The BGS Lexicon of Named Rock Units — Result Details

Grey Shale Member

Computer Code: GREY Preferred Map Code: GSh
Status Code: Full
Age range: Toarcian Age (JT) — Toarcian Age (JT)
Lithological Description: Mudstone and siltstone, grey, shaly, with layers of small calcareous and ferruginous nodules; fossiliferous, with common ammonites in upper beds; laminated and bituminous in parts
Definition of Lower Boundary: Conformable: base of mudstone resting upon ooidal limestone, ironstone or sideritic mudstone nodules of the Cleveland Ironstone Formation. Bed 43 on Bed 42 at Hawsker Bottoms; Bed 57 on Bed 56 at Port Mulgrave (bed numbers of Howarth, 1955).
Definition of Upper Boundary: Conformable: base of bituminous mudstone with large concretions (Mulgrave Shale Member) resting upon non-bituminous shaly mudstone. Bed 33 on Bed 32 at Hawsker Bottoms and Port Mulgrave (bed numbers of Howarth, 1955).
Thickness: 12 to 17m thick on the Yorkshire coast, thinning west and south to between 5 and 7m (Felixkirk and Brown Moor boreholes).
Geographical Limits: Cleveland Basin as far south as Acklam area, becomes indistinguishable southwards (see Supplementary Information).
Parent Unit: Whitby Mudstone Formation (WHM)
Previous Name(s): Grey Shale Series (-3442)
Grey Shales (-1573)
Grey Shales Formation (-2214)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Section  Fully exposed in cliffs and foreshore east of Hawsker Bottoms, North Yorkshire coast, between 16 and 17m thick. Beds 43 to 44 and 1 to 32 of Howarth (1955) Powell, 1984 (gives NGR of NZ 951 077); Simms et al. 2004, pp 262-271. 
Reference Section  Fully exposed in continuous foreshore at Port Mulgrave, North Yorkshire coast, 12 to 15m thick. Beds 57 to 60 and 1 to 32 of Howarth (1955). Simms et al. 2004, pp 281-293. 
Reference(s):
Howarth, M K, 1955. Domerian of the Yorkshire coast. Proceedings of the Yorkshire Geological Society, Vol.30, 147-175. 
Cox, B M, Sumbler, M G and Ivimey-Cook, H C, 1999. A Formational framework for the Lower Jurassic of England and Wales (Onshore Area). British Geological Survey Research Report No. RR/99/01. 
Simms, M J, Chidlaw, N, Morton, N, and Page, K N. 2004. British Lower Jurassic Stratigraphy. Geological Conservation Review Series. No. 30. (Peterborough: Joint Nature Conservation Committee/Chapman and Hall.) 
Arkell W J, 1933. The Jurassic System in Great Britain [Oxford: Clarendon Press.] 
Powell, J H, 1984. Lithostratigraphic nomenclature of the Lias Group in the Yorkshire Basin. Proceedings of the Yorkshire Geological Society, Vol.45, p.51-57. 
Howarth, M K, 1980, Toarcian correlation chart, in Cope, J C W (editor). 1980. A correlation of the Jurassic rocks of the British Isles. Part One: Introduction and Lower Jurassic. Geological Society of London Special Report. No. 14. 
Fox-Strangways, C and Barrow, G, 1915. The geology of the country between Whitby and Scarborough (2nd edition). Memoir of the Geological Survey of the United Kingdom. 
Tate, R, and Blake, J F. 1876. The Yorkshire Lias. (London: J van Voorst.) 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
none recorded or not applicable