sequence is thus of international importance for demonstrating mammalian and palaeoenvironmental response to complex palaeoclimatic change, represented by an interglacial and subsequent cold and warm oscillations. The Hoxnian Interglacial is also significant in Britain for heralding the first appearance of species such as Mercks’ rhinoceros (Stephanorhinus kirchbergensis), narrow-nosed rhinoceros (Stephanorhinus hemitoechus), giant deer (Megaloceros giganteus) and aurochs (Bos primigenius). This interglacial also marks the final appearance in Britain of rabbit (Oryctolagus cuniculus), the extinct small mole Talpa minor, European pine vole (Microtus subterraneus) and the extinct beaver-like rodent T. cuvieri (Plate 27-c). Other infilled basin sites in East Anglia with important vertebrate assemblages of Hoxnian age include Barnham and Beeches Pit at West Stow, both in Suffolk. The former has yielded rich small vertebrate remains and is particularly notable for its herpetofauna, including the currently exotic European pond terrapin (Emys orbicularis), common tree frog (Hyla arborea), moor frog (Rana arvalis) and Aesculapian snake (Zamensis longissimus).

Beeches Pit is characterised by fine-grained tufaceous silt and clay, associated with a former springline, remarkable for its extraordinarily diverse molluscan remains, a characteristic mix of extinct species and taxa whose modern ranges do not overlap at the present day. This distinctive molluscan suite is referred to as the ‘Lyrodiscus fauna’ and has been found in a number of MIS 11 sites in the UK and western Europe. At Beeches Pit, central European forest species are represented by Acicula polita, Ruthenica filograna and Clausilia pumila, south-eastern European species by Acicula diluviana (= Platyla similis), western Pyrenean woodland species by Lamnifera pauli and western Atlantic species by Zenobiella subrufescens and Leiostyla anglica. However, the most unusual occurrence is that of the gastropod Retinella (Lyrodiscus) skertchlyi, a species whose nearest living relatives are now restricted to the Canary Islands.

In contrast to the abundant evidence for the Hoxnian Interglacial, there are no well-established sites of MIS 9 age (0.337 to 0.300 Ma) reported within East Anglia, although a number of important localities lie just over the boundary in Essex, including the richly fossiliferous site of Cudmore Grove. A possible exception is to be found within the deposits of the Third Terrace of the Cam Valley Formation, at Histon Road in Cambridge. The Histon Road deposits were first described in the 1950s and initially attributed to the Ipswichian (Last) Interglacial, now correlated with MIS 5e; indeed for many years, the site was regarded as a key stratigraphical reference site for the latter half of this temperate episode. The mammalian assemblage includes aurochs, red deer, fallow deer, straight-tusked elephant and undetermined rhinoceros, suggesting a mosaic of deciduous or mixed woodland and the presence of more open habitats. Recent investigation of the deposits have added fish including pike (Esox lucius), three-spined stickleback and perch, to the assemblage, as well as common shrew, water vole and horse. The presence of fallow deer and straight-tusked elephant are particularly significant in terms of palaeoclimatic evidence, since both are restricted to temperate occurrences in Britain. Aquatic habitats are indicated by the water vole, which frequents the well-vegetated banks of rivers and lakes with still or slow-flowing water, whereas the fish are most commonly found today in the mid to lower reaches of rivers, overgrown backwaters and ponds with overhanging vegetation. The presence of pike implies winter water temperatures of not less than 5°C. An older (possibly MIS 9) age for at least part of the deposits now seems likely on several grounds, including the presence of horse and the bivalve Corbicula flumalis (both of which are unknown in the Last Interglacial), as well as the stratigraphical position of the site within the Cam terrace sequence.

Deposits of the penultimate (MIS 7) interglacial, around 0.2 Ma, are abundant across East Anglia. Evidence from sites in southern England indicates complexity within this interglacial, with at least one marked period of mammalian turnover and three temperate substages of more-or-less equal intensity. Faunal assemblages from the early part of the interglacial include species indicative of slightly elevated summer temperatures and deciduous woodland, whereas those from the late part of MIS 7 are typified by a co-abundance of horse and a late morphotype of steppe mammoth, M. trogontherii, in association with predominantly open grassland. Small mammal assemblages from sites of this age include a more evolved morphotype of water vole than previously encountered in older interglacials, as well as an extinct small mouse (Apodemus maastrichtiensis) and the abundance of northern vole (Microtus oeconomus). All sites discussed below contain the diagnostic ‘mammoth-horse fauna’ of the later parts of MIS 7. Notable localities include Stoke Tunnel, which lies on the flank of the Orwell Estuary on the outskirts of Ipswich, and the adjacent site of Maidenhall, the former first exposed around 1846 when a railway tunnel was cut through the Stoke Hills. Later excavations revealed a large quantity of fossil mammalian remains from a black Bone Bed and from underlying purple clays, together with freshwater shells, including a Levallois tortoise core, and a small number of worked flints. Fragments of an E. orbicularis carapace were also found in association with remains of mammoth, reportedly the first discovery of this co-occurrence and confirmation of the temperate nature of the deposits. The mammalian assemblage is dominated by horse, steppe mammoth and red deer, with smaller numbers of straight-tusked elephant, roe deer, aurochs, woolly rhinoceros (Coelodonta antiquitatis), lion (Panthera leo), wolf (Canis lupus) and brown bear (Ursus arctos), and a small mammal fauna comprising water vole (Arvicola terrestris cantiana), field or common vole (Microtus agrestis or Microtus arvalis), northern vole (Microtus oeconomus) and wood mouse (Apodemus cf. sylvaticus). Very similar assemblages have been recovered from Jordan’s Pit at Brundon in Suffolk, a former gravel and alluvium pit on the south bank of the River Stour (providing additional records of narrow-nosed rhinoceros and giant deer), from the sites of Stutton and Harkstead exposed in low cliffs comprising sand and silty clay on the northern side of the Stour Estuary (the former also yielding A. maastrichtiensis), and from Stoke Goldington in the valley of the Great Ouse in Bedfordshire. Together, these sites present a consistent palaeoenvironmental picture of a temperate and predominantly open environment, dominated by grassland but with isolated stands of mixed woodland.

Late Pleistocene and Holocene

The Last (Ipswichian) Interglacial, correlated with MIS 5e, around 0.125 Ma, contains a highly diagnostic and unusual element, in the form of hippopotamus (Hippopotamus amphibius). This is the same species that occurs in sub-Saharan Africa today but which was formerly widespread across the Mediterranean during the Pleistocene. The Last Interglacial was a time of exceptional warmth, with mild winters at or above freezing, and mean summer temperatures around 5°C warmer than the present day. This corresponds well with the climatic tolerances of hippopotamus, since this animal cannot tolerate prolonged seasonal freezing of local water bodies. The Ipswichian type site at Bobbitshole in Ipswich provides a detailed record of sedimentation and vegetational history from the latter part of the pre-Ipswichian cold episode to the middle of the ensuing interglacial. The organic deposits are notable for the excellent preservation of plant macrofossils, a rich nonmarine molluscan assemblage and a limited number of small vertebrate remains, including Eurasian beaver and European pond terrapin. The succession of pollen zones compares closely with that of the continental Eemian (Ipswichian) Interglacial.

Although vertebrate remains are rare at Bobbitshole itself, very rich and well-documented faunal assemblages of Ipswichian age are known across East Anglia from sites such as Barrington in Cambridgeshire, Shropham and Swanton Morley in Norfolk, Lavenham in Suffolk and Fulbeck, Maxey and Little Syke in Lincolnshire. These assemblages are typified by large numbers of straight-tusked elephant, narrow-nosed rhinoceros, fallow deer, auroch, bison, giant deer, lion and spotted hyaena, as well as hippopotamus (Plate 27-d). Notable absentees from the Last Interglacial fauna in Britain include Merck’s rhinoceros, horse and Neanderthals, all of which have been found in deposits of equivalent age on the continent. Their absence from Britain is likely to relate to a combination of factors, including the severity of the preceding MIS 6 cold stage, the rapid spread of forests at the start of the ensuing interglacial and island isolation. Many Ipwichian sites have yielded pollen spectra that are characteristic of mixed oak forest, although it is noticeable that at many fluvial sites, arboreal pollen is surprisingly low and pollen of herbs and grasses is higher than would be expected at the climatic optimum. Together with evidence of minerogenic input into the sediments, the presence of a locally open landscape has been attributed to the grazing and trampling effects of large mammals on floodplain habitats.

Mammalian assemblages from the different phases of the last (Devensian) glaciation in Britain are well understood in terms of their succession, particularly from the records preserved within caves in the south-west of England, the Peak District and south Wales. Assemblages of this age have been dated through a combination of mammalian biostratigraphy and Uranium-series dating of associated flowstone deposits, which suggest correlation with MIS 5a (about 80 ka). These Early Devensian faunas are characterised by a restricted range of species, indicative of cold conditions with relatively high snow cover, and comprising mainly bison, reindeer, an extremely large brown bear, wolverine (Gulo gulo), Arctic hare (Lepus timidus) and Arctic fox (Alopex lagopus). Although no unmixed Early Devensian faunas have been reported from East Anglia, it is likely that at least part of the assemblage from Wretton in Norfolk dates to this period. Assemblages attributed to the Middle Devensian (MIS 3, 57 to 29 ka) are somewhat better known in East Anglia. This period records a marked shift in the mammalian fauna, in response to an overall palaeoclimatic amelioration at this time, albeit one punctuated by rapid oscillations of 6 to 7°C on a submillennial scale. The Middle Devensian sees the return to Britain of woolly mammoth, woolly rhinoceros, horse and spotted hyaena, together with Neanderthals, marking the spread of a characteristic steppe–tundra suite of mammals.

Faunal assemblages of this age are generally securely underpinned by radiocarbon dating as well as biostratigraphy and include the celebrated site of Lynford, in Norfolk. Here, remains of twelve mammalian taxa (including Homo, represented on the basis of the artefacts) were excavated from a remnant palaeochannel of the River Wissey, exposed during active quarrying in 2002. The assemblage is dominated by remains of eleven woolly mammoths (Plate 27-e,f), all prime adults apart from a single calf and mostly male where determinable, with smaller numbers of reindeer, woolly rhino, bison, horse, wolf, red fox (Vulpes vulpes), brown bear (Plate 27-g), spotted hyaena, ground squirrel and narrow-skulled vole (Microtus gregalis). The remaining vertebrates comprise pike (Esox lucius), three-spined stickleback (Gasterosteus aculeatus), carp family (Cyprinidae sp.) and perch (Perca fluviatilis), in addition to crake (Porzana sp.) and common frog (Rana temporaria). The combined palaeoenvironmental evidence from plant remains, pollen, molluscs, insects and vertebrates indicates open conditions dominated by grasses, sedges and low-growing herbaceous communities with small stands of birch or scrub, acid heath or wetlands adjacent to a source of slow-flowing permanent water. Beetle remains suggest that the mean summer temperature lay somewhere between 14°C and 12°C, with the mean temperature of the winter months at or below -15°C. Direct evidence of exploitation of reindeer, horse and woolly rhinoceros comes from teeth and bones that appear to have been deliberately smashed for marrow extraction. Evidence for mammoth utilisation is harder to establish, although the predominance of prime individuals, the absence of the meatiest limb bones (despite other large elements being present), the scarcity of carnivore gnawmarks and evidence for tool resharpening and damage on the tips of the associated 47 handaxes collectively support the view that Neanderthals were coming to the site deliberately to exploit (and likely to hunt), mammoth along with other megafauna.

In contrast to the highly detailed record from Lynford, the site of Barnwell in Cambridge, on the second terrace of the River Cam, has produced a very mixed faunal assemblage of predominantly Late Pleistocene age. Rolling and abrasion are apparent on virtually all bones and teeth, which appear to represent a hydraulic mixture of warm and cold climate remains. The material includes rare water vole, indeterminate bear (Ursus sp.), lion, red deer and reindeer, as well as woolly rhinoceros, horse, woolly mammoth, large bovids and hippopotamus (Figure 88). The presence of hippopotamus indicates that elements of Last Interglacial age are present, whereas all other taxa, in particular the reindeer, woolly mammoth and woolly rhinoceros, are likely of Devensian age. Other localities in East Anglia that have yielded Devensian mammalian material include Cavenham and Bramford Road (Ipswich) in Suffolk.

Following the maximum extension of the Last British Ice Sheet at about 27 ka, the mammalian fauna became briefly re-established in Britain during the Late Glacial Interstadial. Sites of this age are very poorly known in East Anglia, the most notable being Sproughton, on the outskirts of Ipswich. Here, sands and gravels of the River Gipping have produced a limited faunal assemblage including horse and reindeer, in association with barbed projectile points. Radiocarbon dates have placed the assemblage at the boundary between the Pleistocene and early Holocene, around 11 to 10 ka. The transition to the current interglacial is marked by the extinction of many key megafaunal species and combined with the effects of island isolation, this has resulted in a considerably impoverished fauna in terms of overall species diversity when compared to earlier interglacials. Nevertheless, a rich early Holocene vertebrate assemblage has been recovered from a number of sites in the Fens, including Burwell and Reach, dating to around 7000 years ago. Species present include wolf, brown bear, otter, Eurasian beaver, roe deer, red deer and auroch, together with bittern (Botauris stellata), mute swan (Cygnus cygnus), whooper swan (Cygnus olor), white-tailed eagle (Haliaetus albicilla), common crane (Grus grus) and razorbill (Alca torda). These provide an insight into the last natural fauna of East Anglia, before the effects of anthropogenic transformation through the processes of domestication, local extinction of a number of key native species and the introduction of alien taxa.

Chapter 13 Early humans and landscape

N Ashton

Introduction

East Anglia provides one of the best-preserved records of early prehistory in Europe and contains the earliest human sites in northern Europe, dating to over 0.8 Ma (Figure 89; Figure 90). The quantity and quality of flint raw material over much of the area provided humans with the means to manufacture an array of stone tools. These were left in abundance on landscapes that have occasionally survived intact, or otherwise the artefacts became incorporated into the fluvial sediments or slope deposits that now make up much of the surface geology of the area. Critical to the preservation and understanding of the chronology of the earliest human evidence are the glacial sediments that date from the early and late Middle Pleistocene. They have been attributed to the ‘Happisburgh’ (MIS 16) and Anglian (MIS 12) glaciations (Chapter 10). In the northern and eastern parts of the region the tills from these glaciations provided protective coverings for older sediments and land surfaces that contain both human evidence and rich environmental data. Inland deposits of similar age are preserved as river terraces and also contain stone tools. After the local decay of the Anglian ice sheet, the landscape still contained pockets of dead ice that melted to form kettleholes that rapidly filled with sediments, whilst new drainage patterns were rapidly established across the region. Kettleholes and river channels commonly contain rich environmental records and evidence of human occupation during the Hoxnian Interglacial (MIS 11). After the Hoxnian evidence is more sporadic.

The subdued nature of the East Anglian landscape has made the differentiation of distinct river terraces and the establishment of a clear chronological framework difficult. Some environmental data has survived, providing the means to date any associated artefacts. The evidence suggests an absence of humans from the end of MIS 7 until about MIS 4/3, a gap of at least 120 000 years. Thereafter, evidence of humans is sporadic until the beginning of the Holocene by which time the occupation of the British Isles was extensive.

Although the evidence of human presence and absence might partly reflect preservation of evidence, the pattern probably also reflects the changing geography of Britain. When the first humans arrived, Britain was connected to mainland Europe (Chapter 7). Cooler climates and lower sea levels would have enlarged the access routes, but conditions would often have been too cold for human survival. Towards the end of the Anglian Glaciation the Chalk between south-east England and northern France was initially breached by meltwaters from a large lake basin in the Southern North Sea creating the Straits of Dover (Chapter 7). This was a critical event for human occupation with a drop in sea level during cooler climates being required to enable humans to migrate into Britain. A further factor was the subsidence of the floor of the North Sea Basin making access across this area increasingly difficult through time.

The actual evidence for humans consists of stone tools, occasionally cut-marked or modified bone and antler, and very rarely, artificial structures such as hearths. The stone tools were primarily made of local fl       and very occasionally of quartzite. The earliest sites contain simple cores, flake and flaketools such as scrapers. From 0.5 Ma hand axes were added to this assemblage. Although no human remains survive in East Anglia, in southern Europe the earliest humans were Homo antecessor, discovered at the site of Atapuerca in Spain. From about MIS 15 this species was replaced by Homo heidelbergensis, who probably started to evolve into early Neanderthals from about MIS 11. From MIS 8, prepared core* technologies, called Levallois, were developed by Neanderthals and this marks the start of the Middle Palaeolithic, when more standardised flake tools were made, some of which may have formed tips for shafted weapons such as spears. Upper Palaeolithic technologies were introduced by modern humans (Homo sapiens) from about 40 ka and consist of tools, such as points and scrapers made on elongated flake called blades. These blade tools would have been hafted and were used in a range of forms till the end of the Pleistocene as climate began to warm at about 11.5 ka.

Pre-Anglian human landscapes

Until recently, the earliest human evidence in northern Europe was thought to date to no earlier than MIS 13 (0.5 Ma). New evidence, collected from fluvial deposits of the Bytham (Bytham Catchments Subgroup) and Ancaster (Cromer Forest-bed Formation) rivers in East Anglia, is now pushing this date back to over 0.8 Ma and possibly as old as 0.9 Ma. At Happisburgh (‘Site 3’) simple flakes, flake tools and cores (Plate 28 c) have been found in fluvial and estuarine sediments at the base of the cliffs beneath glacial deposits of the Happisburgh Glacigenic Formation. The reversed palaoemagnetism of the host sediments combined with the presence of extinct mammalian fossils suggest an age between 1.0 and 0.78 Ma. Together, the fauna and flora indicate that humans occupied the edges of a large river, close to its estuary, in open grassland surrounded by coniferous forest with winters colder than East Anglia today (Figure 91). This evidence has prompted questions about the adaptability of early humans and specifically what sort of technologies would have been required, such as clothing, shelter and fire, to survive this type of environment.

Flint flakes and cores have also been recently found in organic Bytham River sediments at Pakefield near Lowestoft. The stratigraphy at the site and the association of these artefacts with the extinct water vole (Mimomys pusillus) suggests a date of at least 0.7 Ma (MIS 17 or early MIS 19) for the site. As with Happisburgh ‘Site 3’, the environmental data from Pakefield indicates an open river valley, close to the estuary, surrounded by mixed oak woodland in a Mediterranean climate.

Due to the small size of the artefact assemblages from both Happisburgh ‘Site 3’ and Pakefield it is difficult to be certain whether these early humans also had the ability or knowledge to make hand axes. However, these more elaborate tools are not known from the rest of Europe until about 0.6 Ma or MIS 15. Hand axes clearly were being made at a different location at Happisburgh, known as Site 1. Here, a hand axe with flakes and flake tools was found on the edge of an organic channel. Beetle and plant remains suggest the environment was a marsh, surrounded by coniferous woodland in a cool interglacial climate. Bones of deer and bison contain cut marks from butchery. The sediments underlie the Happisburgh Glacigenic Formation, which has been dated by some to MIS 16 (see Chapter 10), suggesting an older date for the hand axe. However, the alternative interpretation is that the Happisburgh Glacigenic Formation is part of the Anglian Glaciation of MIS 12. This view is supported by the occurrence of the more evolved water vole (Arvicola cantiana) at the site, suggesting an age of MIS 13 or perhaps MIS 15 for the associated archaeological evidence.

Stone tools have also been found within several of the older terrace aggradations of the Bytham River especially within the region between Brandon and Bury St Edmunds. In the 19th and early 20th centuries, hand axes were found in quartz and quartzite-rich gravels at Maidscross Hill, Rampart Fields and Brandon Fields (all Suffolk). Recent fieldwork suggests that the hand axes were found in the second terrace of the Bytham River with terrace models indicating that humans were also making hand axes in Britain during MIS 15 (0.65 Ma).

Warren Hill (Suffolk) is one of the richest sites for hand axes in Britain with over 2000 found during gravel extraction in the later 19th and earlier 20th centuries. Recent work suggests that the quartz and quartzite-rich gravels form the lowest terrace of the Bytham River (Ingham Sand and Gravel Formation), indicating an age of MIS 13 (0.5 Ma) for the archaeology.

Deposits at High Lodge lie just 800 m to the north of Warren Hill and are also in part composed of Bytham River sediments, but the stratigraphy at this site is complex. Although the site has been known since the 19th century, the first major excavations were in the 1960s, followed by further work in 1988. This established that floodplain silts from the Bytham River were overridden and glacitectonised by glacier ice during the Anglian Glaciation. This implies that the silts date from MIS 13, or possibly earlier, with the presence of the extinct rhinoceros Stephanorhinus hundseimensis supporting a pre-Anglian age. A rich artefact assemblage consisting of flakes and very fine scrapers was excavated from the silts and refitting of artefacts indicates that they are in primary context. The apparent lack of hand axes could either suggest a different incursion of people into Britain at this time, or could otherwise be a different activity zone on the floodplain, where scrapers, rather than hand axes, were required. Beetles and pollen suggest a cool climate with a boreal forest of pine and birch.

The high number of scrapers implies that hide-working was an important activity; clothing and shelter might have been essential in these cooler environments.

There is no convincing evidence for human presence during the Anglian Glaciation or earlier cold episodes. Although occasionally artefacts survive in outwash gravels, they are generally rolled and almost certainly are derived from earlier land surfaces. One exception is at High Lodge where Anglian outwash gravels that overlie the floodplain silts contain an assemblage of hand axes (Figure 92). The fresh condition of the hand axes, suggests a limited transportation and that they may originate from the underlying silts.

Hoxnian (MIS 11) and possible MIS 9 sites

The post-Anglian landscape of East Anglia contains a wealth of sites with good environmental data, many of which are associated with evidence of human occupation. These sites commonly consist of fine-grained sediments deposited within small localised basins such as kettleholes and channel infills that date from the Hoxnian Interglacial (MIS 11; 0.424 to 0.374 Ma). The Barnham and Elveden sections contain a very similar sequence and developed adjacent to a small stream that occupied a former subglacial tunnel valley. Work during the 1990s has shown that the earliest phases of sedimentation at the sites are lacustrine, with pollen types suggesting rapid warming of climate at the beginning of the Hoxnian. Lacustrine sediments are overlain by fine-grained fluvial sediments, which at the edges of the basins have formed lag gravels. It is these lag gravels that provided the flint raw material for humans. At Barnham several areas along the channel edge were excavated. One area contained purely cores, flakes and flake tools, which had previously been described as ‘Clactonian’, a term used to describe a distinct people without the use of hand axes. However, in a second area, only 50 m away, a hand axe and debris from hand-axe manufacturing was found in the same lag gravel (Figure 93). Whether these were different peoples visiting the area at a similar time, or simply different activity areas, is still being debated. Barnham also has a very rich faunal assemblage which from the amphibians and reptiles, such as tree frogs and European pond terrapins, shows that humans were occupying the site during a warmer climate than today.

Studies in the 1990s at the nearby site of Beeches Pit, West Stow, indicate a Hoxnian age. The site was situated by a spring at the edge of a chalk bluff, where good quality flint was easily available. Here all the artefact assemblages contain hand axes. Uniquely for Britain, the site also contains good evidence for the controlled use of fire, with the identification of a series of hearths in one location. The hearths were surrounded by flint flakes and tools, some of which were burnt.

Hoxne near Diss is another site where lacustrine clay sits in a basin cut into Anglian till. The site has been the subject of a series of investigations from the late 19th century with the most recent study being from 2000 to 2003. Pollen records from the lacustrine deposits show a vegetational succession through the first part of the Hoxnian Interglacial (pollen zones HoI–IIIa). Sediments from the last part of the Hoxnian are absent (HoIIIb–IV), but the final lake sediments indicate a return to cold conditions with the survival of leaves from Arctic and Alpine plants such as dwarf willow and dwarf birch. The human evidence at the site is associated with the overlying fluvial sediments. The fauna from these sediments indicates a return to more temperate conditions with woodland species such as fallow deer and pine voles being present. There are two assemblages from the site, the lowermost being in primary context. This consists of hand axes and flake tools, scattered with bone along the edge of the river channel. Cut marks on some of the bone and teeth indicate horse and deer butchery at the site. The overlying assemblage of hand axes and finely made scrapers is in a secondary context within alluvial and colluvial sediments. Both artefact assemblages are clearly post-Hoxnian in age and probably date to a later temperate event in MIS 11.

Although it is likely that humans were present in East Anglia during MIS 9, it is not apparent which sites can be attributed to this stage. Several important sites with Lower Palaeolithic hand axes have been found in fluvial gravels that lie above modern-day river floodplains, but it is not clear which river terrace they belong to. This is the case with the sites of Whittlingham and Keswick on the River Yare near Norwich, and with Red Hill, White Hill and Santon Downham on the Little Ouse near Thetford. Many of these sites were found in gravel pits in the 19th and early 20th centuries, and most are no longer accessible. There are also sites in late Middle Pleistocene river terraces of the River Great Ouse around Bedford, the most notable being the site at Biddenham. Large numbers of hand axes associated with shells and vertebrate remains were found here from the remarkably early date of 1861. The molluscs suggest a temperate episode, dating to either MIS 9 or MIS 11.

The Early Middle Palaeolithic (MIS 8–7)

Levallois technology seems to have been first used in Britain from early MIS 8 and is associated with early Neanderthals. This technology shows the careful preparation of cores to predetermine the shape of the ensuing flakes. In this way several flakes with all-round sharp edges can be removed from a single core. Several sites contain this technological innovation and probably date to MIS 8 or MIS 7.

Levallois artefacts and hand axes were found in fluvial gravels at Barnham Heath. The gravels form at least one and possibly two terraces of the Little Ouse, but their dating is not secure. There is some indication that the Levallois artefacts and the hand axes were found in different areas, and perhaps in different terraces. Brundon also seems to contain a mixed assemblage and is not well understood. Levallois artefacts and hand axes were recovered from fluvial gravel in the valley of the Stour (Figure 94). The associated mammalian remains suggest a MIS 7 age for the site, supported by U-Series dating of the host sediment. The only other main occurrences of early Middle Palaeolithic artefacts are from organic channel deposits near Stoke Tunnel and Maidenhall in the valley of the Gipping/Orwell and from the River Stour at Stutton and Harkstead. All the sites contain Levallois artefacts associated with much richer faunal assemblages, which are MIS 7 in age.

Although there are other occasional occurrences of probable early Middle Palaeolithic artefacts in East Anglia, they are still rare. This may well reflect low populations of humans in East Anglia at this time, rather than the survival of sediments of this age. If this is the case, then population declined further, not just in East Anglia, but Britain as a whole, with a complete absence of human evidence during the cold stage of MIS 6, the interglacial of MIS 5e, and perhaps until the end of MIS 4, about 60.0 ka. During this gap of 120 000 years, either high sea levels made the North Sea and the English Channel formidable barriers, or during low sea levels the climate was too harsh for humans to survive. It is notable that during the same period in northern France there are several archaeological sites that date to this period of apparent human absence in Britain.

Devensian — The Late Middle Palaeolithic and Upper Palaeolithic (mis 4–2)

The Devensian occupation of East Anglia and Britain was sporadic and dependant on changes in climate and environment, with an apparent absence of humans during the most severe cold (the Dimlington Stadial) between 26.0 and 14.7 ka. Otherwise there was a succession of sporadic incursions by different peoples with distinctive styles of tools through this period.

The first known colonisation during the Devensian was by Neanderthals in the late Middle Palaeolithic from about 60.0 ka. The best British evidence comes from a recently discovered site at Lynford. Excavations have revealed the remains of several mammoth on the swampy edges of a river channel, a former course of the river Wissey, in association with a rich flint assemblage. Although there is no direct evidence for butchery, the association of the tools and bones is strong. The artefacts consist of hand axes, scrapers and waste flakes from final manufacture or resharpening of tools. The hand axes (Plate 28-d) are distinctly different from Lower Palaeolithic forms, sometimes being less symmetrical, often acting simply as scrapers and on occasion in the form of bout coupés. This type of hand axe seems to be characteristic of the late Middle Palaeolithic in Britain. The rich environmental data suggests a cold, treeless landscape with average winter temperatures estimated at -10°C. This implies that Neanderthals by this time had acquired the technology to survive these harsh temperatures through more effective shelter and clothing.

Elsewhere in East Anglia the evidence for the late Middle Palaeolithic is patchy. At a gravel pit near Bramford Road in Ipswich a mixed flint assemblage was recovered from a low-lying terrace of the River Gipping, but which included bout coupé hand axes and Levallois artefacts. The artefacts and associated cold climate fauna were all disgorged from a large extraction pump in the 1930s, so any hope of understanding the context of the finds is poor. The form of the hand axes and the low level of the terrace might suggest a Devensian age. Early Upper Palaeolithic artefacts were also found, which would support this date. A similarly mixed assemblage was recovered from gravel pits near Little Paxton (Cambridgeshire). The presence of bout coupé* hand axes on a low terrace of the Great Ouse again suggests a Devensian age for the gravel. This might be supported by the occurrence of hippopotamus, probably of MIS 5e age, from sediments associated with a higher terrace.

At about 43.0 ka ‘leaf-point’* industries are found in Britain and occasionally in East Anglia. Similar industries are found at this time in Belgium, central Germany and Poland. It is not yet clear, however, whether these tools were introduced by modern humans (Homo sapiens), or were brought in by the last incursion of Neanderthals from northern Europe. It is clear from breakage on their tips that the points were mounted onto spears for hunting. Although there is some confusion between these artefacts and similar Bronze Age artefacts, there are three definite occurrences in East Anglia with single examples found at Barham (near Ipswich), Cross Bank (near Mildenhall) and at least seven examples from Bramford Road (Ipswich) (Figure 95a).

The first definite appearance of modern humans in Britain was from 36.0 ka by people with Aurignacian tools, but there are no sites or examples of these tools from East Anglia. A further incursion of people occurred at about 33 ka, this time with Gravettian tools. There is only one example of their characteristic artefacts in the region, which is a tanged blade again from Bramford Road (Figure 95b).

After the Last Glacial Maximum the climate ameliorated and humans returned once again during the Late Glacial Interstadial from about 14 ka. The tools they brought with them are a form of the Final Magdalenian, often termed Creswellian, consisting of spear or arrow tips, end scrapers and engraving tools. Most of the early sites seem to be concentrated in caves in the west and occasionally north of England, with very few examples of sites in East Anglia. The characteristic weapon tips are obliquely truncated points, which have been found at Cranwich (Norfolk), Wangford (Suffolk) with several examples from the Mildenhall area.

During the later part of the Late Glacial Interstadial slightly different weapon tips are introduced, called ‘penknife points’. These are found more widely across England, perhaps reflecting the greater use of open-air sites at this time, such as at Swaffham Prior and Fulbourn, Cambridgeshire. Barbed antler and bone points also date to this phase with examples from Sproughton (Figure 96) and a fragment of a bone point probably from Barrington.

A short spell of cold climate (the Younger Dryas Stadial) again seems to interrupt occupation from 12.8 ka, but humans returned towards the end of this phase about 11.9 ka. They brought with them the distinctive ‘long blades’, which is probably the final Upper Palaeolithic technology to found in the area. Unlike the previous phases of the Upper Palaeolithic, there is a concentration of 15 sites in East Anglia, including the river valley locations of Sproughton and Lynford. These sites contain blades that are commonly bruised along their edges. There are probably different causes for this damage, but suggestions include the abrasion of striking platforms on cores, the shaping of sandstone hammerstones and the chopping and working of antler. At a site in the Colne Valley in Uxbridge (Greater London), similar tools are associated with the hunting and butchery of reindeer and wild horse. From a contemporary site in north Germany arrow shafts have survived, being the earliest indisputable evidence for the use of bows and arrows. It has been suggested that the East Anglian sites may have been on reindeer migration routes that perhaps crossed the plains of the North Sea basin at this time.

As climate warmed during the early Holocene, East Anglia became more densely populated by Mesolithic hunters with one of the earliest and best known of sites in the British Isles being on Kelling Heath in north Norfolk. Many finds of microliths have been found in the Breckland, with a particular localisation in the Lakenheath area. No site in East Anglia has yielded contemporary organic material, so it is assumed from evidence elsewhere that Mesolithic groups in East Anglia also largely survived by hunting woodland animals such as red deer, roe deer, wild cattle and wild pig. Rising sea levels caused Britain to become an island once more from about 8.0 ka, isolating the population from mainland Europe. This was not for long, as more effective sea craft brought new ideas with the introduction of farming some 2000 years later, and eventually the new skills of forging bronze and iron.

Chapter 14 Geology and anthropogenic impact

J H Powell, S H Bricker, V J Banks and A M Harrison

Humans have utilised the geological resources of the region back into the Palaeolithic Period — possibly as long ago as 0.8 Ma (Chapter 13). Quarrying and mining of high-quality flints found in Cretaceous Chalk became a major industry in the region during the Neolithic Period including at the area known as Grimes Graves. In more recent times groundwater has become a valuable commodity, and various industrial minerals have been worked, including chalk for agricultural and industrial purposes, and sand and gravel aggregates. The legacy of past mining for chalk and flint, along with the occurence of natural solution cavities, has affected development, especially in some urban areas. The landscape characteristics of East Anglia have merited conservation of significant geological and geomorphological features such as glacial landforms, chalk mines and the unique landscape of the Broads National Park. This chapter reviews the relationship between geology, earth resources and human activity in the East Anglia region.

Geodiversity

Geodiversity is the variety of rocks, fossils, minerals, landforms and soils, as well as the natural processes, that determine the character of the landscape and environment. It has strong links with biodiversity, as habitat requirements include a combination of landscape, substrate and climate, all of which are influenced by geology. Understanding the geodiversity of East Anglia is crucial for managing the region’s natural resources (e.g. soil and water) in a sustainable manner — informing planners, protecting landscape heritage plus enhancing public accessibility and understanding through education. The region is blessed with an abundant and extensively studied geodiversity because it possesses a range of internationally significant sites and landscapes. There is a particular focus on aspects of the region’s Cretaceous geological history plus the Quaternary record of sea-level change, interglacial climates and environments, human evolution, periglacial and glacial geology and geomorphology.

Several formal mechanisms exist for recognising and protecting geologically important sites by law and serve to raise awareness of their significance and earth science in general. One of the highest-level formal designations is that of site of special scientifi interest (SSSI) status. This has been awarded to sites with geological or physiological features, or flora and fauna that are of international significance. There are numerous SSSI localities in East Anglia, including sites famous for their geology or geomorphology such as Hunstanton Cliffs (Cretaceous), Wangford Warren (Holocene sand dunes), Wiveton Downs (Blakeney Esker) and West Runton (West Runton Freshwater Bed). Several geological SSSIs in the region also occur within a designated national nature reserve (NNR), local nature reserve (LNR) or area of outstanding natural beauty (AONB) and these provide further legislative protection and recognition of important sites.

County geodiversity sites (CGS), formerly regionally important geological and geomorphological sites (RIGS), compliment SSSIs and recognise sites of local significance. They are not protected by government statute, and are called local sites in government guidance, making them distinct from SSSIs. The main purpose of CGSs is as an educational and research resource, but designation also allows landowners and planners to be alerted to sites of geological interest. An example of a CGS within East Anglia is the Rising Hill Pit near Glandford where quarrying has revealed exposures of Quaternary glacial outwash deposits.

Increased regional awareness of geodiversity has been enhanced by the undertaking of several local geodiversity action plans (LGAPs) since the turn of the century. LGAPs are based on biodiversity action plans, and present the actions required to conserve and enhance the geodiversity of a particular area. They aim to recognise, conserve and improve the best sites that represent the geological history of an area in a scientific, educational, recreational and cultural perspective, to promote sites and make them relevant to people, carry out geodiversity audits and to be involved in the local planning process.

Industrial minerals and aggregates

East Anglia produces a wide range of industrial minerals and aggregates derived from the region’s geology. Extensive sand and gravel resources exist in pre-Anglian fluvial and marine deposits, glacial outwash, postglacial river terrace and alluvial deposits (Figure 97). Sand is mainly used as a fine-grained aggregate in concrete, mortar and asphalt mixes; gravel is mainly used as a coarse aggregate in concrete. Both commodities are used as a constructional fill material. Weakly cemented high-purity silica sands of the Early Cretaceous Leziate Member (Sandringham Sands Formation) are extracted for glass sand and furnace moulding sand.

National and regional guidelines for aggregates provision state that an estimated 236 million tonnes of land-won sand and gravel will need to be provided in the East of England region (an area that includes Essex and Hertfordshire outside the East Anglia area) during the 16-year period 2005 to 2020 of which about 60 per cent would be produced in the East Anglia region. This equates to 14.75 million tonnes per annum for the East of England Region. The majority of this resource is represented by Quaternary sand and gravel with a small amount of rock aggregate sourced from the Cretaceous Carstone Formation and Jurassic Upware Limestone Member (locally referred to as the ‘Cambridgeshire Limestone’ of the West Walton Formation). Average sales, from 2008 to 2010 were over ten million tonnes of sand and gravel, 246 000 tonnes of ‘Cambridgeshire Limestone’ and 113 000 tonnes of Norfolk Carstone Formation.

The region was once a major producer of Portland cement based on extraction of chalk as the raw material although this industry has now ceased in East Anglia. Production in 1989 was 923 000 tonnes. Cement production plants were numerous in the Cam Valley, such as those at Barrington, South Cambridgeshire, although this plant closed in 2008 and the workings have subsequently been designated a SSSI. In the Cam Valley, the Grey Chalk Subgroup and specifically the ‘Chalk Marl’ was quarried extensively for hydraulic lime, where the high clay content made it suitable because the addition of clay material was not necessary.

Bricks have been produced from a number of sources of brick clay in the region. In west Norfolk and Cambridgeshire these include the Jurassic Lower Oxford Clay and Kimmeridge Clay formations, the Early Cretaceous Snettisham Clay Member (Dersingham Formation) and the Gault Formation. To a lesser extent Quaternary deposits including till, glaciolacustrine clays, marine Nar Valley Clay Formation and the Holocene silty clays of the Fenland have been used. Bricks have been manufactured locally from these raw materials since Roman times, and small industries were developed around Holkham (Quaternary till), Downham Market (Kimmeridge Clay Formation), Heacham (Snettisham Clay Member), Grimston and Burwell (Gault Formation), plus the Nar Valley (Nar Valley Clay Formation) during the 17th and 19th centuries. However brickmaking from these sources ceased in the region during the 1960s. The Peterborough Member (Lower Oxford Clay Formation) was worked near Peterborough at Whittlesey and Orton, and at Marston Vale (Stewartby), Bedford. It has been the principal source of brick clay in the region and adjacent areas; in the 1980s the Peterborough Member clay represented 33 per cent of UK brick production (the ‘Fletton’ standard brick). Quaternary tills and glaciolacustrine silts and clays have been utilised throughout the East Anglia region. Both white and red common bricks were produced, the colour commonly dependant on the proportion of lime or the weathered state of the clay. The Corton Till Member (formerly referred to as part of the Norwich Brickearth) has been widely used for brickmaking with ‘brickfields’ sited at Catton near Norwich, and Somerleyton and Burgh Castle near Great Yarmouth. Operations had largely ceased by the 1920s but bricks from the latter sites were famously used in the construction of St Pancras Railway Station in London.

Despite the decline in the use of chalk as a raw material for Portland cement production in the region, this relatively pure limestone is exploited for a variety of uses. These include agricultural and garden lime, brick chalk (ground chalk mixed with brick clay to fire yellow brick for frost resistance), industrial chalk (micronised calcium carbonate for filler in plastics, adhesives, paints and for flue gas absorption), line-marking, heritage mortars, and lump chalk for flooring of buildings and cattle yards. About 100 000 tonnes of granular chalk is produced for industrial purposes from over seven quarries in East Anglia, including Needham Market Chalk Quarry in Suffolk.

Flints, which occur naturally in the Chalk, are utilised as a by-product as black, white and grey ‘knapped’ (split) flints for heritage buildings, e.g. Windsor Castle and Southwark Cathedral (see Building Stones). Other by-products are ‘gallets’, which comprise small shards of flint used in flint walling, and ‘paramoudras’ that comprise large circular flints used for ornaments. Some 1115 former flint mines have been located in the region (602 in Norfolk and 513 in Suffolk). High quality flints, in seams, were exploited underground during the Neolithic Period using red deer antlers and scapulas as digging tools. At Grimes Graves, Norfolk, 433 shallow pits, representing the infilled shafts of former flint mines have been identified over an area of about 400 m2 (Plate 29). In descending sequence, the layers of flint are known as the ‘topstone’, ‘wallstone’ and ‘floorstone’, the latter being the most-prized, high-quality flint at about 9 m depth below ground surface (Figure 98). In contrast, the 19th and early 20th century mines, dug by spade, pick and hammer have a distinctive style – rectangular vertical shafts about 3 m by 1 m, commonly constructed initially through overlying superficial deposits, and narrowing to about 1 m diameter through the Chalk bedrock.

Examples are found around Brandon, Catton and Whittingham where a gunflint knapping industry developed, peaking during the Napoleonic Wars.

Fuller’s earth, a naturally occurring absorbent clay consisting largely of the clay mineral smectite, occurs as thin lenses within the Woburn Sands Formation. It was exploited near the eponymous village and near Clophill, Bedfordshire. Originally used for cleaning or ‘fulling’ woollen cloth, it is now processed for a wide range of industrial products.

Calcium phosphate nodules were formerly dug from a number of geological units for fertiliser in the 19th century, but the practice ceased in the early 20th century as cheaper sources of phosphate were imported. In the Cam Valley, the lower part of the Chalk Marl outcrop is rich in phosphate nodules which were dug by hand in pits for use in fertiliser. These nodules were formerly thought to be coprolites (faecal pellets) but mostly comprise a variety of rolled and bored black or dark grey nodules representing the phosphatised remains of marine organisms. Former sites include Romsey Town Quarry, Cambridgeshire, Leighton Buzzard and Harlington in East Bedfordshire. Phosphate nodules were also dug from the Woburn Sands Formation in Bedfordshire, the uppermost beds of the Gault Formation, the Cambridge Greensand near Burwell and Soham, and from the Red Crag Formation near Ipswich.

Other commodities include minor production, in medieval times, of table salt leached from tidal-flat deposits and concentrated in clay-lined brine pools heated by local peat. The waste material was tipped nearby to produce ‘saltern mounds’ on reclaimed marshland such as the area from Babingley River to North Lynn. Shelly lime-rich sands of the Red Crag and Coralline Crag formation were formerly dug in shallow pits for liming heavier clay soils. Septarian nodules dug from the Oxford Clay were used by the Romans as a source of cement mortar.

Pyrite nodules mainly developed from replacement of fossil wood in the London Clay and Harwich formations were formerly collected from the foreshore around the Stour Estuary and utilised in the manufacture of sulphuric acid.

Building stones

The character of the towns, villages and churches of East Anglia owes much to the use of local building materials, where high-quality bedrock materials are scarce. Prestigious buildings such as cathedrals and important municipal buildings commonly used higher-quality stone such as the Lincolnshire Limestone Formation, local Barnack Stone or Stamford Stone, the latter imported from outside the region. These freestones were commonly used as quoin stone or ashlar blocks, whereas a less-easily-worked or poorer-quality material, such as flint or Carstone, was used in the walls or as rubble fill.

Lincolnshire Limestone Formation (Barnack Stone) was quarried near Barnack from Roman times until the 16th century for use as walling stone in churches and the cathedrals at Peterborough, Bury St Edmunds and Ely. Yellow and pale grey shelly limestone of the Mid Jurassic Cornbrash and Blisworth Limestone formations were formerly quarried as a building stone for use as ashlar and as quoin stones in buildings around Bedford (Plate 30a, b, c).

The Early Cretaceous Carstone Formation (sometimes referred to as ‘carrstone’) is a grey, brown to purplish brown, ferruginous, pebbly sandstone. It crops out in west Norfolk between Hunstanton and Downham Market. Carrstone has been widely used as a building stone in west Norfolk (e.g. Wareham Church) commonly admixed with flint, or as small squared blocks (e.g. Heacham Church) and for quoins (Plate 30b, d, 31a). It was widely used for buildings in New Hunstanton, Downham Market, Heacham, Castle Rising, the estates at Sandringham and Holkham, and the Roman fort at Brancaster. The Carstone Formation is the source of the majority of ‘carrstone’ known locally as ‘big carr’ (larger blocks) in west and north Norfolk (Plate 31a), and was worked until recently at Snettisham. A pebble-rich variety, known as ‘puddingstone’ was used in buildings in Old Hunstanton and Holme-next-the-Sea. The Leziate Member (‘sugarstone’) is a variety of Early Cretaceous sandstone that was used as a building stone (Plate 30d) in north and west Norfolk (and as glass sand, see below). It is generally a pale grey to yellow-grey, fine-to medium-grained quartz sandstone but the outcrop is generally obscured by Quaternary deposits. Where poorly cemented, the sandstone breaks down to a sugary texture, hence its common name. The building stone occurs as better-cemented beds that were worked as blocks and quoins near Castle Rising where it was used in construction of the castle. Leziate Member quartzite was used earlier in the Roman Fort of Branodunum near Brancaster on the north Norfolk coast, and blocks of sandstone from this source were reused in villages in North Norfolk, including Saxon and Norman churches (e.g. St Lawrence, Castle Rising; All Saints, North Wootton).

The Chalk in East Anglia is generally not as hard as its equivalent in Yorkshire and Lincolnshire, and hence has not been much used as a building stone due to its poor weathering characteristics. However, along the Chalk Group outcrop in north-west Norfolk (where it is locally known as ‘white clunch’) it has been used in the walls of farmyards, churches and cottages (Plate 31b, c). It was mostly derived from harder beds in the Chalk such as the Melbourn Rock, Paradoxica Bed, Totternhoe Stone, and Inoceramus Beds or from hard beds in the lower parts of the White Chalk Subgroup from quarries at Hillington, Heacham and Ringstead. Burwell Stone is a variety of Totternhoe Stone that was worked at Houghton Regis and Burwell. It was used in parts of Woburn Abbey and the early college buildings at Cambridge. The basal red chalk, the Early Cretaceous Hunstanton Formation (formerly the Hunstanton Red Rock or Red Chalk) is slightly harder than the overlying white Chalk. However it has rarely been used as a building stone (known locally as ‘red clunch’), except around Hunstanton and Holme-next-the-Sea, mostly in boundary walls mixed randomly as rubble with Carstone, chalk, flint and brick (Plate 31b).

Flint is a common and characteristic building stone in the region, commonly used in conjunction with brick and freestone, which was used for quoins (Plate 30b, c, d). Most of the flint is derived from the White Chalk Subgroup, but secondarily derived flint was also worked from Quaternary deposits and modern river and beach gravels (e.g. Blakeney Spit). Natural and worked (squared or knapped) flints were commonly set into lime mortar that was strengthened with flint chippings (‘gallets’). ‘Galleting’ is a process of inserting small pieces of flint into the mortar joints of a wall before the mortar has set, originally to strengthen the wall, and later for decorative purposes (e.g. Norwich Guidhall). Characteristic flint buildings include circular and octagonal church towers, ‘flushwork’ and ‘proudwork’ which combine knapped flint and limestone ashlar to produce striking architectural patterns, a technique used especially in 15th and 16th century churches (e.g. Southwold Church). Larger flints of regular proportions were occasionally used as corner (quoin) stones, although brick and freestone (e.g. Carstone Formation or the Jurassic Lincolnshire Limestone from Barnack, near Stamford, or Normandy Caen Stone) were most commonly used. The colour of flint used in buildings varies across the region.

The Harwich Stone Bed (Harwich Formation) is a hard cementstone cropping out on the foreshore near sea level around the Stour and Orwell estuaries, it has been extensively utilised locally as a low-grade building stone.

Ferricrete (‘puddingstone’) is a brown iron- and silica-cemented stone with small angular or rounded flints that represents an iron-pan deposit formed by the cementation of near-surface Quaternary gravels by iron-rich groundwater. It has been used locally in various farm buildings and church walls in Norfolk (e.g. Roughton Church) commonly in conjunction with flint. Another form of iron-cemented building sandstone is iron pan. It occurs as orange-brown, secondarily iron-cemented sandstone, locally used as a building stone. Large septarian nodules comprising pale- to medium-brown argillaceous limestone are present in the London Clay Formation that crops out in south-east Suffolk. Septarian nodules were used as a building stone by the Romans, and subsequently in Orford Castle and several churches in Suffolk (e.g. Shottisham and St Osyth Priory). The Pliocene Coralline Crag Formation crops out near Aldeburgh and Orford on the Suffolk coast as carbonate-cemented shelly sandstone. This yellow-buff, shelly limestone has been used locally in church buildings (e.g. Orford, Salcott, Chillesford and Iken), commonly in conjunction with knapped flint. Glacial erratics derived from as far afield as Scotland and Scandinavia are rare but distinctive building stones in East Anglia. They have been used in churches and as walling stone, especially in areas where the covering of superficial deposits is thick and obscures underlying bedrock.

Hydrogeology and water supply

Average annual precipitation (1916 to 1950) within East Anglia is generally less than 700 mm, ranging from 535 mm near to the coast in the south-east of the region, to upto 850 mm in the region of Diss. Annual potential evapotranspiration rates are as high as 530 mm in neighbouring Essex. The high evaporation rates occur in the summer when effective precipitation can be very low, particularly in the low lying areas.

According to the Environment Agency, the ‘Anglian River Basin District’ contains 31 groundwater bodies or aquifers, as defined by the Groundwater Framework Directive, some of which are interconnected (Table 1) and (Table 2). Once supplied by springs and shallow wells, water supply requirements in East Anglia are now largely derived from boreholes. The principal aquifers are the Chalk and Lincolnshire Limestones with significant groundwater also obtained from sand aquifers including the Crag Group, Woburn Sandstone Formation and the Sandringham Sand Formation (Table 1) and (Table 2). Groundwater is used for public water supply, industry and agriculture and is under significant pressure from diffuse pollution, particularly nitrate, phosphates, herbicides and pesticides. Regional groundwater heads (water pressure) are shown on the hydrogeological sheets for northern and southern East Anglia (Figure 99). They are influenced by the coast in the east, the River Thames to the south-east and The Wash in the north-west. Additionally, the Chalk head distribution reflects surface topography in a subdued form, with its greatest depth below high ground. Chalk water levels fluctuate with meteorological conditions and are highest in April and lowest in October to November. Chalk groundwater is increasingly confined in an easterly direction where it is overlain by Eocene strata. Seasonal artesian flow has been recorded along the Wensum and Tas valleys at South Walsham, Cantley and Barsham.

Chalk forms the principal aquifer of the region; it is a weak, pure, fossiliferous, fine-grained limestone with a high porosity (commonly 40 to 50 per cent) and bands of tabular or nodular flint at a range of horizons. The individual particles that constitute the Chalk are predominantly silt grade and this limits the matrix permeability such that fissure flow is a very important component of both permeability and transmissivity. An additional controlling factor for transmissivity is topography. For example, low transmissivities occur in interfluve areas (e.g. 300 m3 per day at Strumpshaw); by contrast, high transmissivity values (e.g. 2600 m3 per day at Thorpe St Andrew) are recorded within valleys and particularly buried valleys. Permeability can be related to the lithostratigraphy, and generally the White Chalk Subgroup produces the highest yields of groundwater. Borehole yields vary widely across the region with typical yield rates ranging between 25 and 120 litres per second. Hard bands, including the Cambridge Greensand and Totternhoe Stone, commonly provide higher yields, and where exposed, form spring lines. Higher groundwater yields are generally associated with the drift-filled buried valleys that have been incised into the Chalk. Figure 100 shows the groundwater flow paths from interfluves to valley locations where superficial cover is absent and where the cover is extensive. Other important aquifers in East Anglia include the Crag Group, especially in the south-east of the region, where the Chalk occurs at considerable depths. In some areas, such as Great Yarmouth and Lowestoft, groundwater is supplemented with surface water from the River Bure, Ormesby Broad and the River Waveney.

Groundwater chemistry varies across the East Anglia in accordance with the geology. Calcium-bicarbonate type groundwater predominates in the Chalk and exhibits total hardness concentrations of between 23 and 4260 milligrams per litre. Where the Chalk Group is overlain by thicker sequences of superficial deposits the water is older and more mineralised, and of the sodium chloride type. Regionally the groundwater chemistry is zoned in a south-easterly direction as it is increasingly confined by the overlying Cenozoic strata so that the calcium bicarbonate water gives way to sodium bicarbonate water. The tills of the Lowestoft Glacigenic Formation are typically more chalk-rich than the other tills and this is also reflected in the groundwater chemistry with more bicarbonate being derived from the formation.

East Anglian aquifer vulnerability reflects a number of different factors such as the extent and nature of overlying superficial cover; the proximity of the water table to the ground surface; farming practices; and the nature of the groundwater flow (fracture or matrix domination). Groundwater is particularly vulnerable in the Lincolnshire Limestone, exposed Chalk in the Bure and Yare valleys and the Cambridgeshire–Bedfordshire Ouse catchments where the aquifers are exposed at the surface and rising nitrate trends are evident. Aquifers, especially close to coastal areas, are also prone to saline intrusion. At Great Yarmouth, for example, overexploitation of the aquifer has caused saline incursion in a zone extending 10 to 20 km inland. This is likely to be further exacerbated by changes in climate and sea level.

Current UK projections for climate and sea-level change predict potential landward migration of saline intrusion in the Crag Group aquifer by up to 1700 m as a consequence of a 57 cm rise in sea level and a 60 per cent reduction in groundwater recharge by 2080.

Fuel and energy

Peat occurs over extensive areas of the region, especially in the lowland sites of former lakes, waterways, wetlands and coastal embayments such as the Fenlands and Broadlands of Norfolk and Suffolk. Fenland peat is estimated to cover about 240 km2. Peat has been worked for fuel since Roman times, especially in areas where there were few trees, and used particularly within the early cloth and salt industries. Lower levels of peat are generally more compacted and therefore a better quality fuel with a higher calorific value, but its extraction involved digging deep pits (turbaries) that were prone to flooding. Extraction of peat in deep pits peaked in the 13th century, but a gradual increase in sea level and storminess caused many of the deep pits adjacent to the coast to be flooded and the industry had declined by the 14th century. However, near-surface peat workings continued on a smaller domestic scale until the 20th century as an adjunct to other fuels such as wood and coal. A legacy of deep excavations for peat is the flooded landscape of the Broads. Peat is no longer extracted for fuel, but its more recent uses include horticulture (growing medium and soil improver) and agriculture (stable litter). Drainage of wetlands and the use of peat lands for arable or horticultural crops have led to a decline in the area of natural peat through shrinkage, compression, oxidation and erosion. There is an indication of the loss of peat volume in the Fens at the Holme Post, Holme Fen, where wastage through draining and arable cultivation has been recorded as a 3.9 m lowering of the ground surface between the 1850s and 1970s. Peat is also a natural store of carbon dioxide and its destruction through wastage or extraction results in increased carbon emissions. The carbon storage within the peat soils of the Fenlands has been estimated at approximately 41 terragrams of carbon, although there is some uncertainty over this figure due to the paucity of data on the extent and thickness of the peat. Carbon emissions from the wastage of Fenland peat has been estimated at 0.4 terragrams of carbon per year which is equivalent to about 0.3 per cent of the annual industrial emissions of carbon dioxide in the UK.

The discovery of oil in Carboniferous rocks in north Nottinghamshire in the 1940s encouraged the Anglo-Iranian Oil Company (D’Arcy Petroleum) to drill a deep exploration borehole in 1945 at North Creake near Hunstanton. However, as a result of the relative structural high of ‘basement’ rock in East Anglia, the borehole was unsuccessful and penetrated Ordovician tuffs (formerly thought to be Precambrian rocks) at 742 m depth underlying the Triassic Sherwood Sandstone Group. A further exploration borehole was drilled by BP in 1969 at South Creake. The presence of oil shale in the Late Jurassic Kimmeridge Clay Formation encouraged exploration during the First World War in the area near Setchey, south of King’s Lynn. An opencast pit and pilot plant pit were established in 1916 with the aim of retorting oil from the shale, and 50 exploration boreholes were drilled in the surrounding area. However, despite early enthusiasm, the plant was deemed uneconomic in 1923. The BGS North Runcton Borehole showed that the total thickness of true oil shale in the Kimmeridge Clay Formation is 7.17 m, but this is dispersed through 80 thin oil shale beds ranging in thickness from 1 to 47 cm thick. Furthermore, only one bed over 2 m in thickness had potential to yield more than 15 gallons per ton. Together with the high sulphur content (4 to 8 weight per cent) and thinness of the seams, the resource was never commercially exploited, although the Kimmeridge Clay Formation is a major hydrocarbon source rock offshore in the North Sea. Hydrocarbons were proved onshore from the basal Leman Sandstone Formation (Rotliegendes Group) in the Somerton 1 Borehole at 965 m depth and in the East Runcton Borehole.

Engineering and geological hazards

The main engineering considerations in the region are briefly outlined here in Table 3. They include foundation conditions, excavatability and suitability as fill. Although the bedrock and superficial deposits of the region are generally suitable for most types of foundations, they may present local problems as a result of weathering, dissolution and compressibility.

The East Anglia region does not face a high risk of major earthquakes. However, the region has witnessed a number of documented historical earthquakes including the 1750 North Sea earthquake, with an estimated magnitude of 4.7 ML (Figure 101). The most damaging earthquake in the region was estimated at 4.3 ML and occurred in the Colchester area on 23nd April 1884; about 1200 buildings needed repair, chimneys collapsed and walls cracked. It was widely felt throughout the region and reported in newspapers at the time. In 1948 the East Anglia Downham Market earthquake (instrumental magnitude 4.0 ML) was felt over much of the region. The 1992 Pondersbridge earthquake had an instrumental magnitude of 3.3 ML, and the 15th February 1994 Norwich earthquake, at a depth of 7.3 km, was recorded as 4 ML.

Underground mining of the Chalk Group for chalk rock and flint has been taking place since the Neolithic Period. The potential for mine collapse is related to their geographical distribution, the presence and thickness of any overburden deposits, the stability of mine pillars, shafts and adits (mine entrances), the depth of mining, and extreme rainfall and flood events. Anthropogenic triggers may include changes in water courses, urban drainage and leakage, and civil engineering schemes resulting in dynamic loading. The majority of documented mine-related collapses are thought to relate to surface and near-surface water arising from heavy rainfall and flood events, leaking water or sewage pipes, and urban run-off. These water-related triggers often follow periods of drought that result in enhanced development of tension cracks allowing subsequent ingress of water. This may result in crown holes and/or the collapse of roads and infrastructure, or general ground subsidence. The most common form of collapse is associated with natural or anthropogenic deposits infilling or capping the former open or backfilled shaft. These poorly consolidated deposits or wooden roof materials may give way catastrophically to reveal a crown hole or more widespread subsidence. In other examples, natural materials in karstic solution pipes have been softened by water ingress causing these materials to flow into adjacent man-made adits that have intercepted the natural solution pipes. Collapse due to failure or destabilisation of adits, mine pillars and roofs is less common, but might lead to collapse and migration of the void upwards to produce a crown hole at the ground surface. Examples of mine collapse have been reported in both Sudbury and Norwich. In Norwich, 34 sites of chalk mining and subsidence have been recognised with catastrophic collapses documented over the past century. In 1927 and 1936, collapses occurred on Merton Road where adits intercepted natural karstic solution pipes. The later subsidence hollow measured about 8 m in diameter and 4.6 m deep and resulted in two deaths and substantial damage to three houses. In 1988, a double-decker bus subsided into a collapsed mine working on Earlham Road.

Natural cavities known as solution sinkholes (or subsidence sinkholes) and swallow holes occur widely across the outcrop of the Chalk Group in East Anglia, and also in the subcrop beneath Quaternary superficial deposits. At least 539 natural cavities have been identified in East Anglia, about 383 of these in the county of Norfolk (Figure 102). Natural cavities may also form as a result of dissolution of calcareous facies of the Crag Group and subsequent infilling by Quaternary superficial deposits. They form as a result of karstic dissolution of natural fissures, generally originating as natural joints and bedding planes in the Chalk and other calcareous formations. Weak carbonic acid (H2CO3), in the form of rainwater and percolating groundwater, gradually dissolves the soluble Chalk (calcium carbonate) leading to enlargement of the fissures to larger cavities, commonly interconnected at depth. Sinkholes commonly form at the boundary between the Chalk bedrock and overlying superficial deposits such as sand and gravel or till. Over time the overlying deposits may be piped downwards into the dissolution pipe with the fine-grained materials potentially being removed by groundwater flow at depth. This causes upward development of a crown hole or inverted cone shape in the superficial deposits, manifested as surface subsidence in the form of a subsidence sinkhole.

In some areas natural sinkholes may be interconnected with underground mine workings such as adits and shafts associated with the mining of chalk and/or flint as noted above. Larger sinkholes such as those located near Briston, north Norfolk, have been reported, up to 18 m wide and 8 m deep. These occur where superficial deposits overlie Chalk and may be due to more widespread lowering of the ground surface due to collapse.

Recorded natural cavities and solution pipes are spatially concentrated around the urban and peri-urban areas of Norwich, to the north and north-east of Thetford, and a zone up to 20 km south from the north Norfolk coast between Fakenham and Sheringham. Natural solution cavities can have serious implications for civil engineering works, especially where superficial deposits overlie Chalk bedrock as is the case in the west of the region, including many of the urban areas. Natural solution pipes in the Chalk infilled with glacial deposits (mostly sand and gravel) have been encountered during the construction of houses, roads and motorways in the area, including the A45 east of Bury St Edmunds, the A11 Thetford Bypass, the A47 Norwich Southern Bypass and the urban areas of Norwich. Abstraction of groundwater may cause a lowering of the water table and can be critical where solution pipes infilled with superficial deposits are hydrostatically supported. Abstraction of groundwater may also cause settlement of the fill and subsidence at the surface. Where they constitute a risk to property and life, natural cavities (and chalk mine voids) can be remediated by infilling with an inert material such as sand, gravel or pulverised fuel ash which subsequently act as a support to the walls and roof of the cavity, thereby reducing the risk of further subsidence or collapse.

Natural cavities such as fissures and widened v-shaped joints known as ‘gulls’ may form on valley sides as a result of cambering of more competent rocks such as limestone, where they overlie less competent rocks such as mudstone or clay. This process commonly occurs at the edge of an escarpment or steep-sided valley. A less competent rock is prone to squeezing and gravitational flow downslope causing the overlying competent rock to tilt, gravitationally, downslope with openings forming along major joints to form parallel-sided fissures up to a few metres wide and extending for up to 100 m length. Superficial deposits may be washed into gulls and fissures or collapse gravitationally into the open space, with the potential to obscure underlying void spaces that may be susceptible to later collapse.

Examples of cambering and gull formation can be seen in south and north Cambridgeshire where the Cretaceous White Chalk Subgroup overlies clay of the Gault Formation. Valley bulge may occur in steep-sided valleys where a less competent rock (e.g. mudstone or clay) is compressed and squeezed upwards along the valley floor. These processes may have been exacerbated during periglacial conditions by removal of ice and subsequent stress release during cyclic freeze-thaw. Inland landslides are not a common feature owing to the subdued relief of the region. However, where rivers have eroded valleys into relatively soft lithologies overlain by more competent lithologies such as limestone, the area may be prone to landslide failure. This is especially so where the overlying more competent rock is permeable and prone to dissolution and stress release along joints on valley sides as a result of cambering. These conditions may have been exacerbated during periglacial conditions (freeze-thaw).

Slope failures have been recorded in the London Clay Formation and Kesgrave Catchments Subgroup sediments along the valleys of the River Orwell where the slope angle exceeds seven degrees.

Radon is a natural radioactive gas produced by the radioactive decay of radium and uranium. The rate of release of radon is largely controlled by the uranium concentration in the source material and the type of minerals in which it resides. In this area the source materials are sedimentary rocks and superficial deposits, and the uranium is generally contained within organic- or phosphate-rich particles. Once radon is released, it is quickly diluted in the atmosphere and does not normally present a hazard. However, where the underlying bedrock has high uranium content and radon is released into poorly ventilated or enclosed spaces, it may reach high concentrations. The health risk arises from inhalation of radon gas under high concentrations. Radon is found in small quantities in all rocks and soils but varies from place to place. Areas affected by radon may include those underlain by the Jurassic Great Oolite Group limestones (including overlying sands and gravels), clays of the Blisworth Clay Formation and Ancholme Clay Group (which includes the Oxford Clay Formation) and Woburn Sands Formation, plus phosphatic horizons within the Red Crag Formation.

Coastline management

East Anglia possesses a dynamic and variable coastline that ranges from low-lying coastal marshes and embayments through to high cliffs. It has been actively managed since the 19th century although local authorities were only granted powers to erect coastal defences via the 1949 Coast Protection Act. Since the 1990s coastal management has been directed by a series of shoreline management plans or SMPs which were first introduced to assess the risks associated with coastal processes such as erosion, flooding and landslides and develop effective coastal management strategies to reduce risk and the impact upon people, infrastructure and the environment. Since the publication of these first generation SMPs, society now possesses a much greater appreciation of the drivers of coastal change and particularly the role played by climate change and rising sea levels. Climate models currently predict an 18 to 26 cm relative sea-level rise for London by 2050 depending on how effectively society reduces greenhouse gas emissions. Even the lower of these sea-level rise predictions for the Southern North Sea would have considerable implications for the coastline of East Anglia, increasing risk and reducing the effectiveness of current coastal management practices. Additionally, many hard-engineered solutions such as groynes, breakwaters (Plate 32) and sea walls have a limited life span and are not necessarily viable or cost-effective long-term solutions. However, more soft-engineered approaches to coastal management are considered to be viable in the long term. For these reasons, second generation SMPs are currently being developed (SMPs 4 to 7). Their aim is to provide a route map for future short-term (0 to 20 years), medium-term (20 to 50 years) and long-term (50 to 100 years) needs, by prioritising specific flood- and erosion-risk-management schemes and monitoring where they are most required.

Three principal coastline management issues are evident along the coast of East Anglia: cliff failure and landslides, erosion, and flooding. Cliff failure and landslides are common along parts of the East Anglia coastline where the cliffs are composed of soft, unlithified glacial and preglacial materials. Their low cohesive shear strength means that they are particularly vulnerable to direct wave attack which undercuts the toe of the cliff making the cliff prone to failure. The amount of undercutting ultimately depends upon the magnitude and duration of exposure of the cliff toe to direct wave attack, which in turn, is controlled by tidal range, wave height and the width of the beach. Increased toe erosion typically occurs during the winter months where increased wave energy and storminess commonly leads to a reduction in beach volume. Groundwater also plays a vital role in cliff stability because constrained water can often pond resulting in saturation and an overall reduction in sediment shear strength. It can also lubricate bedding discontinuities creating potential failure planes. Allied to both groundwater and toe erosion are the geological structure and height of the cliffs.

Large deep-seated rotational slides typically develop in high cliffs (over 30 m) where there is a horizontal to subhorizontal layering within the cliffs — for example between Bacton and Mundesley in north Norfolk. Low cliffs (less than 20 m) that occur discontinuously between Ostend and Dunwich are prone to localised block falls, topples and debris flows that occur through increased undermining of the cliff toe or saturation of the sediment sequences following prolonged periods of rainfall. Where the structural geology of the cliffs contains variably vertical to horizontal structures, then far more complex patterns of landslide may occur. The coastline between Trimingham and Overstrand is a classical example where different types of landslide correspond to specific glacitectonic structures within the cliffs — for instance debris falls are associated with steep bedding and debris flows occur in association with synclines.

Erosion is the process by which the coastline naturally retreats both by the retreat of cliff lines as well as the removal of beach materials (Plate 33a,b). However, this should not simply be viewed as a modern phenomenon as it is likely to have occurred since the Holocene sea-level maximum approximately 5000 years ago. Examination of historical maps and documents including the Doomsday Book reveal that several towns and villages have been lost to the North Sea over the centuries as the coastline has receded. These include Dunwich in Suffolk, Eccles-on-Sea, Wimpwell and Little Waxham in north-east Norfolk, and most famously the small town of Shipden which was inundated during the late 14th century and now lies approximately half a kilometre offshore from Cromer.

Since the 19th century, the construction of coastal defences using a combination of seawalls, groynes and timber palisades has had a marked affect upon the rates of coastal erosion. Various studies estimate erosion rates of between 0.5 and 2.5 m/yr around the coast of East Anglia depending on the nature of coastal management. Between Weybourne and Winterton in north Norfolk, approximately 500 km3/yr of sediment is eroded from the cliffs and transferred into the littoral zone. However, all of these figures should be viewed with caution as they represent medium-term averages which can overlook local and short-term variability. Whilst the construction of coastal defences has generally reduced coastal erosion by limiting lateral sediment transport (longshore drift), it has also resulted in a reduction of sediment supply to downdrift beaches (westwards and eastwards from Sheringham). This causes downdrift starvation and the reduction of beach profiles leading to enhanced cliff erosion in these areas. The local effectiveness of coastal defences is well illustrated by the highly publicised story of coastal erosion at Happisburgh (Plate 34). Timber revetments and groynes at Happisburgh were installed during the 1950s but by the late 1980s had fallen into a state of disrepair. In 1991, 300 m of defences were removed to the south of the Happisburgh due to storm damage and this has resulted in a dramatic increase in coastal erosion. Between 1994 and 2010 the cliff line has receded in this area by up to 150 m with the loss of many properties along Beech Road. Much of the sediment derived from the cliffs at Happisburgh has been trapped further to the south at Sea Palling where a series of shore-parallel reef-style breakwaters were constructed during the late 1990s to prevent coastal flooding. Whilst this scheme has proved locally successful in retaining beach sediment, it has a considerable negative impact on downdrift sediment supply. Other localities facing similar problems to Happisburgh occur along much of the coastline.

Coastal flooding is a hazard that affects a number of low-lying estuarine and marshland areas around the Norfolk and Suffolk coasts (Plate 35) and is predicted to increase with rising sea levels. Not only do they offer obvious hazards to people and infrastructure, rsion poses a significant threat to aquifer-derived drinking water and environmentally sensitive wetland areas. In historical times there have been a number of tidal surges, high tides and severe storms that have resulted in coastal flooding, not least the 1953 tidal surge which caused widespread loss of life and damage to properties and infrastructure around the coast of East Anglia and adjoining areas. Strategies for reducing the risk associated with coastal flooding include the construction of coastal revetments and the natural and artificial maintenance of broad beach profiles (e.g. Sea Palling).

Anthropogenic geology

Anthropogenic (man-made) geology, also known as ‘artificial ground’ is widespread in the East Anglia region. All developed or exploited terrain including urban areas, quarries, shallow mines, landfill sites, golf courses, road and railway foundation possess a veneer of ‘worked’ (extracted), ‘made’ (deposited) or ‘landscaped’ ground. Perhaps the most obvious anthropogenic deposits are those that occur beneath all urban and developed areas including cities, towns and villages all the way down to individual buildings. These can be highly diverse in terms of the composition and may contain crushed rock, concrete, rubble, rubbish and foundation material which can document the development history of an area or site. The thickness of ‘artificial ground’ beneath developed areas in East Anglia has not been studied; however, beneath parts of Greater London and other major urban areas thicknesses in excess of 8 m are not uncommon.

In rural parts of East Anglia, anthropogenic geology is less obvious but still significant. Roads and railways are commonly constructed on foundation bases to prevent movement whilst artificial embankments (levees) and coastal ridges have also been constructed or are artificially maintained to reduce the risk of river and coastal flooding. Arguably the most subtle examples of rural anthropogenic geology correspond to the low-lying coastal embayments such as the Fens and Broads where systematic drainage, reclamation and peat extraction has led to marked changes in the landscape (Chapter 11). These include the major drains and dykes of the Fens such as the Old and New Bedford rivers, the artificial straightening of rivers such as the Nene, along with improvement to existing drains located between the Fenland ‘islands’ such as the Isle of Ely.

Knowledge of the character and extent of anthropogenic geology is increasingly regarded by planners and civil engineers as being crucially important. This is because artificial ground occurs within the shallow subsurface coinciding with the zone with which humans most commonly interact.

Glossary of terms

British Geological Survey publications for East Anglia

BGS 1:50 000 geological maps, memoirs (M) and sheet explanations (SE) for East Anglia

Sheet No. Published Sheet name and memoir/sheet explanation authors
130 2008 Wells-next-the-Sea (SE). Moorlock, B S P, and others
131 2002 Cromer (SE). Moorlock, B S P, and others
132/148 2002 Mundesley and North Walsham (SE). Moorlock, B S P, and others
145 1994 King’s Lynn and the Wash (M). Gallois, R W
147 2014 Aylsham
158 1989 Peterborough (M). Horton, A, and Downing, R
161 1989 Norwich (M). Cox, F C, and others
162 1994 Great Yarmouth (M). Arthurton, R S, and others
173 1988 Ely (M). Gallois, R W
174 2010 Thetford
175 1993 Diss (M). Mathers, S J, and others
176/191 2000 Lowestoft and Saxmundham (M). Moorlock, B S P, and others
186 2006 Wellingborough (M). Barron, A J M, and others
187 1965 Huntingdon and Biggleswade (M). Edmonds, E A, and others
188 1969 Cambridge (M). Worssam, B C, and others
189 1990 Bury St Edmunds (M). Bristow, C R
190 1995 Eye
203 2010 Bedford (SE). Barron, A J M, and others
204 2003 Biggleswade (SE). Moorlock, B S P, and others
205 2003 Saffron Walden (SE). Moorlock, B S P, and others
206 1993 Sudbury (M). Pattison, J, and others
207 2007 Ipswich (SE). Mathers, S J, and others
208/225 2002 Woodbridge and Felixstowe (SE). Mathers, S J, and others
220 1992 Leighton Buzzard (M). Shephard-Thorn, E R, and others
221 1996 Hitchin (M). Hopson, P M, and others

Selected bibliography

Chapter 1 — Bedrock geology of East Anglia: national and global context

Chadwick, R A, and Evans, D J. 2005. A seismic atlas of Southern Britain — images of subsurface structure. Occasional Publication of the British Geological Survey, No. 7.

Cope, J C W, Ingham, J K, and Rawson, P F (editors). 1992. Atlas of palaeogeography and lithofacies. Memoir of the Geological Society of London, No. 13.

King, C. 2006. Palaeogene and Neogene: uplift and a cooling climate. 395–427 in The Geology of England and Wales (2nd edition). Brenchley, P J, and Rawson, P F (editors). (London: The Geological Society.)

Scotese, C R. 2002. http://www.scotese.com, (PALEOMAP website).

Torsvik, T H, and Trench, A. 1991. The Ordovician history of the Iapetus Ocean in Britain: new palaeomagnetic constraints. Journal of the Geological Society of London, Vol. 148, 423–425.

Whittaker, A (editor). 1985. Atlas of onshore sedimentary basins in England and Wales: post-Carboniferous tectonics and stratigraphy. (Blackie: Glasgow & London.)

Woodcock, N H, and Pharaoh, T C. 1993. Silurian facies beneath East Anglia. Geological Magazine, Vol. 130, 681–690.

Woodcock, N H, and Strachan, R (editors). 2000. Geological history of Britain and Ireland. (Blackwells: Oxford.)

Chapter 2 — Concealed geology

Cherns, L, Cocks, L R M, Davies, J R, Hillier, R D, Waters, R A, and Williams, M. 2006. Silurian: the influence of extensional tectonics and sea-level changes on sedimentation in the Welsh Basin and on the Midlands Platform. 75–120 in The Geology of England and Wales (2nd edition). Brenchley, P J, and Rawson, P F (editors). (London: The Geological Society.)

Lee, M K, Pharaoh, T C, and Soper, N J. 1990. Structural trends in central Britain from images of gravity and aeromagnetic fields. Journal of the Geological Society of London, Vol. 147, 241–258.

Millward, D. 2006. Caledonian intrusive rocks of northern England and the Midlands. 147–154 in The Geology of England and Wales (2nd edition). Brenchley, P J, and Rawson, P F (editors). (London: The Geological Society.)

Pharaoh, T C, Merriman, R J, Webb, P C, and Beckinsale, R D. 1987. The concealed Caledonides of eastern England: preliminary results of a multidisciplinary study. Proceedings of the Yorkshire Geological Society, Vol. 46, 355–369.

Pharaoh, T C, Brewer, T S, and Webb, B C. 1993. Subduction-related magmatism of Late Ordovician age in eastern England. Geological Magazine, Vol. 130, 647–656.

Pharaoh, T C, Vincent, C J, Bentham, M S, Hulbert, A G, Waters, C N, and Smith, N J.
2011. Structure and evolution of the East Midlands region of the Pennine Basin. Subsurface Memoir of the British Geological Survey.

Waters, C N, and Davies, S J. 2006. Carboniferous: extensional basins, advancing deltas and coal swamps. 173–223 in The Geology of England and Wales (2nd edition). Brenchley, P J, and Rawson, P F (editors). (London: The Geological Society.)

Woodcock, N H, and Pharaoh, T C. 1993. Silurian facies beneath East Anglia. Geological Magazine, Vol. 130, 681–690.

Woodcock, N H, and Soper, N J. 2006. The Acadian Orogeny: the Mid Devonian phase of deformation that formed the slate belts in England and Wales. 131–146 in The Geology of England and Wales (2nd edition). Brenchley, P J, and Rawson, P F (editors). (London: The Geological Society.)

Woodcock, N H, Soper, N J, and Strachan, R A. 2007. A Rheic cause for the Acadian deformation in Europe. Journal of the Geological Society of London, Vol. 164, 1023–1036.

Chapter 3 — Jurassic: shallow seas and archipelagos

Callomon, J H. 1968. The Kellaways Beds and the Oxford Clay. The geology of the East Midlands. Sylvester-Bradley, P C, and Ford, T D (editors). (Leicester: Leicester University Press.)

Cope, J C W. 2006. Jurassic: the returning seas. 325–363 in The Geology of England and Wales (2nd edition). Brenchley, P J, and Rawson, P F (editors). (London: The Geological Society.)

Cox, B M, and Sumbler, M G. 2002. British Middle Jurassic stratigraphy. Geological Conservation Review Series, No. 26. (Peterborough: Joint Nature Conservation Committee/Chapman and Hall.)

Cox, B M, Hudson, J D, and Martill, D M. 1992. Lithostratigraphical nomenclature of the Oxford Clay (Jurassic). Proceedings of the Geologists’ Association, Vol. 103, 343–345.

Douglas, J A, and Arkell, W J. 1932. The stratigraphical distribution of the Cornbrash: II. The north-eastern area. Quarterly Journal of the Geological Society of London, Vol. 88, 112–170.

Gallois, R W. 1979. Geological investigations for the Wash Water Storage Scheme.
Report of the Institute of Geological Sciences, Vol. 78/19.

Gallois, R W, and Cox, B M. 1976. The stratigraphy of the Lower Kimmeridge Clay of eastern England. Proceedings of the Yorkshire Geological Society, Vol. 41, 13–26.

Gallois, R W, and Cox, B M. 1977. The stratigraphy of the Middle and Upper Oxfordian sediments of Fenland. Proceedings of the Geologists’ Association, Vol. 88, 207–228.

Horton, A, Lake, R D, Bisson, G, and Coppack, B C. 1974. The geology of Peterborough.
Report of the Institute of Geological Sciences, No. 73/12.

Underhill, J R, and Partington, M A. 1993. Jurassic thermal doming and deflation in the North Sea: implications of the sequence stratigraphic evidence. 697–706 in Petroleum geology of Northwest Europe: proceedings of the 4th conference held at the Barbican Centre, London, 29 March-1 April 1992. Parker, J R, and Bartholomew, I D (editors). (London: The Geological Society.)

Wright, J K, and Cox, B M. 2001. British Upper Jurassic Stratigraphy. Geological Conservation Review Series, No. 21. (Peterborough: Joint Nature Conservation Committee/Chapman and Hall.)

Wright, J K, Kelly, S R A, and Page, K N. 2000. The stratigraphy of the ‘Corallian’ facies Middle Oxfordian (Upper Jurassic) deposits at Upware, Cambridgeshire, England.
Proceedings of the Geologists’ Association, Vol. 111, 97–110.

Chapter 4 — Early Cretaceous

Casey, R. 1963. The dawn of the Cretaceous Period in Britain. Bulletin of the South-Eastern Union of Scientific Societies, Vol. 17, 1–15.

Chadwick, R A. 1985. End Jurassic — early Cretaceous sedimentation and subsidence (late Portlandian to Barremian), and the late Cimmerian unconformity. 52–56 in Atlas of onshore sedimentary basins in England and Wales: post-Carboniferous tectonics and stratigraphy. Whittaker, A (editor). (Blackie: Glasgow & London.)

Cope, J C W. 2006. Jurassic: the returning seas. 325–363 in The Geology of England and Wales (2nd edition). Brenchley, P J, and Rawson, P F (editors). (London: The Geological Society.)

Eyers, J. 1992. Sedimentology and palaeoenvironment of the Shenley Limestone (Albian, Lower Cretaceous): an unusual shallow-water carbonate. Proceedings of the Geologists’ Association, Vol. 103, 293–302.

Eyers, J. 1995. The Silty Beds: a tidal flat sequence at the junction of the Lower Greensand and Gault (Albian, Lower Cretaceous) of Bedfordshire , England. Proceedings of the Geologists’ Association, Vol. 106, 107–118.

Gallois, R W, and Morter, A A. 1982. The stratigraphy of the Gault of East Anglia. Proceedings of the Geologists’ Association, Vol. 93, 351–368.

Hancock, J M, and Rawson, P F. 1992. Cretaceous. 131–139 in Atlas of palaeo-geography and lithofacies. Cope, J C W, Ingham, J K, and Rawson, P F (editors). Memoir of the Geological Society of London, No. 13.

Hopson, P M, Wilkinson, I P, and Woods, M A. 2008. A stratigraphical framework for the Lower Cretaceous of England. British Geological Survey Research Report, RR/08/03.

Jeans, C V. 1980. Early submarine lithification in the Red Chalk and Lower Chalk of eastern England: a bacterial control model and its implications. Proceedings of the Yorkshire Geological Society, Vol. 43, 81–157.

Johnson, H D, and Levell, B K. 1995. Sedimentology of a transgressive, estuarine sand complex: the Lower Cretaceous Woburn Sands (Lower Greensand), southern England.
Special Publications of the International Association of Sedimentologists, No. 22, 17–46.

Mitchell, S F. 1995. Lithostratigraphy and biostratigraphy of the Hunstanton Formation (Red Chalk, Cretaceous) succession at Speeton, North Yorkshire, England. Proceedings of the Yorkshire Geological Society, Vol. 50, 285–303.

Owen, H G. 1984. The Albian Stage: European province chronology and ammonite zonation. Cretaceous Research, Vol. 5, 329–344.

Owen, H G. 1992. The Gault — Lower Greensand Junction Beds in the northern Weald (England) and Wissant (France), and their depositional environment. Proceedings of the Geologists’ Association, Vol. 103, 83–110.

Owen, H G. 1995. The upper part of the Carstone and the Hunstanton Red Chalk (Albian) of the Hunstanton Cliff, Norfolk. Proceedings of the Geologists’ Association, Vol. 106, 171–181.

Owen, H G. 1999. Correlation of Albian European and Tethyan ammonite zonations and the boundaries of the Albian Stage and substages: some comments. Scripta Geologica, Special Issue No. 3, 129–149.

Owen, H G, and Mutterlose, J. 2006. Late Albian ammonites from offshore Suriname: implications for biostratigraphy and palaeobiogeography. Cretaceous Research, Vol. 27, 717–727.

Owen, H G, Shephard-Thorn, E R, and Sumbler, M G. 1996. Lower Cretaceous. 61–75 in British regional geology: London and the Thames Valley (4th edition). Sumbler, M G (compiler). (London: HMSO for the British Geological Survey.)

Rawson, P F. 2006. Cretaceous: sea levels peak as the North Atlantic opens. 365–393 in The Geology of England and Wales (2nd edition). Brenchley, P J, and Rawson, P F (editors). (London: The Geological Society.)

Rawson, P F, Curry, D, Dilley, F C, Hancock, J M, Kennedy, W J, Neale, J W, Wood, C J, and Worssam, B C. 1978. A correlation of the Cretaceous rocks in the British Isles. Geological Society of London Special Report, No. 9.

Röhl, U, and Ogg, J G. 1996. Aptian–Albian sea-level history from guyots in the western Pacific. Paleoceanography, Vol. 11, 595–624.

Ruffell, A, and Wach, G. 1998. Estuarine/offshore depositional sequences of the Cretaceous Aptian–Albian boundary, England. 411–421 in Sequence stratigraphy of European basins. Society of Economic Palaeontologists and Mineralogists Special Publication, No. 60.

Wonham, J P, and Elliot, T. 1996. High resolution sequence stratigraphy of a mid Cretaceous estuarine complex: the Woburn Sands of the Leighton Buzzard area, southern England. 41–62 in Sequence stratigraphy in British geology. Hesselbo, S E, and Parkinson, D N (editors). Special Publication of the Geological Society, No. 103.

Woods, M A, Wilkinson, I P, and Hopson, P M. 1995. The stratigraphy of the Gault Formation (Middle and Upper Albian) in the BGS Arlesey Borehole, Bedfordshire.
Proceedings of the Geologists’ Association, Vol. 106, 271–280.

Chapter 5 — Upper Cretaceous: greenhouse climate, tropical seas

Bailey, H W, and Wood, C J. 2010. Chapter 3. The Upper Cretaceous Chalk. 36–60 in Hertfordshire Geology and Landscape, Catt, J (editor). (Welwyn Garden City, Hertfordshire: Hertfordshire Natural History Society.)

Boswell, P G H. 1912. Report of an excursion to Ipswich and the Gipping Valley. Proceedings of the Geologists’ Association, Vol. 23, 229–237.

Boswell, P G H. 1913. Notes on the Chalk of Suffolk. Journal of the Ipswich and District Field Club, Vol. 4, 17–26.

Boswell, P G H. 1927. The Geology of the country around Ipswich. Memoirs of the Geological Survey. Sheet 207 (England and Wales).

Bromley, R G, and Gale, A S. 1982. The lithostratigraphy of the English Chalk Rock. Cretaceous Research, Vol. 3, 273–306.

Brydone, R M. 1932. The lower beds of the Chalk near Ipswich. Journal of the Ipswich and District Natural History Society, Vol. 1, 153–157.

Clayton, C J. 1986. The chemical environment of flint formation in Upper Cretaceous chalks. 43–54 in The scientific study of flint and chert: proceedings of the fourth international flint symposium held at Brighton Polytechnic 10–15 April, 1983. Sieveking, G de G, and Hart, M B (editors). (Cambridge: Cambridge University Press.)

Cope, J C W. 2006. Upper Cretaceous palaeogeography of the British Isles and adjacent areas. Proceedings of the Geologists’ Association, Vol. 117, 129–143.

Gale, A S. 1996. Turonian correlation and sequence stratigraphy of the Chalk in southern England. 177–197 in Sequence stratigraphy in British Geology. Hesselbo, S P, and Parkinson, D N (editors). Special Publication of the Geological Society of London, No. 103.

Gale, A S. 2000. Late Cretaceous to Early Tertiary pelagic deposits: deposition on greenhouse Earth. 356–373 in Geological history of Britain and Ireland. Woodcock, N H, and Strachan, R (editors). (Blackwells: Oxford.)

Gale, A S, Smith, A B, Monks, N E A, Young, J A, Howard, A, Wray, D S, and Huggett, J M. 2000. Marine biodiversity through the Late Cenomanian — Early Turonian: palaeoceanographic controls and sequence stratigraphic biases. Journal of the Geological Society of London, Vol. 157, 745–757.

Grant, S F, Coe, A L, and Armstrong, H A. 1999. Sequence stratigraphy of the Coniacian succession of the Anglo-Paris Basin. Geological Magazine, Vol. 136, 17–38.

Hancock, J M. 1989. Sea-level changes in the British region during the Late Cretaceous. Proceedings of the Geologists’ Association, Vol. 100, 565–594.

Hopson, P M. 2005. A stratigraphical framework for the Upper Cretaceous Chalk of England and Scotland with statements on the Chalk of Northern Ireland and the UK Offshore Sector. British Geological Survey Research Report, RR/05/01.

Iglesias-Rodriguez, M D, Halloran, P R, Rickarby, R E M, Hall, I R, Colmenero-Hidalgo, E, Gittins, J R, Green, D R H, Tyrrell, T, Gibbs, S J, Dassow, von P, Rehm, E, Armbrust, E V, and Boessenkool, K P. 2008. Phytoplankton calcification in a high-CO2 World. Science, Vol. 320, 336–340.

Jenkyns, H C, Gale, A S, and Corfield, R M. 1994. Carbon- and oxygen-isotope stratigraphy of the English Chalk and Italian Scaglia and its palaeoclimatic significance. Geological Magazine, Vol. 131, 1–34.

Jukes-Browne, A J, and Hill, W. 1904. The Cretaceous Rocks of Britain. Vol. 3. The Upper Chalk of England. Memoir of the Geological Survey of the United Kingdom.

Mortimore, R N, and Wood, C J. 1986. The distribution of flint in the English Chalk, with particular reference to the ‘Brandon Flint Series’ and the high Turonian flint maximum. 7–20 in The scientific study of flint and chert. Sieveking, G de C and Hart, M B (editors). (Cambridge: Cambridge University Press.)

Mortimore, R N, Wood, C J, and Gallois, R W. 2001. British Upper Cretaceous stratigraphy. Geological Conservation Review Series, No. 23. (Peterborough: Joint Nature Conservation Committee.)

Peake, N B, and Hancock, J M. 1970. The Upper Cretaceous of Norfolk [reprinted with corrigenda and addenda]. 293–339 in The Geology of Norfolk. Larwood, G P, and Funnell, B M (editors). (Norwich: Soman-Wherry Press Ltd.)

Pitchford, A J. 1990. A summary of the stratigraphy of current exposures of Belemnitella mucronata Zone Chalk (Campanian, Upper Cretaceous) in Norfolk. Bulletin of the Geological Society of Norfolk, Vol. 40, 3–24.

Rawson, P F, Allen, P, and Gale, A S. 2001. The Chalk Group — a revised lithostratigraphy. Geoscientist, 11, 21.

Skelton, P W, Spicer, R A, Kelley, S P, and Gilmour, I. 2003. The Cretaceous World. (Milton Keynes: The Open University; Cambridge: Cambridge University Press.)

The Royal Society. 2005. Ocean acidification due to increasing atmospheric carbon dioxide. Policy Document 12/05.

Stanley, S M, Ries, J B, and Hardle, L A. 2005. Seawater chemistry, coccolithophore population growth, and the origin of Cretaceous chalk. Geology, Vol. 33, 593–596.

Whitham, F. 1991. The stratigraphy of the Upper Cretaceous Ferriby, Welton and Burnham formations north of the Humber, north-east England. Proceedings of the Yorkshire Geological Society, Vol. 48, 227–255.

Whitham, F. 1993. The stratigraphy of the Upper Cretaceous Flamborough Chalk Formation north of the Humber, north-east England. Proceedings of the Yorkshire Geological Society, Vol. 49, 235–258.

Wood, C J. 1988. The stratigraphy of the Chalk of Norwich. Bulletin of the Geological Society of Norfolk, No. 38, 3–20.

Wood C J, and Smith, E G. 1978. Lithostratigraphical classification of the Chalk in North Yorkshire, Humberside and Lincolnshire. Proceedings of the Yorkshire Geological Society, Vol. 42, 263–287.

Wood, C J, Morter, A A, and Gallois, R W. 1994. Appendix 1 in Geology of the country around Great Yarmouth. Arthurton, R S, Booth, S J, Morigi, A N, Abbott, M A W, and Wood, C J. Memoir of the British Geological Survey, Sheet 162 (England and Wales).

Woods, M A, and Chacksfield, B C. 2012. Revealing deep structural influences on the Upper Cretaceous Chalk of East Anglia (UK) through interregional geophysical log correlations. Proceedings of the Geologists’ Association, Vol. 123, 486–499.

Woods, M A, Mortimore, R N, and Wood C J. 2012. The Chalk of Suffolk. 105–132 in Geoscience Suffolk, 10th Anniversary Volume. Dixon, R (editor). (Norwich: Page Bros.)

Woods, M A, Wood, C J, Wilkinson, I P, and Wright, T N. 2007. The stratigraphy of the Chalk Group (Upper Cretaceous) of the Gipping Valley, near Ipswich, Suffolk, UK. Proceedings of the Geologists’ Association, Vol. 118, 347–363.

Wray, D S, and Gale, A S. 2006. The palaeoenvironment of Late Cretaceous Chalks.
Proceedings of the Geologists’ Association, Vol. 117, 145–162.

Wray, D S, and Wood, C J. 1995. Geochemical identification and correlation of tuff layers in Lower Saxony, Germany. Berliner geowiss. Abh., Vol. E16, 215–225.

Wray, D S, and Wood, C J. 1998. Distinction between detrital and volcanogenic clay-rich beds in Turonian–Coniacian chalks of eastern England. Proceedings of the Yorkshire Geological Society, Vol. 52, 95–105.

Chapter 6 — Palaeogene

Aldiss, D T. 2012. The stratigraphical framework for the Palaeogene successions of the London Basin, UK. British Geological Survey Open Report, OR/12/004.

Boswell, P G H. 1915. The stratigraphy and petrology of the Lower Eocene deposits of the north-eastern part of the London Basin. Quarterly Journal of the Geological Society of London, Vol. 71, 536–591.

Bristow, C R. 1983. The stratigraphy and structure of the Crag of mid-Suffolk, England. Proceedings of the Geologists’ Association, Vol. 94, 1–12.

Cande, S C, and Kent, D V. 1992. A new geomagnetic polarity timescale for the Late Cretaceous and Cenozoic. Journal of Geophysical Research, Vol. 97, 13917–13951.

Cornwell, J C, Kimbell, G S, and Ogilvy, R D. 1996. Geophysical evidence for basement structure in Suffolk, East Anglia. Journal of the Geological Society of London, Vol. 153, 207–211.

Ellison, R A, Knox, R W O, Jolley, D W, and King, C. 1994. A revision of the lithostratigraphical classification of the early Palaeogene strata of the London Basin and East Anglia. Proceedings of the Geologists’ Association, Vol. 105, 187–197.

Hamblin, R J O, Moorlock, B S P, Booth, S J, Jeffery, D H, and Morigi, A N. 1997. The Red Crag and Norwich Crag formations in eastern Suffolk. Proceedings of the Geologists’ Association, Vol. 108, 11–23.

Jolley, D W. 1992. Palynofloral association sequence stratigraphy of the Palaeocene Thanet Beds and equivalent sediments in eastern England. Review of Palaeobotany and Palynology, Vol. 74, 207–237.

Jolley, D W. 1996. The earliest Eocene sediments of eastern England: an ultra-high resolution palynological correlation. 219–254 in Correlation of the Early Palaeogene in Northwest Europe. Knox, R W O, Corfield, R M, and Dunay, R E (editors). Geological Society of London Special Publication, No. 101.

King, C. 2006. Palaeogene and Neogene: uplift and a cooling climate. 395–427 in The Geology of England and Wales (2nd edition). Brenchley, P J, and Rawson, P F (editors). (London: The Geological Society.)

King, C. In press. A revised correlation of Palaeogene and Neogene deposits in the British Isles. Geological Society of London Special Report.

Knox, R W O. 1996. Tectonic controls on sequence development in the Paleocene and earliest Eocene of southeast England: implications for North Sea stratigraphy. 209–230 in Sequence Stratigraphy in British Geology. Hesselbro, S P, and Parkinson, D N (editors). Geological Society of London Special Publication, No. 103.

Knox, R W O, and Morton, A C. 1988. The record of early Tertiary North Atlantic volcanism in sediments of the North Sea Basin. 407–419 in Early Tertiary volcanism and the opening of the NE Atlantic. Morton, A C, and Parson, L W (editors). Geological Society of London Special Publication, No. 39.

Martini, E. 1971. Standard Tertiary and Quaternary calcareous nannoplankton zonation. 739–785 in Proceedings of the 2nd International Conference on Planktonic Microfossils Roma: Rome. Vol. 2. Farinacci, A (editor). (Rome: Technoscienza.).

Morton, A C. 1982. The provenance and diagenesis of Palaeogene sandstones of south-east England as indicated by heavy mineral analysis. Proceedings of the Geologists’ Association, Vol. 93, 263–274.

Saunders, A D, Jones, S M, Morgan, L A, Pierce, K L, Widdowson, M, and Xu, Y G. 2007. Regional uplift associated with continental large igneous provinces: the roles of mantle plumes and the lithosphere. Chemical Geology, Vol. 241, 282–318.

Woods, M A, and Chacksfield, B C. 2012. Revealing deep structural influences on the Upper Cretaceous Chalk of East Anglia (UK) through interregional geophysical log correlations. Proceedings of the Geologists’ Association, Vol. 123, 486–499.

Chapter 7 — Overview of Late Neogene to Quaternary geology

Ashton, N, and Lewis, S G. 2012. The environmental contexts of early human occupation of northwest Europe: The British Lower Palaeolithic record. Quaternary International, Vol. 271, 50–64.

Ashton, N, Lewis, S G, Parfitt, S A, Penkman, K E H, and Coope, G R. 2008. New evidence for complex climate change in MIS 11 from Hoxne, Suffolk, UK. Quaternary Science Reviews, Vol. 27, 652–668.

Ashton, N, Lewis, S, Stringer, C, Candy, I, Silva, B, and Lee, J R (editors). 2011. Climates of the early Middle Pleistocene in Britain: environments of the earliest humans in northern Europe. (Elsevier.)

Böse, M, Lüthgens, C, Lee, J R, and Rose, J. 2012. Quaternary glaciations of northern Europe. Quaternary Science Reviews, Vol. 44, 1–25.

Candy, I, Coope, G R, Lee, J R, Parfitt, S A, Preece, R C, Rose, J, and Schreve, D C. 2010.
Pronounced warmth during early Middle Pleistocene interglacials: investigating the Mid-Brunhes Event in the British terrestrial sequence. Earth Science Reviews, Vol. 103, 183–196.

Clark, C D, Gibbard, P L, and Rose, J. 2004. Pleistocene glacial limits in England, Scotland and Wales. 47–82 in Developments in Quaternary Science. Ehlers, J, and Gibbard, P L (editors). Volume 2, Part 1. (Elsevier.)

Clark, C D, Hughes, A L C, Greenwood, S L, Jordan, C, and Sejrup, H P. 2012. Pattern and timing of retreat of the last British-Irish Ice Sheet. Quaternary Science Reviews, Vol. 44, 112–146.

Dowdeswell, J A, and Ottesen, D. 2013. Buried iceberg ploughmarks in the early Quaternary sediments of the central North Sea: a two million year record of glacial influence from 3D seismic data. Marine Geology, Vol. 344, 1–9.

Gao, C, Keen, D H, Boreham, S, Coope, G R, Pettit, M E, Stuart, A J, and Gibbard, P L. 2000. Last Interglacial and Devensian deposits of the River Great Ouse at Woolpack Farm, Fenstanton, Cambridgeshire, UK. Quaternary Science Reviews, Vol. 19, 787–810.

Gibbard, P L, West, R G, Zagwijn, W H, Balson, P S, Burger, A W, Funnell, B M, Jeffery, D H, De, J J, Van, K T, Lister, A M, Meijer, T, Norton, P E P, Preece, R C, Rose, J, Stuart, A J, Whiteman, C A, and Zalasiewicz, J A. 1991. Early and early Middle Pleistocene correlations in the southern North Sea basin. Quaternary Science Reviews, Vol. 10, 23–52.

Keen, D H, Bateman, M D, Coope, G R, Field, M H, Langford, H E, Merry, J S, and Mighall,
T M. 1999. Sedimentology, palaeoecology and geochronology of Last Interglacial deposits from Deeping St James, Lincolnshire, England. Journal of Quaternary Science, Vol. 14, 411–436.

Kemp, R A, Whiteman, C A, and Rose, J. 1993. Paleoenvironmental and stratigraphical significance of the Valley Farm and Barham soils in Eastern England. Quaternary Science Reviews, Vol. 12, 833–848.

Langford, H E, and Briant, R M. 2004. Post-Anglian Pleistocene deposits in the Peterborough area and the Pleistocene history of the Fen Basin. 22–35 in Nene Valley: Field Guide. Langford, H E, and Briant, R M (editors). (London: Quaternary Research Association.)

Lee, J R, Busschers, F S, and Sejrup, H P. 2012. Pre-Weichselian Quaternary glaciations of the British Isles, The Netherlands, Norway and adjacent marine areas south of 68°N: implications for long-term ice sheet development in northern Europe. Quaternary Science Reviews, Vol. 44, 213–228.

Lisiecki, L E, and Raymo, M E. 2007. Plio-Pleistocene climate evolution: trends and transitions in glacial cycle dynamics. Quaternary Science Reviews, Vol. 26, 56–69.

Murton, J B, Whiteman, C A, and Allen, P. 1995. Involutions in the Middle Pleistocene (Anglian) Barham Soil, Eastern England — a comparison with thermokarst involutions from Arctic Canada. Boreas, Vol. 24, 269–280.

Parfitt, S, Barendregt, R W, Breda, M, Candy, I, Collins, M J, Coope, G R, Durbridge, P, Field, M H, Lee, J R, Lister, A, Mutch, R, Penkman, K E H, Preece, R C, Rose, J, Stringer, C B, Symmons, R, Whittaker, J E, Wymer, J, and Stuart, A J. 2005. The earliest record of human activity in northern Europe. Nature, Vol. 438, 1008–1012.

Parfitt, S A, Ashton, N M, Lewis, S G, Abel, R L, Coope, G R, Field, M H, Gale, R, Hoare, P G, Larkin, N R, Lewis, M D, Karloukovski, V, Maher, B A, Peglar, S M, Preece, R C, Whittaker, J E, and Stringer, C B. 2010. Early Pleistocene human occupation at the edge of the boreal zone in northwest Europe. Nature, Vol. 466, 229–233.

Preece, R C, and Parfitt, S A. 2012. The Early and early Middle Pleistocene context of human occupation and lowland glaciation in Britain and northern Europe. Quaternary International, Vol. 271, 6–28.

Rose, J. 2009. Early and Middle Pleistocene landscapes of eastern England. Proceedings of the Geologists’ Association, Vol. 120, 3–33.

Rose, J. 2010. The Quaternary of the British Isles: factors forcing environmental change. Journal of Quaternary Science, Vol. 25, 399–418.

West, R G. 1980. The Pre-glacial Pleistocene of the Norfolk and Suffolk Coasts. (Cambridge: Cambridge University Press.)

Whiteman, C A, and Rose, J. 1992. Thames river sediments of the British Early and Middle Pleistocene. Quaternary Science Reviews, Vol. 11, 363–375.

Chapter 8 — Late Pliocene and Pleistocene marine deposits

Balson, P S. 1990. The ‘Trimley Sands’: a former marine Neogene deposit from eastern England. Tertiary Research, Vol. 11, 145–158.

Bristow, C R. 1983. The stratigraphy and structure of the Crag of mid Suffolk, England. Proceedings of the Geologists’ Association, Vol. 94, 1–12.

Funnell, B M, and West, R G. 1962. The Early Pleistocene of Easton Bavents, Suffolk. Quarterly Journal of the Geological Society of London, Vol. 118, 125–141.

Hamblin, R J O, Moorlock, B S P, Booth, S J, Jeffery, D H, and Morigi, A N. 1997. The Red Crag and Norwich Crag formations in eastern Suffolk. Proceedings of the Geologists’ Association, Vol. 108, 11–23.

Hey, R W. 1967. The Westleton Beds reconsidered. Proceedings of the Geologists’ Association, Vol. 78, 427–445.

Kuhlmann, G, Langeris, C G, Munsterman, D, Van Leeuwan, R J, Verreuseel, R, Meulenkamp, J E, and Wong, T E. 2006. Integrated chronstratigraphy of the Plio-Pleistocene interval and its relation to the regional stratigraphic stages in the southern North Sea region. Netherlands Journal of Geosciences, Vol. 85, 19–35.

Larkin, N R, Lee, J R, and Connell, E R. 2011. Possible ice-rafted erratics in late Early to early Middle Pleistocene shallow marine and coastal deposits in northeast Norfolk, UK. Proceedings of the Geologists’ Association, Vol. 122, 445–454.

Mathers, S J, and Zalasiewicz, J A. 1988. The Red Crag and Norwich Crag formations of southern East Anglia. Proceedings of the Geologists’ Association, Vol. 99, 261–278.

Mathers, S, and Zalasiewicz, J. 1996. A gravel beach-rip channel system: The Westleton Beds (Pleistocene) of Suffolk, England. Proceedings of the Geologists Association, Vol. 107, 57–67.

Rose, J, Moorlock, B S P, and Hamblin, R J O. 2001. Pre-Anglian fluvial and coastal deposits in Eastern England: lithostratigraphy and palaeoenvironments. Quaternary International, Vol. 79, 5–22.

Rose, J, Candy, I, Moorlock, B S P, Wilkinson, I H, Lee, J A, Hamblin, R J O, Lee, J R, Riding, J B, and Morigi, A N. 2002. Early and early Middle Pleistocene river, coastal and neotectonic processes, southeast Norfolk, England. Proceedings of the Geologists’ Association, Vol. 113, 47–68.

West, R G. 1980. The Pre-glacial Pleistocene of the Norfolk and Suffolk Coasts. (Cambridge: Cambridge University Press.)

West, R G, Funnell, B M, and Norton, P E P. 1980. An Early Pleistocene cold marine episode in the North Sea; pollen and faunal assemblages at Covehithe, Suffolk, England. Boreas, Vol. 9, 1–10.

Zalasiewicz, J A, Mathers, S J, Hughes, M J, Gibbard, P L, Peglar, S M, Harland, R, Nicholson,
R A, Boulton, G S, Cambridge, P, and Wealthall, G P. 1988. Stratigraphy and palaeo-environments of the Red Crag and Norwich Crag formations between Aldeburgh and Sizewell, Suffolk, England. Philosophical Transactions of the Royal Society of London, Series B: Biological Sciences, No. 322.

Zalasiewicz, J A, Mathers, S J, Gibbard, P L, Peglar, S M, Funnell, B M, Catt, J A, Harland, R, Long, P E, and Austin, T J F. 1991. The age and relationships of the Chillesford Clay (Early Pleistocene – Suffolk, England). Philosophical Transactions of the Royal Society of London Series, Vol. B333, 81–100.

Post-Anglian marine deposits

Gale, S J, Hoare, P G, Hunt, C O, and Pye, K. 1988. The middle and upper Quaternary deposits at Morston, North Norfolk, UK. Geological Magazine, Vol. 125, -533.

Hoare, P G, Gale, S J, Robinson, R A J, Connell, E R, and Larkin, N R. 2009. Marine Isotope Stage 7–6 transition age for beach sediments at Morston, north Norfolk, UK: implications for Pleistocene chronology, stratigraphy and tectonics. Journal of Quaternary Science, Vol. 24, 311–316.

Horton, A, Keen, D H, Field, M H, Robinson, J E, Coope, G R, Currant, A P, Graham, D K,
Green, C P, and Phillips, L M. 1992. The Hoxnian Interglacial deposits at Woodston, Peterborough. Philosophical Transactions of the Royal Society of London, Vol. B338, 131–164.

Rowe, P J, Richards, D A, Atkinson, T C, Bottrell, S H, and Cliff, R A. 1997. Geochemistry and radiometric dating of a Middle Pleistocene peat. Geochimica et Cosmochimica Acta, Vol. 61, 4201–4211.

Scourse, J D, Austin, W E N, Sejrup, H P, and Ansari, M H. 1999. Foraminiferal isoleucine epimerization determinations from the Nar Valley Clay, Norfolk, UK: implications for Quaternary correlations in the southern North Sea Basin. Geological Magazine, Vol. 136, 543–560.

Ventris, P A. 1996. Hoxnian interglacial freshwater and marine deposits in northwest Norfolk, England and their implications for sea-level reconstruction. Quaternary Science Reviews, Vol. 15, 437–450.

West, R G. 1987. A note on the March Gravels and Fenland sea levels. Bulletin of the Geological Society of Norfolk, Vol. 37, 27–34.

West, R G, Andrew, R, Knudsen, K L, Peglar, S M, and Pettit, M E. 1995. Late Pleistocene deposits at Chatteris, March and Wimblington, Cambridgeshire, UK. Proceedings of the Geologists’ Association, Vol. 106, 195–210.

Chapter 9 — Pleistocene fluvial deposits and soils

Pre-Anglian fluvial deposits and palaeosols

Bridgland, D R. 2000. River terrace systems in north-west Europe: an archive of environmental change, uplift and early human occupation. Quaternary Science Reviews, Vol. 19, 1293–1303.

Candy, I, Silva, B, and Lee, J R. 2011. Climates of the early Middle Pleistocene in Britain: environments of the earliest humans in northern Europe. 11–22 in The ancient human occupation of Britain. Ashton, N, Lewis, S, and Stringer, C (editors). Developments in Quaternary Science. (Elsevier.)

Hamblin, R J O, and Moorlock, B S P. 1995. The Kesgrave and Bytham Sands and Gravels of Eastern Suffolk. Quaternary Newsletter, Vol. 77, 17–31.

Hey, R W. 1965. Highly quartzose pebble gravels in the London Basin. Proceedings of the Geologists’ Association, Vol. 76, 403–420.

Kemp, R A, Whiteman, C A, and Rose, J. 1993. Paleoenvironmental and stratigraphic significance of the Valley Farm and Barham soils in Eastern England. Quaternary Science Reviews, Vol. 12, 833–848.

Lee, J R, Rose, J, Candy, I, and Barendregt, R W. 2006. Sea-level changes, river activity, soil development and glaciation around the western margins of the southern North Sea Basin during the Early and early Middle Pleistocene: evidence from Pakefield, Suffolk, UK. Journal of Quaternary Science, Vol. 21, 155–179.

Murton, J B, Whiteman, C A, and Allen, P. 1995. Involutions in the Middle Pleistocene (Anglian) Barham Soil, eastern England — a comparison with thermokarst involutions from arctic Canada. Boreas, Vol. 24, 269–280.

Rose, J, and Allen, P. 1977. Middle Pleistocene stratigraphy in south-east Suffolk. Journal of the Geological Society of London, Vol. 133, 83–102.

Rose, J, Allen, P, Kemp, R A, Whiteman, C A, and Owen, N. 1985. The early Anglian Barham Soil in southern East Anglia. 197–229 in Soils and Quaternary Landscape Evolution. Boardman, J (editor). (Chichester: Wiley.)

Rose, J, Whiteman, C A, Allen, P, and Kemp, R A. 1999. The Kesgrave Sands and Gravels: ‘preglacial’ Quaternary deposits of the River Thames in East Anglia and the Thames valley. Proceedings of the Geologists’ Association, Vol. 110, 93–116.

Rose, J, Moorlock, B S P, and Hamblin, R J O. 2001. Pre-Anglian fluvial and coastal deposits in eastern England: lithostratigraphy and palaeoenvironments. Quaternary International, Vol. 79, 5–22.

Westaway, R, Maddy, D, and Bridgland, D. 2002. Flow in the lower continental crust as a mechanism for the Quaternary uplift of south-east England: constraints from the Thames terrace record. Quaternary Science Reviews, Vol. 21, 559–603.

Whiteman, C A, and Rose, J. 1992. Thames river sediments of the British Early and Middle Pleistocene. Quaternary Science Reviews, Vol. 11, 363–375.

Post-Anglian fluvial deposits

Boreham, S, White, T S, Bridgland, D R, Howard, A J, and White, M J. 2010. The Quaternary history of the Wash fluvial network, UK. Proceedings of the Geologists’ Association, Vol. 121, 393–409.

Briant, R M, Bateman, M D, Coope, R G, and Gibbard, P L. 2005. Climatic control on Quaternary fluvial sedimentology of a Fenland Basin river, England. Sedimentology, Vol. 52, 1397–1423.

Gao, C, Keen, D H, Boreham, S, Coope, R G, Pettit, M E, Stuart, A J, and Gibbard, P L.
2000. Last Interglacial and Devensian deposits of the River Great Ouse at Woolpack Farm, Fenstanton, Cambridgeshire, UK. Quaternary Science Reviews, Vol. 19, 787–810.

Gao, C, Boreham, S, Preece, R C, Gibbard, P L, and Briant, R M. 2007. Fluvial response to rapid climate change during the Devensian (Weichselian) late glacial in the River Great Ouse, southern England, UK. Sedimentary Geology, Vol. 202, 193–210.

Gibbard, P L, and Lewin, J. 2002. Climate and related controls on interglacial fluvial sedimentation in lowland Britain. Sedimentary Geology, Vol. 151, 187–210.

Langford, H E. 2012. A comment on the MIS 8 glaciation of the Peterborough area, eastern England. Quaternary Newsletter, Vol. 127, 6–20.

Langford, H E, and Briant, R M. 2004. Post-Anglian Pleistocene deposits in the Peterborough area and the Pleistocence history of the Fen Basin. 22–35 in Nene Valley: Field Guide. Langford, H E, and Briant, R M (editors). (London: Quaternary Research Association.)

Langford, H E, Bateman, M D, Penkman, K E H, Boreham, S, Briant, R M, Coope, G R, and Keen, D H. 2007. Age-estimate evidence for Middle–Late Pleistocene aggradation of River Nene 1st Terrace deposits at Whittlesey, eastern England. Proceedings of the Geologists’ Association, Vol. 118, 283–300.

Chapter 10 — Pleistocene glacial and periglacial geology

Allen, P, Cheshire, D A, and Whiteman, C A. 1991. The tills of southern East Anglia. 255–278 in Glacial deposits of Britain and Ireland. Ehlers, J, Gibbard, P L, and Rose, J (editors). (Rotterdam: Balkema.)

Banham, P H. 1968. A preliminary note on the Pleistocene stratigraphy of north-east Norfolk. Proceedings of the Geologists’ Association, Vol. 79, 507–512.

Banham, P H. 1975. Glaciotectonic structures: a general discussion with particular reference to the contorted drift of Norfolk. 69–84 in Ice Ages: Ancient and Modern. Wright, A E, and Moseley, F (editors). (Liverpool: Seel House Press.)

Bridge, D M, and Hopson, P M. 1985. Fine gravel, heavy mineral and grain size analysis of mid-Pleistocene glacial deposits in the lower Waveney valley. Modern Geology, Vol. 9, 129–144.

Clayton, K M. 2000. Glacial erosion of the Wash and Fen Basin and the deposition of the chalky till of eastern England. Quaternary Science Reviews, Vol. 19, 811–822.

Ehlers, J, Gibbard, P L, and Whiteman, C A. 1991. The glacial deposits of north-western Norfolk. 223–232 in Glacial deposits in Great Britain and Ireland. Ehlers, J, Gibbard, P L, and Rose, J (editors). (Rotterdam: Balkema.)

England, A C, and Lee, J A. 1991. Quaternary deposits of the eastern Wash margin. Bulletin of the Geological Society of Norflok, Vol. 40, 67–99.

Fish, P R, and Whiteman, C A. 2001. Chalk micropaleontology and the provenancing of Middle Pleistocene Lowestoft Formation Till in eastern England. Earth Surface Processes and Landforms, Vol. 26, 953–970.

Gibbard, P L, West, R G, Boreham, S, and Rolfe, C J. 2012. Late Middle Pleistocene ice-marginal sedimentation in East Anglia, England. Boreas, Vol. 41, 319–336.

Hamblin, R J O, Moorlock, B S P, Rose, J, Lee, J R, Riding, J B, Booth, S J, and Pawley, S M.
2005. Revised Pre-Devensian glacial stratigraphy in Norfolk, England, based on mapping and till provenance. Geologie en Mijnbouw, Vol. 84, 77–85.

Harmer, F W. 1928. The distribution of erratics and drift. Proceedings of the Yorkshire Geological Society, Vol. 21, 83–150.

Hart, J K, Hindmarsh, R C A, and Boulton, G S. 1990. Styles of subglacial glaciotectonic deformation within the context of the Anglian ice-sheet. Earth Surface Processes and Landforms, Vol. 15, 227–241.

Lee, J R, Rose, J, Riding, J B, Moorlock, B S P, and Hamblin, R J O. 2002. Testing the case for a Middle Pleistocene Scandinavian glaciation in eastern England: evidence for a Scottish ice source for tills within the Corton Formation of East Anglia, UK. Boreas, Vol. 31, 345–355.

Lee, J R, Rose, J, Hamblin, R J, and Moorlock, B S. 2004. Dating the earliest lowland glaciation of eastern England: a pre-MIS 12 early Middle Pleistocene Happisburgh Glaciation. Quaternary Science Reviews, Vol. 23, 1551–1566.

Lee, J R, Phillips, E, Booth, S J, Rose, J, Jordan, H M, Pawley, S M, Warren, M, and Lawley, R S. 2013. A polyphase glacitectonic model for ice-marginal retreat and terminal moraine development: the Middle Pleistocene British Ice Sheet, northern Norfolk, UK. Proceedings of the Geologists’ Association, Vol. 124, 753–777.

Mathers, S J, Zalasiewicz, J A, Gibbard, P L, and Peglar, S M. 1993. The Anglian–Hoxnian evolution of an ice-marginal drainage system in Suffolk, England. Proceedings of the Geologists’ Association, Vol. 104, 109–122.

Pawley, S M, Candy, I, and Booth, S J. 2006. The Late Devensian terminal moraine ridge at Garrett Hill, Stiffkey valley, north Norfolk, England. Proceedings of the Yorkshire Geological Society, Vol. 56, 31–39.

Pawley, S M, Bailey, R M, Rose, J, Moorlock, B S P, Hamblin, R J O, Booth, S J, and Lee, J R. 2008. Age limits on Middle Pleistocene glacial sediments from OSL dating, north Norfolk, UK. Quaternary Science Reviews, Vol. 27, 1363–1377.

Perrin, R M S, Rose, J, and Davies, H. 1979. The distribution, variation and origins of pre-Devensian tills in eastern England. Philosophical Transactions of the Royal Society of London, Vol. B287, 535–570.

Phillips, E, Lee, J R, and Burke, H. 2008. Progressive proglacial to subglacial deformation and syntectonic sedimentation at the margins of the Mid Pleistocene British Ice Sheet: evidence from north Norfolk, UK. Quaternary Science Reviews, Vol. 27, 1848–1871.

Preece, R C, Parfitt, S A, Coope, G R, Penkman, K E H, Ponel, P, and Whittaker, J E. 2009. Biostratigraphic and aminostratigraphic constraints on the age of the Middle Pleistocene glacial succession in north Norfolk, UK. Journal of Quaternary Science, Vol. 24, 557–580.

Rose, J. 2009. Early and Middle Pleistocene landscapes of eastern England. Proceedings of the Geologists’ Association, Vol. 120, 3–33.

Sparks, B W, and West, R G. 1964. The drift landforms around Holt, Norfolk. Transactions of the Institute of British Geographers, Vol. 35, 27–35.

Straw, A. 1973. The glacial geomorphology of central and north Norfolk. The East Midland Geographer, Vol. 5, 333–354.

Woodland, A W. 1970. The buried tunnel-valleys of East Anglia. Proceedings of the Yorkshire Geological Society, Vol. 37, 521–578.

Periglacial

Ballantyne, C K, and Harris, C. 1994. The periglaciation of Great Britain. (Cambridge: Cambridge University Press.)

Bateman, M D. 1995. Thermoluminescence dating of the British cover-sand deposits. Quaternary Science Reviews, Vol. 14, 791–798.

Bateman, M D, and Van Huissteden, J. 1999. The timing of the Last Glacial periglacial and aeolian events, Twente, Eastern Netherlands. Journal of Quaternary Science, Vol. 14, 579–588.

Catt, J A. 1977. Loess and cover sands. 222–229. British Quaternary studies, recent advances. Shotton, F W (editor). (Oxford: Oxford University Press.)

Chorley, R J, Stoddart, D R, Haggett, P, and Slaymakerm, H O. 1966. Regional and local components in the areal distribution of surface sand facies in the Brecklands, Eastern England. Journal of Sedimentary Petrology, Vol. 36, 209–220.

Clarke, M L, Rendell, H M, Hoare, P G, Godby, S P, and Stevenson, R C. 2001. The timing of cover-sand deposition in north-west Norfolk, UK: a cautionary tale. Quaternary Science Reviews, Vol. 20, 705–713.

French, H M. 2007. The Periglacial Environment (3rd edition). (Chichester: Wiley.)

Hoare, P G, Stevenson, C R, and Godby, S P. 2002. Sand sheets and ventifacts: the legacy of aeolian action in west Norfolk, UK. Proceedings of the Geologists’ Association, Vol. 113, 301–318.

Nicholson, F H. 1969. An investigation of patterned ground. Unpublished PhD Thesis, University of Bristol.

Nicholson, F H. 1976. Patterned ground formation and description as suggested by low Arctic and sub-Arctic examples. Arctic and Alpine Research, Vol. 8, 329–342.

Perrin, R M S, Davies, H, and Fysh, M D. 1974. Distribution of Late Pleistocene aeolian deposits in eastern and southern England. Nature, London, Vol. 248, 320–324.

Preece, R C, Parfitt, S A, Bridgland, D R, Lewis, S G, Rowe, P J, Atkinson, T C, Candy, I, Debenham, N C, Penkman, K E H, Rhodes, E J, Schwenninger, J L, Griffiths, H I, Whittaker, J E, and Gleed-Owen, C. 2007. Terrestrial environments during MIS 11: evidence from the Palaeolithic site at West Stow, Suffolk, UK. Quaternary Science Reviews, Vol. 26, 1236–1300.

Scheib, A, and Lee, J R. 2010. The application of regional-scale geochemical data in defining the extent of aeolian sediments : the Late Pleistocene loess and cover-sand deposits of East Anglia, UK. Quaternary Newsletter, Vol. 120, 5–14.

Sparks, B W, Williams, R G, and Bell, F G. 1972. Presumed ground-ice depressions in East Anglia. Proceedings of the Royal Society of London A, Vol. 327, 329–343.

Watt, A S, Perrin, R M S, and West, R G. 1966. Patterned ground in Breckland —  structure and composition. Journal of Ecology, Vol. 54, 239–258.

Williams, R B G. 1964. Fossil patterned ground in eastern England. Biul Peryglac, Vol. 14, 337–349.

Chapter 11 — The Holocene

Tidal embayments and barrier coastlines

Andrews, J E, Boomer, I, Bailiff, I K, Balson, P, Bristow, C, Chroston, P N, Funnell, B M, Harwood, G M, Jones, R E, Maher, B A, and Shimmield, G B. 1999. Sedimentary evolution of the North Norfolk barrier coastline in the context of Holocene sea-level change. 219–251 in Holocene land–ocean interaction and environmental change around the North Sea. Shennan, I, and Andrews, J E (editors). Geological Society of London Special Publication, No. 166.

Behre, K-E. 2007. A new Holocene sea-level curve for the southern North Sea. Boreas, Vol. 36, 82–102.

Boomer, I, and Horton, B P. 2006. Holocene relative sea-level movements along the North Norfolk Coast, UK. Palaeogeography, Palaeoclimatology, Palaeoecology, Vol. 230, 32–51.

Carr, A P. 1972. Aspects of spit development and decay: the estuary of the River Ore, Suffolk. Field Studies, Vol. 3, 633–653.

Carr, A P, and Baker, R E. 1968. Orford, Suffolk: evidence for the evolution of the area during the Quaternary. Transaction of the Institute of British Geographers, Vol. 45, 107–123.

Coles, B J. 1998. Doggerland: a speculative survey. Proceedings of the Prehistoric Society, Vol. 64, 45–81.

Fitch, S, Thomson, K, and Gaffney, V. 2005. Late Pleistocene and Holocene depositional systems and the palaeogeography of the Dogger Bank, North Sea. Quaternary Research, Vol. 64, 185–196.

Funnell, B M, Boomer, I, and Jones, R. 2000. Holocene evolution of the Blakeney Spit area of the North Norfolk coastline. Proceedings of the Geologists’ Association, Vol. 111, 205–217.

Gaffney, V L, Thomson, K, and Fitch, S. 2007. Mapping Doggerland: the Mesolithic landscapes of the southern North Sea. (Oxford: Archaeopress.)

Gallois, R W. 1979. Geological investigations for the Wash Water Storage Scheme. Report of the Institute of Geological Sciences, 78/19.

Godwin, H. 1978. Fenland: its ancient past and uncertain future. (Cambridge: Cambridge University Press.)

Godwin, H, and Clifford, H M. 1938. Studies of the postglacial history of British vegetation. I. Origin and stratigraphy of Fenland deposits near Woodwalton, Hunts. Philosophical Transactions of the Royal Society of London, Vol. B29, 323.

Horton, B P, Innes, J B, Shennan, I, Lloyd, J M, and McArthur, J J. 2004. Holocene coastal change in East Norfolk, UK: Palaeoenvironmental data from Somerton and Winterton Holmes, near Horsey. Proceedings of the Geologists’ Association, Vol. 115, 209–220.

Lambeck, K. 1995. Late Devensian and Holocene shorelines of the British Isles and North Sea from models of glacio-hydro-isostatic rebound. Journal of the Geological Society of London, Vol. 152, 437–448.

Lewis, S G. 1999. Eastern England. 10–27 in A revised correlation of Quaternary deposits in the British Isles. Bowen, D Q (editor). Special Report of the Geological Society of London, No. 23.

Shennan, I. 1989. Holocene crustal movements and sea-level changes in Great Britain.  Journal of Quaternary Science, Vol. 4, 77–89.

Shennan, I, and Horton, B. 2002. Holocene land- and sea-level changes in Great Britain.  Journal of Quaternary Science, Vol. 17, 511–526.

Skertchley, S B J. 1877. The geology of Fenland. Memoir of the Geological Survey of England and Wales.

Smith, D M, Zalasiewicz, J A, Williams, M, Wilkinson, I P, Redding, M, and Begg, C. 2010.  Holocene drainage systems of the English Fenland: roddons and their environmental significance. Proceedings of the Geologists’ Association, Vol. 121, 256–269.

Wheeler, A J, and Waller, M P. 1995. The Holocene lithostratigraphy of Fenland, eastern England: a review and suggestions for redefinition. Geological Magazine, Vol. 132, 223–233.

Inland blown sand

Bailey, M. 1988. The rabbit and medieval East Anglian economy. Agricultural History Review, Vol. 36, 1–20.

Bailey, M. 1991. Sand into gold: the evolution of the fold-course system in west Suffolk, 1200–1600. Agricultural History Review, 579–588.

Bateman, M D, and Godby, S P. 2004. Late Holocene inland dune activity in the UK: a case study from Breckland, East Anglia. The Holocene, Vol. 14, 579–588.

Evans, R. 1997. Soil erosion in the UK initiated by grazing animals – a need for a national survey. Applied Geography, Vol. 17, 127–141.

Hoare, P G, Stevenson, C R, and Godby, S P. 2002. Sand sheets and ventifacts: the legacy of aeolian action in west Norfolk, UK. Proceedings of the Geologists Association, Vol. 113, 301–318.

Schwan, J. 1986. The origin of horizontal alternating bedding in Weichselian aeolian sands in Northwestern Europe. Sedimentary Geology, Vol. 49, 73–108.

Sheail, J. 1978. Rabbits and agriculture in post-Medieval England. Journal of Historical Geography, Vol. 4, 342–255.

Silvester, R J. 1989. Ridge and Furrow in Norfolk. Norfolk Archaeology, Vol. 40, 286–295.

West, S. 1989. West Stow. The Prehistoric and Romano-British occupations. East Anglian Archaeology, Vol. 48, 125pp.

Wright, T. 1668. A Curious and Exact Relation of a Sand-Floud, Which Hath Lately Overwhelmed a Great Tract of Land in the County of Suffolk; Together with an Account of the Check in Part Given to It; Communicated in an Obliging Letter to the Publisher, by That Worthy Gentleman Thomas Wright Esquire, Living upon the Place, and a Sufferer by That Deluge. Philosophical Transactions, Vol. 3, 722–725.

Chapter 12 — Quaternary mammals

Adams, A L. 1881. Monograph on the British fossil elephants. Part III. Palaeontographical Society Monograph, No. 46.

Backhouse, J. 1886. On a Manible of Machærodus from the Forest-bed. Quarterly Journal of the Geological Society of London, Vol. 42, 309–312.

Bassinot, F C, Labeyrie, L D, Vincent, E, Quidelleur, X, Shackleton, N J, and Lancelot, Y.
1994. The astronomical theory of climate and the age of the Brunhes–Matuyama magnetic reversal Earth and Planetary Science Letters, Vol. 126, 91–108.

Boismier, W A, Gamble, C, and Coward, F (editors). 2012. Neanderthals amongst Mammoths: excavations at Lynford Quarry, Norfolk. (London: English Heritage.)

Lewis, S G, Ashton, N M, and Jacobi, R. 2011. Testing human presence during the Last Interglacial (MIS 5e): a review of the British evidence. 125–164 in The ancient human occupation of Britain. Ashton, N M, Lewis, S G, and Stringer, C B (editors). Developments in Quaternary Science. (Amsterdam: Elsevier.)

Lister, A M. 1993. The stratigraphical significance of deer species in the Cromer Forest-bed Formation. Journal of Quaternary Science, Vol. 8, 95–108.

Lister, A M, and Stuart, A J. 2011. The West Runton mammoth (Mammuthus trogontherii) and its evolutionary significance. Quaternary International, Vol. 228, 180–209.

Mayhew, D F, and Stuart, A J. 1986. Stratigraphic and taxonomic revision of the fossil vole remains (Rodentia, Microtinae) from the Lower Pleistocene deposits of eastern England. Philosophical Transactions of the Royal Society of London Series B, Biological Sciences, Vol. 312, 431–485.

Preece, R C. 2001. Molluscan evidence for differentiation of interglacials within the `Cromerian Complex’. Quaternary Science Reviews, Vol. 20, 1643–1656.

Preece, R C, and Parfitt, S A. 2000. The Cromer Forest-bed Formation: new thoughts on an old problem. 1–28 in The Quaternary of Norfolk and Suffolk: Field Guide. Lewis, S G, Whiteman, C A, and Preece, R C (editors). (London: Quaternary Research Association.)

Preece, R C, Parfitt, S A, Bridgland, D R, Lewis, S G, Rowe, P J, Atkinson, T C, Candy, I, Debenham, N C, Penkman, K E H, Rhodes, E J, Schwenninger, J L, Griffiths, H I, Whittaker, J E, and Gleed-Owen, C. 2007. Terrestrial environments during MIS 11: evidence from the Palaeolithic site at West Stow, Suffolk, UK. Quaternary Science Reviews, Vol. 26, 1236–1300.

Preece, R C, and Parfitt, S A. 2012. The Early and early Middle Pleistocene context of human occupation and lowland glaciation in Britain and northern Europe. Quaternary International, Vol. 271, 6–28.

Schreve, D C. 1997. Mammalian biostratigraphy of the later Middle Pleistocene in Britain. Unpublished PhD thesis, University of London (University College).

Schreve, D C. 2000. The vertebrate assemblage from Hoxne, suffolk. The Quaternary of Norfolk and Suffolk: Field Guide. Lewis, S G, Whiteman, C A, and Preece, R C (editors). (London: Quaternary Research Association.)

Schreve, D C. 2001. Mammalian evidence from Middle Pleistocene fluvial sequences for complex environmental change at the oxygen isotope substage level. Quaternary International, Vol. 79, 65–74.

Schreve, D C. 2006. The taphonomy of a Middle Devensian (MIS 3) vertebrate assemblage from Lynford, Norfolk, UK, and its implications for Middle Palaeolithic subsistence strategies. Journal of Quaternary Science, Vol. 21, 543–556.

Stuart, A J. 1996. Vertebrate faunas from the early Middle Pleistocene of East Anglia. 9–24 in The Early Middle Pleistocene of Europe. Turner, C (editor). (Rotterdam: Balkema.)

Stuart, A J, and Lister, A M. 2001. The mammalian faunas of Pakefield/Kessingland and Corton, Suffolk, UK: evidence for a new temperate episode in the. Quaternary Science Reviews, Vol. 20, 1677–1692.

Stuart, A J, and Lister, A M. 2011. The West Runton Freshwater Bed and the West Runton Mammoth: Summary and conclusions. Quaternary International, Vol. 228, 241–248.

Wymer, J, Jacobi, R, and Rose, J. 1975. Late Devensian and early Flandrian barbed points from Sproughton, Suffolk. Proceedings of the Prehistoric Society, Vol. 41, 235–241.

Chapter 13 — Early humans and landscape

Ashton, N M, and Lewis, S G. 2005. Maidcross Hill, Lakenheath. Proceedings of the Suffolk Institute of Archaeology and Natural History, Vol. XLI, 122–123.

Ashton, N M, and Lewis, S G. 2012. The environmental contexts of early human occupation of north-west Europe: The British Lower Palaeolithic record. Quaternary International, Vol. 271, 50–64.

Ashton, N M, Cook, J, Lewis, S G, and Rose, J. 1992. High Lodge: excavations by G de G Sieveking, 1962–68, and J Cook, 1988. (London: British Museum Press.)

Ashton, N M, Lewis, S G, and Parfitt, S A (editors). 1998. Excavations at the Lower Palaeolithic site at East Farm, Barnham, Suffolk 1989–94. British Museum Occasional Paper, No. 125. (London: British Museum Press.)

Ashton, N M, Lewis, S G, Parfitt, S A, Candy, I, Keen, D H, Kemp, R A, Penkman, K E H, Thomas, G, Whittaker, J E, and White, M J. 2005. Excavations at the Lower Palaeolithic site at Elveden, Suffolk, UK. Proceedings of the Prehistoric Society, Vol. 71, 1–61.

Ashton, N, Lewis, S G, Parfitt, S A, Penkman, K E H, and Russell Coope, G. 2008. New evidence for complex climate change in MIS 11 from Hoxne, Suffolk, UK. Quaternary Science Reviews, Vol. 27, 652–668.

Boismier, W A, Gamble, C, and Coward, F. 2012. Neanderthals among Mammoths: excavations at Lynford Quarry, Norfolk. (London: English Heritage.)

Bridgland, D R, Lewis, S G, and Wymer, J J. 1995. Middle Pleistocene stratigraphy and archaeology around Mildenhall and Icklingham, Suffolk: report on the Geologists’ Association Field Meeting, 27 June, 1992. Proceedings of the Geologists’ Association, Vol. 106, 57–69.

Candy, I, Lee, J R, and Harrison, A M (editors). 2008. The Quaternary of northern East Anglia. Field Guide. (London: Quaternary Research Association.)

Parfitt, S, Barendregt, R W, Breda, M, Candy, I, Collins, M J, Coope, G R, Durbridge, P, Field, M H, Lee, J R, Lister, A, Mutch, R, Penkman, K E H, Preece, R C, Rose, J, Stringer, C B, Symmons, R, Whittaker, J E, Wymer, J, and Stuart, A J. 2005. The earliest record of human activity in northern Europe. Nature, Vol. 438, 1008–1012.

Parfitt, S A, Ashton, N M, Lewis, S G, Abel, R L, Coope, G R, Field, M H, Gale, R, Hoare, P G, Larkin, N R, Lewis, M D, Karloukovski, V, Maher, B A, Peglar, S M, Preece, R C, Whittaker, J E, and Stringer, C B. 2010. Early Pleistocene human occupation at the edge of the boreal zone in north-west Europe. Nature, Vol. 466, 229–233.

Preece, R C, Parfitt, S A, Bridgland, D R, Lewis, S G, Rowe, P J, Atkinson, T C, Candy, I, Debenham, N C, Penkman, K E H, Rhodes, E J, Schwenninger, J L, Griffiths, H I, Whittaker, J E, and Gleed-Owen, C. 2007. Terrestrial environments during MIS 11: evidence from the Palaeolithic site at West Stow, Suffolk, UK. Quaternary Science Reviews, Vol. 26, 1236–1300.

Singer, R, Gladfelther, B G, and Wymer, J J (editors). 1993. The Lower Paleolithic Site at Hoxne, England. (Chicago: University of Chicago Press.)

Stringer, C B. 2005. Homo britannicus. (London: Allen Lane.)

Wymer, J J. 1985. Palaeolithic Sites in East Anglia. (Norwich: Geobooks.)

Wymer, J J. 1999. The Lower Palaeolithic occupation of Britain. (Trowbridge: Wessex Archaeology and English Heritage.)

Chapter 14 — Geology and anthropogenic impact

General

Arthurton, R S, Booth, S J, Morigi, A N, Abbott, M A W, and Wood C J. 1994. Geology of the country around Great Yarmouth. Memoir of the British Geological Survey, Sheet 162 (England and Wales).

Barron, A J M, Sumbler, M G, Morigi, A N, Reeves, H J, Benham, A J, Entwisle, D C, and Gale, I N. 2010. Geology of the Bedford district. British Geological Survey Sheet Explanation, Sheet 203 (England and Wales).

Boswell, P G H. 1927. The Geology of the country around Ipswich. Memoir of the Geological Survey, Sheet 207 (England and Wales).

Bristow, C R. 1990. Geology of the country around Bury St Edmunds. Memoir of the British Geological Survey, Sheet 189 (England and Wales).

Cox, F C, Gallois, R W, and Wood, C J. 1989. Geology of the country around Norwich. Memoir of the British Geological Survey, Sheet 161 (England and Wales).

Gallois, R W. 1988. Geology of the country around Ely. Memoir of the British Geological Survey, Sheet 173 (England and Wales).

Gallois, R W. 1994. Geology of the country around King’s Lynn and The Wash. Memoir of the British Geological Survey, Sheet 145 and part of sheet 129 (England and Wales).

Horton, A. 1989. Geology of the Peterborough district. Memoir of the British Geological Survey, Sheet 158 (England and Wales).

Mathers, S J, and Smith, N J P. 2002. Geology of the Woodbridge and Felixstowe district. Sheet Explanation of the British Geological Survey. Sheets 208 and 225 (England and Wales).

Mathers, S J, Woods, M A, and Smith, N J P. 2007. Geology of the Ipswich district. Sheet Explanation of the British Geological Survey. Sheet 207 (England and Wales).

Moorlock, B S P, Hamblin, R J O, Booth, S J, and Morigi, A N. 2000. Geology of the country around Lowestoft and Saxmundham. Memoir of the British Geological Survey. Sheets 176 and 191 (England and Wales).

Moorlock, B S P, Hamblin, R J O, Booth, S J, and Woods, M A. 2002. Geology of the Mundesley and North Walsham district. Sheet Explanation of the British Geological Survey. Sheets 132 and 205 (England and Wales).

Moorlock, B S P, Hamblin, R S J, Booth, S J, Kessler, H, Woods, M A, and Hobbs, P R N.
2002. Geology of the Cromer district. Sheet Explanation of the British Geological Survey. Sheet 131 (England and Wales).

Moorlock, B S P, Boreham, S, Woods, M A, and Sumbler, M G. 2003. Geology of the Saffron Walden. Sheet Explanation of the British Geological Survey. Sheet 205 (England and Wales).

Moorlock, B S P, Booth, S J, Hamblin, R J O, Pawley, S J, Smith, N J P, and Woods, M A. 2008. Geology of the Wells-next-the-Sea district. Sheet Explanation of the British Geological Survey. Sheet 130 (England and Wales).

Pattison, J, Berridge, N, Allsop, J M, and Wilkinson, I P. 1993. Geology of the country around Sudbury (Suffolk). Memoir of the British Geological Survey, Sheet 206 (England and Wales).

Shephard-Thorn, E R, Moorlock, B S P, Cox, B M, Allsop, J M, and Wood, C J. 1994. Geology of the country around Leighton Buzzard. Memoir of the British Geological Survey, Sheet 220 (England and Wales).

Worssam, B C, and Taylor, J H. 1969. Geology of the country around Cambridge. Memoir of the Institute of Geological Sciences, Sheet 188 (England and Wales).

Aggregates

East of England Aggregates Working Party. 2010. Annual Monitoring Report (2010), pp.29.

Building stones

Allen, J R L. 2004. Carstone in Norfolk buildings: distribution, uses, associates and influences. BAR British Series, 371, pp.177.

Hart, S. 2000. Flint architecture of East Anglia. (London: Giles de la Mere.)

Hydrogeology and water supply

Allen, D J, Brewerton, L J, Coleby, L M, Gibbs, B R, Lewis, M A, MacDonald, A M, Wagstaff, S J, and Williams, A T. 1997. The physical properties of major aquifers in England and Wales. British Geological Survey Technical Report, WD/97/34. Environment Agency Research & Development Publication, No.8.

Boland, M P, Klinck, B A, Robins, N S, Stuart, M E, and Whitehead, E J. 1999. Guidelines and protocols for investigations to assess site specific groundwater vulnerability. Environment Agency Research and Development Project Report, P2/042/01.

Environment Agency. 2009a. Water for life and livelihoods: river basin management plan Anglian River Basin District. 67pp.

Environment Agency. 2009b. Groundwater quality review: summary report Norfolk and Suffolk Chalk. 37pp.

Environment Agency. 2009c. Groundwater quality review: summary report North Essex Chalk. 31pp.

Hiscock, K M. 1991. The hydrogeology of the chalk aquifer system of North Norfolk. Bulletin of the Geological Society of Norfolk, Vol. 41, 3–43.

Hiscock, K, and Tanaka, Y. 2006. Potential impacts of climate change on groundwater resources: from the High Plains of the US to the flatlands of the UK. National Hydrology Seminar, 19–26.

Hiscock, K M, George, M A, and Dennis, P F. 2011. Stable isotope evidence for the hydrogeological characteristics of clay-rich till in northern East Anglia. Quarterly Journal of Engineering Geology and Hydrogeology, Vol. 44, 173–189.

Ineson, J, and Downing, R A. 1963. Changes in the chemistry of ground waters of the Chalk passing beneath argillaceous strata. Bulletin of the Geological Survey of Great Britain, Vol. 20, 176–192.

Marks, R J, Lawrence, A R, Whitehead, E J, Cobbing, J E, Mansour, M M, Darling, W G, and Hughes, A G. 2004. Chalk recharge beneath thick till deposits in East Anglia. British Geological Survey Internal Report, IR/04/179.

Natural Envrionmental Research Council (NERC). 1976. Hydrogeological map of northern East Anglia. 1:125 000 scale.

Natural Envrionmental Research Council (NERC). 1981. Hydrogeological map of southern East Anglia. 1:125 000 scale.

Toynton, R. 1983. The relation between fracture patterns and hydraulic anisotropy in the Norfolk Chalk, England. Quarterly Journal of Engineering Geology, Vol. 16, 169–185.

Wooldand, A W. 1970. The buried tunnel-valleys of East Anglia. Proceedings of the Yorkshire Geological Society, Vol. 37, 521–578.

Fuel and energy

Gallois, R. 2012. The Norfolk oil-shale rush, 1916–1921. Proceedings of the Geologists’ Association, Vol. 123, 64–73.

Holman, I P. 2009. An estimate of peat reserves and loss in the East Anglian Fens (commissioned by the RSPB). Cranfield University.

Engineering and geological hazards

Applied Geology Limited. 1993. Natural underground cavities in Great Britain; the nature and occurrence of natural underground cavities in East Anglia, Regional Report, Vol. 1.6, pp.39.

Bell, F G, and Forster, A. 1991. The geotechnical characteristics of the till deposits of Holderness. 111–118 in Forster, A, Culshaw, M G, Cripps, J C, Little, J A, and Moon, C F (editors). Geological Society of London, Engineering Geology Special Publications, Vol. 7.

Edmonds, C N. 2008. Karst and mining geohazards with particular reference to the Chalk outcrop, England. Quarterly Journal of Engineering Geology and Hydrogeology, Vol. 41, 261–278.

Edmonds, C N, Green, C P, and Higginbottom, I E. 1990. Review of underground mines in the English Chalk: form, origin, distribution and engineering significance. 511–520 in Chalk. Proceedings of the International Chalk Symposium, Brighton Polytechnic, 1989. (London: Thomas Telford).

Lomas, P R, Green, B M R, Miles, J C H, and Kendall, G M. 1996. Radon atlas of England. Report of the National Radiological Protection Board, No. R290, (London: HMSO).

Miles, J C H, Green, B M R, and Lomas, P R. 1996. Radon affected areas: England and Wales. Documents of the National Radiological Protection Board, Vol. 7, No.2.

Musson, R M W. 1994. A Catalogue of British Earthquakes. British Geological Survey Technical Report, WL/94/04.

Coastline management

Hutchinson, J N. 1976. Coastal landslides in cliffs of Pleistocene deposits between Cromer and Overstrand, Norfolk, England, 155–182 in Janbu, N, Jorstad, F, and Kjaernsli, B (editors). Laurits Bjerrum Memorial Volume, Contributions to Soil Mechanics. (Oslo: Norwegian Geotechnical Institute.)

(Figure 1) Topographical map of East Anglia showing the extent of the Regional Guide area, the physical relief, and major drainage systems.

(Figure 2) Simplified bedrock geology of East Anglia and adjoining onshore areas showing the distribution of the main rock types and major faults.

(Figure 3) Summary chronostratigraphical column showing the principal pre-Quaternary bedrock units in the East Anglia region.

(Figure 4) Summary chronostratigraphical column showing the principal Quaternary units in the East Anglia region.

(Figure 5) Summary diagram showing the main subdivisions of geological time and the primary geological environments and events that affected the bedrock record of East Anglia and adjoining areas.

(Figure 6) Bedrock fence diagram for the East Anglia Regional Guide area showing the distribution of selected geological units. Based upon part of the UK National Geological Model (bedrock).

(Figure 7) Palaeogeographical maps showing the configuration of the continents during the Mid Ordovician (a), Early Carboniferous (b), Early Triassic (c), Late Jurassic (d), Late Cretaceous (e) and Mid Eocene (f). Based on maps produced by C R Scotese (2002; http://www.scotese.com, (PALEOMAP website)).

(Figure 8) (a) Regional gravity data for East Anglia and southern Britain showing the location of the Variscan Front and the Glinton Thrust. (b) Schematic interpretation of the Glinton Thrust based upon deep seismic data. G = granite.

(Figure 9) Palaeogeographical evolution of the East Anglia region from the late Silurian through to the Early Jurassic. Based on Cope et al. (1992) with permission from the Geological Society of London. For numerical ages see (Figure 3).

(Figure 10) Palaeogeographical evolution of the East Anglia from the Mid Jurassic through to the Early Eocene. Based on Cope et al. (1992) and King (2006) with permission from the Geological Society of London. For numerical ages see (Figure 3).

(Figure 11) Solid geology map of East Anglia and adjoining areas showing the location of deep boreholes within the region.

(Figure 12) (a) Palaeogeography during the late Neoproterozoic, showing the relative positions of the Gondwana Supercontinent and several smaller microcontinents or terranes including Avalonia, which East Anglia was part of, Laurentia, Siberia and Baltica; Palaeogeographical reconstruction of East Anglia during the late Neoproterozoic showing the development of an oceanic island arc system relating to the subduction of oceanic crust beneath Avalonia.

(Figure 13) Contour map showing the subcrop of Precambrian and Early Palaeozoic rocks beneath East Anglia and adjacent areas. The surface of this subcrop is the Acadian Unconformity.

(Figure 14) Cross-section through the bedrock geology of East Anglia showing the geometry of the main concealed bedrock strata.

(Figure 15) Palaeozoic palaeogeography (Ordovician to Carboniferous), showing changes through time in the distribution of oceans, continents and terranes, and the position of the East Anglia region. Based on: Palaeozoic palaeogeography: A North Atlantic viewpoint. Torsvik, T H. 1998. GFF, © Geologiska Foreningen, reprinted by permission of Taylor & Francis Ltd, www.

 tandfonline.com on behalf of The Geologiska Foreningen. For numerical ages see (Figure 3).

(Figure 16) Aeromagentic data for East Anglia showing a range of magnetic highs (A to F).

(Figure 17) Gravity data showing gravity highs (green) and lows (blue).

(Figure 18) Schematic cross-section across the East Midlands, East Anglia and Southern North Sea showing the main structural architecture of the deep geology. These include the Dowsing–South Hewett Fault Zone situated offshore, deep seismic reflector (1) interpreted as an Ordovician subduction zone, the Glinton Thrust (6) and other back-thrust features.

(Figure 19) Contour map showing the supercrop of the oldest rocks (Permian and Triassic) that overstep the Variscan Unconformity.

(Figure 20) Jurassic stratigraphy of the East Anglia region: lithostratigraphical classification with relationship to the standard chronostratigraphical framework. Shading indicates vertical non-sequences between units, and lateral absence. Grey arrows indicate inferred relative original extent across the London Platform.

(Figure 21) Isopachytes of the Lias Group. Pecked lines denote uncertainty.

(Figure 22) Isopachytes of the Inferior Oolite Group plus Great Oolite Group. Pecked lines denote uncertainty.

(Figure 23) Isopachytes of the Ancholme Group. Pecked lines denote uncertainty.

(Figure 24) Generalised vertical section of the Ancholme Group related to the chronostratigraphical subdivisions of the Callovian to Tithonian stages.

(Figure 25) Marine reptiles of the Oxford Clay. Marine reptiles of the Oxford Clay (P914162) Life was prolific in the Mid Callovian sea in which the mudstones of the lower part of the Oxford Clay (Peterborough Member) were deposited. Microscopic phytoplankton and zooplankton sustained a rich invertebrate biota, with giant marine reptiles at the pinnacle of the food chain. Shallow water conditions predominated, typically a few tens of metres deep, with dark, organic-rich shales providing evidence of the high fertility of this open marine environment. Periods of thermal stratification of the water column prevented deeper water from mixing with that closer to the surface, and the sea-bed environment often became oxygen depleated, providing optimal conditions for fossil preservation. Some units in the Oxford Clay are named for their abundant fossil content, such as the 'Gryphaea and Reptile Bed' near the base (Jason Zone). Excavation of light (calcareous-rich) and dark grey (organic-rich) banded Peterborough Member at King's Dyke clay pit, Whittlesey. Near complete fossil skeleton of Pachycostasaurus dawni Cruickshank, Martill & Noe (a marine or possibly estuarine pliosaur) 3m long, found at King’s Dyke clay pit in 1994. Peterborough Museum. Since the development of the brickmaking industry around Peterborough in the 19th century, the area has become famous for its fossils of marine vertebrates, particularly fish and reptile remains, many of which can be seen in national museums, including the Peterborough Museum. The fish include a tail fragment (2.74 m in span) belonging to the plankton feeding Leedsichthys problematicus, which at an estimated length of 27 m, is believed to be the largest fish ever to have lived. Cryptoclidus skeleton (the 'Dogsthorpe plesiosaur') about 4 m long. Excavated at Dogsthorpe brick pit in 1987. Peterborough Museum. Crocodiles, such as the 4.9 m long Steneosaurus durobrivensis found at Fletton in 1923, make up about a fifth of the finds, but the remains of plesiosaurs, ichthyosaurs and pliosaurs are the most spectacular. These include the 4 m-long near-complete Cryptoclidus skeleton (the ‘Dogsthorpe plesiosaur’) collected in 1987, and a juvenile pliosaur Simolestes vorax from the same locality with a skull length of 1.3 m. Near complete fossil skeleton of a juvenile, possibly newborn Opthalmosaurus (ichthyosaur) found at Star Pit, Whittlesey. Skull reconstructed. Peterborough Museum. Skull of Simolestes vorax Andrews ('the Dogsthorpe pliosaur') from Dogsthorpe brick pit, near Peterborough. Peterborough Museum. As well as marine reptiles, the remains of land-dwelling dinosaurs in the Peterborough clay pits suggests proximity to a shore line a few kilometres away. They include herbivorous sauropods and stegosaurs, and possibly carnivorous theropods, together with abundant fossil wood at many levels. Steneosaurus durobrivensis Andrews skeleton (marine crocodilian), 4.9 m long, found at Fletton brick pits in 1923. Peterborough Museum. (Figure 26) Outcrop of Early Cretaceous rocks in the East Anglia region, key localities and boreholes. Inset maps show Late Berriasian (a) and Late Aptian (b) palaeogeography (modified from Hancock and Rawson, 1992, maps K1 and K2b, with permission from the Geological Society).

(Figure 26) Outcrop of Early Cretaceous rocks in the East Anglia region, key localities and boreholes. Inset maps show Late Berriasian (a) and Late Aptian (b) palaeogeography (modified from Hancock and Rawson, 1992, maps K1 and K2b, with permission from the Geological Society).

(Figure 27) Stratigraphy and correlation of Early Cretaceous geological units in East Anglia.

(Figure 28) Stratigraphical relationships of the Late Jurassic to Early Cretaceous succession in north Norfolk. See (Figure 26) for borehole locations.

(Figure 29) Stratigraphy of the Gault Formation in East Anglia.

(Figure 30) Stratigraphical relationships of Albian formations and presumed depositional environments immediately prior to the Late Albian.

(Figure 31) Stratigraphy of the Chalk of East Anglia. Not to scale. U. anglicus Zone not recognised in East Anglia. (a) = base of Lewes Nodular Chalk in Southern Province; (b) base of Lewes Nodular Chalk as mapped in East Anglia.

(Figure 32) Sketch map of the Chalk outcrop and subcrop in East Anglia showing key localities mentioned in the text. Map excludes superficial deposits (Pleistocene and Holocene) which extensively cover the region. 1–5 is the line of borehole correlation shown on (Figure 33).

(Figure 33) Correlation of borehole resistivity logs and gamma log (g) in the Chalk Group, showing lateral correlation of marker beds, and thinning of the lower part of the White Chalk Subgroup in the Stowlangtoft Borehole. For line of borehole correlation see (Figure 32). a. base of Lewes Nodular Chalk in Southern Province; (b) base of Lewes Nodular Chalk as mapped in East Anglia.

(Figure 34) Correlation of key boreholes and outcrops in the Chalk Group of the East Anglia region. Cen. = Cenomanian; Maast. = Maastrichtian.

(Figure 35) Stratigraphy and correlation of sections and boreholes in the Chalk Group of the Gipping Valley and Ipswich area. Based on figs 1, 3 and 5 of Woods et al. (2007) with permission of the Geological Society.

(Figure 36) Major Palaeogene basins around Britain and main onshore outcrops.

(Figure 37) Distribution of Palaeogene deposits in East Anglia, and location of key boreholes and sections.

(Figure 38) Stratigraphy of Palaeogene deposits in East Anglia.

(Figure 39) Correlation of Palaeogene successions in East Anglia. The ‘Harwich’ section is composite, combining information from exposures at Wrabness and Walton-on-the Naze and the Shotley Gate Borehole. The ‘red-brown unit’ can be recognised in the clays and silts of the Ormesby Clay Member, and also in the silts and sands of the Thanet Formation.

(Figure 40) Stratigraphical framework for the Quaternary (a) and Neogene (b) periods showing the marine isotope record (data from Lisiecki and Raymo, 2007), stage names for Europe and the UK and the distribution of Quaternary deposits in East Anglia. Key to abbreviations: HRB – Hunstanton Raised Beach, MRB – Morston Raised Beach, NCF – Nar Clay Formation, WM – Woodston Member, CF-bF – Cromer Forest-bed Formation, HOG – Holderness Glacigenic Formation, TM – Tottenhill Member, BLF – Britons Lane Glacigenic Formation, SCG – Sheringham Cliffs Glacigenic Formation, WGF – Wolston Glacigenic Formation, LGF – Lowestoft Glacigenic Formation, HGF – Happisburgh Glacigenic Formation.

(Figure 41) Schematic diagram showing the three principal orbital forcing cycles (Milankovitch Cycles) that affected climate during the Late Neogene to Quaternary.

(Figure 42) Palaeogeographical models for central Britain and Europe prior to the Anglian Glaciation. (a) Western Europe during the Early Pleistocene showing the general distribution of drainage and coastlines; (b) Central and eastern England during the Early Pleistocene showing the extent of the major river and the approximate coastline of the ‘Crag Basin’; (c) Western Europe during the late Early and early Middle Pleistocene showing the general distribution of drainage and coastlines; (d) Central and eastern England during the latest Early and early Middle Pleistocene showing the extent of the major river and the approximate coastline of the Crag Basin.

(Figure 43) Geography of the major Pleistocene glaciations to affect East Anglia showing the currently known extent and limit of the British Irish Ice Sheet (BIIS) and Fennoscandian Ice Sheet (FIS). (a) Geography of the UK, the North Sea Basin and western Europe during the late Middle Pleistocene Anglian Glaciation (MIS 12; about 0.45 Ma) with ice covering the majority of the East Anglia region; (b) Reconstruction of the Late Devensian Dimlington Stadial glaciation in the UK, North Sea Basin and western Europe showing confluent British and Fennoscandian ice sheets — the southern margins of the North Sea lobe of the British Ice Sheet reached the coast of north Norfolk.

(Figure 44) Palaeogeography of western Europe during the early Holocene about 9 ka.

(Figure 45) Chronology and oxygen isotope values for the past 30 000 years covering the Late Devensian and Holocene interglacial based upon the isotope record from the GISP2 ice core in Greenland (data from Grootes et al., 1997). The figure also depicts several major climatic events including Heinrich Events (H0–H3) and the Holocene Climatic Optimum (HCO).

(Figure 46) Lithostratigraphy of the Pliocene to early Middle Pleistocene ‘Crag Group’ deposits in East Anglia. The hashed lines show the broad stratigraphical position of major unconformities.

(Figure 47) Map of eastern East Anglia showing sites referred to within the text, the western limit of the Crag Group and the topography of the rockhead surface across the region.

(Figure 48) a) Distribution of the Coralline Crag in the Aldeburgh–Orford area; b) Sedimentological model for deposition of the formation.

(Figure 49) Lithostratigraphy of the Red and Norwich Crag formations between Ipswich and Sizewell showing the distribution of major facies. Around Aldeburgh and Sizewell, the Red Crag Formation can be subdivided into the Sizewell and Thorpeness members.

(Figure 50) Graphic log of the BGS borehole drilled at Ormesby, south Norfolk. It contains over 40 m of sediment correlated with the Crag Group including the Red, Norwich and Wroxham crag formations.

(Figure 51) The Westleton Beds. (a) Summary lithological log for the beds at Wangford Common; (b) Sketch of quarry face at Quay Lane, Reydon; (c) Map showing the distribution of palaeocurrent measurements within the Westleton Beds around Dunwich and Southwold.

(Figure 52) Sedimentological model for the Westleton Beds showing the development of the beach shoreface and channels generated by tidal rip currents. Reprinted from Proceedings of the Geologists’ Association, Vol. 107; Mathers and Zalasiewicz, A gravel beach rip system: the Westleton Beds (Pleistocene) of Suffolk, England, pp.57–67, 1996; with permission from Elsevier.

(Figure 53) Bi-plot showing the composition of gravels (8 to 16 mm size fraction) from the Norwich and Wroxham Crag formations and other named gravel units in East Anglia.

(Figure 54) Schematic log of the Wroxham Crag Formation at Sidestrand in north-east Norfolk, showing the main lithofacies and environments of deposition. HCO = hummochy cross-stratification.

(Figure 55) Schematic cross-section across the Nar Valley in north-west Norfolk showing the buried valley infilled with Mid Pleistocene glacial deposits (Oadby Till Member, varved clays) that pass upwards into interglacial freshwater (Nar Valley Freshwater Beds) and marine (Nar Clay Formation) sediments.

(Figure 56) Map of East Anglia showing the major modern river systems, the sediment tracts and approximate courses of the major pre-Anglian rivers.

(Figure 57) Lithostratigraphical framework for the Dunwich Group comprising Early and early Middle Pleistocene fluvial deposits of the region. Sediments belonging to the Cromer Forest-bed Formation and their palaeontological associations are described in further detail within Chapter 11.

(Figure 58) Distribution (inset) and reconstructed terrace staircase of the Kesgrave Catchment Subgroup in Suffolk and neighbouring Essex showing the major aggradational sand and gravel bodies, organic deposits and non-Kesgrave (outwash) sediments. Reprinted (with modifications) from Proceedings of the Geologists’ Association, Vol. 100; Rose et al., The Kesgrave Sands and Gravels: ‘preglacial’ Quaternary deposits of the River Thames in East Anglia and the Thames valley, pp.93–116, 1999; with permission from Elsevier.

(Figure 59) Schematic cross-section showing the preglacial terrace aggradations of the Kesgrave–Thames shown in relation to the elevation of the lowest col through the Cotswold escarpment. Reprinted (with modifications) from Proceedings of the Geologists’ Association, Vol. 100; Rose et al., The Kesgrave Sands and Gravels: ‘preglacial’ Quaternary deposits of the River Thames in East Anglia and the Thames valley, pp.93–116, 1999; with permission from Elsevier.

(Figure 60) Vertical and lateral distribution of sands and gravels of the Ingham Sand and Gravel Formation in central East Anglia. The interpretation of different aggradational bodies within this sediment package remains somewhat ambiguous with several possible interpretations including the six-terrace model shown here (modified from Lee et al., 2006).

(Figure 61) Generalised river-terrace model showing the major climate-driven phases of river-terrace aggradation and incision within a lowland river catchment. Reprinted from Quaternary Science Reviews, Vol. 19; Bridgland; River terrace systems in northern Europe: an archive of environmental change, uplift and early human occupation, pp.1293–1303, 2000; with permission from Elsevier.

(Figure 62) Schematic cross-sections through the post-Anglian terrace sequences of the River Nene, River Great Ouse and the River Cam. Reprinted (with modifications) from Proceedings of the Geologists’ Association, Vol. 121; Boreham et al., River terrace systems in northern Europe: an archive of environmental change, uplift and early human occupation, pp.393–409, 2010; with permission from Elsevier.

(Figure 63)a Map of central and eastern England showing the East Anglia Regional Guide area, Anglian, ‘Tottenhill’ and ‘Devensian’ ice limits (after Clark et al., 2004) and Anglian tunnel valleys (after Woodland, 1970).

(Figure 63)b Various stratigraphical schemes for the Middle Pleistocene glacial deposits of East Anglia showing the correlation of the major stratigraphical units.

(Figure 64) (a) Schematic cross-section through the Waveney valley showing the geometry of the units within the Happisburgh Glacigenic Formation (modified from Bridge and Hopson, 1985). (b) Correlation of tills and outwash sands and gravels within the Waveney valley and north-east Norfolk.

(Figure 65) Palaeogeographical evolution of northern East Anglia during the deposition of the Happisburgh Glacigenic Formation.  (a) The preglacial landscape of the region  showing the approximate position of the coastline and major drainage catchments. (b) First ice advance and deposition of the Happisburgh Till Member. (c) Retreat of the ice margin and development of small glacial lake basins, drainage of outwash into the Bytham River valley. (d) Re-advance of ice margin and deposition of the Corton Till Member across eastern Norfolk and northern Suffolk, ice encroaches into Bytham River valley. (e) Blocking of lower reaches of Bytham River valley and deposition of waterlain facies of Corton Till Member at Corton and Scratby, valley topography is neutralised with outwash drainage flowing southwards unconstrained by topography depositing the Leet Hill Sand and Gravel Member. Mass wastage of ice margin, formation of braided outwash plain (sandur) with lake basins, deposition of the Corton Sand Member.

(Figure 66) Lithostratigraphy of glacial deposits in the East Anglia Regional Guide area.Plate 19 (a) Foliation (yellow arrow) and crenulation lineations (green arrow) developed within an isoclinal fold, West Runton (P914184). (b) Stretching lineations (dashed lines) and foliation (arrow) developed with the Bacton Green Till Member at West Runton (P914185). (c) Glacitectonised Happisburgh Till Member (green arrow) and Walcott Till Member (yellow arrow) contain rotated sand intraclasts, West Runton (P914186). (d) Thrust-stacked rafts of chalk bedrock at Overstrand (raft emplacement from right to left) — the chalk bedrock surface lies several metres beneath the modern beach (P914187). (e) Narrow shear zone developed beneath a small raft of chalk and Wroxham Crag within the Happisburgh Till Member, Sheringham (P914188).

(Figure 67) (a) Modelled depth of the overdeepened Bytham River valley near Diss by the formation of a major subglacial tunnel valley during the Anglian Glaciation. (b) Schematic cross-section of the buried valley along Line A–B

(Figure 68) Schematic cross-section of the coastal cliffs between West Runton and Beeston Hill on the outskirts of Sheringham showing the major glacitectonic structures produced by a west to east ice advance across north Norfolk (adapted from Phillips et al., 2008).

(Figure 69) (a) NEXTMAP digital surface model (DSM) of north Norfolk with hill-shaded relief showing some of the main glacial geomorphological features of the region (b–e). Sequential model showing the evolution of glacigenic landforms and glacitectonic structures during: Maximum known extent of ice (Stage 1). (c) Rapid northwards retreat of the ice margin (Stage 2) and stillstand (Stage 3). (d) Episodes of stillstand (Stage 4), minor (Stage 6) and major advance (Stage 7 and 9), retreat (Stages 5, 8). (e) Mass-wastage and generation of the Kelling (Stage 11i) and Salthouse (Stage 11ii) sandurs, re-advance and stillstand position (Stage 12).

(Figure 70) Models for Middle Pleistocene glaciations within East Anglia. (a) The conventional Anglian glaciation model showing glaciation by British and Fennoscandian ice sheets (after Perrin et al. (1979), Bowen et al. (1986) and Clark et al. (2004)). (b) Proposed configuration of multiple Middle Pleistocene glaciations during MIS 16, MIS 10, MIS 12 and MIS 6 (after Hamblin et al., 2005). Multiple glaciation model tentatively suggested by this study showing the ice flow paths associated with glaciations during ?MIS 16, MIS 12 and ?MIS 6 or 8.

(Figure 71) Map of northern East Anglia showing the Late Devensian ice limit (after Clark et al., 2004) and the distribution of glacigenic deposits (Holderness Glacigenic Formation) and landforms. Potential ice-dammed lakes derived by modification from Brand et al. (2002).

(Figure 72) (a) The Breckland area of western Norfolk and Suffolk showing the distribution of mapped Late Devensian coversand, patterned ground (modified from Nicholson, 1969), palsas and pingos. (b) Model for the development of periglacial striped and patterned ground according to slope gradient.

(Figure 73) Soil geochemical map of Norfolk and Suffolk showing the concentration of Zr (zirconium) and Hf (hafnium) which collectively provide a good proxy for the distribution of aeolian sediment (coversand or loess) within soil.

(Figure 74) Palaeogeography of Britain and the North Sea region during (a) The Late Glacial Interstadial and (b) The early Holocene, showing the progressive rise of global sea level and drowning of ‘Doggerland’.

(Figure 75) Holocene sea-level curve for the Southern North Sea with highlighted points showing the stages of submergence of ‘Doggerland’ and the ‘Dogger Hills’ plus the onset of coastal erosion in East Anglia. From Behre, K-E. 2007. A new Holocene sea-level curve for the Southern North Sea. Boreas, Vol. 36, 82–102. Publisher - Wiley.

(Figure 76) Map of East Anglia and adjoining areas showing the distribution of wind-blown sediment (Devensian to Holocene), river terrace deposits (late Middle Pleistocene to Holocene), peat, alluvium and the key lowland coastal and estuarine environments.

(Figure 77) The Fen and Wash basins showing the distribution of major drainage systems and surface lithologies including alluvium and peat.

(Figure 78) Lithostratigraphy of Holocene deposits within the Fen Basin showing previous and current stratigraphical nomenclature. Abbreviation: WM – Whittlesea Member.

(Figure 79) The Broads of southern Norfolk and northern Suffolk showing the main river systems and the distribution of unreclaimed and drained marshland.

(Figure 80) Schematic diagram showing the lithostratigraphy of Holocene coastal deposits inland from Great Yarmouth. Collectively they form the Breydon Formation.

(Figure 81) Schematic diagram showing a generalised model for barrier coastline and back-beach marsh development in East Anglia.

(Figure 82) Location map of Quaternary mammal sites mentioned in the text.

(Figure 83) Selected Early Pleistocene teeth from small mammals. (1a) Right lower first molar of Mimomys rex occlusal view and (1b) lateral view, from Bramerton. (2a) Right lower first molar of Mimomys pliocaenicus occlusal view and (2b) lateral view, from Bramerton. (3a) Left lower first molar of Mimomys reidi occlusal view and (3b) lateral view, from Trimingham. (4a) Right lower first molar of Mimomys newtoni occlusal view and (4b) lateral view, from Bramerton. (5a) Left lower first molar of Mimomys altenburgensis occlusal view and 5b lateral view, from Bramerton. Image reprinted from: Mayhew, D F, and Stuart, A J. 1986. Stratigraphical and taxonomic revision of the fossil vole remains (Rodentia, Microtinae) from the Early Pleistocene deposits of eastern England. Philosophical Transactions of the Royal Society of London Series B – Biological Sciences, Vol. 312, 431–485.

(Figure 84) Occlusal and lateral views of a left lower second molar of Mammuthus meridionalis, Norfolk coast (from Adams, 1881).

(Figure 85) Summary stratigraphical subdivision and correlation table of early Middle Pleistocene sites in Britain, shown against the marine oxygen isotope curve of Bassinot et al. (1994) and indicating key biostratigraphical indicators in the microtine rodents and molluscs. Redrawn after Preece and Parfitt (2000).

(Figure 86) Right ramus of Homotherium latidens, from Pakefield (Backhouse, 1886).

(Figure 87) Schematic representation of the West Runton mammoth showing bone elements recovered. Reprinted (with modifications) from Quaternary International, Vol. 228; Lister and Stuart, The West Runton mammoth (Mammuthus trogontherii) and its evolutionary significance, pp.180–209, 2011; with permission from Elsevier.

(Figure 88) Reconstruction of the winter landscape adjacent to the Devensian site at Barnwell, Cambridgeshire, showing a pride of feeding lions following an attack on a juvenile woolly mammoth.

(Figure 89) Map of the East Anglia region showing archaeological sites referred to within the text.

(Figure 90) Stratigraphical table showing the human occupation of East Anglia. Shading within the palaeogeography column refers to periods where the UK was either joined to (beige) or separated from (pale blue) mainland Europe.

(Figure 91) Reconstruction of the landscape at Happisburgh inspired by an artist’s impression of the site by John Sibbick. The reconstruction shows early humans butchering a deer near to the banks of an ancient river estuary.

(Figure 92) Lower Palaeolithic flint scrapers and hand axes from High Lodge, Suffolk. Sturge Collection, British Museum [Illustrations: P. Dean].

(Figure 93) Lower Palaeolithic hand axes from Barnham, Suffolk. Sturge Collection, British Museum [Illustrations: P. Dean].

(Figure 94) Early Middle Palaeolithic artefacts from Brundon, Suffolk showing (a) a Levallois core and (b) a Levallois flake. Reid Moir Collection, Ipswich Museum [Illustrations: J. Wymer].

(Figure 95) (a) Late Middle Palaeolithic blade leaf point from Bramford Road, Ipswich, Suffolk. Reid Moir Collection, Ipswich Museum [Illustration: J. Wymer]. (b) Early Upper Palaeolithic Gravettian tanged blade from Bramford Road, Ipswich, Suffolk. Reid Moir Collection, Ipswich Museum [Illustration: H. Martingell].

(Figure 96) (a) Late Upper Palaeolithic bone point. (b) Antler point from Sproughton, Suffolk. Both Ipswich Museum [Illustrator: not known].

(Figure 97) Active quarries in East Anglia (2010) largely extracting sand and sand and gravel from Quaternary deposits.

(Figure 98) Reconstruction of a Neolithic flint mine at Grimes Graves showing the quarrying of specific flint bands for use as stone tools.

(Figure 99) Regional groundwater level contours for East Anglia and adjoining areas.

(Figure 100) Groundwater flow paths from interfluves to valley locations. (a) Unconfined chalk groundwater flow system. (b) Confined chalk groundwater flow system with bedrock overlain by superficial deposits.

(Figure 101) Map showing the spatial distribution and magnitude of earthquakes in East Anglia (up to 2012) and adjoining onshore and offshore areas.

(Figure 102) Bedrock geology of East Anglia and adjoining areas showing the distribution of known karstic and carbonate dissolution features.

Plates

(Front cover)

(Frontispiece) Ammonite plaster of Rasenia spp. in core specimen from the BGS North Wootton Borehole, Kimmeridge Clay Formation, bed KC12, Cymodoce Zone (P815563).

(Plate 1) (Opposite) Characteristic fossils from the Mid and Late Jurassic strata (P914204). a. Cylindroteuthis puzosiana (d’Orbigny); mainly Oxford Clay Formation, Peterborough Member. Length 165 mm. b. Gryphaea dilatata J Sowerby; Oxford Clay Formation, Weymouth Member, West Walton and lower Ampthill Clay formations. Width 90 mm. c. Quenstedtoceras lamberti (J Sowerby); Oxford Clay Formation, Stewartby Member. e. Maximum diameter 70 mm. f. Gryphaea lituola Lamarck; Oxford Clay Formation, Stewartby Member. Length 70 mm. g. Gryphaea dilobotes Duff; Kellaways Formation and basal Peterborough Member. Length 72 mm. h. Trochocyathus magnevillianus Michelin; Oxford Clay Formation, Stewartby Member. I. Maximum diameter 10 mm. j. Genicularia vertebralis (J de C Sowerby); Oxford Clay Formation, Peterborough Member and basal Stewartby Member. Length of ringed fossil 9 mm. k. Bositra buchii (Roemer); all members of the Oxford Clay Formation. Maximum dimension of ringed fossil 6.4 mm. l. Praeexogyra hebridica (Forbes); Great Oolite Group. Length 38 mm. m.  Rasenia spp.; Kimmeridge Clay Formation. Diameter of ringed fossil 14 mm. n. k Nanogyra virgula (Defrance); Kimmeridge Clay Formation. Length 17 mm.

(Plate 2) Fossils from the Sandringham Sands, Gault and Hunstanton formations. Scale bars represent 10 mm (P914163). a i, ii Lynnia icenii Casey (Sandringham Sands Formation) b Runctonia runctoni Casey (Sandringham Sands Formation) c i, ii Bojarkia tealli Casey (Sandringham Sands Formation) d Hoplites (Hoplites) spathi Breistroffer (Gault Formation) e Ostrea papyracea Sinzow (Gault Formation) f Hysteroceras varicosum (J de C Sowerby) (Gault Formation) g Hysteroceras cf. orbignyi (Spath) (Gault Formation) h Actinoceramus concentrica (Parkinson) (Gault Formation) i Actinoceramus sulcatus (Parkinson) (Gault Formation) j Aucellina (Gault Formation) k i, ii Nielsenicrinus cretaceus (Leymerie) (Gault Formation) l i, ii Euhoplites loricatus Spath (Hunstanton Formation) m Inoceramus lissa (Seeley) (Hunstanton Formation) n i, ii Mountonithyris dutempleana (d’Orbigny) (Hunstanton Formation) o Neohibolites minimus (Lister) (Hunstanton Formation)

(Plate 3) Junction of the Leziate Member (pale sediments) and Dersingham Formation (orange-brown sediments), at Wolferton railway cutting, near Sandringham (P210692).

(Plate 4) Junction of the Leziate Member (Sandringham Sands Formation) and Carstone Formation at Blackborough sand pit, near North Runcton, Norfolk. Wind erosion has revealed the three-dimensional form of elongate burrows infilled with Carstone (orange, ferruginous sediment) extending downwards into Leziate Member (pale grey sediments). An irregular erosion surface separates the two formations (P211376).

(Plate 5) Woburn Sands Formation exposed near Leighton Buzzard, showing large-scale cross-bedding that is typical of a high-energy marine-shelf environment (P213297).

(Plate 6) Rectilinear jointing in the Carstone Formation exposed at low tide on Hunstanton foreshore (P210686).

(Plate 7) Coastal cliff sections at Hunstanton showing the famous sequences of Carstone Formation (base, dark brown), Hunstanton Formation (lower middle red horizon), Ferriby Chalk Formation (upper white horizon) with the thin bed of Totternhoe Stone (upper middle grey band within the Ferriby Chalk Formation) (P210683).

(Plate 8) Cambridge Greensand Member at the base of the Grey Chalk Subgroup. Arlesey Brickworks, Bedfordshire [TL 1878 3477] (P528345).

(Plate 9) Fossils from the Chalk Group. Scale bars represent 10 mm unless otherwise stated (P914164). a Inoceramus crippsi Mantell (Early Cenomanian) b Schloenbachia varians J Sowerby (Early Cenomanian) c Aucellina gryphaeoides (J de C Sowerby) (Early Cenomanian) d i,ii Orbirhynchia mantelliana (J de C Sowerby non Sedgwick) (Cenomanian) e Acanthoceras rhotomagense (Brongniart) (Mid Cenomanian) f Mantelliceras (Early Cenomanian) g Mytiloides mytiloides Mantell (Early Turonian) h Terebratulina lata Etheridge (Turonian) i Plesiocorys (Sternotaxis) plana (Mantell) (Turonian) j Volviceramus involutus (J de C Sowerby) (Coniacian) k Micraster coranguinum (Leske) (Coniacian to Santonian) l Marsupites testudinarius (Schlotheim) (Santonian) m Echinocorys conica (Agassiz) (Campanian) n Belemnitella mucronata (Schlotheim) (Campanian) o Echinocorys scutata Leske (Maastrichtian)

(Plate 10) Flint-free Blakenham Chalk Member (Newhaven Chalk Formation) at Needham Market Chalk Quarry [TM 0940 5395], near Ipswich (P584983).

(Plate 11) Paramoudra flint in the Paramoudra Chalk at Whitlingham chalk pit [TG 2678 0766], near Norwich (P210913). Hammer for scale is about 80 cm long.

(Plate 12) Raft of Chalk encased in glacial sediments, Overstrand, north Norfolk (P667958).

(Plate 13) River cliff near Wrabness, Essex, showing Harwich Formation (Wrabness Member) with numerous pale yellow-brown volcanic ash horizons (P212362).

(Plate 14) Fossils from the London Clay Formation in East Anglia and adjacent regions. Scale bars represent 20 mm for 1–5 and 7, 200 mm for e and g (P914165). (b) Atrina affinis (J Sowerby) (c) Halecopsis insignis Delvaux & Orlieb c i Deltoidonautilus sowerbyi Sowerby c ii Deltoidonautilus sowerbyi Sowerby d Fossil wood bored by Teredo e Lytoloma crassicostatum Owen f Hippochrenes amplus (Solander) g Crocodile skull

(Plate 15) Fossils of the Red Crag and Coralline Crag. Scale bars represent 20 mm (P914166). a. Neptunea contraria (Linnaeus), Red Crag Formation. b. Laevicardium (Dinocardium) parkinsoni (J Sowerby), Red Crag Formation. c. Aequipecten opercularis Linnaeus, Red Crag Formation. d. Fossiliferous Basement Bed of the Red Crag Formation. e. Calliostoma subexcavatum (Wood), Coralline Crag Formation. f. Glycymeris glycymeris Linnaeus, Red Crag Formation. g. Mya (Arenomya) arenaria Linnaeus, Red Crag Formation. h. Panopea faujasi Menard, Coralline Crag Formation. i. Hornera reteporacea Canu, Coralline Crag Formation. j. Blumenbachium globosum Koenig, Coralline Crag Formation. k. Balanus concavus Bronn, Coralline Crag Formation. l. Carcharocles megalodon Agassiz, reworked into Coralline Crag Formation. m. Odontaspis elegans Agassiz, Red Crag Formation. n. Emarginula crassa J Sowerby, Coralline Crag Formation. o. Pecten maximus Linnaeus, Coralline Crag Formation. p. Pygocardia rustica (J Sowerby), Coralline Crag Formation. q. Terebratula grandis Blumenbach, Coralline Crag Formation.

(Plate 16) (a) Cross-stratified deposits in the Sudbourne Member of the Coralline Crag at Crag Pit, Crag Farm, Sudbourne (P914167). (b) Shell-rich beds of Red Crag Formation at Buckanay Farm Pit near Alderton. Height of section is 1 m (P914168) R Hamblin. (c) Wedge-shaped bodies of beach gravels and sands — the Westleton Beds at Dunwich Heath (P914169). (d) Weakly cemented sands with rip-up clasts of clay form ‘tempestite’ beds (foreground), overlain by estuarine muds and stratified sands and gravels (cliffs) — the Wroxham Crag Formation at East Runton (P914170). (e) Rhythmic tidal stratification and burrows, overlain by horizontal and rippled sands; Wroxham Crag Formation (How Hill Member), Pakefield (P914171). (f) Flint cobbles forming the Morston Raised Beach in north Norfolk. Beach gravels are overlain by the Devensian Holkham Till Member. The photo dates to the 1930s when gravels were extracted from the site for building stone (P914172) H Ashley.

(Plate 17) (a) Sudbury Formation sands and gravels (Beaconsfield Member) of the Kesgrave Catchment Subgroup within a now disused quarry at Alphamstone near Sudbury, overlain by Lowestoft Till Member (P914173) J Rose. (d) Ingham Sand and Gravel Formation showing stratified flint- and quartzose-rich sands and gravels and an armoured till clasts next to the scrapper, Kirby Cane Quarry, Norfolk (P914174). (c) The red Valley Farm Soil horizon developed in the upper part of the Sudbury Formation deposits at Great Blakenham near Ipswich (P914175) J Rose. (d) Patterned polygonal ground developed within Kesgrave Catchment Subgroup deposits showing the surface expression of ice wedge casts. The overlying Lowestoft Glacigenic Formation deposits have been removed as overburden during the quarrying process. Newney Green near Chelmsford, Essex (P914176).

(Plate 18) (a) Brown sandy diamicton (Corton Till Member) overlain by fine stratified sands (Corton Sand Member), Hopton — the large boulder adjacent to the trowel is an alkali feldspar granite (‘Drammensgranitt’) from Drammensfjord in southern Norway (P914180). (b) Massive and finely laminated clays, and rippled silty fine-grained sands within the Ostend Clay Member, Happisburgh (P914181). (c) Cromerian-age rootlet bed (green arrow) and shallow marine Wroxham Crag Formation (yellow arrow) at Pakefield, overlain by sandy outwash (Corton Sand Member — pink arrow) and chalky diamicton (Lowestoft Till Member — white arrow) (P914182). (d) Chalky diamicton of the Walcott Till Member at Paston, overlying glacitectonised preglacial sediments of the Wroxham Crag Formation — note flame-like nature of folding and water escape structure (sand volcano — yellow arrow) indicating high pore-water pressures during till deposition (P914183). (e) Laminated and rippled lower beds (Oulton Member) and subaqueous flow ‘till’ (Pleasure Gardens Till Member) at Corton (P914177). (f) Extensional microfaulting (arrows) within the Corton Sand Member at Corton (P914178). (g) Grey-brown sandy diamicton (Bacton Green Till) showing folding (green arrow) and a sand-filled hydrofracture, Bacton (P667406).

(Plate 19) (a) Foliation (yellow arrow) and crenulation lineations (green arrow) developed within an isoclinal fold, West Runton (P914184). (b) Stretching lineations (dashed lines) and foliation (arrow) developed with the Bacton Green Till Member at West Runton (P914185). (c) Glacitectonised Happisburgh Till Member (green arrow) and Walcott Till Member (yellow arrow) contain rotated sand intraclasts, West Runton (P914186). (d) Thrust-stacked rafts of chalk bedrock at Overstrand (raft emplacement from right to left) — the chalk bedrock surface lies several metres beneath the modern beach (P914187). (e) Narrow shear zone developed beneath a small raft of chalk and Wroxham Crag within the Happisburgh Till Member, Sheringham (P914188).

(Plate 20) (a) Middle Pleistocene involutions in uppermost unit at Beeches pit, West Stow. Photo: M Bateman (P914189). (b) Periglacial stripes near Grimes Graves, Brandon, showing how the stripes are picked out by the grasses over the chalk and ericaceous vegetation over the sand-filled stripes. Photo: M Bateman (P914190). (e) Topsoil removed from striped ground at Thetford Heath, showing frost-shattered chalk and sand-filled stripes — note the upslope continuation of stripes depicted by stones (arrows) and vegetation. Photo: T Lawson (P914191). (d) Brecciated frost-shattered chalk ‘host’ and the sand incorporated within the stripe itself. Photo: M Bateman (P914194). (e) Aerial view of patterned ground (arrow) at Brettenham Heath, Thetford © UKP/ Getmapping Licence No. UKP2006/01 (P914192). (f) Cross-section through the patterned ground at Brettenham Heath revealing the sand-filled polygons and intervening brecciated frost-shattered chalk, irregularity of the features is attributed in part to postdepositional chalk solution beneath the sand filled features. Photo: M Bateman (P914193).

(Plate 21) Oblique angle aerial photograph looking eastwards across Thompson Common illustrating the extensive development of palsas within the valley bottom of a tributary of the River Wissey [Photo: © Mike Page www.mike-page.co.uk].

(Plate 22) Aerial photograph of Lower Knarr Fen, near Thorney, showing well-developed sand- and silt-filled abandoned channels called ‘roddons’ that now form elevated ridges within fields underlain by compacted peat. © UKP/Getmapping Licence No. UKP2006/01.

(Plate 23) Oblique-angle aerial photograph looking eastwards over Blakeney Spit showing the development of successive beach ridges as the spit has migrated westwards. The quays at Blakeney and Morston can be seen adjacent to the main channels that extend southwards across the salt marshes [Photograph: © Mike Page www.mike-page.co.uk].

(Plate 24) Oblique-angle aerial photograph of Orford Ness, Suffolk, looking towards the north-east, showing the spit morphology, the development of classic beach ridges and the back-beach saltmarsh area [Photograph: © Mike Page www.mike-page.co.uk].

(Plate 25) Oblique-angle aerial photograph looking eastwards across Scolt Head Island showing a classical offshore barrier island. Clearly shown within the photograph are the main accretionary beach ridges and the drainage channels within the tidal saltmarsh [Photograph: © Mike Page www.mike-page.co.uk].

(Plate 26) Vegetated sand dunes at Wangford Warren near Brandon, northern Suffolk. Dune fields within Breckland have historically been susceptible to remobilisation and migration due to changing land-use practices, increased storminess and climate change (P728323).

(Plate 27) Quaternary mammalian fossils recovered from deposits in East Anglia (P914195). a) First lower molar of Mimomys savini with rooted teeth, West Runton, Norfolk [Photo: D. Schreve]. b) Un-rooted first lower molar of Arvicola terrestris cantiana, Purfleet Essex [Photo: D. Schreve]. 30) Distal left tibia of Trogontherium cuvieri, Hoxne [Photo: H. Taylor]. d) Skull of Hippopotamus amphibius from Barrington. e, f) Associated right and left second molars of Mammuthus primigenius, Lynford. g) Associated first lower molars of Ursus arctos, Lynford. Acknowledgements a, b Reproduced from Morigi, A N et al. 2011. The Thames through time: The archaeology of the gravel terraces of the Upper and Middle Thames. Early prehistory to 1500 BC. Part 1 — The Ice Ages. No.1. (Oxford: Oxford Archaeology). j Reproduced from Schreve, D c. 1997. Mammalian biostratigraphy of the later Middle Pleistocene in Britain. Unpublished PhD Thesis, University of London (University College London). k Reproduced with kind permission from the Sedgwick Museum of Earth Sciences, University of Cambridge. e–g Reproduced from Boismier, W A et al. (eds), 2012, © Natural History Museum, London.

(Plate 28) a, b Lower Palaeolithic flakes, Happisburgh (‘Site 3’) Excavation 2005, The British Museum. c Lower Palaeolithic retouched flake, Happisburgh (‘Site 3’). d Late Middle Palaeolithic hand axe from Lynford Quarry, Norfolk. Excavation 2002, Norwich Castle Museum.

(Plate 29) Oblique-angle aerial photograph (looking south) showing former Neolithic flint mine workings at Grimes Graves, near Lynford, Norfolk — note visitors’ centre building for scale [Photo: © Mike Page www.mike-page.co.uk].

(Plate 30) (a) Masonry at Woodford Church near Wellingborough showing Northamptonshire Sandstone (orange, brown), Blisworth Limestone Formation (flaky, pale grey) and Lincolnshire Limestone Formation (Barnack Stone, pale cream) (P914196). (b) Use of Lincolnshire Limestone Formation (grey) for quoins and architraves, chequerwork flint (lower courses) and Carstone Formation (brown), Little Massingham Church (P914197). (c) Knapped flints used for the main part of the church tower with architraves and quoin stones of Barnck Stone or Leziate Sandstone, Holme-next-the-Sea Church (P914198). (d) Leziate Sandstone (grey blocks near base of tower) above brown Carstone Formation, the upper part is mostly unworked flint with some Carstone, Gayton Thorpe Church (P914199).

(Plate 31) (a) Variably sized Carstone Formation (‘big carr’ and ‘little carr’) used in the walls of the church at Downham Market (P914200). (b) Carstone Formation and red and white chalk brickwork in a cottage at Burnham Thorpe (P914201). (c) White chalk brickwork in a cottage at Burnham Thorpe (P914202).

(Plate 32) View looking eastwards along the north Norfolk coast from Beeston Hill towards West Runton showing coastal protection measures including coast- parallel timber revetments and groynes which are designed to trap sediment and maintain the beach profile (P914203).

(Plate 33) (a) Rock armour and failing timber revetments and groynes at Happisburgh, north Norfolk (P732115). (b) Cliff erosion and damage to properties on Beach Road, Pakefield near Lowestoft following a major storm coinciding with a high tide on the 30th November 1936 (P025917).

(Plate 34) Oblique-angle aerial photograph looking north-westwards along the coast from Cart Gap towards Happisburgh. Removal of a section of breakwater in 1991 due to storm damage has led to the development of a large embayment due to accelerated rates of coastal erosion [Photo: © Mike Page www.mike-page.co.uk].

(Plate 35) Coastal flooding is a significant hazard for low-lying coastal areas of East Anglia. This photograph shows inland flooding after the breaching of sand dunes by storms at Horsey in 1942. Photograph looking seawards with remaining sand dunes on the left (P256627).

Tables

(Table 1) Hydrogeological characteristics of pre-Quaternary units in East Anglia.

(Table 2) Hydrogeological characteristics of Quaternary units in East Anglia.

(Table 3) Summary of ground engineering issues relating to geology.