The BGS Lexicon of Named Rock Units — Result Details

Great Limestone Member

Computer Code: GL Preferred Map Code: GL
Status Code: Full
Age range: Pendleian Substage (CE) — Pendleian Substage (CE)
Lithological Description: Limestone (bioclastic packstone), medium to dark blue-grey, thickly bedded with thin shaly mudstone partings along uneven or wavy bedding planes. There is much crinoid debris throughout and there are many other beds rich in brachiopods and/or corals. The internal stratigraphy of the member is, in parts, remarkably consistent throughout the region and four informal divisions are recognised (Fairbairn, 1980), and referred to from the base upwards as the Bench, Main and Transitional posts and the Tumbler Beds. Beds rich in fossils are widespread. Most noteable and widespread are: the Chaetetes Band (Johnson, 1958) which occurs near the base; this comprises a sponge biostrome along with locally abundant brachiopods, corals and ostracods; within the Main Posts are the Brunton Band comprising the rare alga Calcifolium (Johnson, 1958; Cossey, et al, 2004), and the Frosterly Marble (Johnson, 1958). At the top, the Tumbler Beds, typically 2-5m thich, comprise thick beds of limestone interbedded with persistent mudstone units.
Definition of Lower Boundary: Taken at the generally conformable, sharp base of the first bed of limestone that overlies measures of the Alston Formation; in most localities the limestone directly overlies the Tuft Sandstone, a brown, micaceous fine-grained sandstone that has a rooty upper part and which locally may be overlain by a thin carbonaceous smear or a coal.
Definition of Upper Boundary: Taken at the top of the uppermost limestone beds that is overlain by a sequence of dark grey siltstones and mudstones at the base of the Stainmore Formation.
Thickness: 14-18m north of the Lake District; c 12m in the Vale of Eden; 16-22m on the Alston Block; 22-24m with a maximum of 40m on the Askrigg Block and 8-15m in the Northumberland Trough; c 22m in the Langholm area and Archerbeck Borehole.
Geographical Limits: Occurs throughout northern England at the top of the Alston Formation
Parent Unit: Alston Formation (AG)
Previous Name(s): Main Limestone (ML)
Great Limestone (-931)
First Limestone (-3434)
Dryburn Limestone (-2826)
Catsbit Limestone [Obsolete Name And Code: Use GL] (CTLS)
Alternative Name(s): none recorded or not applicable
Reference Section  Archerbeck Borehole (BGS Reg No NY47NW1), 2km northeast of Canonbie, Dumfriesshire. Lumsden and Wilson (1961). 
Reference Section  Rookhope Borehole (BGS Reg No NY94SW1), Rookhope, Weardale, Co Durham. Johnson and Nudds, 1996. 
Reference Section  Brunton Bank Quarry, c 1km southeast of Chollerford, Northumberland. Cossey et al., 2004. 
Type Section  Greenleighton Quarry, c 10km south of Rothbury, Northumberland Cossey et al., 2004. 
Reference Section  Eastgate Quarry, Weardale, Co. Durham. 
Reference Section  Tendley Hill Quarry, Cumbria. Young and Boland, 1992. 
Fairbairn, R A. 1978. Lateral persistence of beds within the Great Limestone (Namurian E1) of Weardale. Proceedings of the Yorkshire Geological Society, Vol 41, 533-544. 
Fairbairn, R A. 2001. Thestratigraphy of the Namurian Great/Main Limestone on the Alston Block, Stainmore Trough and Askrigg Block of northern England. Proceedings of the Yorkshire Geological Society, Vol 53, 265-274. 
Johnson, G A L. 1958. Biostromes in the Great Limestone of northern England. Palaeontology, Vol 1, 147-157. 
Lumsden G I and Wilson R B. 1961. The stratigraphy of the Archerbeck Borehole, Canonbie Dumfriesshire. Bulletin of the Geological Survey of Great Britain, No.18, 1-89. 
Young, B and Boland, M P. 1992. Geology and land-use planning: Great Broughton-Lamplugh area, Cumbria. BGS Technical Report WA/92/54. 
Fairbairn, R A. 1980. The Great Limestone (Namurian) of south Northumberland. Proceedings of the Yorkshire Geological Society, Vol 43, 158-167. 
Johnson, G A L and Nudds, J R. 1996. Carboniferous biostratigraphy of the Rookhope Borehole, Co. Durham. Transactions of the Royal Society of Edinburgh: Earth Sciences, Vol.86, 181-226. 
Dunham, K C, and Wilson, A A. 1985. Geology of the Northern Pennine Orefield. Volume 2 Stainmore to Craven. Economic Memoir of the British Geological Survey, Sheets 40, 41 and 50, and parts of Sheets 31, 32, 51, 60 and 61(England and Wales). 
Cossey, P J, Adams, A E, Purnell, M A, Whiteley, M J, Whyte, M A and Wright, V P. 2004. British Lower Carboniferous stratigraphy. Geological Conservation Review Series No.29. Joint Nature Conservation Committee, Peterborough. 
Burgess, I C and Holliday, D W. 1979. Geology of the country around Brough-under-Stainmore. Memoir for 1:50 000 geological sheet 31 and parts of sheets 25 and 30. Geological Survey of Great Britain (England and Wales). [London: HMSO.] 131pp. 
Day, J B W and others, 1970. Geology of the neighbourhood around Bewcastle. Memoir of the British Geological Survey, Sheet 12. (England and Wales). 
Dunham, K C. 1990. Geology of the Northern Pennine Orefield, Vol.1. Tyne to Stainmore, (2nd edition) Economic Memoir of the British Geological Survey, Sheets 19 and 25, parts of 13, 24, 26, 31, 32 (England and Wales). 
Eastwood, T, Hollingworth, S E, Rose, W C C, and Trotter, F M. 1968. Geology of the country around Cockermouth and Caldbeck. Memoir of the Geological Survey of Great Britain, England and Wales, Sheet 23. 
Chadwick, R A, Holliday, D W, Holloway, S and Hulbert, A G. 1995. The structure and evolution of the Northumberland-Solway Basin and adjacent areas. Subsurface Memoir of the British Geological Survey. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E032 E031 E025 E024 E020 E018 E023 E026 E014 E004 E006 E013 E019 E011 E001 E002 E009 E012 E030 E040