Geology of the Huddersfield district. A brief explanation of the geological map Sheet 77 Huddersfield

R Addison, C N Waters, and J I Chisholm abridged by A A Jackson from the Sheet Description

Bibliographic reference: Addison, R, Waters, C N, and Chisholm, J I. 2005. Geology of the Huddersfield district — a brief explanation of the geological map. Sheet Explanation of the British Geological Survey. 1:50 000 Sheet 77 Huddersfield (England and Wales).

Keyworth, Nottingham: British Geological Survey, 2005.

© NERC 2005 All rights reserved

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.

(Front cover) View of Halifax from Beacon Hill [SE 103 254] (Photograph C Adkin; MN39864)

(Rear cover)

(Geological succession)

Notes

Throughout this report the word 'district' refers to the area covered by the geological 1:50 000 Series Sheet 77 Huddersfield. National Grid references are given in square brackets. Borehole records referred to are prefixed by the code of the National Grid 25 km² area upon which the site falls, for example SE12NW.

Acknowledgements

This Sheet Explanation has been abridged by A A Jackson from the more detailed Sheet Description by R Addison, J I Chisholm, and C N Waters. R A Chadwick and C P Royles contributed to the section on Structure and concealed geology; N J Riley identified fossils and G E Strong provided petrographical descriptions; C R Hallsworth determined heavy mineral assemblages for sandstones. The Applied geology section was compiled from contributions by K J Northmore and P R N Hobbs (engineering geology and landslides), D E Highley (mineral resources) and C Cheney (hydrogeology). Figures were produced by P Laggage, BGS Cartography, Keyworth and page-setting was by A Hill.

We are grateful to Local Authorities of Calderdale, Kirklees and the City of Bradford, the Coal Authority, Mineral Valuers Office, Environment Agency, British Rail and civil engineering consultants and acknowledge their help in permitting the transfer of records to the National Geosciences Records Centre. The cooperation of landowners, tenants and quarry companies is gratefully acknowledged.

Maps and diagrams in this book use topography based on Ordnance Survey mapping.

© Crown copyright. All rights reserved. Licence Number: 100017897/2005.

Geology of the Huddersfield district. (summary from the rear cover)

An Explanation of Sheet 77 (England and Wales) 1:50 000 series map.

(Geological succession)

The landscape of the Huddersfield district is dominated, in the west, by the upland moors and gritstone edges of the Millstone Grit Group. The Millstone Grit Group formed as deltaic sediments deposited at the mouths of large river systems flowing from the north about 320 million years ago. At first the rivers discharged into a deep, marine basin but as sediments accumulated the deltas formed as thick sheets of sand and are now evident as the sandstones of the escarpments.

As the basin filled with sediment, the Carboniferous rivers flowed across a broad and very gently sloping delta plain upon which shallow freshwater lakes and mire-swamps developed. The Coal Measures Group accumulated in these environments. It was the presence of the coal seams, fireclays, ironstone and building stone, most notably the Rough Rock Flags and Elland Flags, which provided the basis for major industries and urban developments in Bradford, Huddersfield and Halifax. Legacies from mineral extraction are the difficult ground conditions of the coalfield areas.

Following the deposition of the Coal Measures Group no record is preserved of the geological history until the Pleistocene glaciations of the Quaternary Period. At the peak of the last glacial period the southern margin of the Devensian ice sheet lay across the district, and till was deposited in the north-east. Scouring and erosion by meltwater rivers resulted in the formation of the deep valleys of the Calder and Colne and their tributaries. In this period also, the steep slopes of mudstone below the gritstone edges were prone to landslides.

Chapter 1 Introduction

This Sheet Explanation provides a summary of the geology of the district covered by the geological 1:50 000 Series Sheet 77 Huddersfield published in a Solid and Drift edition in 2003. A fuller account of the geology is given in the Sheet Description (Addison et al., 2005), and detailed information can be found in the Technical Reports for the component 1:10 000 scale geological maps (p.31).

The district lies within the county of West Yorkshire and includes large areas of the Metropolitan Boroughs of Calderdale and Kirklees, as well as parts of the cities of Leeds, Wakefield and Bradford; it includes the former coalfield area in the eastern part of the district. The Pennine moorlands and valleys in the west are more sparsely populated.

The bedrock is composed entirely of sedimentary strata deposited during the later part of the Carboniferous Period, about 323 to 311 million years ago. The oldest strata proved in the Huddersfield district are of the Namurian (Upper Carboniferous) Millstone Grit Group, which crops out in the west where it forms the high moorlands of Blackstone Edge, Buckstones Moss, Great Manshead Hill, Withens Moor and Midgley Moor. The high silica and low lime content of the rocks results in a poor acidic soil, which supports the characteristic Pennine vegetation of heather and sparse grass on a blanket of peat. Sandstones, such as the Rough Rock or Huddersfield White Rock, form west-facing escarpments with extensive dip slopes that reflect the gentle easterly dip of the strata. The Millstone Grit Group is overlain by the Coal Measures Group that crops out over the eastern part of the district and generally forms lower ground, although sandstones such as the Elland Flags and Thornhill Rock form imposing escarpments. The Coal Measures Group, in addition to coal, has yielded abundant minerals such as fireclay, brickclay, pyrite, ganister, ironstone and dimension stone. In the 19th and 20th centuries mineral exploitation stimulated the early growth of the urban areas, and although mineral extraction is much reduced, the fireclay, common clay, flagstone and dimension stone industries are still contributors to the local economy.

Geological history

During the Namurian Epoch, northern England lay within an actively subsiding basin connected to the sea. Rivers draining from lands to the north carried sediment to feed deltas that built out into the basin. Coarser grained sediment, deposited in fluvial channels, levées, deltas and submarine fans, lithified as sandstone, whereas mud and silt settling in areas of standing water or in deeper marine environments lithified as mudstone and siltstone.

The Millstone Grit Group succession in the Pennine region consists of a series of sedimentary cycles (cyclothems), which are now generally believed to have resulted from sedimentation during cyclical glacio-eustatic variations in sea level, superimposed on subsidence of the basin (Leeder, 1988). Each cycle begins with mudstone containing marine faunas. These marine bands range from a few centimetres up to 7 m or more in thickness, and generally contain distinctive faunal assemblages that can be recognised regionally as important marker horizons. They are inferred to have been deposited at times of high global sea level. The marine mudstone commonly passes up into non-marine mudstone and siltstone, and then into sandstone, each upward-coarsening unit representing an advance of the delta. Open-water environments were therefore replaced by delta slopes, and finally by distributary channels of the delta top. The delta top environments were colonised by plants, leading to the development of soils and deposits of peat. Once subjected to lithification the soil horizons became seatearth and the peats compacted to coal. This pattern of deposition was repeated with each rise and fall in sea level.

The Coal Measures Group, of Westphalian age, was deposited in riverine and lake environments, with periodic flooding by the sea. Coal seams developed from peat beds that formed in poorly drained low-lying environments. Recent work has shown that the large river systems that transported the clastic sediments came from widely separated source regions, which provided different palynological and detrital mineral assemblages (Chisholm et al., 1996; Leng et al., 1999; Hallsworth and Chisholm, 2000; Hallsworth et al., 2000). These assemblages have allowed changes of provenance to be established. Up to the top of the Elland Flags, the sediments were derived mainly from a northern terrain that had also provided the sediments of the Millstone Grit Group. In contrast, the sediments that formed the overlying beds came mainly from a western source. Four 'northern' sandstones have been identified within the sequence of 'western' sandstones: in ascending order these are Grenoside Sandstone, Kirkburton Sandstone unit 2, Linfit Sandstone and a localised part of the Emley Rock.

Following the deposition of the Coal Measures Group no record is preserved of the geological evolution of the district, until the Quaternary Period. Early glacial erosion may be represented by minor remnants of sand and gravel that lie perched above the Calder floodplain or buried beneath it. At the peak of the most recent glacial period the southern margin of an ice sheet lay across the district. In the north-east, which was covered by ice, a thin blanket of till remains. Scouring and erosion by meltwater rivers resulted in the formation of the deep, steep-sided valleys of the Calder and Colne and their many tributaries. In this period also, steep slopes of mudstone, and gritstone edges, were prone to landslide (Plate 1).

Chapter 2 Geological description

Namurian

Namurian rocks crop out over much of the west of the district and occur at depth beneath Westphalian rocks in the east; they belong to the Millstone Grit Group. Seismic data suggest that the total thickness of Namurian strata in the district is about 1000 m, of which the highest 525 m occur at outcrop. The Namurian Epoch is divided into seven stages but only the upper three are present at outcrop in the district (Figure 1). The stages are subdivided into chronozones recognised by the presence of diagnostic ammonoid (goniatite) faunas (Ramsbottom et al., 1978), and these are indicated on the map (see Sheet 77 Generalized Vertical Section).

Millstone Grit Group

The Millstone Grit exposed in the district comprises interbedded mudstone, siltstone and sandstone with some coal seams (Figure 2). Only the sandstones are widely exposed; these form the mappable units that are distinguished on Sheet 77 by colour according to stage. The sandstone units are generally similar to each other and are distinguished mainly by their position relative to the marine faunal bands.

The sandstone nomenclature is broadly that used during the previous survey, but some names have been changed to conform with usage in the Bradford district (Waters, 2000). The use of the terms 'grit' and 'rock' is maintained for sandstone names; the terms are considered to be synonymous. Previous surveyors used the term 'Millstone Grit Series' to include all the strata exposed below the Coal Measures. They divided the 'Millstone Grit Series' into four parts, namely 'Sabden Shales', 'Kinderscout Grits', 'Middle Grits' and 'Rough Rock Series' (Wray et al., 1930). The three highest units correspond in general to the stage names used in this account: Kinderscoutian, Marsdenian and Yeadonian. The former Sabden Shales of the district are now included with the Kinderscoutian strata. A report on the outcrop area (Waters, 2001) provides the basis for the stratigraphy used here.

Kinderscoutian strata are at least 255 m thick in the district, and include several thick sandstones. The lowest beds exposed are predominantly argillaceous, and are seen in the north-west, in Hebden Water, Crimsworth Dean, the upper Calder valley, on Stoodley Pike and in the vicinity of Withens Clough Reservoir. In Halifax, they were penetrated by the Clark Bridge Mills Borehole (Figure 2).

The lowest sandstones that have been mapped are two unnamed beds (about 5 to 10 m thick) around Crimsworth Dean. Three marine bands have been recorded above these sandstones. The two higher bands are classified provisionally as Reticuloceras reticulatum (R_1c) and are likely to be R_1c1 and R_1c2. The lowest band has not yielded a diagnostic fauna.

The Todmorden Grit is fine to coarse grained, about 5 m thick but exceptionally up to 60 m thick in isolated crags at Horsehold Scout and Cat Scout. These exposures may be sections of infilled channels cut into unexposed siltstone. The grit is underlain and overlain by Reticuloceras reticulatum marine bands.

The Spittle Clough Marine Band has been recorded in mudstone above the Todmorden Grit (Bisat and Hudson, 1943); this band may represent the highest of the Reticuloceras reticulatum marine bands (R_1c3). Higher in the sequence, the Healey Clough A Marine Band may represent the Reticuloceras coreticulatum Marine Band (see below). Thus, in the Withens Moor area about 90 m of mudstone overlie the Todmorden Grit and appear to have replaced the main lower leaf of the Lower Kinderscout Grit (Bisat and Hudson, 1943).

The Lower Kinderscout Grit is formed of several interconnected leaves that show dramatic thickness variations. The sandstone is generally medium to very coarse grained, locally with quartz pebbles, and fines upwards. It is thickly bedded and cross-bedded, with individual cross-bed sets up to 15 m thick. The succession equates broadly with the combined Addingham Edge Grit, Long Ridge Sandstone and Doubler Stones Sandstone in the Bradford district (Waters, 2000). The main sandstones are commonly overlain by seatearths with thin coals. East of Pecket Well [SD 9986 2893], a coal up to 0.3 m thick rests on the highest sandstone leaf and was worked locally.

The Reticuloceras coreticulatum Marine Band (R_1c4) underlies the highest leaf of the Lower Kinderscout Grit. The Butterly Marine Band (Bromehead et al., 1933; Aitkenhead and Riley, 1996) occurs just above the highest leaf, and was identified in the Manshead Tunnel and other boreholes. Thus the sandstone described by Wray et al. (1930) as the lower leaf of the Upper Kinderscout Grit is included here as the upper leaf of the Lower Kinderscout Grit.

The succession between the Lower and Upper Kinderscout Grits is up to 19 m thick, thinning in the south-west to about 5 m, and absent where channels have been eroded at the base of the Upper Kinderscout Grit. It is thickest in the Noah Dale Borehole, where three upward-coarsening cycles occur; each is about 6 m thick and consists of coal and black mudstone overlain by dark grey mudstone and siltstone that pass up into very fine-grained sandstone. Similar cycles have been observed in detailed logs of the Manshead Tunnel boreholes.

The Upper Kinderscout Grit (the upper leaf of the Upper Kinderscout Grit of Wray et al., 1930) is equivalent to the High Moor Sandstone of the Bradford district (Waters, 2000). The Upper Kinderscout Grit varies from very fine grained to very coarse grained with granules, and is cross-bedded or massive; it is broadly upward-fining, becoming micaceous and very thinly bedded towards the top. It shows marked variations in thickness, and is thickest in the Hebden Bridge, Withens Moor, Mytholmroyd and Sowerby areas, where very coarse-grained sandstone probably infilled a fluvial channel. Erosion at the base of this channel appears to have removed one or more leaves of the underlying Lower Kinderscout Grit. The Bilinguites gracilis Marine Band has been proved in the overlying mudstone sequence in a number of boreholes in the district.

Marsdenian (R₂) strata outcrop over much of the western part of the district, notably at Midgley Moor, Sowerby, Outlane and Slaithwaite Moor. They comprise sandstone, mudstone and siltstone, with a total thickness of up to 200 m. All the main marine bands have been recognised in the district (Figure 2).

The Bilinguites gracilis Marine Band (R_2a1) marks the base of Marsdenian strata. It is typically underlain by a 2 to 3 m sequence of mudstone with abundant Cordaites coarsening upwards to medium-grained sandstone with rare Sanguinolites; the fossils indicate deposition within a restricted marine environment. The marine band (1.5 to 7 m thick) consists of dark grey, finely laminated mudstone with the diagnostic B. gracilis, Dunbarella and Posidoniella. The lowermost Bilinguites bilinguis Marine Band (R_2b1) occurs about 6 to 7 m above the R_2a1 band, but is restricted to the south-west of the district.

The Readycon Dean Flags and East Carlton Grit belong to a single fluviodeltaic system, underlying the middle Bilinguites bilinguis Marine Band (R_2b2) (Brettle et al., 2002). The name Readycon Dean Flags is restricted to a fine-grained component of the former Scotland Flags (Wray et al., 1930). They comprise thin beds of fine-grained, micaceous, planar laminated sandstone interbedded with micaceous siltstone and mudstone; they are mapped where sandstone beds comprise over 30 per cent of the strata. The East Carlton Grit comprises fine- to coarse-grained, micaceous, cross-bedded, ripple cross-laminated sandstone that is thinly planar bedded.

In the north of the district, the mudstone overlying the East Carlton Grit includes a sandstone that has been correlated with the Woodhouse Flags of the Bradford district. It consists of upward-fining beds of fine-grained sandstone to siltstone. The sandstones are bioturbated and the siltstones display common Olivellites traces. The uppermost Bilinguites bilinguis Marine Band (R_2b3), which elsewhere rests upon the Woodhouse Flags has not been proved at outcrop in the district, but may be present in the Colne Road Mills Borehole.

The Midgley Grit (MgG) forms prominent escarpments such as Buckstones Moss, Slaithwaite Moor, and the type locality at Midgley Moor. This is the Pule Hill Grit of Wray et al. (1930), known in Lancashire as the Gorpley Grit. It is a coarse- to very coarse-grained, quartzo-feldpathic sandstone that is cross-bedded to massive with common log impressions and mudstone intraclasts. The base of the sandstone is typically sharp and erosive, and internal erosion surfaces are also common. In the Bankfield Mills (Mold Green) Borehole the Midgley Grit is overlain by seatearth and a thin coal (Wray and Melmore, 1931).

In the south of the district the Midgley Grit is divided into two leaves by a mudstone up to 7 m thick. Near Slaithwaite, the mudstone has yielded a marine fauna (Wray et al., 1930, p.39), which is probably the Bilinguites eometabilinguis Marine Band (R_2b4).

Immediately above the Midgley Grit is a thin coal, up to 0.3 m thick around Sowerby Bridge and Barkisland Mills [SE 066 197] where it was worked (Wray et al., 1930).

The Guiseley Grit was formerly known as the Nab End Sandstone or Beacon Hill Flags (Wray et al., 1930). It varies from 5 to 22 m thick, and is typically fine to medium grained, flaggy and micaceous, cross-bedded and ripple cross-laminated. At Wham Quarry, the sandstone beds are interleaved with laminated mudstone, the lowermost sandstone containing abundant Pelecypodichnus traces. In the Sowerby area the sandstone forms prominent dip slopes and has been worked in numerous small quarries. The Lower Meltham Coal is present locally on top of the Guiseley Grit.

In the overlying mudstone, the Bilinguites superbilinguis Marine Band (R_2c1) was recorded by Benfield (1969) who estimated that it lay about 15 m below the base of the Huddersfield White Rock. The Verneulites sigma Marine Band (R_2c2) has not been identified during this survey, but was described by Wray et al. (1930) as occurring around Black Brook, Barkisland.

The Huddersfield White Rock forms prominent escarpments, for example on the eastern side of Luddenden Dean, and long dip slopes to the west of Huddersfield. The name is used here for sandstones previously referred to as Warley Rock (Wray et al., 1930) and Holcombe Brook Grit. This sandstone ranges from fine grained, thinly planar bedded and ripple cross-laminated, to coarse grained and cross-bedded.

One or two thin coals occur in the sequence above the Huddersfield White Rock (Figure 2); the higher of the seams is the Upper Meltham Coal. In the vicinity of Pole Hill a single seam of coal, about 0.3 m thick, was worked from bell pits and shafts.

Above the Upper Meltham Coal there is a thick succession of mudstone, the lowest 5 to 7 m of which lie below the Cancelloceras cancellatum Marine Band, and thus belong to the Marsdenian Stage. The mudstone includes two Lingula bands and a non-marine bivalve fauna.

The base of the Yeadonian strata (G_l) is defined at the base of the Cancelloceras cancellatum Marine Band (Gla1), and the Cancelloceras cumbriense Marine Band (G_lb1) lies some 10 to 35 m higher. Between the C. cumbriense Marine Band and the base of the Rough Rock Flags, the sequence varies greatly in thickness (Figure 2). It is about 35 m thick in the Sowerby Bridge area, and includes a thin sandstone, up to 6 m thick. In Crawstone Clough this sandstone is micaceous, laminated and fine grained and is lithologically distinct from the less micaceous, greenish grey Haslingden Flags that are known from Lancashire (Collinson and Banks, 1975) and are inferred from features mapped at Bleakedgate Moor near Denshaw.

The Rough Rock Flags crop out on steep slopes below the Rough Rock, but also form large areas of dip slope at Ovenden Moor, Hunter Hill, Mount Tabor and Crosland Moor (Plate 2); exposures are usually limited to quarry sections. The Rough Rock Flags comprise fine- to medium-grained cross-bedded, planar laminated or ripple laminated micaceous sandstone. The base of the Rough Rock Flags is generally gradational by interdigitation from the mudstone that overlies the C. cumbriense Marine Band. The base is taken where sandstone beds form more than half the thickness of the section. During this survey it was not possible to separate the Rough Rock from the Rough Rock Flags over much of the Stainland area because of poor exposure. Lateral variations in thickness of the Rough Rock may result from filling of fluvial channels (Bristow, 1988).

The Rough Rock is the youngest sandstone of the Millstone Grit Group. It comprises coarse- to very coarse-grained, massive and cross-bedded quartzo-feldspathic sandstone with granules and small rounded quartz pebbles. It forms prominent escarpments with extensive dip slopes at Ovenden Moor, Illingworth Moor, Halifax and Elland town centres, Norland Moor, Wholestone Moor and Crosland Moor.

The Pot Clay and Pot Clay Coal (0.05 to 0.2 m thick) overlie the Rough Rock. The Pot Clay (1.5 m thick) is the seatearth to the coal, and was formerly extracted for bricks and pottery (Wray et al., 1930).

The highest Namurian strata are mudstone and siltstone that contain nonmarine bivalves (Wray and Melmore, 1931), and underlie the Subcrenatum Marine Band, a few metres above the top of the Rough Rock.

Key localities

Todmorden Grit: Crimsworth Dean Beck [SD 9899 3081]

Lower Kinderscout Grit: Derby Delph Quarry [SE 0165 1609] to [SE 0186 1613]

Reticuloceras coreticulatum Marine Band: Horodiddle [SD 9771 3151]

Upper Kinderscout Grit: Windy Hill Roadcut, M62 [SD 977 147] to [SD 981 147]

Bilinguites gracilis Marine Band: Castle Shore Clough, M62 [SD 9759 1459]

Readycon Dean Flags: Dean Head Clough [SE 029 149]

East Carlton Grit ('Scotland Flags'): Foster Clough Delphs [SE 0210 2731]

Bilinguites bilinguis Marine Band: Green Withens Clough [SD 9972 1641]

Midgley Grit: Only House Quarry [SE 0741 1847] to [SE 0735 1840]

Bilinguites metabilinguis Marine Band: Highlee Clough [SE 0478 2129]

Guiseley Grit: Beacon Hill Quarry [SE 0416 1847]

Bilinguites superbilinguis Marine Band: Caty Brook, Wainstalls [SE 045 289]

Huddersfield White Rock: Beestones Quarry, [SE 0689 1952]

Cancelloceras cumbriense Marine Band:

Crawstone Clough [SE 0758 2109]

Rough Rock Flags: Elland Road Cut [SE 103 215]

Rough Rock: Elland Road Cut [SE 103 215]

Pot Clay Coal: Queensbury Railway Tunnel, Holmfield [SE 0880 2920]

Westphalian

The Westphalian Series is divided into four stages of which only the lower two are present in the district (Figure 1). The Lower Coal Measures corresponds to the Langsettian Stage (Westphalian A), and the Middle

Coal Measures of the district belong to the Duckmantian Stage (Westphalian B). The Coal Measures Group rests conformably upon the Millstone Grit Group; the base is taken at the base of the Subcrenatum Marine Band. Biostratigraphical classification is based on stages defined by marine marker bands, and on nonmarine bivalve zones (Ramsbottom et al., 1978).

Coal Measures Group

The Coal Measures Group of the district consists of about 760 m of interbedded mudstone, siltstone and sandstone with subordinate coal, seatearth and ironstone (Figure 3). Nonmarine bivalves are common, and rarer marine faunas also occur; trace fossils are present in places. Ironstone is present at many horizons, generally as flat nodules a few centimetres thick. The mudstone of the Coal Measures varies from grey to black, and from massive to fissile. Siltstone is typically medium grey and contains plant debris. All these lithologies may grade vertically and laterally into each other. Sedimentary structures include parallel lamination and ripple cross-lamination.

The sandstones commonly form positive, topographic features and are distinguished on the map. Otherwise, mudstone, siltstone and thin sandstones are shown as Lower or Middle Coal Measures (undivided). The sandstones vary from very fine to medium grained, and are quartzo-feldspathic with variable mica content. They are grey where fresh, but weather to yellowish brown. Sedimentary structures include planar lamination, ripple lamination, cross-bedding and massive beds. Plant debris is common on bedding surfaces. Sandstones of 'northern' provenance are more micaceous, coarser grained, and less clayey than those of 'western' origin.

Coal seams are common, and they are generally underlain by seatearths. Some coals are widespread but vary in thickness and quality, and in the number and thickness of dirt partings (Figure 4).

Seatearths are palaeosols or lithified soil profiles that developed during periods of subaerial exposure. Where developed in sandstone, they may be referred to as ganisters, and where formed in mudstone as fireclay. They are characterised by the presence of root casts such as Stigmaria.

Marine bands commonly overlie the coals and seatearths (see Sheet 77 generalized vertical section). They commonly grade up into deposits that contain nonmarine bivalve faunas. Ten marine bands are recognised in the district. Most contain restricted faunas of foraminifera, conodonts, Lingula, or marine bivalves, but the Subcrenatum and Listeri marine bands contain rich faunas, with diagnostic ammonoids. The near-marine Low Estheria Band is also known in the district.

Wray et al. (1930) provided a valuable account of the Coal Measures in the Huddersfield district, with information on rock exposures that are no longer extant, and details of mineral workings. However, the stratigraphy used by these authors has been amended during the recent geological resurvey. In particular, the term Elland Flags is now used in a more restricted sense (see below), and a miscorrelation of the Grenoside Sandstone with the Kirkburton Sandstone has been corrected.

Lower Coal Measures

The lowest part of the Lower Coal Measures from the base to the horizon of the 80 Yard Coal has many marine bands (Figure 3); (Plate 3), and has been divided into a number of cyclic units; the boundary between any two cycles is taken at the top of a coal (or seatearth if the coal is absent). In Yorkshire, the cycles have been named informally after prominent beds within them (Waters et al., 1996a; Chisholm et al., 1996; Wilson and Chisholm, 2002), and in upward succession include the Soft Bed cycle (21 to 45 m thick), the Middle Band cycle (4.5 to 17 m), the Hard Bed cycle (7.5 to13 m), the Stanningley cycle (24 to 35 m), the 48 Yard cycle (9 to 23 m) and the 80 Yard cycle (7.5 to 35 m). All are of northern provenance. The main coals and marine bands are shown on the map (Sheet 77, Generalized Vertical Section) and the succession is described in detail by Wilson and Chisholm (2002). The Soft Bed and Hard Bed coals were widely worked, and several seatearths were worked for fireclay and ganister.

The succession between the 80 Yard Coal and the Better Bed Coal (Figure 3) includes common sandstones and few coal seams.

The sequence is in three parts (Chisholm, 1990; Waters et al., 1996a; Chisholm et al., 1996). The Elland cycle, 40 to 80 m thick, is of northern provenance; the Greenmoor cycle, 25 to 60 m thick, is of western provenance; and the Grenoside cycle, 25 to 30 m thick, is of northern provenance. The name Elland Flags was used by Wray et al. (1930) for sandstones in all three cycles, but this is now known to be incorrect. The Elland Flags are strongly micaceous sandstones that were widely worked for flagstones and tilestones (Godwin, 1984). They are present only in the lowest cycle, and die out southwards near Castle Hill, Huddersfield. Greenmoor Rock is the name given to greenish grey sandstones in the middle cycle; these thicken southwards. Grenoside Sandstone is the name for sandstones in the top cycle.

The Better Bed Coal has a thick seatearth, and was widely worked. The seatearth was also worked locally for refractory clay.

Nonmarine bands are recorded from the strata between the Better Bed Coal and Blocking Coal (Figure 3) and individual upward-coarsening units are of limited extent. Coals are more common than in the beds below, and seam splits are common.

Most of the clastic sediment is of western provenance, but northern-sourced lithologies have been identified at two levels (see below).

The interval between the Better Bed Coal and the Black Bed Coal (35 to 40 m thick) generally consists of two upward-coarsening units. The sandstone of the lower unit is unnamed, that in the upper unit is the Thick Stone. The thin Better Bed Band Coal overlies the lower sandstone. Erosion at the base of the Thick Stone has removed the Better Bed Band Coal in places and as a result the sandstones coalesce. The Black Bed Coal was widely worked underground. Between the Black Bed Coal and the Crow Coal, the succession is variable (10 to 20 m thick) with a number of sandstones collectively referred to as Kirkburton Sandstone. In the north, the Black Bed is overlain by mudstone with ironstone bands, the Black Bed Ironstone (or Low Moor Ironstone) that was worked in the past around Low Moor and Bowling. In the south, a variable thickness of sandstone, siltstone and mudstone (unit 1 of the Kirkburton Sandstone) rests on the coal. Rootlets in these beds suggest that they lie in southward-thickening splits from the Black Bed Coal. Unit 2 of the Kirkburton Sandstone is of northern provenance. The Crow Coal is widespread but contains many splits; it was worked in the north around Shelf.

The 22 Yard Coal and 32 Yard Coal are thin but widespread in the north, and occur in the lowest 20 m or so of the strata overlying the Crow Coal. Above these coals, the dominant lithology is sandstone which in this part of the succession is given the general name Clifton Rock. Among the sandstones is one of distinctive pale coloured quartzitic lithology that is unique among beds of western origin (Chisholm et al., 1996; Hallsworth and Chisholm, 2000).

The Beeston Group of Coals is a complex of seams spread through some 10 to 40 m of strata, and derived by a series of splits and coalitions from the Beeston Coal of the Leeds area. It includes various leaves of the Shertcliffe Coal, the Top and Low Whinmoor Coals, the Black Band (or 'Beeston') Coal and the Linfit Lousey Coal. In the north-east the Churwell Thin and Churwell Thick Coals are apparently split from the Top Beeston Coal (Lake, 1999), the Churwell Thick further splitting into the Shertcliffe Coal and Little Coal (Green et al., 1878). The various local names used in the past were not applied consistently across the district even during the period when the coals were being worked (Addison et al., 2005). The Beeston Group of coals was widely worked underground and from opencast sites around Lepton.

Between the Beeston group of coals and the Blocking Coal are some 35 to 55 m of variable strata. The Linfit Lousey Coal is overlain by the Linfit Sandstone, a micaceous bed of probable northern provenance (Hallsworth and Chisholm, 2000). In the north, two thin coals, the Trub Coal and the Top Lousey Coal, were worked around Wyke. The higher seam lies immediately under the Low Estheria Band, which consists of 10 cm of dark grey fissile mudstone with 'Estheria' and is an important regional marker horizon. The sequence that includes the Low Estheria Band is capped by the Blocking (Bed) Coal, or Silkstone Coal, which was widely worked and is reliably correlated across the entire coalfield. The Blocking Coal was worked opencast with the Top Lousey Coal at Hartshead Moor and at Hunsworth, south of Bradford, and to a lesser extent around Houses Hill, Lepton.

Unlike the preceding strata, the measures between the Blocking Coal and Middleton Little Coal (Figure 3) are consistent in their development across the district, but vary in total thickness from 60 to 75 m. The roof measures of the Blocking Coal contain a thin ironstone, a correlative of the Claywood Ironstone of Sheffield and Barnsley. Above the Blocking Coal, the Falhouse Rock is very variable in thickness; its thicker deposition was broadly central to the Gainsborough Trough (Figure 3). The Middleton Eleven Yards Coal was worked over much of the district. In some areas it was previously misidentified as the Wheatley Lime Coal.

The overlying measures include the Wheatley Lime (Three Quarters) Coal, which is generally well developed and was worked over the entire area as a single coal, up to 1 m thick. It was extracted by opencast workings at Hartshead and Mirfield Moor and at Houses Hill, north-west of Grange Moor.

The Wheatley Lime Coal is overlain closely by an unnamed sandstone (2 to 10 m thick) that forms marked features in Cleckheaton, Birkenshaw, East Bierley, Batley and Thornhill. Presumed downcutting of this sandstone has produced a washout in the seam about 500 m wide extending north to south between Thornhill and Overton (Wray et al., 1930). The measures above the Wheatley Lime include the Middleton Main (New Hards) Coal, a widespread and consistently developed coal of former economic importance. The sequence is capped by the Middleton Little (Green Lane) Coal, which was worked in the north-east, around Gildersome, and in the south, around Emley. It is now believed to correlate with the Parkgate Coal to the east and south of the district (Lake, 1999).

The Middleton Little Coal is overlain by mudstone that contains nonmarine bivalves and fish remains and passes up into a variable sequence that includes the Lepton Edge Rock and the Birstall Rock, as well as the First, Second and Third Brown Metal coals; the First Brown Metal is the highest. Downcutting beneath the Birstall Rock has resulted in local washout of the two upper coals of the group. The Third Brown Metal has been worked around Howden Clough in the north, in conjunction with the other Brown Metal Coals, and in the south, where it was commonly referred to as the Stone Coal, it was worked separately around Moor Head west of Emley Moor. Around Emley Moor it is overlain by the Birstall Rock, and is subject to washout between Thornhill Lees and Savile Town. It is equivalent to the Low Fenton Coal of the Wakefield district (Lake, 1999) although correlations are not entirely certain.

The Second Brown Metal Coal (or Old Hards Coal) was formerly important as a source of subanthracitic coal (Wray et al., 1930). At Emroyd Colliery, Thornhill Edge and around Grange Moor it is washed out by sandstone of the Birstall Rock; the washout has the form of a sinuous channel. North of the Calder, the Second Brown Metal extends into a split seam, previously termed the Two Yard Coal, which is effectively a combination of the Old Hards and the First Brown Metal. The seams are washed out from areas along the north-east of Smithies Beck at Birstall, and the Second Brown Metal reappears farther east as a thin remnant of the seam beneath the Birstall Rock in the Batley West End Shaft. North of there, at Howden Clough, a thick and fully representative sequence of the Brown Metal Coals was worked opencast; it would appear that all three Brown Metal Coals are represented at Howden Clough.

The term Birstall Rock has been applied to any sandstone that overlies any or all of the Brown Metal Coals. The Birstall Rock is thickest in the type area (30 m thick) thinning to the north and west. Washouts of the underlying coals occur where the sandstone is thickest and has a coarser grain size. To the south-east, at Inghams Bye Pit, Thornhill, a stacked sequence of sandstones, over 16 m thick, is developed entirely above the First Brown Metal, but between Middletown and Grange Moor the base of the sandstone that overlies the First Brown Metal cuts down progressively westwards, eroding the First Brown Metal and the Second Brown Metal and merging with the sandstone that overlies the Third Brown Metal. The main depocentre of the Birstall Rock and washout of the underlying coals appears to lie along a south-trending line.

The Flockton Thin Coal has been mined extensively underground throughout the district and was extracted by opencast workings in the south around Flockton, Thornhill Lees and Thornhill Edge and in the north at Gildersome Street.

The Flockton Thin Coal is generally overlain by fissile mudstone with nonmarine bivalves, but around Drighlington in the north and around Emley in the south, it is overlain directly by the Emley Rock, which forms much of the interval below the Flockton Thick Coal. Over the entire district north of Flockton, the uppermost bed of this coal is a waxy cannel coal that was formerly important for its gas and oil content. The main seam was extracted from opencast workings along much of the outcrop south of the Calder, between Thornhill Lees, Thornhill Edge, Flockton and Emley. North of the Calder opencast sites are limited to Gildersome Street and Upper Batley.

In places, the Tankersley Ironstone forms the roof measures of the Flockton Thick Coal. This mussel band ironstone was extensively worked in medieval times and numerous bell pits and spoil heaps remain in the woods and pastures in the area east of Emley (Wray, 1929). The cycle is capped by the Joan Coal, a thin but widely developed seam of poor quality. It was worked underground around Flockton and east of Emley Moor.

Middle Coal Measures

About 160 m of Middle Coal Measures crop out on the eastern margin of the district (Figure 3). The base of the Middle Coal Measures, and of the Duckmantian Stage (Westphalian B), is defined at the base of the Vanderbeckei (Clay Cross) Marine Band developed in the mudstone that immediately overlies the Joan Coal. The marine band is recorded in boreholes immediately east of the district at Thornhill. Named and worked seams of the Middle Coal Measures of the district are listed in (Figure 4).

The lowest part of the Middle Coal Measures includes the Thornhill Rock, which forms major escarpments, and has been quarried in a number of localities. It consists of a single leaf (about 40 m thick) around Batley and Bruntcliffe or up to four leaves interbedded with mudstone and thin coals with an over-all thickness of about 60 m, as around Gawthorpe. At Howley Park Quarry a seatearth with a thin coal appears to fill channels in the top of the Thornhill Rock. The Lidget Coal is recorded only in the narrow graben between splays of the Horbury Bridge Fault (Lake 1999), to the south-east of Flockton. Around Dewsbury the Lidget Coal may have been washed out at the base of a sandstone that rests directly on the Thornhill Rock.

The Low Haigh Moor Coal is known in opencast workings at Hostingley, southeast of Thornhill and it outcrops north of the Staincliffe Fault at Hanging Heaton, Dewsbury where it is separated from the Top Haigh Moor Coal by 7 to 10 m of sandstone and mudstone. Immediately to the north, around Lower Soothill in the former Solway opencast site, the Top and Low Haigh Moor Coals are mapped together and occur as leaves of one split seam with a total thickness of 0.9 m. The Haigh Moor Rock lies close above or rests directly on the Haigh Moor Coals in former quarries at Lower Soothill.

Above the Haigh Moor Rock, records of the Soothill Wood opencast sites indicate 40 m of measures that include the Swallow Wood Coal, 27 Yard Coal, Gawber Coal, Beck Bottom Stone Coal and Warren House (Gawthorpe) Coal. Between the Beck Bottom Stone Coal and the Warren House Coal, a 6 m-thick sequence of thin sandstone and siltstone interbedded with mudstone represents the Horbury Rock.

Key localities

Subcrenatum Marine Band: Elland railway tunnel [SE 104 216]

Soft Bed Flags: River cliff, Lockwood [SE 140 153]

Holbrook Marine Band and Springwood Marine Band: Springwood railway tunnel [SE 137 163]

Middle Band Rock: Old rail cut, Shearing Cross [SE 143 178]

Stanningley Rock: Stream section, Ainleys [SE 113 198]

36 Yard & Hard Bed Band Coals and Meadow Farm Marine Band: Calder brickpit [SE 125 215]

48 Yard Rock, 48 Yard Coal, Amaliae Marine Band, Norton Mussel Band, 80 Yard Rock: Storth brickpit [SE 118 203]

80 Yard Coal: Calder brickpit [SE 125 215]

Elland Flags: Stream section Northowram [SE 122 264]

Benomley Siltstones: Benomley Beck [SE 159 157]

Greenmoor Rock: Horton Bank Reservoir, Bradford [SE 126 308]

Grenoside Sandstone: Horton Bank Reservoir, Bradford [SE 126 308]

Better Bed Coal and Better Bed Band Coal: Kirkheaton brickpit [SE 185 174]

Thick Stone: Cliff by Beldon Brook [SE 196 140]

Black Bed Coal: Excavation near Kirkheaton brickpit [SE 189 174]

Kirkburton Sandstone: Old adit, Beldon Brook [SE 199 139]

Clifton Rock: Bradley Quarry [SE 172 206]

Whinmoor Coal(s): Stream Section, Rods Beck [SE 202 160]

Shertcliffe Coal: Covey Clough [SE 201 182]

Linfit Lousey Coal and Linfit Sandstone:

Stream near Yew Tree Farm, Linfit [SE 209 137]

Top Lousey Coal and Low Estheria Band: Stream, Jagger Park Wood [SE 134 280]

Falhouse Rock: Old quarry, Falhouse Lane [SE 219 171]

Lepton Edge Rock: Old quarry, Hall Hill [SE 208 163]

Birstall Rock: Old railway cutting, Birstall [SE 222 269]

Middleton Main Coal and Middleton Little Coal: Old rail tunnel, Gomersal [SE 209 267]

Emley Rock: Road cut, Leeds Road, Birstall [SE 231 264]

Thornhill Rock: Road cut, Carlinghow Hill [SE 240 251]

Quaternary

Ice sheets advanced over the Pennine region at least three times during the Pleistocene, although evidence of the earlier glaciations in the Huddersfield district has been all but obliterated by subsequent erosion particularly during the most recent (Devensian) cold periods. The Quaternary deposits cover only a relatively small part of the district. Buried channels up to 12 m deep underlie the alluvium in the valleys of the rivers Calder and Colne. Erosional benches, overlain by glaciofluvial sand and gravel, are perched on the hill slopes up to about 40 m above the present-day alluvium, and probably predate the erosion of the buried channels.

Till occurs on high ground in the north-eastern part of the district, and dates from the main Devensian glaciation. During the latest Devensian cold stage, the entire district lay to the south of an ice sheet and was subjected to subarctic conditions under which freeze-thaw processes generated a thick mantle of fractured rock and weathered debris. During warmer seasons both the till and the weathering products became unstable and flowed down slopes to form head deposits. Freeze-thaw action on bedrock strata initiated extensive landslides. From the extent of till deposits it is inferred that the maximum southward advance of the Devensian ice sheet extended over only the upland areas of the north-eastern part of the district.

Following the Devensian glaciations, the modern drainage pattern became established, with alluvial deposition within the valleys of Calder and Colne, and associated tributary streams.

Glacial deposits

Till, formerly termed boulder clay, is an unsorted heterogeneous mixture (diamicton) of clay, silt, sand and erratic stones, with locally derived clasts of sandstone. The main till deposits in the district form extensive, featureless spreads, generally less than 5 m in thickness. The deposits are generally restricted to the area around Buttershaw and Low Moor, south Bradford where weathered yellow clay is commonly encountered in site investigations.

Glaciofluvial deposits are present both in the valley floor of the River Calder and perched on valley sides at levels up to 35 or 40 m above the river. Deposits of similar appearance have been proved in boreholes within the channels buried beneath the alluvium of the rivers Calder and Colne. The deposits comprise sand and gravel with cobbles and boulders, with some thin, laterally impersistent beds of clay.

In the Calder valley, at Mytholmroyd [SE 005 260], unstratified sand and gravel deposits contain mainly local clasts along with water-worn glacial erratic cobbles of granophyre, andesite, rhyolite, granite and Silurian sandstone, derived from farther afield, some possibly from the Lake District. Wray et al. (1930) inferred that the upper Calder valley carried glacial meltwaters that overflowed from the Cliviger gorge of East Lancashire. The deposits on the lower ground around Elland are markedly heterolithic and appear to merge with the sand and gravel deposits that are continuous below the alluvium of the Calder downstream from Elland through Brighouse, Mirfield, Dewsbury and Thornhill. The base of the alluvial channel slopes gently and evenly from about 70 m above OD around Mytholmroyd to about 55 m OD at Elland and 22 m above OD around Savile Town; the deposits are generally about 6 to 10 m thick. In profile, the channel has a flat floor with steeper sides that may be overlapped and concealed by the more recent alluvial clay and silt.

In the Colne valley at Huddersfield, minor deposits of gravel with locally derived sandstone clasts lie at various levels above the present flood plain. The highest, at Hillhouse [SE 150 182] is 20 m above the alluvium level, and downstream near Rawthorpe [SE 166 182] gravel lies just above the floodplain and appears to be continuous with the gravel that underlies the alluvium. Glacial meltwater channels with misfit streams cross the Aire–Calder catchment divide at Odsal and Rooley in south Bradford, flowing into the Spen.

Glacial to postglacial deposits

Head

Head is an unsorted deposit of silt, clay and rock debris, which is derived by slow downhill movement of superficial deposits or weathered bedrock under the influence of gravity. Its composition closely reflects that of the source material. The deposits are difficult to distinguish from weathered bedrock or till, particularly in borehole records. The development was initiated during the Devensian but colluvial processes are still active. Head is widespread throughout the district, but has been mapped only where it exceeds 1 m in thickness, and where it is readily distinguishable from either weathered bedrock or till. The deposits have accumulated in hollows or at the base of steep slopes, such as below the scarp of the Midgley Grit in the upper Ryburn valley [SE 035 163]. Up to 9 m of head have been mapped on Namurian strata, and in the Calder valley around Hebden Bridge [SD 995 270] there are deposits up to 19 m thick.

Lacustrine deposits

Lacustrine deposits of silty clay have been mapped in an enclosed hollow at Dalton Green [SE 171 168], east of Huddersfield. Wray et al. (1930) reported the discovery of the remains of Aurochs or wild ox (Bos primigenius) from this site.

Landslides

Landslides develop where the natural slopes are steep (usually in excess of 10°). Other contributory factors include the presence of deeply weathered or fractured, fissile mudstone (particularly claystone), or a permeable water-bearing sandstone capping an impermeable mudstone (particularly if the dip is towards the valley axis), or the presence of springs or seeps. Landslides are common on the steep north- or east-facing slopes of the major escarpments.

Scree

Scree, or talus, deposits occur on the steep slopes of the major escarpments of the Millstone Grit sandstone units. The deposits accumulated mainly as rockfalls from crags and consist of clast-supported sand, gravel and blocks commonly over 3 m across. The deposits themselves are up to several metres thick and may be intermixed with debris flow from rock-slides and hillwash. Deposits of scree may pass laterally into deposits of head.

Postglacial deposits

River Terrace Deposits

River Terrace Deposits have been mapped only in the valley of the river Calder downstream from Mirfield. Lake (1999) described the Calder terraces and their deposits, discussing their composite nature. The deposits around Ravensthorpe, Thornhill Lees and Savile Town are up to 10 m above the alluvium of the present river, and consist of up to 2.5 m of clay or sandy silt with lenses of gravel, resting on 2 to 5 m of interbedded sand and gravel. The deposits rest on a bedrock surface that forms a concealed sloping ramp.

Alluvium

Alluvium forms wide, flat spreads in Calderdale, and the Colne and Holme valleys; it consists of grey and grey-brown silt and clay with lenses of sand, gravel and peat. Narrow discontinuous tracts of thin alluvium lie along the tributary streams. The alluvium of the main valleys of the Calder and Colne overlies deposits of sand and gravel (8 to 10 m thick) that fill concealed channels. These channel deposits are indistinguishable from the lower beds of the overlying alluvium and from the sand and gravel of the terrace deposits (see above).

Alluvial fan deposits are of limited extent, and have been recognised on the River Calder and Spen where minor tributaries meet the main rivers.

Peat

Peat is extensive on the moorland in the south-west and north-west of the district. Upland peat formed in areas of acid soil through the accumulation and decomposition of dead plant material under conditions of relatively low temperatures, poor aeration, water saturation and low evaporation. Palaeolithic flint implements are recorded from thin sands below the peat while Neolithic flints are associated with a basal layer containing tree debris (Wray et al., 1930). The peat is generally 1 to 4 m thick but may be considerably thicker in places.

The extent of peat mapped during this resurvey is less than that of the previous survey, which included extensive areas of peat less than 1 m thick. In addition, since then erosion has formed a network of gullies, or 'haggs', up to 3 m deep, for example at Linsgreave Head [SD 995 133]. Peat was formerly worked in the west of the district, often with detrimental effects to the moorland habitats, for example on Stake Hill [SE 02 33].

Artificially modified ground

The industrial development of the district has left extensive areas of modified ground. The artificial deposits mapped are those identified at the date of survey. They were delineated in the field and by examination of archival topographical maps, aerial photographs and site investigation data. Only the more obvious deposits can be mapped by these methods and the boundaries shown may be imprecise. Only those deposits in excess of 100 m wide and known to be more than 1.5 m thick are shown.

Infilled ground is mapped where the ground surface has been excavated and partly or wholly backfilled. Disused railway cuttings have been used in the district for the disposal of waste materials. Mineral excavations and quarries have commonly been filled with spoil or imported waste after the completion of mineral extraction. Where quarries and pits have been restored there may be no surface indication of the extent of the backfilled void.

Made ground includes engineered embankments, spoil from mineral extraction industries, demolition rubble, industrial waste such as foundry sand, slag and ash and domestic waste. Landfill sites may be raised or occupy topographical depressions such as the glacial meltwater channels at Odsal [SE 164 296]. Construction of the urban area has commonly taken place on compacted rubble of previous developments.

Structure and concealed geology

Dinantian strata are concealed beneath the Namurian and Westphalian rocks of the Pennine region. These were deposited in a system of half-graben basins and tilt-block highs (Kirby et al., 2000). The district lies within one of these half-grabens, the Huddersfield Basin, which is bounded to the north-east by the Morley–Campsall line and to the west by the structurally complex north-trending Pennine Line (Evans et al., 2002; (Figure 5)). The Holme High lies to the south. Within the basin, depths to Caledonian basement increase from less than 2000 m in the west to more than 3000 m in the east (see Sheet 77 cross-section and inset map of structural features). Along the line of section the Dinantian succession has a maximum thickness of about 1400 m.

The district lies on the eastern limb of the north-trending Pennine Anticline, which intersects the south-west corner of the district, and, in general, strata dip eastward at 2° to 5°. Dips of up to 50° or more may occur in the vicinity of the faults. Faults may occur as single discrete planes, or as fracture zones up to several tens of metres wide. The portrayal of such a fault zone as a single line on the map is therefore a generalisation. As faults are rarely exposed, field investigations and data compilation may not be sufficient to locate the surface position of a fault precisely. In areas of thick and extensive superficial deposits, the positioning of faults may rely on projection to surface of underground mining information.

The district has been affected by extensive faulting at surface, with dominant fault trends of north-west and north-east with less common east–west structures. The faults display dominantly normal and strike-slip displacement. The surface faults are considered to be late Carboniferous features, but east–west trends may reflect control by earlier basement structures. Only the north-east and north-west-trending faults extend into Permo-Triassic strata to the east (Lake, 1999) indicating reactivation in Mesozoic times. Neogene (Miocene) compressive stresses may also have resulted in reactivation of many of the faults. Slickensides found on north-west-trending fault and joint planes are invariably subhorizontal. The main faults affecting Carboniferous strata are illustrated in (Figure 5).

The Tong Fault is one component of the Morley–Campsall Fault Zone that lies above a major line of partition within the basement, and defines the north-east margin of the Gainsborough Trough. The south-west side of the trough is marked by the Denholme Clough Fault, which is continued at surface by the Bailiff Bridge and Cleckheaton fractures (Kirby et al., 2000). Within the area of the Gainsborough Trough, subordinate faults run either subparallel to the main north-west-trending faults or at an obtuse angle to them. The orientation is consistent with sinistral transpression under regional shortening, oblique and anticlockwise to the axis of the Gainsborough Trough, during Variscan inversion. To the south-west of the Gainsborough Trough, numerous splay faults, including the Mirfield Moor Fault and Roberttown Fault, diverge from the Bailiff Bridge and Cleckheaton Fractures. These splays, mostly with downthrow to the north-east, effectively form a stepped margin to the basement trough.

To the south, the Rishworth–Stainland Fault Zone is developed above an east–west basement fault, parallel to the Holme Fault (Kirby et al., 2000). The zone extends eastwards as a graben along the Staincliffe Fault, which turns south-east to join the Roundwood–Thorntree Hill Fault Zone in the Wakefield district (Lake, 1999).

Thickness variations within the Millstone Grit across the Denholme Clough Fault in the area of Oxenhope in the south of the Bradford district suggest syndepositional movement on the fault during Kinderscoutian and Marsdenian times. This structure is contiguous with the Bailiff Bridge Fractures. Variations in thickness of some Coal Measures sandstones, such as the Birstall Rock and Lepton Edge Rock, and coal seams such as the Middleton Little Coal and Brown Metal Coals, may indicate structural control of sedimentation. However, the influences on sedimentation of differential compaction or basin and channel morphologies are difficult to eliminate from an assessment of structural controls (Rippon, 1996).

The Bouguer gravity anomaly map (inset map Sheet 77) shows a strong north–south contour trend with a pronounced eastward decrease in Bouguer anomaly values in the western part and a low in the eastern part. The eastward decrease cannot be entirely due to the lower density of the Carboniferous rocks in the Huddersfield Basin and may indicate higher density basement to the west and south. The change in basement density may occur across the Pennine Line and the absence of a magnetic response suggests that the higher and lower density basements are both sedimentary in nature (J C Cornwell, personal communication, 2003). On the aeromagnetic anomaly map, the north-west-trending anomalies that cross the north-east of the district are closely associated with the Morley–Campsall– Askern–Spital Fault Zone and the Denholme Clough Fault. The magnetic anomaly over the Morley– Campsall structure persists for about 40 km to the south-east; the source of the anomaly is not known but it may indicate the presence of a steeply dipping igneous body.

Earthquakes

This area lies on a zone of seismic activity running roughly north-east from Merseyside towards the Skipton area, on the western side of the Pennines. The largest earthquake close to the Huddersfield district was the Todmorden earthquake of 7 March 1972 (4.0 ML) (Tillotson, 1974). This event had an epicentre in the Todmorden–Bacup area and caused minor damage at Bacup, Chadderton, Middleton and Rochdale. Seismic activity in this area is due to reactivation of old deep structures that are favourably orientated with respect to the direction of maximum compressive stress associated with continuing opening of the North Atlantic.

Chapter 3 Applied geology

This chapter provides a brief guide to the earth science issues that should be taken into account in the planning and development process. Geological factors have had a significant role in the industrial expansion of Huddersfield, Halifax, Bradford and neighbouring towns. Mining, quarrying and heavy industry have left areas of derelict land. In planning the development of derelict land, action may be taken to ensure that the development is compatible with ground conditions or that measures are taken to mitigate problems. Geoscience information may also be used in the selection of sites for nature conservation and recreation. Waters et al. (1996b) provide more details of the key issues for the Bradford Metropolitan District.

Mineral resources

The resources in the district are those minerals that can be won at or near to the surface, as the economics of underground mining are unlikely to be favourable in the future.

Coal

Coal has been mined in the district, perhaps as early as the 13th century, but no coal is produced in the district today. Almost all of the workable coal seams have been mined and many have been worked by opencast methods. Any future commercial interest in the coal resources of the area is likely to be where urban sites are being redeveloped. Mining ceased in 1987, but Caphouse Colliery has been converted into the National Coal Mining Museum of England. The workings date from at least 1789, and the colliery has the oldest coal mine shaft still in everyday use, for underground visits, in Britain today.

Natural gas and oil

Natural gas and oil are common as traces in the Carboniferous rocks of the district. Natural gas has been encountered in boreholes penetrating Namurian and Westphalian sandstones at a number of sites around the Huddersfield urban area. Gas under high pressure was intersected in Namurian sandstone traps (Wray et al., 1930) and boreholes drilled in the early 20th century were still seeping gas some 60 years later. During the 19th century oil was produced from the cannel coal portion of the Flockton Thick Coal.

Fireclay

Fireclay formed the basis of an important extractive industry in Britain in the 19th and early part of the 20th centuries. Today, fireclays that have a relatively low iron content are used for the production of buff-coloured facing bricks. The only fireclay mine now operating in Britain is in the Shibden valley, near Halifax, where the Hard Bed fireclay is extracted. This unusual fireclay is used in the manufacture of glasshouse pots — a refractory pot used for melting speciality glasses such as lead crystal.

Brick clay

Brick clay and mudstone are used mainly in the manufacture of structural clay products, such as facing and engineering bricks, pavers, clay tiles and vitrified clay pipes. Of these, brick manufacture consumes by far the largest tonnage. Clay may also be used as a source of constructional fill and for lining and sealing landfill sites.

Clay facing bricks are produced at the Calder Brickworks [SE 123 217], near Elland using Lower Coal Measures mudstone from an adjacent quarry. On the extreme eastern boundary of the district, Middle Coal Measures mudstones overlying the Thornhill Rock are worked at the Howley Park quarry [SE 262 255].

Sand and gravel resources

Sand and gravel resources in the district are limited to areas of alluvium, river terrace deposits and buried glaciofluvial deposits present in the Calder valley (Addison et al., 2005). However, many resources are now largely inaccessible as a result of industrial development.

Sandstone

Sandstone is the principal mineral currently extracted in the district, and demand for this resource is likely to continue in the future. The sandstones of the Millstone Grit and Coal Measures of Yorkshire are marketed under the generic term 'York Stone'. The main resources identified are those sandstones that have been worked historically, namely the Elland Flags, Thornhill Rock, Clifton Rock, Rough Rock (Plate 4), Rough Rock Flags, Huddersfield White Rock, Midgley Grit and East Carlton Grit. The sandstones are very resistant to attack by acid rain water, and are attractive building stones suitable for walling, paving and cladding. Coarse-grained sandstones ('grits'), formerly worked for grindstones, pulpstones and millstones, are now worked for construction fill and for sand. In general, the sandstones are too weak, porous and susceptible to frost damage for them to be used for good quality roadstone or concrete aggregate. They may be used in road construction below the level of possible frost damage and for some of the less demanding concrete applications. The Elland Flags particularly are used in the manufacture of concrete paving slabs and kerbs.

Peat

Peat occurs as a thin deposit across parts of the upland areas, and was formerly worked for fuel on a limited scale. The peat is unsuitable for horticultural purposes.

Mine and quarry waste

Mine and quarry waste is present in many parts of the district, but has been little utilised to date. The inert nature of sandstone spoil makes it ideal for bulk-fill, in particular for the construction of road embankments. Colliery spoil, or mine stone, can be utilised as fill, but its placement requires careful control.

Ironstone occurs as nodules or thin beds of siderite (iron carbonate) within the Coal Measures, but the deposits are no longer of economic significance.

Surface mineral workings

Former or active quarries or pits may provide suitable voids for waste disposal, may be reopened as a source of minerals or may be developed as industrial sites or local nature reserves for educational, recreational and environmental purposes. Steep, unstable rock faces may be a constraint to development. The majority of open excavations are in sandstone, but former fireclay, sand and gravel and brickclay workings are also common.

Engineering ground conditions

Construction and development should take into account the suitability of the ground to support structural foundations, ease of excavation and the use of the ground materials in engineered earthworks and fills. These issues are summarised for the main engineering geological units in the district in (Figure 6) (Waters et al., 1996b). Foundation conditions are not only affected by the engineering properties of the bedrock and superficial deposits, but also by factors such as the geological structure, slope stability, the presence of undermining and the depth and degree of weathering. Variability of made ground, notably around landfill sites and areas of colliery spoil, may result in differential settlement. Colliery spoil may contain iron sulphides that are prone to oxidation and dissolution as sulphate-rich, acidic leachates, which may be harmful to concrete in foundations or buried services. The oxidation process may also result in expansion and differential heaving of foundations constructed upon such deposits. Large deposits of quarry spoil are common in the district, and the sites affected may provide poor foundation conditions if cavities are present or material was deposited on steep slopes.

Subsidence risk due to undermining

The underground mining of coal, fireclay, ironstone and sandstone are no longer carried out in the district, but mining was formally an important industry in the east of the district. Mining of coal from the Millstone Grit is also recorded at a few localities around Pecket Well, Scammonden, Barkisland and Pole Moor. Sandstone mining was largely limited to working of the Elland Flags (Godwin, 1984). Underground mining of the flags took place around Hipperholme, Northowram, Southowram and Rastrick. Fireclay was worked underground around Ambler Thorne, Park Nook, Sunny Bank, Beacon Hill and Shibden Hall and continues in the Shibden valley.

In areas of former mining the principal concerns relate to ground instability caused by the collapse of unsupported shallow workings. This may be evident as general ground subsidence or as the development of crown-holes. Structures straddling a fault may be susceptible to uneven settlement. Collapse of shaft fill, linings or cappings may also result in surface subsidence. A review of mining instability in the UK is provided by Arup Geotechnics (1991), which also provides information on the sandstone mining industry of West Yorkshire. Records of shafts and abandoned mines are lodged with the Coal Authority, who should be consulted prior to development.

Slope stability

Development, particularly for housing, has extended from the lowland areas of the main valleys onto the steep valley sides.

Construction on these slopes may encounter problems in areas of existing landslide, where the bedrock is weak (Plate 5), and where thicker head deposits have accumulated. Renewed instability may occur on landslides if the slopes are undercut or top-loaded, or if large volumes of water are introduced as a result of heavy rainfall or the alteration of drainage during development.

Pollution potential and leachate movement

Artificially modified ground may contain toxic residues as primary components or as products of chemical or biological reactions; these may migrate within the deposit or into adjacent strata (Waters et al., 1996b).

Leachates from old tips may present particular problems where tipping was uncontrolled and where little effort was made to prevent pollutant migration. The problems may be more severe where faults in bedrock provide pathways for leachate migration. Contamination may be associated with former gasworks, chemical works, textile mills, iron and steel works, railway land and sewage works.

Mine-drainage waters that reach the surface commonly have high pH, iron precipitates and elevated levels of manganese, aluminium and sulphates, which can result in the loss of riverine flora and fauna.

Gas emissions

Methane, carbon dioxide, carbon monoxoide, and radon can migrate through permeable strata and may accumulate in poorly ventilated enclosed spaces such as basements, foundations, or excavations. The gas may occur naturally within strata, such as the Coal Measures, or be generated by the decomposition of material in landfill sites (Hooker and Bannon, 1993). A rise of the water table through mines as a result of the cessation of pumping may force mine gas to the surface (Younger and Robins, 2002). The gas may be explosive, toxic or may act as an asphyxiant; it may cause vegetation die back.

A number of instances have been recorded in the Huddersfield urban area of water boreholes that have intersected strata yielding methane. In some instances, explosions have occurred when such trapped gas, in enclosed spaces, has been accidentally ignited. Methane may also be generated in marshes, peatlands and lakes including mill ponds.

Radon is a naturally occurring radioactive gas derived from rocks, soils and groundwater containing uranium and thorium, and is potentially carcinogenic. The levels of natural uranium and thorium are generally low in this district, although higher concentrations may be associated with marine bands, carbonaceous mudstone and coal seams in the Millstone Grit and Coal Measures (Ball et al., 1991). Radon may also occur in higher concentrations in high permeability rocks, such as sandstone or sand and gravel deposits, where these are present above a source.

Water resources

The River Calder and its tributaries drain much of the district, but in the north drainage is northwards towards the River Aire. Public water supplies are obtained from surface reservoirs in the Pennine valleys in the west of the district (Plate 6).

The Millstone Grit and Coal Measures constitute complex multi-layered minor aquifers from which significant quantities of potable groundwater are obtained. Most of the groundwater abstracted is used for industrial purposes with only small quantities being used for private domestic water supplies. The more important aquifers are the Kinderscout Grit, the Midgley Grit, the Rough Rock, the Huddersfield White Rock, the Elland Flags and the Thornhill Rock. The groundwater potentials of the main aquifers are very variable and borehole yields may range from 4 to 72 m3/h.

Water from the aquifers of the Millstone Grit is very soft and was used widely in the textile industries of the district (Wray et al., 1930). Groundwater from the Coal Measures is generally of good quality but hard and predominantly of calcium bicarbonate type. Former mine workings and mine drainage pumping make development of groundwater resources in the Coal Measures difficult due to the lowering of water levels and the widespread risk of contamination.

Strongly alkaline or ferruginous springs (or spas) at Lockwood and Slaithwaite were used in the early 19th century for medicinal purposes (Wray et al., 1930).

Conservation sites

Many of the sites described in this account may be important for earth science research and teaching, and for recreational purposes; many are in disused quarries and pits. There is increasing pressure to use such excavations for landfill, particularly those near to urban centres. Some of the localities have been designated as a Sites of Special Scientific Interest (SSSI) including Crimsworth Dean [SD 988 300], Derby Delph Quarry [SE 017 162] and Elland Bypass Cutting [SE 119 202]. Additional locations have been recognised by the local authorities and conservation groups as having special geological importance and have been designated as Regionally Important Geological Sites (RIGS).

Information sources

Enquiries concerning geological data for the district should be addressed to the Manager, National Geological Records Centre, BGS, Keyworth. For information on wells, springs and water borehole records contact: BGS Hydrogeological Enquiries, Maclean Building, Crowmarsh Gifford, Wallingford, Oxfordshire, OX10 8BB; Telephone 01491 838800, Fax 01491 692345.

Other geological information held by the British Geological Survey include borehole records, fossils, rock samples, thin sections and hydrogeological data. Searches of indexes to some of the collections can be made on the GeoIndex system in BGS libraries and on the web site, which also gives access to the BGS Lexicon of named rock units and part of the photographic collection. BGS catalogue of maps and books is available on request (see back cover for addresses).

Maps

• 1:50 000 and 1:63 360
• Sheet 77 Huddersfield (Solid & Drift) 2003
• 1:10 000 and 1:10 560
• The maps covering the 1:50 000 Series Sheet 77 Huddersfield are not published, but are available for public reference in BGS libraries in Keyworth and Edinburgh and the London Information Office in the Natural History Museum, South Kensington, London. Uncoloured dyeline copies are available for purchase from BGS Sales Desk. Copies of the fair-drawn maps of the earlier surveys may be consulted at the BGS Library, Keyworth.
• Digital geological map data
• Many BGS maps are available in digital form, which allows the geological information to be used in GIS applications. These data must be licensed for use. Details are available from the Intellectual Property Rights Manager at BGS Keyworth. The current availability can be checked on the BGS web site:
• http://www.bgs.ac.uk/products/ digitalmaps/digmapgb.html
• Geophysical maps
• 1:1 500 000
• Colour shaded relief gravity anomaly map of Britain, Ireland and adjacent areas, 1997. Colour shaded relief magnetic anomaly map of Britain, Ireland and adjacent areas, 1998.
• Geochemical atlases
• 1:250 000
• Point-source geochemical data processed to generate a smooth continuous surface presented as an atlas of small-scale colour-classified digital maps.
• Geochemical Survey Programme data are also available in other forms including hard copy and digital data.
• Hydrogeological map
• 1:100 000
• Southern Yorkshire and adjoining areas (Sheet 12), 1982
• Groundwater vulnerability map, south Pennines (Sheet 11)

Books and reports

Documentary collections

Boreholes and shafts

Borehole and shaft data are catalogued in the BGS archives at Keyworth. For the Huddersfield district the collection consists of the sites and logs of about 10 000 boreholes. For further information contact: The Manager, National Geosciences Records Centre, British Geological Survey, Keyworth, Nottingham NG12 5GG.

Mine plans

BGS maintains a collection of plans of underground mines for minerals other than coal, mostly for sandstone and fireclay.

Geophysics

Gravity and aeromagnetic data are held in the National Gravity Databank and the National Aeromagnetic Databank at BGS Keyworth. Seismic reflection data is available for the south and central parts of the district.

Hydrogeology

Data on water boreholes, wells and springs and aquifer properties are held at BGS, Maclean Building, Crowmarsh Gifford, Wallingford, Oxfordshire OX0 8BB. Telephone 01491 838800. Fax 01491 692345.

Material collections

Palaeontological collection

Palaeontological samples collected from the district are held at BGS Keyworth. Enquiries concerning the material should be directed to the Curator, Biostratigraphy Collections, BGS Keyworth.

Petrological collections

Hand specimens and thin sections are held in the England and Wales Sliced Rocks collection at BGS Keyworth. A collection database is maintained and charges and conditions of access to the collection are available on request from BGS, Keyworth.

Borehole core collection

Samples and core from a number of boreholes in the district are held by the National Geosciences Records Centre, BGS, Keyworth

BGS (Geological Survey) photographs

Photographs used in this report are held in the BGS Library, Keyworth. Copies can be supplied at a fixed tariff.

Other relevant collections

Coal abandonment plans

Coal abandonment plans are held by The Coal Authority (for address see below).

Groundwater licensed abstractions, Catchment Management Plans and landfill sites Information on licensed water abstraction sites, for groundwater, springs and reservoirs, Catchment Management Plans with surface water quality maps, and extent of washlands and licensed landfill sites are held by the Environment Agency.

Earth science conservation sites

Information on Sites of Special Scientific Interest within the Huddersfield district is held by English Nature, Northminster House, Peterborough, PE1 1UA.

Addresses for data sources

Mine plans

Coal, ironstone and fireclay

Copies of abandonment plans are held by the Mining Records Office, Coal Authority, 200 Lichfield Lane, Berry Hill, Mansfield, NG18 4RG, Telephone 01623 638233. These plans are held by the Coal Authority in the public domain, but are not available for reference at BGS.

References

British Geological Survey holds most of the references listed below, and copies may be obtained via the library service subject to copyright legislation (contact libuser@bgs.ac.uk for details). The library catalogue is available at: http://geolib.bgs.ac.uk

Addison, R, Waters, C N, and Chisholm, J I. 2005. Geology of the Huddersfield district. Sheet Description of the British Geological Survey, Sheet 77 (England and Wales).

Aitkenhead, N, and Riley, N J. 1996. Kinderscoutian and Marsdenian successions in the Bradup and Hag Farm boreholes, near Ilkley, West Yorkshire. Proceedings of the Yorkshire Geological Society, Vol. 51, 115–125.

Arup Geotechnics. 1991. Review of mining instability in Great Britain. Report to the Department of the Environment, Arup Geotechnics, Ove Arup and Partners. (London: H MS O.)

Ball, T K, Cameron, D G, Colman, T B, and Roberts, P D. 1991. Behaviour of radon inthe geological environment: a review. Quarterly Journal of Engineering Geology, Vol. 24, 169–182.

Benfield, A C. 1969. The Huddersfield White Rock Cyclothem in the Central Pennines. 20th to 23rd September 1968. Proceedings of the Yorkshire Geological Society. Vol. 37, 181–187.

Bisat, W S, and Hudson, R G S. 1943. The Lower Reticuloceras (R1) goniatite succession in the Namurian of the north of England. Proceedings of the Yorkshire Geological Society, Vol. 24, 383–440.

Brettle, M J, McIlroy, D, Elliott, T, Davies, S J, and Waters, C N. 2002. Identifying cryptic tidal influences within deltaic successions: an example from the Marsdenian (Namurian)interval of the Pennine Basin, U K. Journal of the Geological Society of London, Vol. 159, 379–391.

Bristow, C S. 1988. Controls on sedimentation of the Rough Rock Group (Namurian) from the Pennine Basin of northern England. 114–131 in Sedimentation in a synorogenic basin complex: the Upper Carboniferous of north west Europe. Besley, B M, and Kelling, G (editors). (Glasgow and London: Blackie.)

Bromehead, C E N, Edwards, W, Wray, D A, and Stephens, J V. 1933. The geology of the country around Holmfirth and Glossop. Memoir of the Geological Survey of Great Britain, Sheet 96 (England and Wales).

Chisholm, J I. 1990. The Upper Band–Better Bed sequence (Lower Coal Measures) in the central and south Pennine area of England. Geological Magazine, Vol. 127, 55–74.

Chisholm, J I, Waters, C N, Hallsworth, C R, Turner, N, Strong, G E, and Jones, N S. 1996. Provenance of Lower Coal Measures around Bradford, West Yorkshire. Proceedings of the Yorkshire Geological Society, Vol. 51, 153–166.

Collinson, J D, and Banks, N L. 1975. The Haslingden Flags (Namurian G1) of south-east Lancashire; finger-bar sands in the Pennine Basin. Proceedings of the Yorkshire Geological Society, Vol. 40, 431–458.

Evans, D J, Walker, J S D, and Chadwick, J S D, and Chadwick, R A. 2002. The Pennine Anticline — a continuing enigma? Proceedings of the Yorkshire Geological Society, Vol. 54, 17–34.

Giles, J R A. 1998. Geology and land-useplanning: Morley–Rothwell–Castleford. British Geological Survey Technical Report, WA/88/33.

Godwin, C G. 1984. Mining in the Elland Flags: a forgotten Yorkshire Industry. Report of the British Geological Survey, Vol. 16, No. 4.

Green, A H R, Russell, R, Dakyns, J R, Ward, J C, Fox Strangways, C, Dalton, W H, and Holmes, T V. 1878. The geology of the Yorkshire Coalfield. Memoir of the Geological Survey of Great Britain. (London: H MS O.)

Hallsworth, C R. 1994. Mineralogical evidence for variations in provenance of the Millstone Grit and Lower Coal Measures of the Bradford District. British Geological Survey Technical Report, WH/95/200R.

Hallsworth, C R, and Chisholm, J I. 2000. Stratigraphic evolution of provenance characteristics in Westphalian sandstones of the Yorkshire Coalfield. Proceedings of the Yorkshire Geological Society, Vol. 53, 43–72.

Hallsworth, C R, Morton, A C, Claoué-Long, J and Fanning, C M. 2000. Carboniferous sand provenance in the Pennine Basin, U K: constraints from heavy mineral and detrital zircon age data. Sedimentary Geology, Vol. 137, 147–185.

Hooker, P J, and Bannon, M P. 1993. Methane: its occurrence and hazards in construction. Construction Industry Research and Information Association (C IR IA), Report No. 130.

Kirby, G A, Baily, H E, Chadwick, R A, Evans, D J, Holliday, D W, Holloway, S, Hulbert, A G, Pharaoh, T C, Smith, N J P, Aitkenhead, N, and Birch, B. 2000. The structure and evolution of the Craven Basin and adjacent areas. Subsurface Memoir of the British Geological Survey. (London: The Stationery Office.)

Lake, R D. 1999. The Wakefield district —a concise account of the geology. Memoir of the British Geological Survey, Sheet 78 (England and Wales). (London: The Stationery Office.)

Lake, R D, Northmore, K J, Dean, M T, and Tragheim, D G. 1992. Leeds: a geological background for planning and development. British Geological Survey Technical Report, WA/92/1.

Leeder, M R. 1988. Recent developments in Carboniferous geology: a critical review with implications for the British Isles and north-west Europe. Proceedings of the Geologists' Association, Vol. 99, 73–100.

Leng, M J, Glover, B W, and Chisholm, J I. 1999. Nd and Sr isotopes as clastic provenance indicators in the Upper Carboniferous of Britain. Petroleum Geoscience Vol. 5, 293–301.

Ramsbottom, W H C, Calver, M A, Eager, R M C, Hodson, F, Holliday, D W, Stubblefield, C J, and Wilson, R B. 1978. A correlation of Silesian rocks in the British Isles. Geological Society of London Special Report, No. 10.

Rippon, J H. 1996. Sand body orientation, palaeoslope analysis and basin-fill implications in the Westphalian A–C of Great Britain. Journal of the Geological Society London, Vol. 153, 881–900.

Tillotson, E. 1974. Earthquakes, explosions and the deep underground structure of the United Kingdom. Journal of Earth Sciences Leeds, Vol. 8, 353–364.

Waters, C N. 2000. Geology of the Bradford district. Sheet Description of the British Geological Survey 1:50 000 series Sheet 69 Bradford (England and Wales).

Waters, C N. 2001. Geology of the western part of the Huddersfield district (Sheet 77). British Geological Survey Technical Report, WA/00/27.

Waters, C N, Aitkenhead, N, Jones, N S, and Chisholm, J I. 1996a. Late Carboniferousstratigraphy and sedimentology of the Bradford area, and its implications for the regional geology of northern England. Proceedings of the Yorkshire Geological Society, Vol. 51, 87–101.

Waters, C N, Northmore, K J, Prince, G, and Marker, B R. (editors). 1996b. A geological background for planning and development in the City of Bradford Metropolitan District. British Geological Survey Technical Report, WA/96/1.

Wilson, A A, Chisholm, J I. 2002. Reference sections in the Lower Coal Measures at Elland, West Yorkshire. British Geological Survey Internal Report, I R/02/027.

Wray, D A. 1929. The mining industry in the Huddersfield district. The Naturalist, 227–245.

Wray, D A, Melmore, S. 1931. Notes on some recent deep borings at Huddersfield. Proceedings of the Yorkshire Geological Society, Vol. 22, 31–51

Wray, D A, Stephens, J V, Edwards, W N, and Bromehead, C E N. 1930. Geology of the country around Huddersfield and Halifax. Memoir of the Geological Survey of Great Britain, Sheet 77 (England and Wales). (London: H MS O.)

Younger, P L, and Robins, N S. 2002. Challenges in the characterization and prediction of the hydrogeology and geochemistry of mined ground. 1–16 in Mine water hydrogeology and geochemistry. Younger, P L, and Robins, N S (editors). Geological Society of London Special Publication, No. 198.

Index to the 1:50 000 Series maps of the British Geological Survey

The map below shows the sheet boundaries and numbers of the 1:50 000 Series geological maps. The maps are numbered in three sequences, covering England and Wales, Northern Ireland, and Scotland. The west and east halves of most Scottish 1:50 000 maps are published separately. Almost all BGS maps are available flat or folded and cased.

The area described in this sheet explanation is indicated by a solid block.

British geological maps can be obtained from sales desks in the Survey's principal offices, through the BGS London Information Office at the Natural History Museum Earth Galleries, and from BGS-approved stockists and agents.

Northern Ireland maps can be obtained from the Geological Survey of Northern Ireland.

Figures and plates

Figures

(Figure 1) Marine bands found in the Huddersfield district.

(Figure 2) Millstone Grit: correlation of selected boreholes of the district. All sandstones are of northern provenance (based on outcrop evidence).

(Figure 3) Borehole and section illustrating the Coal Measures succession. Surface section is based on data from BGS Technical reports (p.31).

(Figure 4) Former use and thickness of named coal seams and thickness of interseam strata.

(Figure 5) Principal early Carboniferous structures of the district and main near-surface faults.

(Figure 6) Enginnering geological characteristics of the rocks and soils of the district. A general guide only to the engineering characteristics of the deposits in the district is indicated above. In practice, ground conditions are further influenced by such factors as geological structure, topography, the presence of undermining, the presence of faults, the variable depths and degrees of weathering and human activity; such factors should also be considered prior to undertaking engineering development.

Plates

(Plate 1) Landslide, west of March Haigh Reservoir, viewed from the north-west [SE 008 132] (GS1304).

(Plate 2a) Massive coarse-grained sandstone of the Rough Rock over finer grained cross-bedded sandstone of the Rough Rock Flags, in old quarry on Crosland Moor, Linthwaite [SE 107 146] (GS1302).

(Plate 2b) The base of the Rough Rock lies at the base of the paler coloured massive beds roughly one third from the top of the section, road cut at Elland [SE 102 215] (GS1301).

(Plate 3) Elland Edge [SE 120 125] is capped by the Elland Flags (Lower Coal Measures). An old brickpit at the foot of the slope shows a section of grey mudstone from just above the 36 Yard Coal up to the base of the 80 Yard Rock (three pale layers at the top of the face) (GS1253).

(Plate 4) Shaw's quarry, Crosland Hill. Rough Rock freestone used for building locally and elsewhere. View looking east [SE 1176 1478] (A3600).

(Plate 5) Landslide at Pike End, Rishworth Moor [SE 028 174] (GS1303).

(Plate 6) Booth Wood Reservoir viewed from the north-west [SE 020 160]. The M62 motorway passes on the southern side of the reservoir below the escarpment of the Midgley Grit (GS1300).

(Front cover) View of Halifax from Beacon Hill [SE 103 254] (Photograph C Adkin; MN39864)

(Rear cover)

(Geological succession) Geological succession of the district.

Figures

(Geological succession) Geological succession of the district

(see (Geological succession) for exact layout)

(Figure 1) Marine bands found in the Huddersfield district

(Figure 4) Former use and thickness of named coal seams and thickness of interseam strata

(Figure 6) Engineering geological characteristics of the rocks and soils in the district

(Figure 6) continued