The BGS Lexicon of Named Rock Units — Result Details

Upper Calcareous Grit Formation

Computer Code: UCG Preferred Map Code: UCG
Status Code: Full
Age range: Oxfordian Age (JO) — Oxfordian Age (JO)
Lithological Description: Sandstone, fine-grained, calcareous, spicule-rich, bioturbated, massive, ammonitiferous (Spaunton Sandstone Member) overlain in the west and centre of the Cleveland Basin by sandstone, very fine-grained, calcareous, spicule-rich, bedded to flaggy (Snape Sandstone Member); in the east and centre underlain by grey calcareous mudstone and flaggy clayey sandstone (Newbridge Member); succession passes south and west from the base upwards into calcareous mudstone (Langton Clay Member) overlain by spicular silty fine-grained limestone interbedded with calcareous sandstone or mudstone (North Grimston Cementstone Member) with shelly clayey sandstone (Limekiln Member) locally at the base
Definition of Lower Boundary: Non-sequence: rubbly coralliferous shelly limestone (Coral Rag Member) or where absent, ooidal limestone (Malton Oolite Member, both of Coralline Oolite Formation) sharply overlain by silty mudstone and fine-grained sandstone (Newbridge Member) or fine-grained calcareous sandstone (Spaunton Sandstone Member) or interbedded unfossiliferous fine-grained limestone and calcareous sandstone and mudstone (North Grimston Cementstone Member) or mudstone (Langton Clay Member) or sandstone (Limekiln Member), all of Upper Calcareous Grit Formation.
Definition of Upper Boundary: Locally conformable but more widely non-sequential or unconformable: fine-grained sandstone, spicule-rich and/or calcareous, passing up or sharply overlain by grey silty mudstone (Ampthill Clay Formation). In the south, fine-grained limestone (North Grimston Cementstone Member) or calcareous mudstone (Langton Clay Member) sharply overlain by grey silty mudstone (Ampthill Clay Formation).
Thickness: Typically 14 to 24m (Arkell, 1933, p.421), 9m (Harome Borehole), 22m (Brown Moor Borehole, SE86SW/4 [81266 62043] ), possibly up to 33m (BGS Sheet 54 Scarborough)
Geographical Limits: Cleveland Basin, North Yorkshire: as far south as Birdsall-Acklam area, overstepped by Ampthill Clay/Kimmeridge Clay formations. Present in Brown Moor Borehole, SE86SW/4 [81266 62043] (Gaunt et al., 1980).
Parent Unit: Corallian Group (CR)
Previous Name(s): Upper Calcareous Grit (-1171)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Section  West Newton Grange Borehole (SE68SW/2), 37.44 to 48.53m depth, penetrating full thickness comprising grey calcareous siltstone or fine-grained limestone passing up into bioturbated sandstone with burrowed top, conformably overlain by Ampthill Clay Formation. Sharply overlies white coralliferous limestone of Coral Rag Member. Cores of this interval retained by BGS. Wright, 1996a. 
Reference Section  Newbridge Quarry, Pickering, North Yorkshire, exposing the lower part of the formation, the Newbridge and Spaunton Sandstone members, totalling about 5.5m in thickness, non-sequentially underlain by the Coralline Oolite Formation. Wright and Cox, 2001, pp 161-164. 
Partial Type Section  Partial Type Section proposed here. Railway cuttings and quarries at Nunnington, North Yorkshire, exposing the lower part of the formation, the Newbridge and Spaunton Sandstone members, totalling over 7m in thickness, underlain by the Coralline Oolite Formation. Wright and Cox, 2001, pp 173-179. 
Partial Type Section  Partial Type Section proposed here. Snape Hill Quarry, Kilburn, North Yorkshire. Exposes the North Grimston Cementstone, Spaunton Sandstone and Snape Sandstone members, totalling about 20m, although faulted. Formerly exposed a further 2m of North Grimston Cementstone overlying the Coral Rag Member (Coralline Oolite Formation) (Fox-Strangways, 1892). Wright and Cox, 2001, pp 170-173; Powell et al., 1992. 
Reference Section  Harome H3 Borehole (SE68SE/2), 119.33 to 128.68m depth, penetrating full thickness comprising grey silty mudstone and bioturbated sandstone with burrowed top, conformably overlain by Ampthill Clay Formation. Sharply overlies 'reef limestone' of Coral Rag Member. Cox and Richardson, 1982. 
Reference(s):
Wright, J K. 2009. The geology of the Corallian ridge (Upper Jurassic) between Gilling East and North Grimston, Howardian Hills, North Yorkshire. Proceedings of the Yorkshire Geological Society, Vol. 57, 193-216. 
Wright, J K. 1996a. Perisphinctid ammonites of the Upper Calcareous Grit (Upper Oxfordian) of North Yorkshire. Palaeontology, Vol. 39, 433-469. 
Wright, J K. 1996b. The Amoeboceras faunas of the Upper Calcareous Grit Formation (Jurassic, Upper Oxfordian) of North Yorkshire. Proceedings of the Yorkshire Geological Society, Vol. 51, 33-43. 
Wright, C D. 1976. New outcrops of Ampthill Clay north of Market Weighton, North Yorkshire, and their structural implications. Proceedings of the Yorkshire Geological Society, Vol. 41, 127-140. 
Cox, B M, and Richardson, G. 1982. The ammonite zonation of Upper Oxfordian mudstones in the Vale of Pickering. Proceedings of the Yorkshire Geological Society, Vol. 44, 53-58. 
Wright, J K. 1972. The stratigraphy of the Yorkshire Corallian. Proceedings of the Yorkshire Geological Society, Vol. 39, 225-266. 
Phillips, J. 1829. Illustrations of the geology of Yorkshire, or a description of the strata and organic remains. Part I, the Yorkshire Coast. (York.) 
Powell, J H, Cooper, A H C and Benfield, A C. 1992. Geology of the country around Thirsk. Memoir of the British Geological Survey, Sheet 52 (England and Wales). 
Rawson, P F and Wright, J K. 1995. Jurassic of the Cleveland Basin, North Yorkshire. 173-208 in Taylor, P D (Ed.) Field Geology of the British Jurassic. (London: Geological Society.) 
Gaunt, G D, Ivimey-Cook, H C, Penn, I E and Cox, B M. 1980. Mesozoic rocks proved by the Institute of Geological Sciences boreholes in the Humber and Acklam areas. Report of the Institute of Geological Sciences, No. 79/13. 
Fox-Strangways, C. 1892. The Jurassic Rocks of Britain, Vol.1. Yorkshire. Memoir of the Geological Survey of the United Kingdom. 
Arkell W J, 1933. The Jurassic System in Great Britain [Oxford: Clarendon Press.] 
Wright, J K, and Cox, B M. 2001. British Upper Jurassic Stratigraphy (Oxfordian to Kimmeridgian). Geological Conservation Review Series. No. 21. (Peterborough: Joint Nature Conservation Committee/Chapman and Hall.) 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E044 E052 E053 E054 E063