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Geology of the Glossop district — a brief explanation of the geological map Sheet 86 Glossop

C N Waters, J I Chisholm, E Hough, and D J Evans

Bibliographic reference Waters, C N, Chisholm, J I, Hough, E, and Evans, D J. 2012. Geology of the Glossop district — a brief explanation of the geological map. Sheet Explanation of the British Geological Survey. 1:50 000 Sheet 86 Glossop (England and Wales).

Keyworth, Nottingham: British Geological Survey © NERC 2012 All rights reserved. Printed in the UK for the British Geological Survey by B&B Press Ltd, Rotherham.

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(Front cover) War Memorial and cross-bedded Lower Kinderscout Grit at Pots and Pans [SE 0102 0512], north-east of Tunstead. P671006.

(Rear cover)

Notes

'District' refers to the area covered by the geological 1:50 000 Series Sheet 86 Glossop. Ordnance Survey National Grid references are given in square brackets and prefixed by the letters denoting the 100 km square: SD, SE, SJ or SK. Symbols in round brackets after lithostratigraphical names are those used on the geological map. The serial number given with the plate captions is the registration number in the BGS National Archive of Geological Photographs. Boreholes referred to in the text are identified by their BGS Registration Number in the form (SE10SW/11), where the prefix indicates the 1:10 000 scale National Grid sheet.

Acknowledgements

This Sheet Explanation was written by C N Waters, J I Chisholm, E Hough and D J Evans. The report has been edited by Don Aldiss; figures were produced by H Holbrook, BGS Cartography, Keyworth, and page-setting was by A J Hill.

We acknowledge the help provided by the holders of data in permitting the transfer of these records to the National Geosciences Records Centre, BGS Keyworth. We are especially grateful for the assistance provided by members of Local Authorities, the Coal Authority, Environment Agency, and numerous civil engineering consultants. Landowners, tenants and quarry companies are thanked for permitting access to their lands.

The National Grid and other Ordnance Survey data © Crown copyright and database rights 2012. Ordnance Survey licence number 100021290.

Geology of the Glossop district (summary from rear cover)

Geology of the Glossop district. An explanation of sheet 86 (England and Wales) 1:50 000 series map

(Rear cover)

(Geological succession) Summary of the geological succession in the district.

The bedrock is composed of sedimentary rocks deposited from about 355 to 314 million years ago, during the Carboniferous Period. The oldest known rocks, present in the subsurface and proved only by boreholes, comprise Lower Palaeozoic slates, overlain by Tournaisian to Visean limestones of the Holme High Limestone Group, and then by the mudstone-dominated succession of the Craven Group, of early to mid Namurian age. The oldest strata found at the surface belong to the Millstone Grit Group, of Namurian age, which crops out over most of the western, central and south-eastern parts of the district. This fluviodeltaic succession includes prominent sandstones, which form dissected plateaux. Many of the sandstones were formerly extensively quarried for aggregate, building stone or flagstone.

The Millstone Grit Group is overlain by the Pennine Coal Measures Group, which crops out over the north-eastern part of the district, forming part of the East Pennine Coalfield. It also crops out in limited areas in the west of the district, representing the eastern margin of the Lancashire Coalfield. These strata have yielded abundant minerals such as fireclay, brick clay, ganister, ironstone and building stone, in addition to coal. The modern distribution of the coalfields was controlled by the distant effects of late Carboniferous Variscan deformation, including the formation of the Pennine Line, a deep-seated, north–south-oriented tectonic structure that crosses the west of the district. To the east, the regional dip is gentle, towards the east and north-east, whereas north–south-trending folds and steeper dips prevail in the west.

The geological evolution of the district is next represented by the glaciations of the Quaternary Period. Although the Anglian glaciation of about 500 000 years ago is thought to have extended across the district, the unconsolidated deposits of till and glaciofluvial sand and gravel, present in valleys in the west of the district, were deposited during the Devensian glaciation, which ceased about 11 000 years ago. During the most recent (Flandrian) age, alluvial and river terrace deposits have been deposited within the larger river systems, and peat accumulated over the uplands. Mass movement deposits, including landslide and head deposits, formed during the latter part of the Devensian through to the Flandrian and are a significant local feature of steep valley sides.

Chapter 1 Introduction

This Sheet Explanation provides a summary of the geology of the district covered by the geological 1:50 000 Series map Sheet 86 Glossop published as a bedrock and superficial edition in 2012.

The district lies in parts of the Kirklees Metropolitan District of West Yorkshire, the Barnsley and Sheffield Metropolitan Districts of South Yorkshire, the High Peak District of Derbyshire, and the Tameside District and Oldham Metropolitan District of Greater Manchester. The main population centres are in the west of the district, including Mossley, Stalybridge, Hyde and Glossop, and in the north-east, including Holmfirth and Penistone. These towns are separated by areas of farmland and scattered villages. Large tracts of moorland and valleys present in the north-western, central and southern parts of the district are sparsely populated. The upland moors form parts of the South Pennines and the Dark Peak, occurring respectively to the north and south of Longdendale. Within the Dark Peak, Bleaklow Hill forms the highest point within the district at 633 m above Ordnance Datum. The district is drained by the upper reaches of a number of rivers, including the Holme, Dearne, Don, Derwent, Etherow and Tame. These rivers and their tributary streams have been dammed to form a large number of reservoirs, supplying water for public consumption and industrial usage. Many of these reservoirs now also provide important recreational amenities.

The bedrock at outcrop (Figure 1) is composed of sedimentary rocks that were deposited during the Carboniferous Period, from about 320 to 314 Ma. The oldest rocks known in the district are Lower Palaeozoic laminated slates, proved only in the Wessenden 1 oil exploration borehole (SE00NE/7). In this borehole, the Lower Palaeozoicstrataareoverlainunconformably by platform carbonates, the Holme High Limestone Group, of Tournaisian to Visean (Mississippian) age, approximately 355 to 330 Ma. The limestone-dominated succession is restricted to the subsurface of the central parts of the district, where it accumulated over a basement structure known as the Holme High. In this area, the limestones are overlain by hemipelagic mudstones of the Craven Group of early to mid Namurian (Late Mississippian to Early Pennsylvanian) age, which are also proved only in the subsurface. To north and south of the Holme High, in the Huddersfield and Alport basins respectively, the platform carbonates pass laterally into thick developments of Tournaisian and Visean basinal mudstones and limestones of the Craven Group.

The oldest strata found at outcrop are of the Namurian (Pennsylvanian) Millstone Grit Group, which crops out over most of the western, central and south-eastern parts of the district, where it forms the high moorlands of Saddleworth Moor, Wessenden Moor, Holme Moss, Thurlstone Moss, Howden Moors and Bleaklow. The high silica and low lime content of the rocks produces 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, Huddersfield White Rock, Lower and Upper Kinderscout grits, form dissected plateaux. Many of the sandstones have been extensively quarried for aggregate, building stone or flagstone, although the number of quarries now working is small. The Millstone Grit Group is overlain by the Pennine Coal Measures Group, which crops out over the north-eastern part of the district, forming generally lower ground, which is part of the East Pennine Coalfield. However, sandstones within the Pennine Lower Coal Measures such as the Greenmoor Rock and Grenoside Sandstone form imposing west-facing escarpments, with extensive dip slopes that reflect the gentle easterly dip of the strata. The Pennine Coal Measures Group also crops out in limited areas in the west of the district, representing the eastern margin of the Lancashire Coalfield. The Pennine Coal Measures have yielded abundant minerals such as fireclay, brick clay, ganister, ironstone and building stone in addition to coal. In the 19th and 20th centuries mineral exploitation stimulated the early growth of the urban areas, and although mineral extraction is much reduced in scale, the fireclay, common clay, flagstone and building stone industries are still contributors to the local economy.

Following the deposition of the Pennine Coal Measures Group no record is preserved of the geological evolution of the district until the glaciations of the Quaternary Period. A thick (possibly Anglian-age) ice-sheet is believed to have extended across the Pennine region (Aitkenhead et al., 2002), although there is little evidence in the district of deposits associated with this glaciation. During a subsequent Devensian-age glaciation, unconsolidated deposits of till and glaciofluvial sand and gravel were deposited on the western flank of the Pennines, within valleys in the west of the district. During the most recent (Flandrian) age, alluvial and river terrace deposits have been laid down in association with the larger stream and river systems, and peat accumulated over the moorland areas between the valleys. Mass movement deposits, including landslide and head deposits, probably formed during the latter part of the Devensian through to the Flandrian. These deposits are a significant feature of the steep valley sides present within the outcrop of the Millstone Grit Group.

Chapter 2 Geological description

Pre-Carboniferous basement

Throughout the Pennine region the pre-Carboniferous rocks are mainly mudstones and sandstones of late Precambrian to Early Palaeozoic age, strongly deformed during the Caledonian Orogeny (Aitkenhead et al., 2002). In the present district, knowledge of these comes from Wessenden 1 oil exploration borehole (SE00NE/7) [SE 0546 0649] (Figure 2). They were encountered in the borehole from 1103.3 m to the terminal depth of 1127.7 m (base not proved), a thickness of 24.4 m, and comprise pale to medium green, locally slightly calcareous, laminated slates with structures indicating turbiditic deposition. The precise age of these rocks is not known, but they are overlain unconformably by Lower Carboniferous strata.

Early Carboniferous (Tournaisian and Visean)

Rocks of this age do not crop out in the district, but their general nature can be inferred from their development in surrounding areas, where they consist mainly of marine mudstones and limestones (Aitkenhead et al., 2002, p.21–22; Kirby et al., 2000). Within the district, evidence from the Wessenden 1 Borehole and from seismic reflection profiles (Evans and Kirby, 1999; Kirby et al., 2000) shows that a body of shallow-water (shelf or platform) carbonates (the Holme High Limestone Group) was deposited over a concealed basement high (the Holme High; (Figure 3)). These shallow water strata are surrounded by sequences of mudstones and limestones (the Craven Group), which were deposited in deeper water, basinal settings. The water depth and sediment thickness variations are the result of extensional (rift) faulting of the basins during deposition.

Holme High Limestone Group

The platform carbonates of the Holme High Limestone Group, proved in the Wessenden 1 Borehole (Figure 2), accumulated over the Holme High during the Tournaisian to late Visean (Evans and Kirby, 1999; Waters et al., 2009). The lowermost part of the succession, from 982.0 to 1103.3 m, a thickness of 121.3 m, is dominated by medium brown to grey dolostone, with a characteristic highly serrated and generally high gamma log profile, interpreted as being Courceyan to Chadian in age (Evans and Kirby, 1999). Within the dolostone-dominated succession are units of brecciated basalt, extensively replaced by calcite and pyrite, with chlorite-filled vesicles. The upper part of this interval also includes dark brown to grey limestone, mainly a fine- to medium-grained grainstone. Above this basal division, the succession from about 610.0 to 982.0 m, a thickness of 372 m, is dominated by fine- to medium-grained, light to dark grey limestones. This succession has gamma ray responses that are generally lower and more subdued than the basal division and are interpreted as representing strata of Chadian to Arundian age (Evans and Kirby, 1999). This age is supported by biostratigraphical analysis of a sample from a depth of 863.3 m, which included a foraminifer, Mediocris sp. (Riley, 1993), indicative of an age no older than the upper part of the foraminiferal Cf4α1 Subzone (early Chadian or younger). Strata of Holkerian age have not been identified in the borehole. The uppermost part of the carbonate interval, from 489.5 to about 610.0 m, a thickness of 120.5 m, comprises limestone with terrigenous grainstones and lithic clasts, and dark grey fissile mudstone interbeds, thought to be early Asbian in age (Evans and Kirby, 1999). This interval is characterised by a highly serrated gamma log profile, indicating numerous interbedded limestones and mudstones. A sample from near the top of the succession (496.5 m depth) contained the archaediscid foraminifer Archaediscus at the angulatus stage and the dasyclad alga Koninckopora inflata (Riley, 1993), supporting this age interpretation. Strata of late Asbian and Brigantian age may be absent from the borehole, as suggested by Evans and Kirby (1999), or may be present in condensed mudstone facies of the overlying Craven Group.

To north and south of the Holme High, in the Huddersfield and Alport basins respectively (Figure 3), the platform carbonates are interpreted from seismic reflection data (Evans and Kirby, 1999), to pass laterally into thick developments of Tournaisian and Visean basinal mudstones and limestones typical of the Craven Group. Details of this succession have not been proved in boreholes hereabouts, but similar facies are present at outcrop to the north in, for example, the Skipton Anticline (Evans and Kirby, 1999; Kirby et al., 2000). On the Holme High, however, in the Wessenden Borehole, the lower part of the Craven Group may be missing: the thin development of mudstone that overlies the limestone there (Figure 2) may belong to the higher part of the group. The seismic reflection data reveal a feature that can be mapped over part of the Holme High and which appears to represent an embayment within the platform carbonate succession (Figure 3). The seismic character of the infilling sediments is suggestive of sequences connecting to those with a seismic character more representative of the basinal facies. The feature thus represents the ultimate drowning and overstep of the platform carbonate succession during late Visean times.

Namurian

Namurian rocks crop out over much of the district, and continue at depth beneath Westphalian rocks in the north-east. Seismic reflection data suggest that the total thickness of Namurian strata in the district is about 800 to 1300 m, of which only the uppermost 700 m appear at outcrop. The Namurian Regional Stage (formerly Epoch), as defined by Heckel and Clayton (2006), is divided into seven substages, which are subdivided into chronozones recognised by the presence of diagnostic ammonoid (goniatite) faunas. Only strata belonging to the three highest substages, the Kinderscoutian, Marsdenian and Yeadonian, are present at outcrop in the district (Figure 4). Older Namurian strata, ranging from Pendleian to Alportian in age, probably lie within the mudstone-dominated succession of the Bowland Shale Formation (Craven Group).

During the Namurian Regional Stage, northern England lay within the large, actively subsiding Pennine Basin, which had a restricted connection to the sea. Rivers draining from lands to the north carried sediment to feed extensive deltas that built out into the basin. Coarser-grained sediment, deposited in fluvial channels, levées, deltas and submarine fans, eventually lithified as sandstone, whereas mud and silt settling in areas of standing water on the delta surface and in deeperwater off-delta environments, lithified as mudstone and siltstone.

Craven Group

The Craven Group does not crop out in the district, but is well exposed about 10 km to the south, in Edale, where it consists of mudstones with marine faunas showing a full succession of Namurian substages from Pendleian to Kinderscoutian (Stevenson and Gaunt, 1971, pp.163–171, fig. 16, plate XV: 'Edale Shales'). In the Wessenden 1 Borehole (Figure 2), the Holme High Limestone Group is overlain by 35.7 m (453.8 to 489.5 m) of dark grey, fissile, finely micaceous, locally slightly calcareous, mudstone of the Bowland Shale Formation (formerly Edale Shales) of the Craven Group (Waters et al., 2009). The age of this mudstone in the borehole has not been constrained, but comparison with the Derbyshire limestone shelf, to the south, suggests that it is entirely Namurian in age (Aitkenhead et al., 1985), and rests unconformably on Asbian limestones.

Millstone Grit Group

The Millstone Grit Group in the district comprises interbedded mudstone, siltstone and sandstone with some coal seams. These lithologies are typically arranged in a series of sedimentary cycles (cyclothems), which are believed to have resulted from sedimentation during cyclical glacioeustatic variations in sea level, superimposed on subsidence of the basin (Leeder, 1988). Each cycle begins with mudstone containing marine faunas. These marine bands (Figure 4) range from a few centimetres up to 4 m or more in thickness in the district, and are important stratigraphical marker horizons because each generally contains a distinctive faunal assemblage. They are inferred to have been deposited at times of high global sea level. The marine mudstone commonly passes up into unfossiliferous mudstone and siltstone, and then into sandstone, each upward-coarsening unit representing an advance of a delta. Open-water environments were therefore replaced by delta slopes, and finally by distributary channels and shallow lakes of the delta top. The delta-top environments were colonised by plants, especially during times of lowered sea level, 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.

Depositional models have been provided by Walker (1966b), Collinson (1968, 1969), McCabe (1977, 1978) and Hampson (1997) for the Kinderscoutian part of the succession, by Wignall and Maynard (1996) and Brettle et al. (2002) for the early Marsdenian, by Waters et al. (2008) for the late Marsdenian and by Bristow (1988) and Hampson et al. (1996) for the Yeadonian. Collinson (1988) has reviewed the sedimentation of the Millstone Grit as a whole.

Only the sandstones are widely exposed; these form the mappable units and many of the thicker and more persistent sandstones are distinguished on Sheet 86 by colour according to their age. The sandstone units are generally similar in their petrographical and sedimentological features, and are distinguished mainly by their position relative to the marine faunal bands. The sandstone nomenclature is broadly similar to that used during the previous survey (Bromehead et al., 1933) but some names have been changed to conform with usage in the adjoining Huddersfield district to the north (Addison et al., 2005a, b) and Barnsley district to the east (Hough et al., 2007). The use of the terms 'grit' and 'rock' is maintained for sandstone names where usage is well established in the literature; the terms are regarded as synonymous. Details of sandstone lithology and thickness are shown on (Figure 5).

The Millstone Grit Group is subdivided into formations based upon the chronostratigraphical subdivisions, with the Hebden, Marsden and Rossendale formations, of Kinderscoutian (R₁), Marsdenian (R₂) and Yeadonian (G₁) age, respectively (Waters et al., 2009), being recognised within the district.

The Hebden Formation (Heb) overlies the Bowland Shale Formation in the Wessenden 1 Borehole. The 453.8 m of interbedded sandstone and subordinate mudstone with rare beds of coal represents almost the complete thickness of the Hebden Formation (Figure 2). Other borehole provings are shown in (Figure 6). The lowest part of the formation is not exposed at the surface but the higher parts, which include several sandstones tens of metres in thickness, form much of the high moorland in the western and southern parts of the district, notably around Saddleworth Moor [SE 03 07] and Bleaklow [SK 10 96].

The lowermost part of the Hebden Formation, the Mam Tor Beds, is not exposed in the district. However, these beds crop out some 10 km to the south, at Mam Tor (Stevenson and Gaunt, 1971), where they comprise a series of distal turbidite sandstones with interbedded siltstones and mudstones (Allen, 1960). In the Wessenden 1 Borehole (Figure 2) the lowermost 110 m of the formation is inferred to represent the Mam Tor Beds ((Figure 2); Waters et al., 2009). Above this, the upward succession of Shale Grit, Grindslow Siltstones and Kinderscout Grit proved in the borehole is directly equivalent to that exposed at surface within the Glossop district.

The Shale Grit (SG) includes the oldest beds at outcrop in the district, but exposures are few. The succession, of 120 to 150 m thickness, comprises interbedded mudstone, siltstone and sandstone, the latter generally in beds up to 1 m thick with sedimentary structures indicating that they are proximal turbidites laid down in a system of migrating submarine fans (Walker, 1966b). Some thicker beds of massive sandstone form laterally impersistent features, commonly interpreted during the previous survey as indicating truncation by complex faults. These massive sandstones, which are particularly evident in Longdendale [SK 04 98] to [SK 07 99], are now interpreted as deltaslope turbidite channel deposits (Walker, 1966a). The channel fills may range up to 90 m in thickness and 300 m in width (Smart et al., 1978). Palaeocurrents, mainly based upon channel orientations, flowed towards the south (Walker, 1966b).

The Grindslow Siltstones, which overlie the Shale Grit, are typically poorly exposed, forming a concave slope below the plateau capping of the Kinderscout Grit. They comprise grey, well-bedded, micaceous mudstones and siltstones between 30 and 145 m thick, the maximum thickness proved in the Marsden Borehole (Figure 6) and the area to the north-west of Dove Stones Reservoir [SE 01 03]. About 110 m were recorded in the Wessenden 1 Borehole (Figure 2). The lowest 5 m of the succession is dominated by dark grey, laminated mudstone (Collinson, 1969). It is probably within this part of the succession that a marine band containing the ammonoid Reticuloceras reticulatum (Holroyd and Barnes, 1896), interpreted as a Reticuloceras reticulatum Marine Band (R_1c) (Figure 4), has been recorded at Greenfield [SD 99 03]. The remainder of the succession is dominated by 'striped' siltstones, which show a broad upwards coarsening with complementary increase in abundance of burrowing (Collinson, 1969). Mapped sandstones that occur within the middle and upper parts of the Grindslow Siltstones are lithologically similar to those present within the Shale Grit. They were interpreted as leaves of the Lower Kinderscout Grit by Hampson (1997), but are here mapped as unnamed sandstone. The succession, as a whole, is interpreted as a set of low-energy sediments deposited from suspension on a prograding delta slope (Walker, 1966b), with development of isolated turbidite channels.

The Lower Kinderscout Grit (LK) is exposed widely in the west and south of the district, forming broad moorland plateaux (Plate 1). It comprises several interconnected sandstone leaves that show dramatic thickness variations (Hampson, 1997). Partings between sandstones generally comprise grey siltstone and mudstone with thin, fine-grained sandstone beds. The main sandstones are commonly overlain by seatearths with thin coals. North of Longdendale the succession (110 m thick in the Marsden Borehole) typically forms three or four main leaves of sandstone (Figure 6). To the south of Longdendale, the leaves appear to amalgamate into a single thick sand body, 110 m thick, with an erosive base (Smart et al., 1978). Although dominated by cross-bedded sandstones, locally the basal part of the Lower Kinderscout Grit is very thickly bedded and internally massive (Plate 2), similar in appearance to the Shale Grit. This lithology is interpreted as the infill of deep fluvial channels (Collinson, 1969) incised within the upper slope deposits of the Grindslow Siltstones. Erosion surfaces forming channels as much as 6 m deep and 85 m wide are seen within the lowermost leaf at Buckton Vale Quarry [SD 991 016] (Hampson, 1997; McCabe, 1977). The lowermost leaf of the Lower Kinderscout Grit is typically the thickest, and in places contains giant cross-beds up to 12 m thick, for example at Ladcastle and Den Quarries, Uppermill [SD 995 060] (McCabe, 1977) and Shire Hill (Plate 2). Giant cross-beds are also found in higher leaves, as at the Woodhead Tunnel entrance, Longdendale [SK 114 999] (Collinson, 1968). Palaeocurrents are generally directed to between the south-west and south-east (Collinson, 1968, 1969; Hampson, 1997; McCabe, 1978) and the sandstones commonly show internal erosion surfaces (Plate 3).

The Butterly Marine Band (R_1c5) occurs just above the highest leaf of the Lower Kinderscout Grit south of Marsden, at Butterly [SE 049 105], and is found elsewhere in the west of the district (Figure 6). The marine band separates the Lower Kinderscout Grit from the overlying Upper Kinderscout Grit. During the previous survey (Bromehead et al., 1933), the two sandstones were differentiated only in the north-west of the district, the name 'Kinderscout Grit' being used elsewhere. The marine band commonly contains the brachiopod Lingula mytilloides and the bivalve Sanguinolites, but lacks ammonoids (goniatites). It is recorded in the Millwall Works Borehole at Hadfield and the Marsden Borehole (Figure 6), and is also recorded within the Chapel-en-le-Frith district to the south (Stevenson and Gaunt, 1971), suggesting that it is more widely developed than suggested by Bromehead et al. (1933). Despite the Butterly Marine Band not having been recorded in the central part of the district, correlation of sandstone units during this resurvey and the mapping of the regionally extensive Butterly Coal, which occurs immediately beneath the marine band, has allowed the separation of the Lower from the Upper Kinderscout Grit to be shown over most the area. The succession between the two sandstones is up to 45 m thick in the south-east, thinning in the south-west and north-west to about 7 m.

The Upper Kinderscout Grit (UK) shows marked variations in lithology and thickness. Palaeocurrents flowed broadly towards the south (Collinson, 1969). The sandstone is commonly upwards-fining, becoming very micaceous, thinly bedded and cross-laminated in the upper part. The top surface of the sandstone is commonly sharp and planar, forming well-developed dip slopes, as at Close Moss [SE 02 11].

The Marsden Formation (Mar), which in this area corresponds with strata of Marsdenian age, crops out over much of the north-west, south-west, south-east and central parts of the district (Figure 1), notably around Marsden [SE 04 12], Meltham [SE 10 10], Holme Moss [SE 09 04] and Midhope Moors [SK 20 98]. The previous survey (Bromehead et al., 1933) used the term 'Middle Grits' for the succession broadly equivalent to the Marsden Formation (Figure 6). The formation comprises sandstone, mudstone and siltstone, with a total thickness proved in the district of up to 255 m. The main marine bands of the Marsdenian Substage have been recognised in the district (Figure 4).

The Bilinguites gracilis Marine Band (R_2a1) marks the base of the Marsden Formation (Figure 4) and the section of this marine band at Park Clough [SE 030 125], west of Marsden, is the proposed stratotype of the Marsdenian Regional Substage (Cleal and Thomas, 1996; Ramsbottom, 1981). It is typically underlain by a seatearth clay and thin coal. The marine band (1.5 to 4 m thick) consists of dark grey, finely laminated mudstone with Bilinguites gracilis, and with the bivalves Dunbarella and Posidoniella commonly present near the top and base. The diagnostic ammonoid for this marine band, B. gracilis, was described for the first time by Bisat (1924) from a section at Rake Dike [SE 100 052], near Holme, who named it Reticuloceras reticulatum mut. α. Above the marine band a mudstone-dominated succession 20 to 30 m thick commonly forms concave slopes below the scarp feature of the overlying sandstone. The Bilinguites bilinguis Marine Band (R_2b1) occurs about 10 m above the top of the Bilinguites gracilis Marine Band, in the north-west of the district. The marine band was described as containing Reticuloceras reticulatum 'early β' forms (Bromehead et al., 1933), now known as the diagnostic ammonoid B. bilinguis. The overlying mudstone succession is broadly upwards-coarsening with an increase in abundance and thickness of siltstone and sandstone beds.

The Readycon Dean Flags (RDF) and East Carlton Grit (EC) are now interpreted as belonging to a single fluviodeltaic system, underlying the Bilinguites bilinguis Marine Band (R_2b2) (Brettle et al., 2002). The name Readycon Dean Flags is generally restricted to finer-grained sandstones, interpreted as distal mouth-bar deposits, while the overlying coarser-grained proximal mouth-bar and fluvial channel deposits of the same river system are referred to the East Carlton Grit. In this part of the Marsden Formation, fine-grained sandstone beds comprising over about 30 per cent of the strata are assigned to the Readycon Dean Flags, which commonly forms prominent escarpments. The thickness and number of its component leaves are very variable, and it locally dies out, as at the west side of Pule Hill [SE 033 105]. A succession of sandstone and siltstone 85 m thick present in the Woodhead Tunnel No. 1 Shaft (Figure 6) is attributed to this unit. It extends as far south as Langsett Moors [SK 183 996] but is absent in the south of the district; an area formerly mapped as Readycon Dean Flags north of Glossop [SK 03 95] (Bromehead et al., 1933) is now reinterpreted as Fletcher Bank Grit. A coarse-grained facies is present in the upper part of the Readycon Dean Flags in a few places between Holmbridge [SE 110 073] and Langsett Moors [SK 16 99], but insufficient information is available to allow this to be distinguished as East Carlton Grit. As a whole, this part of the succession represents a major deltaic complex that advanced from north to south, reaching its southern limits across the central part of the district.

The mudstone-dominated succession above the Readycon Dean Flags and East Carlton Grit is about 20 to 30 m thick, and includes the Bilinguites bilinguis Marine Band (R_2b2) at the base. The succession is capped by one or other of three sandstones of equivalent age, the Midgley Grit, Heyden Rock and Fletcher Bank Grit (Figure 7). The Midgley Grit and Heyden Rock probably represent deposits from two distinct distributaries of the same river system. The Midgley Grit (MgG), formerly referred to as the Pule Hill Grit (Bromehead et al., 1933), forms prominent escarpments in the north-west and central parts of the district, including Pule Hill [SE 033 105]. A Lingula band in a mudstone parting within the Midgley Grit at Bradley Brook [SE 080 127], north-west of Meltham, approximately 20 m above the base of the sandstone, is interpreted to be the Bilinguites eometabilinguis Marine Band (R_2b4) (Addison et al., 2005a). Within the district, the Midgley Grit shows a broadly southward-fining trend, from coarse-grained and locally pebbly, with large-scale foresets, in the north around Pule Hill, to fine- to medium-grained around Heyden Brook [SE 09 03]. Palaeocurrent flows were directed towards the south at both localities (Figure 6) and (Figure 7). In the latter section, the lowermost 25 m of the Midgley Grit includes a fine-grained, turbiditic sandstone facies, not observed further to the north. The Midgley Grit contrasts markedly with the Heyden Rock (HR), which is typically coarse-grained and pebbly, with palaeocurrents directed towards the west. The boundary between the two sand bodies is now considered to occur much further to the south than determined by Bromehead et al. (1933), and as a result the former type section of the Heyden Rock, at Heyden Brook, is now interpreted to lie in the Midgley Grit (Figure 6) and (Figure 7). The Fletcher Bank Grit (FB), which occurs in the west of the district, was also previously mapped as Pule Hill Grit (Bromehead et al., 1933). The name Fletcher Bank Grit is now used for this sandstone throughout Lancashire, including the Manchester district (Crofts et al., 2012), and replaces the term Gorpley Grit, formerly used in parts of north Lancashire. Limited data indicate that the grade of the Fletcher Bank Grit ranges up to coarse-grained sand, with palaeocurrent flow towards the south-east. These palaeocurrents are sufficiently distinct from those of the Midgley Grit to suggest that the two sandstones should continue to be separately named (Figure 7). The absence of strata of this interval between Lees Hill [SK 009 993], near Hollingworth, and Sliddens Moss [SE 07 03] prevents any resolution of the relationship between these two sand bodies in this district.

Immediately above the Midgley Grit, in the Marsden area, is a seatclay and an unnamed coal 0.1 m thick. The Bilinguites metabilinguis Marine Band (R_2b5) lies near the base of about 9 to 12 m of succeeding mudstones. This marine band appears to be absent further to the south, in the vicinity of Holme Moss, but may be represented by a Lingula band in one section, in West Withins Clough [SE 107 021].

The Guiseley Grit (G), formerly referred to in this district as the Beacon Hill Flags (Bromehead et al., 1933), forms prominent escarpments in the north of the district, notably to the north-east of Pule Hill [SE 035 110]. The lower part of the sandstone comprises mainly fine-grained flaggy sandstones, whereas the upper part is dominated by ganisters, which were formerly worked. The Lower Meltham Coal (LM) is present locally in the Meltham area [SE 087 090] to [SE 100 100] between the flaggy sandstone and the ganister (Bromehead et al., 1933). In the north-west of the district, around Delph [SD 98 08], the sandstone is about 9 m thick, predominantly ganisteroid and extensively quarried. The Guiseley Grit thins southwards, and in the west of the district it appears to be absent south of Uppermill [SD 98 07]. In the central area it thins over the Holme High, and around Holme Moss [SE 09 04] is too thin to map, but it reappears to the south near Withens Edge [SE 11 02], with prominent features around Pike Lowe [SK 21 97]. The succession represents a major deltaic complex that advanced from north to south, reaching its southern limit close to the south-east corner of the district, near Broomhead Reservoir [SK 26 96].

In the north of the district the mudstone overlying the Guiseley Grit is about 25 m thick and includes the Bilinguites superbilinguis Marine Band (R_2c1) at the base. This mudstone-dominated succession thins southwards to about 15 m at Holme Moss, concomitant with the decrease in thickness of the underlying Guiseley Grit. The Verneulites sigma Marine Band (R_2c2) occurs between 1 and 3 m above the Bilinguites superbilinguis Marine Band (Waters et al., 2008).

The Huddersfield White Rock (WR) forms prominent escarpments around Meltham [SE 10 10], Holme Moss [SE 09 04], Thurlstone Moor [SE 17 01] and Ewden Height [SK 23 98]. The sandstone is typically fine- to medium-grained and of mouth-bar facies, characterised by ripple cross-lamination and cross-bedding, with palaeocurrents towards the west, in the north of the district, and south-west, in the central part of the district (Waters et al., 2008). The upper part of the sandstone is typically ganisteroid. The sandstone is also present in the south-west of the district, near Glossop, occurring as two leaves separated by a mudstone-dominated succession about 30 m thick, which is well exposed at Mouselow Quarry (Plate 4). The upper leaf is typical of the mouth-bar facies. The lower leaf consists of thin- to very thick-bedded, internally massive sandstones deposited from density currents on the delta slope, with palaeocurrents towards the south-south-west. The succession represents a major deltaic complex that advanced from east to west across the region, with the comparatively deeper water deposits limited to the lower part of the succession in the south-west of the district (Waters et al., 2008). In the west of the district, the Huddersfield White Rock comprises a fine-grained sandstone with rooted palaeosol horizons, and was previously mapped as the Holcombe Brook Grit (Bromehead et al., 1933). However, the Holcombe Brook Grit of the type area (near Ramsbottom, west of the present district) is now considered to belong to a separate, slightly younger, delta lobe of the same river system (Waters et al., 2008), so the name is not applied to the sandstone here.

The Upper Meltham Coal (UM) occurs immediately above the Huddersfield White Rock. Thickness variations in the district are detailed by Bromehead et al. (1933). It is thickest in the Meltham area [SE 10 10], where it was formerly worked from bell pits and shafts. Further south, in a section exposed at Winscar Reservoir [SE 152 030] (Plate 5), it has probably thinned to nothing, its horizon lying between a prominent ganister and overlying thick shale. The Cancelloceras cancellatum Marine Band is assumed to lie unexposed a short distance above. An underlying coal is unnamed. In the west of the district, the Holcombe Brook Coal (HBC), or its likely equivalent to the south of Glossop, the Simmondley Coal (SC), overlies the Huddersfield White Rock. The base of the Rossendale Formation (Ros) is defined at the base of the Cancelloceras cancellatum Marine Band (Gla1). It is overlain by 35 to 45 m of mudstone, broadly thinning towards the south. Within this mudstone, the Cancelloceras cumbriense Marine Band (G_lb1) lies some 12 to 25 m above the Cancelloceras cancellatum Marine Band, the intervening thickness increasing towards the west.

The Rough Rock Flags (RF) crop out on steep slopes below the Rough Rock. Extensively quarried areas of its dip slope are present around Harden Clough [SE 15 03], where local steep dips, as at Cook's Study [SE 131 042], provide evidence of synsedimentary deformation (Bristow, 1988). The base of the Rough Rock Flags is generally gradational from the underlying mudstones, by upward increase in the thickness and frequency of siltstone and sandstone beds. The base is drawn where sandstone beds form more than half the thickness of the section. The top is generally an erosion surface at the base of the Rough Rock but locally, in old quarries [SE 146 041] near Harden Clough, a seatearth capped by an unnamed coal up to 0.6 m thick occurs between the two sandstones. Where it is difficult to define a lower, finer unit, the entire sandstone has been mapped as Rough Rock. It is probable, in some such places, that the Rough Rock Flags are absent (Figure 6), but elsewhere it is poor exposure and lack of topographical character that hinders their recognition. The Rough Rock Flags were deposited in lobate shallow water deltas, with palaeocurrents flowing towards the south and west. Lateral variation in thickness may be attributed, in part, to erosion by fluvial currents prior to the deposition of the Rough Rock (Bristow, 1988).

The Rough Rock (R) is the youngest sandstone of the Millstone Grit Group. It forms prominent escarpments, commonly quarried, with extensive dip slopes at Deer Hill Moss [SE 07 10], Honley [SE 13 11], Hade Edge [SE 15 05] and Midhopestones [SK 24 99]. The sandstone ranges from fine- to coarse-grained, with local scattered quartz pebbles. Cross-bedding is common. A thin coal, the Sand Rock Coal (SR), occurs about 5 m below the top of the Rough Rock in the western part of the district, west of Uppermill [SD 98 06]. The Rough Rock is interpreted as the deposit of a braided river, which in the present district flowed towards the south (Bristow, 1988; Bristow and Myers, 1989; Shackleton, 1962). The top of the Rough Rock was formerly taken as the top of the Millstone Grit (Bromehead et al., 1933). However, the top of the Millstone Grit Group is now regionally defined at the top of the Namurian Regional Stage, which is drawn at the base of the Subcrenatum Marine Band, a few metres above the top of the Rough Rock. The interval between the Rough Rock and this marine band contains the Pot Clay and Pot Clay Coal (PCC) of the eastern part of the district and Six Inch Coal (SI) of the western part. The Pot Clay (up to 1.2 m thick) is a fireclay, the seatearth to the coal.

Key localities

• Shale Grit: Hunters Hill road cutting [SE 005 092]
• Grindslow Siltstones: Shire Hill Quarry [SK 054 944]
• Lower Kinderscout Grit: Buckton Quarry [SD 991 016]
• Butterly Marine Band: Butterley Reservoir [SE 049 105]
• Upper Kinderscout Grit: Standedge road cutting [SE 023 097]
• Bilinguites gracilis Marine Band: Hey Green, Marsden [SE 030 124]
• Readycon Dean Flags: Alison and Bingley Quarries, Digley Reservoir [SE 109 073], [SE 110 073]
• Bilinguites bilinguis Marine Band: Pule Hill [SE 032 101]
• Midgley Grit: Pule Edge Quarry, Pule Hill [SE 032 108]
• Heyden Rock: Greystone Edge Quarries [SE 123 005]; Loftshaw Brook [SK 166 998]
• Fletcher Bank Grit: River Tame [SD 974 011]
• Guiseley Grit: Lower Windleden Reservoir [SE 156 017]; Cabin Clough [SK 164 999]
• Bilinguites superbilinguis Marine Band: Mark Bottoms Dike [SE 140 089]: Black Dike [SE 079 054]
• Verneulites sigma Marine Band: Black Dike [SE 079 054]
• Huddersfield White Rock: Deer Stones, Upper Heyden [SE 097 033] (delta-top);
• Mouselow [SE 025 952] to [SE 026 950] (delta-slope)
• Upper Meltham Coal: Honley Wood Bottom [SE 120 122]Cancelloceras cancellatum Marine Band: Meltham Cop, Meltham [SE 095 122]
• Cancelloceras cumbriense Marine Band: Snailsden Pike End [SE 127 034]
• Rough Rock Flags: Low Edge Quarries, Harden Clough [SE 146 041]
• Rough Rock: Shooters Nab, Deer Hill Moss [SE 062 108]; Low Edge Quarries, Harden Clough [SE 146 041]
• Pot Clay Coal: Little Don River, Langsett [SE 223 003]

Westphalian

The Westphalian Regional Stage (formerly Epoch), represented by the Pennine Coal Measures Group, is divided on the basis of marker bands into four substages, of which the lower two are present in the district (Figure 4). The base of the Subcrenatum Marine Band defines the base of the Langsettian (Westphalian A) Substage and the Pennine Lower Coal Measures Formation; the base of the Vanderbeckei Marine Band defines the base of the Duckmantian (Westphalian B) Substage and the base of the Pennine Middle Coal Measures Formation (Stubblefield and Trotter, 1957). Biostratigraphical classification is based on marine marker bands and on nonmarine bivalve zones (Calver, 1968). The Pennine Lower Coal Measures are up to 600 m thick, with the lowermost part of the succeeding Pennine Middle Coal Measures, of which only 18 m are recorded in the district, present in the extreme north-east.

Bromehead et al. (1933) provided a valuable account of the Coal Measures in the district, with information on rock exposures that are no longer visible, and details of mineral workings (coal, fireclay, brick clay, sandstone) that were active at the time of their survey. However, the stratigraphical succession as understood by these authors has been amended during the recent geological resurvey.

Pennine Coal Measures Group

The Pennine Coal Measures Group consists of interbedded grey mudstone, siltstone, sandstone, seatearth and coal, with some ironstone and rare tonstein, arranged in cyclic units (cyclothems), as seen in the underlying Millstone Grit Group. However, within the Pennine Coal Measures Group the cycles are typically thinner, marine bands are less frequently developed and commonly lack fully marine ammonoid faunas, sandstones are thinner and typically finer grained, and coals are more common and generally thicker than within the Millstone Grit Group.

The Pennine Coal Measures Group crops out over the north-eastern part of the district, forming part of the East Pennine Coalfield, and in small areas in the west and south-west of the district, in the extreme eastern part of the South Lancashire Coalfield (Figure 1). The succession was deposited in fluvial and lake environments, with periodic flooding by the sea (Guion and Fielding, 1988). Coal seams developed from peat beds that formed in these poorly drained low-lying environments. The thickest seams, from the Whinmoor to the Joan coals, occur within the upper part of the Pennine Lower Coal Measures Formation. Recent work has shown that the large river systems that transported the clastic sediments into the Pennine region drained widely separated source areas, which had different palynological, geochemical and heavy mineral signatures (Chisholm et al., 1996; Hallsworth and Chisholm, 2000; Hallsworth et al., 2000; Leng et al., 1999). These differences have allowed the shifts of provenance to be identified through the succession.

Westphalian sandstones commonly form positive, mappable, topographical features and are thus distinguished individually on the map (Figure 8). They consist mainly of subangular to subrounded quartz and feldspar, with variable mica content. The grain size is generally very fine to medium, with minor coarse-grained and conglomeratic units occurring locally. The sandstones are grey when fresh, but commonly weather to yellowish brown. Many sandstone units have erosional bases. Sedimentary structures include planar lamination, ripple lamination, cross-bedding and massive bedding. Coalified plant fragments are common on bedding surfaces. Siltstones are typically medium grey, parallel-laminated and ripple cross-laminated, and contain plant debris. They grade both vertically and laterally into sandstones and mudstones and are commonly intimately interbedded with both. The sandstones and siltstones relate to a variety of fluvial environments of deposition including distributary channels, crevasse splays and channels, overbank flood basins and lacustrine delta fronts (Guion and Fielding, 1988). Coarsening-upwards sequences generally indicate minor deltas.

The mudstones are generally grey to black, varying from massive to fissile and weather to a stiff, orange-brown mottled grey clay. Some beds contain nonmarine bivalves. Nodules of sideritic ironstone are common, ranging in size from a few millimetres up to 0.5 m, commonly nucleated around fossil remains, and developed in lacustrine environments. Mudstones were deposited in a number of environments including lakes and fluvial overbank or interdistributary bay areas; they are also interbedded with the coarser lithologies or form part of coarsening-upwards sequences.

Marine bands (Figure 4) are beds of black mudstone with a marine fauna, generally occurring close above a coal or a seatearth. They are normally a few centimetres thick but in rare instances attain thicknesses of several metres in the present district. They commonly grade upwards into grey-black mudstones with a nonmarine fauna. The marine bands are recognised across large areas and are important, isochronous, marker horizons. Eight Westphalian marine bands are recognised in the district. Some contain restricted faunas of foraminifera, conodonts, the brachiopod Lingula, or marine bivalves, but three (the Subcrenatum, Listeri and Vanderbeckei marine bands) contain rich faunas with ammonoids diagnostic of their particular horizon.

Seatearth is the name given to a fossil soil profile (palaeosol) that commonly underlies a coal seam. Seatearths may be useful for correlation as they indicate a period of subaerial emergence. They are developed in various lithologies and are characterised by the presence of rootlets. In general, the soil-forming processes have disrupted primary sedimentary structures. Where developed in sandstone, seatearths include compact quartzites termed 'ganisters'.

Coal seams (Figure 9) are numerous, and some can be traced over long distances. They vary laterally in thickness and composition, chiefly by variation in the number of 'dirt' (non-coal, siliciclastic) partings present within the seam. Where such partings are present, the separate coals, known as leaves, may be individually named. Individual leaves or entire seams commonly die out laterally.

The Pennine Lower Coal Measures Formation (PLCM) can be divided into a number of cyclic units (cyclothems) that have been traced throughout the central and south Pennine region (Aitkenhead et al., 2002); the boundary between any two cyclothems is taken at the top of a coal (or seatearth if coal is absent). The cyclic successions may represent lake-fill deposits, with accommodation space resulting from compaction-induced subsidence. However, those that include a marine band at the base are in part a product of sea level rise. In Yorkshire, the cycles have been named informally after prominent beds within them (Chisholm et al., 1996; Waters et al., 1996; Wilson and Chisholm, 2004).

The lowest part of the formation, from the base of the Subcrenatum Marine Band to the horizon of the 80 Yard Coal, has many marine bands and relatively thin coal seams (Figure 9) and (Figure 10). The main coals and marine bands are shown on the map (Figure 4) and (Figure 9); Sheet 86, generalised vertical section). Within this succession, the sediments were derived mainly from a northern terrain that was also the source of the sediments of the Millstone Grit Group.

The Subcrenatum Marine Band (SMB) marks the base of the Pennine Lower Coal Measures Formation; the section of this marine band in the banks of The Porter or Little Don [SE 2215 0041], south of Langsett, is the proposed stratotype of the Langsettian Regional Substage (Cleal and Thomas, 1996; Ramsbottom, 1981).

The lowest cyclic unit is the Soft Bed cycle (up to 35 m thick). It includes the Soft Bed Flags (SBF) and overlying Soft Bed Coal (SB). The fine-grained, micaceous sandstones of the Soft Bed Flags are present across the north-eastern part of the district, but are seen to fail near to Hazlehead [SE 199 024]. The Crawshaw Sandstone, which includes coarser-grained beds, is present at the equivalent level to the south in much of the East Midlands, but it does not extend into the present district. The Soft Bed Flags are interpreted as a deltaic complex that migrated from north-east to south-west, whereas the Crawshaw Sandstone delta migrated from east to west (Guion and Fielding, 1988). The Woodhead Hill Rock (WHR), present in the west of the district, is a coarser-grained sandstone comparable to the Crawshaw Sandstone, of which it may be the basinward equivalent. The Bassy Coal (B), which overlies the Woodhead Hill Rock, is the Lancashire Coalfield equivalent of the Soft Bed Coal of the East Pennine Coalfield.

The Middle Band cycle (up to 30 m) includes mudstone with two thin marine bands, overlain by a thin sandstone, the Middle Band Rock (MBR), and the overlying Middle Band Coal (MB). The Springwood Marine Band is locally recorded about 10 m below the Middle Band Coal, but the Holbrook Marine Band, which normally lies a few metres lower, has not been recorded in the district (Figure 10). Within the district, the southern limit of the Middle Band Rock is at Langsett [SE 226 004], although this sandstone reappears to the south-east in the Barnsley district (Hough et al., 2007).

The overlying Hard Bed cycle (up to 20 m), capped by the Hard Bed Coal (HB), is regionally notable for the rarity of sandstones, though a thin unnamed bed is locally developed around Penistone (Figure 10). The Honley Marine Band is a Lingula band in the immediate roof of the Middle Band Coal; its type locality is in a railway cutting [SE 1445 1263] near Honley (Bromehead et al., 1933; Ramsbottom et al., 1978). The Hard Bed Coal and underlying ganister have been extensively worked in the district, both in underground mines and at opencast sites (Plate 6).

The base of the Stanningley cycle (37 to 55 m) is readily recognised by the presence of the Listeri Marine Band, overlain by nonmarine mudstones and capped by the Stanningley Rock (SR) (Plate 6) and overlying 36 Yard Coal (36Y). A further marine band, the Parkhouse Marine Band, is locally found about 10 m above the Listeri Marine Band. The southern limit of the Stanningley Rock in the district is at Langsett [SE 227 005]. Near Stocksbridge, in the south-east of the district, the cycle includes a thin representative of the Loxley Edge Rock (LxR), which in the Barnsley district to the east, developed as a thick, coarse-grained sandstone (Hough et al., 2007).

The 48 Yard cycle (14 to 25 m), with the Meadow Farm Marine Band locally recorded at the base (Figure 10), and overlying 80 Yard cycle (15 to 32 m), are comparatively difficult to map, due to an absence of coal workings to delineate the positions of the 48 Yard Coal (48Y) and 80 Yard Coal (80Y) and the thin and intermittent development of the sandstones, the 48 Yard Rock (48YR) and 80 Yard Rock (80YR) (Figure 8) and (Figure 10). In the south-east of the district, near Stocksbridge, a thin development of the Wharncliffe Rock (WhR) is present in the 80 Yard cycle. It thickens and becomes coarse-grained in the Barnsley district (Hough et al., 2007).

The succession between the 80 Yard Coal and the Better Bed Coal is notable for its sandy nature and paucity of coal seams and marine bands (Figure 10). Difficulties in correlating the succession, due to this rarity of marker beds, resulted in several miscorrelations by Bromehead et al. (1933), which have been resolved by provenance studies (Chisholm et al., 1996; Hallsworth and Chisholm, 2000; Hallsworth et al., 2000; Leng et al., 1999). The succession is now known to consist of three sedimentary cycles: in upward sequence they are the Elland cycle, the Greenmoor cycle, and the Grenoside cycle. Their regional variations are summarised by Hallsworth and Chisholm (2008). Sandstones in the lowest cycle are called Elland Flags, and are prominent in the Bradford and Huddersfield districts to the north (Addison et al., 2005b; Waters, 2000). They pass southwards into mudstone, so are absent from the present district. The Greenmoor Rock sandstones, which are widespread in the present district, lie in the second cycle. They were correctly named 'Greenmoor Rock' by Bromehead et al. (1933), but incorrectly regarded by them as synonymous with the 'Elland Flags'. Sandstone in the third cycle is called Grenoside Sandstone. This was correctly named by these authors but was thought to lie above, rather than below, the Black Bed Coal, so was miscorrelated with a higher bed now called Kirkburton Sandstone. It was also thought that the Better Bed Coal lay immediately above the Greenmoor Rock, whereas this seam actually occurs higher up, above the Grenoside Sandstone.

The Elland cycle (18 to 21 m) consists entirely of grey to dark grey mudstone. The Greenmoor cycle (80 to 95 m) contains fine-grained sandstone of western provenance, the Greenmoor Rock (GM), and is distinguished by weakly micaceous lithologies with a greenish grey colour.

The Grenoside cycle (30 to 44 m) contains medium-grained sandstone of northern provenance, the Grenoside Sandstone (GR), which was transported into the area from the east. Sediments in this cycle are distinguished from those of the Greenmoor cycle by their generally micaceous lithologies and lack of greenish grey colour. The Better Bed Coal (BB) at the top of the Grenoside cycle is comparatively thin within the present district (Figure 9) and has been of little economic importance.

In the strata between the Better Bed Coal and Whinmoor Coal, marine bands are absent (Figure 10) and individual upward-coarsening units are of limited extent. Coals are more common than in the beds below, though generally thin, and seam splits are common at some levels. The stratigraphical positions of the impersistent Lower Penistone (LPC) and Penistone Green (PGC) coals are, as a result, difficult to determine. The former may correlate with the Black Bed Coal of districts to the north. Most of the clastic sediment forms a series of lenticular sandstones collectively known as the Penistone Flags (PF), with the Kirkburton Sandstone (K) limited to the extreme north of the district at Kirkburton [SE 20 13]. The top of the Penistone Flags was drawn by Bromehead et al. (1933) below the Cumberworth Thin Coal (CT), but during the current resurvey the upper limit has been drawn slightly higher, below the more laterally extensive Whinmoor Coal, as by Green et al. (1878).

The Beeston Group of Coals is loosely defined as a plexus of seams spread through some 40 m of strata, and derived by a complex series of splits from the thick Beeston Coal of the Leeds area to the north-east (Lake, 1999). In the Glossop district, it includes the Whinmoor Coal (W), the Black Band Coal (BD) and the Top Lousey Coal (TL), located beneath the Low 'Estheria' Band, a 10 cm-thick dark grey fissile mudstone with the small branchiopod crustacean 'Estheria', which is an important regional marker horizon.

The Blocking Coal (Bk), which lies above the Low 'Estheria' Band, was formerly taken as the boundary between the Lower and the Middle Coal Measures in the district (Bromehead et al., 1933). The seam is persistent but its thickness decreases southwards from 43 cm in the north of the district to about 8 cm round Clayton West [SE 25 11] (Bromehead et al., 1933), an example of the regional lateral changes associated with the Holme Fault. It correlates with the Top Silkstone Coal of South Yorkshire (Hough et al., 2007).

The measures between the Blocking Coal and the Joan Coal are up to 135 m thick. Correlations of coals in this interval implied by Bromehead et al. (1933) have now been confirmed. Above the Blocking Coal, the Falhouse Rock (FR) is very variable in thickness and number of leaves. The Wheatley Lime Coal (WL) caps the interval that includes the Falhouse Rock and the locally developed Middleton Eleven Yards Coal, and was worked over much of the district. The Wheatley Lime Coal is the equivalent of the Silkstone Four Foot of the Barnsley district to the east (Hough et al., 2007). The measures above the Wheatley Lime Coal include the Middleton Main Coal (MM), a widespread and consistently developed coal of former economic importance (in places known as the New Hards Coal), and the Middleton Little Coal (ML), locally called Green Lane Coal. Sandstones within this interval are unnamed and laterally impersistent.

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 (LER), overlain by a group of three coals, the Third, Second and First Brown Metal coals (3BM, 2BM and 1BM) and the Birstall Rock (BR). The term Birstall Rock has been applied to any sandstone that overlies any or all of the Brown Metal coals. Downcutting beneath the Birstall Rock has locally resulted in washout of the two upper coals of the group. The Flockton Thin Coal (Fn) caps the interval that includes the Brown Metal coals and the Birstall Rock.

The roof of the Flockton Thin Coal generally consists of fissile mudstone, overlain by the Emley Rock (ER), which forms much of the succession below the Flockton Thick Coal (Fk). The Tankersley Ironstone (TI) forms the roof measures of the Flockton Thick Coal within the district. The interval is capped by the Joan Coal (J), a thin but widely developed seam of poor quality.

About 18 m of the Pennine Middle Coal Measures Formation (PMCM) crop out on the extreme north-eastern margin of the district, near Emley (Figure 1). The base of this formation, and of the Duckmantian Substage (Westphalian B), is defined as the base of the Vanderbeckei (Clay Cross) Marine Band (VMB) (Figure 4). This band is developed in the mudstone that immediately overlies the Joan Coal. Bromehead et al. (1933) took the base of the Middle Coal Measures at the Silkstone (or Blocking) Coal, well below the Vanderbeckei Marine Band. The lowest cycle of the formation, and the only one present within the district, includes the Thornhill Rock (TR), which consists of a single leaf around White Cross [SE 257 127]. No coal seams are recorded within this part of the succession.

Key localities

• Subcrenatum Marine Band: Little Don River, Langsett [SE 223 003]
• Soft Bed Flags: Stream section, east of New Mill [SE 1697 0850]
• Woodhead Hill Rock: High Moor Quarry, Uppermill [SD 973 066]
• Middle Band Rock: Stream section, east of Brockholes [SE 158 107]
• Middle Band Coal: Railway cutting 200 m north-west of Honley Station [SE 144 126]
• Honley Marine Band: Railway cutting 200 m north-west of Honley Station [SE 144 126]
• Hard Bed Coal, Listeri Marine Band and Stanningley Rock: Middlecliffe Clay Pit, Crow Edge opencast workings [SE 196 043] (Plate 6)
• 36 Yard Coal: Stream below Fulstone Hall [SE 1700 0889]
• 80 Yard Rock: Old quarry and waterfall near Holme House Wood [SE 1751 0815]
• Greenmoor Rock: Hullock Bank [SE 1740 0750]
• Grenoside Sandstone: Old quarry, Bird's Edge [SE 201 080]; old railway cutting, Thurlstone [SE 232 032]
• Penistone Flags: Railway cutting, Skelmanthorpe (Kirklees Light Railway) [SE 217 106] to [SE227 110]; river cliff, Scissett [SE 248 101]
• Kirkburton Sandstone: Ravine, Kirkburton [SE 1996 1241]
• Cumberworth Thin Coal: Bromley Farm Opencast [SE 215 089]
• Whinmoor Coal: Bromley Farm Opencast [SE 215 089]
• Black Band Coal: Stream bed west of Lower Cumberworth [SE 214 096]
• Top Lousey Coal and Low 'Estheria' Band: Stream section, Nineclogs Dike [SE 240 116]

Quaternary

Quaternary events in the central Pennine region have been summarised by Aitkenhead et al. (2002). At least two glaciations affected the region, the Anglian (about 450 000 years before present) and the Devensian (about 26 000 years before present), which produced suites of sediments previously termed 'Older Drift' and 'Newer Drift', respectively. Later deposits, laid down during the Flandrian climatic amelioration (10 000 years ago to present), include peat mosses and the alluvium of the river systems.

In the present district, a significant area in the west was affected by the Devensian glaciation, and deposits of glacial till, sand and gravel were deposited there. A prominent buried palaeochannel extending to the south-south-west of Mottram in Longdendale [SD 99 96] may represent a dominant southward drainage direction immediately prior to the advance of a Late Devensian ice-sheet into the Manchester embayment (Crofts et al., 2012). Pre-Devensian deposits may exist beneath the mantle of Late Devensian till and glaciofluvial deposits. The central and eastern parts of the district are thought to lie south and east of the Devensian limit (Aitkenhead et al., 2002), however, and periglacial permafrost conditions prevailed there, withdevelopmentofhead(solifluction deposits) and landslide deposits. Deposits related to the earlier, Anglian, glaciation could be present in places here, especially beneath Devensian or later deposits, but none has been positively identified.

The climatic oscillations during the Quaternary caused significant changes in sea level, which produced successive phases of fluvial incision and aggradation. A period of rapid incision in Late Devensian times was followed by a rise of sea level during the Flandrian Stage, when thick sequences of alluvial deposits were laid down in the previously incised channels. The deposits that occupy the fluvial channels are almost certainly composite in origin. These various sediments were subject to subsequent incision and recycling during the formation of terrace deposits.

Till deposits, representing the material eroded, transported and deposited directly from the Late Devensian Irish Sea ice-sheet, are restricted to the valley bottoms and lower slopes of the western part of the district. Up to 15 m thickness has been recorded in boreholes south-south-west of Mottram in Longdendale. The till typically comprises poorly sorted stiff, red-brown, sandy clay with varying proportions of pebbles, cobbles and boulders, mainly of Carboniferous and Triassic sandstones. The deposits tend to be sandier where they thin towards upland areas. Minor amounts of far-travelled 'exotic' clasts also occur, including examples from the Lake District, typical of Devensian deposits brought by Irish Sea ice. These erratics may be 1 m or more in diameter. Beds of sand, gravel and soft laminated clays have been recorded in boreholes within the till deposits (Smart et al., 1978).

Glaciofluvial deposits are represented by thin sandy gravels with a variable content of finer-grained materials (including interbedded silts) that are found in parts of the west of the district, typically overlying till. Near to Hattersley, approximately 7.5 m of sand has been proved in a borehole [SJ 9840 9536], passing down to till deposits of gravelly silty clay with beds of sand. The glaciofluvial deposits are thought to derive ultimately from the outwash of the Late Devensian glaciation, with broadly flat-topped deposits mapped as glaciofluvial sheet deposits. Some of the lower-lying isolated patches may relate to the earlier (Anglian) glaciation, but this remains to be confirmed. Glaciofluvial ice contact deposits can be distinguished from sheet deposits where the surface is irregular or moundy. Small areas of uncertain glaciofluvial origin have been mapped as glaciofluvial deposits (undifferentiated). The clast content is generally dominated by Carboniferous sandstones, with some exotic material.

The few patches of river terrace deposits in the district, typically comprising sand and gravel, are restricted to the valleys of the Don [SE 207 029], Dearne [SE 253 112] and Dinting Vale [SK 013 953] to [SK 060 947], possibly relating to two periods of aggradation. Many of the undifferentiated and first river terraces occur between 1 and 3 m above the present-day alluvial flat. The second river terrace at Hadfield [SK 020 965] and Brookfield [SK 013 953] occurs about 5 to 6 m above the floodplain of the River Etherow. Alluvial fan deposits have been mapped where deposits of gravelly or clayey sand and gravel have debouched from a minor tributary valley. Good examples are evident in Longdendale, with deposits at the mouth of Torside Clough [SK 065 980] exceeding 20 m thickness (Smart et al., 1978). Modern streams tend to incise the fan deposits.

The floodplains of the major rivers and their tributaries are underlain by alluvium, which has two distinct components, together up to 4 m thick in the major valleys, such as the Etherow valley. The upper part of the deposit consists of soft to firm silt and clay, mottled brown and grey. Locally, organic peat-rich horizons may be present, in part derived from erosion of upland peats. Commonly, there is a sand or gravel component, which increases downwards. The lower part of the deposit comprises fine- to coarse-grained sands and angular to rounded, fine- to coarse-grained gravels in varying proportions; a variable clay content is also present. At many urban locations, the soft upper part of the alluvium has been removed prior to the construction of foundations and commonly has been replaced by fill material.

Spreads of solifluction material and hillwash (together classified as head) mantle the lower flanks of most valleys, the floors of some small tributary valleys and some of the isolated cols. However, these deposits are generally difficult to delineate in any consistent fashion and are shown on the map only where their presence is unmistakeable. Typically, the composition of these deposits reflects that of the parent materials upslope and commonly is of angular sandstone fragments in a matrix of sandy clay or clayey silt. A thickness of 2 to 4 m is thought to be fairly typical for the major developments of head. Such deposits are commonly thicker on north- and east-facing slopes. Locally, the head may represent mudflow deposits that developed at the toes of landslides.

An extensive covering of peat, commonly several metres thick, is developed on high ground across the district, most extensively in an area extending from Standedge [SE 02 10], in the north-west, to Saddleworth Moor [SE 03 06], Black Hill [SE 07 04], Bleaklow [SK 10 96] and Broomhead Moor [SK 21 95] in the south-east. It is particularly, though not exclusively, associated with areas underlain by the Hebden Formation (Figure 1) and (Plate 1). Smaller areas of peat have accumulated in hollows within areas of landslide deposits, for example on the south side of Longdendale to the south of Woodhead and Torside reservoirs. A poorly drained upland peat deposit is commonly referred to as a 'Moss' on topographical maps. Much of the upland peat areas are being actively eroded by streams and wind. Blockfield deposits, or felsenmeer, have been described from near the summit of Pike Lowe [SK 210 973] and nearby north-east-facing slopes. The blockfields are surfaces covered by rock debris derived largely from weathering of the underlying Millstone Grit Group sandstones under periglacial conditions.

Superficial structures

The bedrock strata are thought to be affected locally by the processes of cambering and valley bulging. Cambering may occur where sandstone caps the higher ground and overlies mudstone. The softer mudstone is squeezed out laterally, causing the capping unit to drape down towards the valley, sometimes with consequent fracturing to form dip-and-fault structure. Fissures between the individual blocks may be filled with superficial deposits, or remain as open voids. A related process, involving lateral pressures on mudstone in the valley-floor, may result in the formation of locally faulted anticlinal structures or valley bulges, which are characteristically expressed in poorly exposed stream beds by steep dips unrelated to the wider bedrock structure. Such features are probably more common in the more deeply incised valleys and formed in response to rapid erosion and downcutting during the Pleistocene (Johnson, 1980). The bedrock successions in the lower slopes of Longdendale are irregularly fractured and jointed, effects that have been attributed to valley bulging (Smart et al., 1978).

Landslides are common within the district, largely on the steeper slopes associated with the outcrop of the Millstone Grit Group. Many of the landslides are very extensive and include thick deposits, particularly those present in Longdendale, described by Smart et al. (1978) and Johnson (1980). The landslides of Longdendale all occur on bedrock of the Hebden Formation, and tend to include displacement of thick sandstone successions, similar to that shown in (Plate 7). On the north side of the Longdendale valley, deeply incised tributary valleys tend to have landslides on east-facing slopes, e.g. that of Crowden Great Brook (Plate 1), reflecting the general dip of bedrock strata towards the south-east (Johnson, 1980). The backscarps commonly contain slipped blocks that have moved downslope, but which have not become detached from the scarp, and the main slide deposits are commonly mantled by rock debris derived from rock falls that occurred before the main slip movement (Johnson, 1980), as evident in (Plate 7). Where rockfall deposits have accumulated to a significant extent, they are mapped as talus deposits, e.g. Raven Stones Brow, Saddleworth Moor [SE 038 049]. Rakes Rocks, shown in the left-hand side of (Plate 1), is the backscarp of a translational slide that moved 250 m downslope; the depression at the foot of the scarp contains debris and peat, with pollen indicating infill to have commenced 8000 years ago (Tallis and Johnson, 1980).

A spectacular large landslide, 'Canyards Hills', is located on the south flank of Broomhead Reservoir [SK 25 95]. This is a complex of deep-seated rotational landslides, of which about 1 km² lies within the district. It contains fine examples of subparallel 'ridge-and-trough' features (Plate 8), as well as mudslides, and is a candidate Geological Conservation Review site (Cooper, 2007). The features are believed to result from disruption of the sliding mass during a single movement, with pre-existing joints in the Huddersfield White Rock probably controlling the nature of the break-up (Cooper, 2007).

Landslides have resulted from extensive erosion during the Pleistocene and Flandrian, at times of dramatic climatic variation. This ranges from extreme cold during the Late Devensian, when the central and eastern parts of the district were located just outside of the ice front, to strong pluvial activity at times during the Flandrian.

Artificially modified ground

Artificial deposits have been delineated during field survey, and by examination of archival topographical maps, aerial photographs and site investigation data. Only the more obvious areas of modified ground can be mapped by these methods, and the boundaries shown at 1:10 000 scale may be imprecise; further generalisation of the boundaries of these deposits may have taken place during compilation of the 1:50 000 Series geological map.

Made ground includes artificially raised ground, such as quarry spoil tips, landfill sites developed on natural ground, and embankments. Typically, small areas of colliery spoil are present in the north-east of the district, on the outcrop of the Pennine Coal Measures Group. Construction in urban areas commonly takes place on compacted rubble and fill.

Worked ground represents open excavations from which natural material has been removed, such as areas of mineral extraction at quarries, and road and railway cuttings.

Infilled ground is mapped where the ground surface has been excavated and partly or wholly backfilled. Mineral excavations, notably opencast mining operations and quarries, have commonly been filled with spoil or imported waste. Where such excavations have been restored there may be no surface indication of the extent of the backfilled void, and boundaries shown on the map are necessarily based on documentary evidence.

A further two categories of artificially modified ground have been mapped at 1:10 000 scale but not shown on the 1:50 000 Series map for reasons of clarity. These include disturbed ground (which includes areas of bell-pitting for coal or ironstone) and landscaped ground, which includes areas of shallow cut-and-fill, for example in industrial estates or sports grounds.

Structure

The Glossop district lies across the central Pennines, where there is a pronounced contrast between the structural styles to east and west of the 'Pennine Line' (Aitkenhead et al., 2002, fig. 35; Kirby et al., 2000), a structure variably observed as a north–south-trending monocline or anticline. Generally, to the east of this line gentle regional dips towards the east and north-east prevail; to the west of it the structure is more complex, with north– south-trending folds and steeper dips. The west of the Glossop district is dominated by structures subparallel to the Pennine Line. In the north-west of the district a north-north-west-trending anticline, the southern extent of the Pennine Anticline, is evident, with the fold hinge cut through by the Castleshaw Fault (Figure 1). This fold overlies a reversed fault that affects the basement (Kirby et al., 2000, p.60 and fig. 36). Farther south the Pennine Line is represented by the north–south-trending Tame Fault (Figure 1), (Figure 3) and (Figure 11), which throws down to the west. In the hanging wall, strata dip steeply towards the west, whereas dips in the footwall are typically steep but variable. The Tame Fault, in its southern part coincides with the axial trace of the Mossley Anticline (Aitkenhead et al., 2002, fig. 35; Kirby et al., 2000). The northern end of the Goyt Syncline enters the district to the east of the Mossley Anticline. The age of the main compressional deformation in the district is Late Carboniferous (due to distant effects of the Variscan Orogeny), with later extensional movements responsible for many of the normal faults. Three fault trends are dominant in the district: broadly west–east, broadly north–south and north-north-west– south-south-east (Figure 1). Subordinate, largely impersistent, north-east-trending faults also occur.

Earlier Carboniferous syndepositional fault movements have been proved in some instances. In the region east of the Pennine Line, two broadly east–west structures affect the pre-Carboniferous basement: the Holme Fault across the north of the district and the Alport Fault that just impinges on the southern margin of the district and extends east-south-east into the Chapel-en-le-Frith district (Figure 3) and (Figure 11). Both faults originated during a phase of syndepositional extensional faulting (rifting), each having thick lower Carboniferous sediments on its hanging wall (northern) side and thinner deposits on its footwall (southern) side (Evans and Kirby, 1999; Kirby et al., 2000). Smaller thickness contrasts in the later Carboniferous deposits may be due to the effect of differential subsidence during the post-rifting, thermal subsidence phase of extension. The sense of movement on some parts of these faults was reversed during late Carboniferous (Variscan) compression.

The Holme Fault can be traced from east of Denby Dale [SE 260 085], via Holmfirth [SE 150 080] to Wessenden Head Moor [SE 060 065], where the fault changes to a southwest–north-east orientation, extending close to the Tame Fault in the west (Figure 1). The existence of the fault was first inferred from gravity surveys (Lee, 1988) and was subsequently identified in seismic reflection profiles (Evans and Kirby, 1999; Kirby et al., 2000). It affects both the Lower Palaeozoic basement and overlying Carboniferous successions. The fault marks the northern boundary of the Holme High, upon which platform carbonates accumulated in relatively shallow water during the early Carboniferous (Figure 3). To the north of the fault, the early Carboniferous succession comprises mudstones and limestones that accumulated in the deeper waters of the Huddersfield Basin. On its south side, the Holme High slopes into the deep-water Alport Basin, which is bounded by the northerly dipping Alport Fault, and which contains thick Lower Carboniferous sediments. Displacements on the Holme Fault at depth are up to 1100 m at the top of the Lower Palaeozoic basement (Figure 11), but until recently the fault was assumed not to reach the surface; only short segments of it are shown on the previous edition of the Glossop 1:50 000 Series geological map. However, the current resurvey has identified its surface position over a continuous distance of some 30 km, and has demonstrated a surface throw of up to 100 m, down to the north. Within the hanging-wall block, immediately to the north of the fault, strata dip towards the fault in a rollover, which formed initially during normal displacement, but which developed into an anticline by reverse displacement on the structure during the late Carboniferous Variscan compression. A parallel syncline occurs to the north of the anticline (Figure 11), and is clearly evident in the landscape as the 'saddle' of the Rough Rock outlier dip slope at West Nab [SE 077 088]. The Millstone Grit Group succession is thicker within the hanging wall, and the Pennine Lower Coal Measures show facies changes across an east–west zone in the general area of the fault, which reflect the contrasts in the West Yorkshire and South Yorkshire coalfield sequences (Bromehead et al., 1933, pp. 126– 128, figs. 11 and 16; Wray, 1927). Bromehead et al. (1933) called this zone the 'Holme Disturbance', recognising its likely origin in syndepositional earth movements.

The Alport Fault, located mainly to the south of the district (Figure 11), also has a northward downthrow, up to 3000 m, at the top of the Lower Palaeozoic basement (Kirby et al., 2000, pp. 34 and 44, fig. 18). The Alport Dome (Bromehead et al., 1933, fig. 13) is considered to be a rollover anticline developed in the hanging wall of the Alport Fault, involving the thick lower Carboniferous succession in the Alport Basin. The Westend–Smallfield Fault, in the south of the district (Figure 1), is a synthetic structure in the hanging wall of the Alport Fault.

A series of north-north-west–south–south-east-trending faults are present across the district. These faults have comparatively small normal displacements (up to tens of metres). In the north of the district, such faults, including the Lepton, Kirkburton, Longwood, Marsden and Wessenden faults all show a throw down to the east (Figure 1) and terminate against the Holme Fault.

Chapter 3 Applied geology

A history of mining and quarrying associated with the development of heavy industry in the district has left areas of derelict and despoiled land. By considering the nature of earth science issues at an early stage in the planning process, appropriate decisions may be taken concerning future site development.

Mineral resources

Mineral resources that are currently exploited are those that can be worked close to the surface, the main materials extracted in the district being shale, fireclay and sandstone. Factors hindering extraction are significant thicknesses of overburden, sterilisation of resources by urban development, and possible detrimental effects on the landscape and environment. The economics of underground mining are currently generally unfavourable, although underground coal workings continue on a small scale at Hay Royds Colliery, Clayton West [SE 250 094] (Cameron et al., 2008).

Shale and fireclay

Shale and fireclay from the Pennine Lower Coal Measures are worked in numerous pits for production of pipes and bricks. The main intervals worked are: below and above the Hard Bed Coal at Middlecliffe, Penistone [SE 196 043] (Plate 6); Oxlee, Holmfirth [SE 165 051]; between the Greenmoor Rock and Grenoside Sandstone at Greenley Carr [SE 201 051]; between sandstones of the Penistone Flags at Henperch, Denby Dale [SE 237 094], and Peace Wood, Skelmanthorpe [SE 218 113]; and above and below the Cumberworth Thin Coal at Bromley, Upper Cumberworth [SE 216 089], and Bromleys, Denby Dale [SE 220 087]. Brick clays are worked at Mouselow Quarry, Glossop [SK 023 950], in the mudstone interval between leaves of the Huddersfield White Rock (Plate 4).

Sandstone

Sandstone extraction has historically been a major industry in the district and many quarries continue to work sandstone from both the Millstone Grit Group and Pennine Lower Coal Measures. The main sandstones worked are: the Kinderscout Grit at Shire Hill, Glossop [SK 054 945] (Plate 2); Huddersfield White Rock (lower leaf) at Mouselow Quarry, Glossop [SK 023 950] (Plate 4); Huddersfield White Rock (upper leaf) at Windy Edge, Holmfirth [SE 131 063], Hillhouse Edge, Holmfirth [SE 132 065], and Canyards Hill [SK 257 948]; Greenmoor Rock at Appleton, Shepley [SE 194 085], and Sovereign, Shepley [SE 197 088]; and Grenoside Sandstone at Carr Hill, Shepley [SE 198 087]. The sandstones are variously worked for crushed rock aggregate, building stone, block stone, and dimension stone (Cameron et al., 2008).

Quarries that have not been backfilled represent an important resource because they may provide a suitable void for waste disposal, may be reopened as a source of minerals, or may be developed as sites of educational, recreational and ecological value.

Oil and gas

The existence of exploration boreholes and of many line-kilometres of seismic reflection data across the southern Pennines attest to the oil and gas prospectivity of the region. Lying at depth beneath the district is the Bowland Shale Formation, which is thought to thicken to the north and south into the Huddersfield and Alport basins, respectively. Outside of the district at outcrop to the north and west, these shales are commonly associated with a strong smell of oil and during hydrocarbon exploration they have been identified as the potential source rock.

Within the district, the Wessenden 1 Borehole was drilled on a structural high by Enterprise Oil plc in 1987–88, in the search for oil and gas. The exploration borehole was presumably targeting hydrocarbons that might have been generated in and migrated out of the deeper Huddersfield and Alport basins. There were no recorded shows and the exploration well was plugged and abandoned as a dry hole in February 1988. To the north-west of the district, in the Forest of Bowland, there is interest in the thick Bowland Shale Formation succession as a source of shale gas. If tests prove the shale sequences capable of supplying shale gas economically, then other areas with thick developments of the Bowland Shale Formation might become targets for shale gas exploration, including parts of the Glossop district.

Engineering ground conditions

The most important ground conditions relevant to construction and development are the suitability of the ground to support structural foundations, the ease of excavation, and the use of excavated material in engineered earthworks and fills. These issues are summarised for the main engineering geological units in the district in (Figure 12). Foundation conditions are not only affected by the engineering properties of the local rock units 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. Variable man-made ground conditions, notably from landfill sites and areas of colliery spoil, may present problems with respect to severe differential settling. Colliery spoil, mainly present in the north-east of the district, may contain iron pyrites. This is prone to oxidise and produce sulphate-rich, acidic leachates, which may be harmful to concrete in foundations or buried services, thus requiring the use of sulphate-resisting cement. This oxidation process may also result in expansion and differential heaving of foundations constructed on such deposits. Large volumes of quarry spoil are present in the district, and the areas affected may present poor foundation conditions if large cavities are present, or where the spoil was deposited on steep slopes. The foundation characteristics of Upper Carboniferous rocks are described by Meigh (1968).

Mining subsidence

Abandoned mine workings are present in the north-east of the district, and subsidence due to mining represents a significant hazard in this area. Mining here has a long history, and includes workings for coal, fireclay, ganister and ironstone. Of these, coal and fireclay have been of greatest importance. The subsidence has largely developed due to the collapse of abandoned underground workings and of the associated shafts and adits once used for access. The coal mines tend to be shallow (less than 30 m deep) and to date from the 19th century or earlier. These mines used partial extraction methods such as 'pillar and stall'. These tend to produce more concentrated subsidence features than do modern long-wall methods, which tend to have less severe effects albeit over larger areas. It is known that faults can be re-activated by mining subsidence, and can result in significant linear subsidence features (Taylor, 1968).

Fireclay mining has been widespread from the late 1800s, particularly in the north-eastern part of the district. Workings were for non-refractory products (i.e. bricks, pipes and tiles), the clay being taken along with coal and ganister, or from separate workings. The fireclay-bearing strata are found towards the base of the Pennine Lower Coal Measures Formation, and to a lesser extent within the Millstone Grit Group. Mining was carried out principally using pillar and stall methods. Fireclay mining plans are held by the Health and Safety Executive.

Shafts represent a hazard, particularly where either incompletely or loosely backfilled. Similarly, adits may have been blocked without being backfilled. Mine collapse may be delayed for many years following abandonment, depending on the type and size of working and on changes in the groundwater regime. Modern geophysical methods (McCann et al., 1987), thermal imaging, and other remote techniques may successfully detect old mine workings.

Slope stability

There are 140 landslides recorded from the present district within the BGS national landslide database. Some of the entries were derived from previously published BGS maps (Geomorphological Services Ltd, 1987). Most of the landslides are within bedrock, principally within the Millstone Grit Group. The large, deep-seated landslides present in the district, such as those in Longdendale, are mainly ancient in origin, with only shallow superficial movements occurring in them at the present time (Johnson, 1980). However, where such shallow movements occur in areas of buildings or major transport routes, their effect can be significant.

The presence of a landslide indicates significant ground movement past or present (occasionally both), and hence represents a hazard. Ancient landslides may be reactivated by earth moving and other engineering operations, by natural erosion, and by water leakage or drainage failure. Landslides developing within man-made spoil (e.g. colliery tips) are also hazardous, particularly where these become saturated and have the potential for a long run-out. Where possible, any form of development on landslides should be avoided. Special precautions should be exercised when site investigations are carried out on or near landslides.

Pollution potential

Consideration of pollution potential applies particularly to artificial (man-made) deposits that may contain toxic residues, either as a primary component or generated secondarily by chemical or biological reactions. Significant sites of potential pollution include areas of landfill, former gasworks, chemical works, textile mills, foundries, railway sidings and sewage works. Leachate migration may be a problem where groundwater percolates through waste and becomes enriched in potentially harmful soluble components. The problem may be enhanced in fractured bedrock where the discontinuities can provide pathways for leachate migration. Mine-drainage waters may also be a problem near former mine workings because of their acidity, in addition to iron precipitation and the commonly elevated levels of manganese, aluminium and sulphates.

Should shale gas extraction prove to be viable for sequences beneath the district, the current extraction processes, which include injecting water and sand into the rocks at depth to cause fracturing and release of the gas, could lead to negative environmental impacts.

Gas emissions

Mine gas may be generated from underground colliery workings and from colliery spoil at the surface within, and to some extent beyond, the Coal Measures outcrop. These gases include components of methane, carbon dioxide, and carbon monoxide. These gases, in particular methane, can also be generated from natural deposits such as carbonaceous mudstones. Such gases are able to travel significant distances from their source through fissures formed either naturally or by mining subsidence. Where these gases are allowed to collect, fire or explosion is a possibility.

Radon is a natural radioactive gas produced by the radioactive decay of radium and uranium. Radon is found in small quantities in all rocks and soils, although the amount varies from place to place. Geology is the most important factor controlling the source and distribution of radon (Appleton and Ball, 1995). Radon Affected Areas have been declared by the Radiation Protection Division of the Health Protection Agency (former National Radiological Protection Board) where it is estimated that the radon concentration exceeds the Action Level (200 Bq m⁻³) in 1 per cent or more of homes (Green et al., 2002).

Radon that enters poorly ventilated enclosed spaces in buildings, caves, mines and tunnels may reach high concentrations. Inhalation of radon gas increases the chance of developing lung cancer. Radon protective measures may need to be installed in new dwellings (and extensions to existing ones) in areas where it is estimated that the radon concentration exceeds the Action Level in 3 per cent or more of homes (BRE, 1999).

Water resources

Reservoirs provide an important source of water for domestic supplies. Licensed abstraction of groundwater also provides water supply for domestic and industrial purposes. The Carboniferous sandstone units in the district are classified as minor aquifers, and the intervening mudstones as aquitards or aquicludes. The Millstone Grit sandstones are considered to provide better quality groundwater supplies than those from the Coal Measures sandstones, which tend to have higher concentrations of sulphates, iron and trace metals. Faults may act as conduits for groundwater flow, potentially increasing yields from boreholes, but faults with large displacements may reduce the interconnectivity of aquifer sandstones, thus limiting groundwater flow.

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 includes borehole records, fossils, rock samples, thin sections and hydrogeological data. Searches of indexes to some of the collections can be made on the website, which also gives access to the BGS Lexicon of Named Rock Units and to the photographic collection. The booklet BGS catalogue of maps and books is available on request (see back cover for addresses).

Maps

• Geology maps
• 1:50 000
• Sheet 86 Glossop (Bedrock and Superficial) 2012
• 1:10 000
• The maps at this scale covering the 1:50 000 Series Sheet 86 Glossop 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. Full colour digital copies are available for purchase from BGS Sales Desk. Copies of the fairdrawn maps of the earlier surveys may be consulted at the BGS Library, Keyworth. 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 website.
• 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.
• Data from the Geochemical Baseline Survey of the Environment (G-BASE) are also available in other forms including hard copy and digital data.
• Hydrogeological maps
• 1:625 000
• Sheet 1 (England and Wales) 1977
• 1:100 000
• Southern Yorkshire and adjoining areas (Sheet 12), 1982
• Groundwater Vulnerability Map, South Pennines (Sheet 11); produced by the Environment Agency.

BGS books and reports

• Regional
• British Regional Geology: The Pennines and adjacent areas. Fourth edition, 2002
• Subsurface Memoir
• The structure and evolution of the Craven Basin and adjacent areas, 2000.
• Memoirs
• Sheet 86 Holmfirth and Glossop, 1933. This is out of print; a scanned copy may be purchased from BGS at a tariff that is set to cover the cost of copying.

Documentary collections

Boreholes and shafts

Borehole and shaft data are catalogued in the BGS archives at Keyworth. For the Glossop district, the collection currently includes the records of about 2000 boreholes. For further information contact: The Manager, National Geosciences Records Centre, BGS, Keyworth.

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 digitally in the National Gravity Databank and the National Aeromagnetic Databank at BGS Keyworth. Seismic reflection data are available for parts of the district through the UK Onshore Geophysical Library (UKOGL: http://www.ukogl.org.uk/).

Material collections

Palaeontological collection

Macrofossils and micropalaeontological 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 entire core from a small number of boreholes in the Glossop 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 an advertised tariff.

Other relevant collections

Coal abandonment plans

Coal abandonment plans are held by The Coal Authority.

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 (SSSI) within the Glossop district is held by English Nature, Northminster House, Peterborough, PE1 1UA.

Information on Regionally Important Geological and Geomorphological Sites (RIGS) is held by UKRIGS, National Stone Centre, Porter Lane, Middleton by Wirksworth, Derbyshire DE4 4LS.

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.

Further information regarding mining in South Yorkshire is available from the South Yorkshire Mines Advisory Service (SYMAS), Barnsley MBC, Town Hall, Barnsley, South Yorkshire, S70 2TA.

References

Most of the references listed here can be consulted at the BGS Library, Keyworth. Copies of BGS publications can be obtained from the sources described in the previous section. The BGS Library may be able to provide copies of other material, subject to copyright legislation. Links to the BGS Library catalogue and other details are provided on the BGS website.

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

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

Aitkenhead, N, Chisholm, J I, and Stevenson, I P. 1985. Geology of the country around Buxton, Leek and Bakewell. Memoir of the Geological Survey of Great Britain, Sheet 111 (England and Wales).

Aitkenhead, N, Barclay, W J, Brandon, A, Chadwick, R A, Chisholm, J I, Cooper, A H, and Johnson, E W. 2002. British regional geology: The Pennines and adjacent areas. (Keyworth, Nottingham: British Geological Survey.)

Allen, J R L. 1960. The Mam Tor Sandstones: A 'turbidite' facies of the Namurian deltas of Derbyshire, England. Journal of Sedimentary Petrology, Vol. 30, 193–208.

Appleton, J D, and Ball, T K. 1995. Radon and background radioactivity from natural sources: characteristics, extent and relevance to planning and development in Great Britain. British Geological Survey Technical Report, WP/95/2.

Bisat, W S. 1924. The Carboniferous goniatites of the north of England and their zones. Proceedings of the Yorkshire Geological Society,Vol. 20, 40–124.

B RE. 1999. Radon: guidance on protective measures for new dwellings. Building Research Establishment, B R211.

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 the sediment-ation 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 Northwest Europe. Besly, B M,and Kelling, G (editors). (Glasgow and London: Blackie.)

Bristow, C S, and Myers, K J. 1989. Detailed sedimentology and gamma-ray log characteristics of a Namurian deltaic succession 1: Sediment-ology and facies analysis. 75–80 in Deltas: Sites and Traps for Fossil Fuels. Whateley, M K G,and Pickering, K T (editors). Geological Society of London Special Publication, No. 41.

Bromehead, C E, Edwards, W N, Wray, D A, and Stephens, J V. 1933. Geology of the country around Holmfirth and Glossop. Memoir of the Geological Survey of Great Britain, Sheet 86(England and Wales).

Calver, M A. 1968. Coal Measure invertebrate faunas. 147–177 in Coal and coal-bearing strata. Murchison, D G, and Westoll, T S (editors).(Edinburgh: Oliver and Boyd.)

Cameron, D G, Idoine, N E, McDonnell, P M,Hyslop, E K, Brown, T J, and Hill, A J. 2008. Directory of Mines and Quarries 2008 (8th edition). (Keyworth, Nottingham: British Geological Survey.)

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.

Cleal, C J, and Thomas, B A. 1996. British Upper Carboniferous stratigraphy. Geological conservation review series. No. 11. (London: Chapman and Hall.)

Collinson, J D. 1968. Deltaic sedimentation units in the Upper Carboniferous of Northern England. Sedimentology, Vol. 10, 233–245.

Collinson, J D. 1969. The sedimentology of the Grindslow Shales and the Kinderscout Grit:A delta complex in the Namurian of northern England. Journal of Sedimentary Petrology, Vol. 39,194–221.

Collinson, J D. 1988. Controls on Namurian sedimentation in the Central Province basins of northern England. 85–101 in Sedimentation in a synorogenic basin complex: the Upper Carboniferous of Northwest Europe. Besly, B M, and Kelling, G (editors). (Glasgow and London: Blackie.)

Cooper, R G. 2007. Mass Movements in Great Britain. Geological Conservation Review Series, No. 33. (Peterborough: Joint Nature Conservation Committee.)

Crofts, R G, Hough, E, Humpage, A J, and Reeves, H J. 2012. Geology of the Manchester district. Sheet Explanation of the British Geological Survey, Sheet 85 (England and Wales).

Evans, D J, and Kirby, G A. 1999. The architecture of concealed Dinantian carbonate sequences over the Central Lancashire and Holme highs, northern England. Proceedings of the Yorkshire Geological Society, Vol. 52, 297–312.

Geomorphological Services Ltd. 1987. National review of research into landsliding in Great Britain. Report to the Department of the Environment.

Green, A H, 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.

Green, B M R, Miles, J C H, Bradley, E J, and Rees, D M. 2002. Radon Atlas of England and Wales. National Radiological Protection Board Report, NRPB-W26 (NRPB: Chilton, Didcot).

Guion, P D, and Fielding, C R. 1988. Westphalian A and B sedimentation in the Pennine Basin, U K. 153–177 in Sedimentation in a Synorogenic Basin Complex: the Upper Carboniferous of Northwest Europe. Besly, B M, and Kelling, G (editors). (Glasgow and London: Blackie.)

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, and Chisholm, J I. 2008. Provenance of late Carboniferous sandstones in the Pennine Basin (U K) from combined heavy mineral, garnet geochemistry and palaeocurrent studies. Sedimentary Geology, Vol. 203, 196–212.

Hallsworth, C R, Morton, A C, Claoué-Long, J C, 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.

Hampson, G J. 1997. A sequence stratigraphic model for deposition of the Lower Kinderscout Delta, an Upper Carboniferous turbidite-fronted delta. Proceedings of the Yorkshire Geological Society, Vol. 51, 273–296.

Hampson, G J, Elliott, T, and Flint, S S. 1996. Critical application of high resolution sequence stratigraphic concepts to the Rough Rock Group (Upper Carboniferous) of northern England. 221–246 in High Resolution Sequence Stratigraphy: Innovations and Applications. Howell, J A, and Aitken, J F (editors). Geological Society of London Special Publication, No. 104.

Heckel, P H, and Clayton, G. 2006. The Carboniferous System. Use of the official names for the subsystems, series, and stages. Geologica Acta, Vol. 4, 403–407.

Holroyd, W F, and Barnes, J. 1896. Rocks and fossils of the Yoredale series of the Marsden and Saddleworth valleys. Transactions of the Manchester Geological Society, Vol. 24, 70–99.

Hough, E, Lake, R D, and Hobbs, P R N. 2007. Geology of the Barnsley district Sheet Explanation of the British Geological Survey, Sheet 87 (England and Wales).

Johnson, R H. 1980. Hillslope stability and landslide hazard — a case study from Longdendale, north Derbyshire, England. Proceedings of the Geologists' Association, Vol. 91, 315–325.

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.

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

Lee, A G. 1988. Carboniferous basin configuration of central and northern England modelled usinggravity data. 69–84 in Sedimentation in a synorogenic basin complex: the Upper Carboniferous of North-west Europe. Besly, B M, and Kelling, G (editors). (Glasgow and London: Blackie.)

Leeder, M R. 1988. Recent developments in Carboniferous geology: a critical review withimplications for the British Isles and N W 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.

McCabe, P J. 1977. Deep distributary channels and giant bedforms in the Upper Carboniferous of the central Pennines, northern England. Sedimentology, Vol. 24, 271–290.

McCabe, P J. 1978. The Kinderscoutian delta (Carboniferous) of northern England: A slope influenced by density currents. 116–126 in Sedimentation in submarine canyons, fans and trenches. Stanley, D J, and Kelling, G (editors). (Stroudsburg, Pennsylvania: Dowden, Hutchinson and Ross.)

McCann, D M, Jackson, P D, and Culshaw, M G. 1987. The use of geophysical surveying methods in the detection of natural cavities and mineshafts. Quarterly Journal of Engineering Geology, Vol. 20, 59–73.

Meigh, A C. 1968. Foundation characteristics of the Upper Carboniferous rocks. Quarterly Journal of Engineering Geology, Vol. 1, 87–114.

Ramsbottom, W H C. 1981. Field guide to the boundary stratotypes of the Carboniferous stages in Britain. Biennial Meeting of the Subcommisson of Carboniferous Stratigraphy, Leeds.

Ramsbottom, W H C, Calver, M A, Eagar, 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. Special Report of the Geological Society of London, No. 10.

Riley, N J. 1993. Foraminiferal/algal biostratigraphy of Enterprise, Wessenden No. 1 Borehole: Cores 1 and 2. British Geological Survey Technical Report, WH/93/9.

Shackleton, J. 1962. Cross-strata of the Rough Rock (Millstone Grit Series) in the Pennines. Liverpool and Manchester Geological Journal, Vol. 3, 109–118.

Smart, J G O, Calver, M A, Ramsbottom, W H C, and Owens, B. 1978. The geology of Longdendale and report on the Manchester–Sheffield proposed routes in Longdendale by Institute of Geological Sciences. British Geological Survey Technical Report, WA/L E/78/3.

Stevenson, I P, and Gaunt, G D. 1971. The geology of the country around Chapel-en-le-Frith. Memoir of the Geological Survey of Great Britain, Sheet 99 (England and Wales).

Stubblefield, C J, and Trotter, F M. 1957. Divisions of the Coal Measures on Geological Survey maps of England and Wales. Bulletin of the Geological Survey of Great Britain, Vol. 13, 1–5.

Tallis, J H, and Johnson, R H. 1980. The dating of landslides in Longdendale, North Derbyshire, using pollen analytical techniques. 189–205 in Timescales in geomorphology. Cullingford, R A, Davidson, D A, and Lewis, J (editors). (Chichester and New York: J.Wiley.)

Taylor, R K. 1968. Site investigations in coal fields — the problem of shallow mine workings. Quarterly Journal of Engineering Geology, Vol. 1, 115–134.

Walker, R G. 1966a. Deep channels in turbidite-bearing formations. Bulletin of the American Association of Petroleum Geologists, Vol. 50, 1899–1917.

Walker, R G. 1966b. Shale Grit and Grindslow Shales: Transition from turbidite to shallow water sediments in the Upper Carboniferous of Northern England. Journal of Sedimentary Petrology, Vol. 36, 90–114.

Waters, C N. 2000. Geology of the Bradford district. Sheet Explanation of the British Geological Survey, Sheet 69 (England and Wales).

Waters, C N, Aitkenhead, N, Jones, N S, and Chisholm, J I. 1996. Late Carboniferous stratigraphy 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, Chisholm, J I, Benfield, A C, and O'Beirne, A M. 2008. Regional evolution of a fluviodeltaic cyclic succession in the Marsdenian (Late Namurian Stage, Pennsylvanian) of the Central Pennine Basin, U K. Proceedings of the Yorkshire Geological Society, Vol. 57, 1–28.

Waters, C N, Waters, R A, Barclay, W J, and Davies, J R. 2009. Lithostratigraphical framework for Carboniferous successions of southern Great Britain (onshore). British Geological Survey Research Report, RR/09/01.

Wignall, P B, and Maynard, J R. 1996. High-resolution sequence stratigraphy in the early Marsdenian (Namurian, Carboniferous) of the central Pennines and adjacent areas. Proceedings of the Yorkshire Geological Society, Vol. 51, 127–140.

Wilson, A A, and Chisholm, J I. 2004. Reference sections of faunal bands in the Lower Coal Measures Formation at Elland, west Yorkshire, U K. Proceedings of the Yorkshire Geological Society, Vol. 55, 21–32.

Wray, D A. 1927. The Barnsley Coal and its variations. 127–137 in Summary of Progress of the Geological Survey of Great Britain for the year 1926.Index to the 1:50 000 Series maps of the British Geological Survey

Figures and plates

Figures

(Figure 1) Bedrock geology of the Glossop district.

(Figure 2) Stratigraphy from Wessenden 1 Borehole geophysical log.GR - Gamma Ray log; SONL - Sonic log.

(Figure 3) Concealed Carboniferous strata of the Holme High. Extent of Tournaisian and Visean platform carbonates in the subsurface, in relation to the Holme High and its defining faults. Subsurface information based on Evans and Kirby (1999, (Figure 7)) and Kirby et al. (2000).

(Figure 4) Marine bands found in the Glossop district.

(Figure 5) Namurian sandstones of the Glossop district.

(Figure 6) Boreholes and sections illustrating Millstone Grit Group stratigraphy.

(Figure 7) Palaeocurrent and grain size data for the Midgley Grit (north), Heyden Rock (east) and Fletcher Bank Grit (west).

(Figure 8) Westphalian sandstones of the Glossop district.

(Figure 9) Named coal seams of the Glossop district.

(Figure 10) Boreholes illustrating Pennine Lower Coal Measures Formation stratigraphy.

(Figure 11) Main faults and folds within and adjacent to the Glossop district. Contours on pre-Carboniferous basement and location of major faults at basement level (based on Aitkenhead et al., 2002, fig. 34). Surface position of Holme Fault and hanging-wall folds based on recent resurvey.

(Figure 12) Engineering geological classification of major formations/deposits.

(Index map) Index to the 1:50 000 Series maps of the British Geological Survey.

(Front cover) War Memorial and cross-bedded Lower Kinderscout Grit at Pots and Pans [SE 0102 0512], north-east of Tunstead. P671006.

(Rear cover)

(Geological succession) Summary of the geological succession in the district.

Plates

(Plate 1) View of the valley of Crowden Great Brook [SK 0713 9991], looking north, showing an escarpment formed by the Lower and Upper Kinderscout Grits. The Upper Kinderscout Grit forms the plateau seen in the centre of the photograph. The Lower Kinderscout Grit is present as two thick sand bodies, the upper forming the crag seen to the right separated by a thin mudstone from a lower leaf, which forms the convex feature mid-way down the slope. The irregular topography in the lower part of the slope, in the centre of the photograph, is an area of landslide. In front of this is an area of head deposits forming a grass-covered bench, which has been incised by the current brook. P670966.

(Plate 2) Shire Hill Quarry [SK 0521 9445], workings in the Lower Kinderscout Grit. View to the north. The photograph shows a lower succession of coarse- to very coarse-grained, lenticular-bedded sandstones, with internally massive very thick beds, interpreted as a turbidite feeder channel. This is overlain by an upper succession of pebbly, very coarse-grained to granular sandstone with large-scale cross-bedding, interpreted as a laterally-accreting fluvial bar form. The transition between the two facies may indicate deposition during falling sea level, with the fluvial deposits occupying a pre-existing turbidite channel formed at times when the sea level was higher. P670949.

(Plate 3) Disused quarry in the Lower Kinderscout Grit above Upperwood House [SE 0217 0605], Saddleworth, looking west. The upper 8 m of the face comprises very coarse-grained to granular sandstone, massive in appearance, but with trough cross-bedding evident at the top, indicating a palaeocurrent towards the south-east. This sandstone has a markedly erosive base, which cuts down westward through a mudstone (up to 0.2 m thick) and the underlying very coarse-grained to granular, bedded sandstone. P671039.

(Plate 4) Mouselow Quarry [SK 023 949], near Glossop, view towards the south showing an upper leaf of the Huddersfield White Rock, of mouth-bar facies, forming the top of the section in the right of the photograph. This is underlain gradationally by an upwards-coarsening succession of mudstone to siltstone, 30 m thick. The base of the section, within the lower leaf of the Huddersfield White Rock, comprises thickly bedded, internally massive sandstones, deposited from density currents. P774914.

(Plate 5) Section exposed at Winscar Reservoir [SE 1521 0303], near Dunford Bridge, looking towards the west. A succession of cross-bedded sandstones in the upper part of the Huddersfield White Rock, seen above water level in the left of the photograph, is overlain by a thin unnamed coal. The coal is overlain by a 6 m succession of upwards-coarsening siltstone to sandstone cycles interpreted as thin lacustrine deltas. This is capped by a leached ganister palaeosol, sharply overlain by 6 m of barren dark grey mudstone. P774910.

(Plate 6) Middlecliffe Clay Pit, Crow Edge opencast workings [SE 196 043], looking north. The Hard Bed Coal (0.8 m thick), seen in the left of the photo, is underlain by a pale grey ganister and seatclay palaeosol. The Stanningley Rock (2.8 m seen) is exposed at the top of the section, about 30 m above the Hard Bed Coal. P774911.

(Plate 7) Landslide at Sail Bark Rocks, looking north-east from Birchen Clough [SE 0387 0474]. The back scarp is within sandstones of the Lower Kinderscout Grit. The landslide is a complex of rotational slides and rockfall. P671031.

(Plate 8) Landslide at Canyards [SK 257 949], south of Wigtwizzle, looking towards the west. The back scarp is within Huddersfield White Rock, with slipped sandstone forming prominent ridges and hummocks. P774912.

Figures

(Figure 4) Marine bands found in the Glossop district

(Figure 5) Namurian sandstones of the Glossop district

(Figure 8) Westphalian sandstones of the Glossop district

(Figure 9) Named coal seams of the Glossop district

(Figure 12) Engineering geological classification of major formations/deposits