The BGS Lexicon of Named Rock Units — Result Details

Cloughton Formation

Computer Code: CLH Preferred Map Code: notEntered
Status Code: Full
Age range: Bajocian Age (JB) — Bajocian Age (JB)
Lithological Description: The lower and upper parts of the formation (Sycarham and Gristhorpe members respectively) are dominated by planar laminated grey mudstones and siltstones with yellowish grey, fine- to medium-grained, cross-stratified sandstones. Plant remains and rootlets are common in both members, with rare thin coals, and grey mudstone seatearths. Mudstones, ferruginous sandstones and ooidal limestones with a marine macrofossil and trace fossil assemblage occur in the middle part of the formation, differentiated as the Lebberston Member (Hemingway and Knox, 1973) and also known formerly as the Whitwell Oolite and/or the Millepore Bed.
Definition of Lower Boundary: The lower boundary is conformable, or disconformable, at the abrupt upward transition from the fossiliferous mudstone and ripple laminated sandstones of the upper part of the Eller Beck Formation to the cross-stratified, plant debris-rich sandstones, siltstones and mudstones of the Cloughton Formation.
Definition of Upper Boundary: The upper boundary is conformable, at the abrupt transition from the sandstones, siltstones and mudstones with rootlets and plant remains of the upper part of the Cloughton Formation, to the bioturbated and fossiliferous, variably calcareous mudstones, siltstones and fine-grained sandstones, and limestone of the lower part of the Scarborough Formation.
Thickness: 50 to 70m on the North Yorkshire Coast between Whitby and Scarborough and inland in the North Yorkshire Moors and Cleveland Hills; 36 to 50m (thinning southwards) on the western escarpment of the North Yorkshire Moors (Frost, 1998; Powell et al., 1992).
Geographical Limits: North Yorkshire Moors, Cleveland Hills and Howardian Hills; well exposed in several coastal cliff sections between Hawsker Bottoms (northwest of Robin Hood's Bay) and Gristhorpe Bay, southeast of Scarborough. South of the Howardian Hills the unit is truncated by the unconformity at the base of the Chalk. Equivalent strata in Humberside and Lincolnshire are dominated by limestones (Cave Oolite and Lincolnshire Limestone, Cope et al., 1980). Offshore, the formation is equivalent, in part, to the Strangways Formation of the West Sole Group (Lott and Knox, 1994).
Parent Unit: Ravenscar Group (RAG)
Previous Name(s): Middle Deltaic Series (Hemingway, 1949) (-789)
Middle Estuarine Series (Pars) (Fox-Strangways, 1892) (-2095)
Middle Deltaic Series (-3938)
Middle Estuarine Series (-3939)
Middle Estuarine "Series" [Obsolete Name And Code: Use CLH] (MES)
Lower Estuarine "Series" [Obsolete Name And Code: See CLH, GRF, SWK And EBB] (LET)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Reference Section  Partial section through the upper part of the Sycarham Member, Lebberston Member and Gristhorpe Member. The section extends along the wave cut platform at Lebberston Cliff, from [TA 080 844] (upper part of Sycarham Member on foreshore) to [TA 085 843] where the Lebberston Member (including the Yons Nab Beds) and Gristhorpe Member are exposed below the overlying Scarborough Formation. Yellow, trough cross-bedded fine- to medium-grained sandstone with plant fragments (Gristhorpe Member) is overlain sharply by fossiliferous grey mudstone of the Scarborough Formation. 
Type Section  Cliff/coast section between Iron Scar [TA 017 964] (base) and Cloughton Wyke [TA 020 950] (top) (Hemingway and Knox, 1973). Yellow weathering, bioturbated sandstone and siltstone of the Eller Beck Formation are overlain by yellow weathering, cross-bedded, medium-grained sandstone and siltstone with sporadic plant fragments at the base of the Cloughton Formation. The upper boundary is well exposed at Hundale Point [TA 026 949], where grey, weakly bedded mudstone, locally with plant fragments and rootlets (Sycarham Member, Cloughton Formation) passes up to dark grey, well laminated, calcareous siltstone with sparse bivalves, overlain by heavily bioturbated sandstone with u-shaped Diplocraterion burrows (Scarborough Formation).The Lebberston Member is not well exposed in this section - see Reference Section. 
Reference(s):
Whyte, M A and Romano, M. 2006. Middle-Upper Jurassic sequence between Cayton Bay and Yons Nab. 174-182 in Scrutton, C T and Powell, J H (eds), Yorkshire Rocks and Landscapes - A Field Guide, 3rd Edition. (Leeds: Yorkshire Geological Society.) 
Fox-Strangways, C. 1892. The Jurassic Rocks of Britain, Vol.1. Yorkshire. Memoir of the Geological Survey of the United Kingdom. 
Rawson, P F and Wright, J K. 2000. The Yorkshire Coast. Geologists' Association Guide No.34. (London: The Geologists' Association.) 130pp. 3rd Edition. 
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). 
Butler, N, Charnock, M A, Hager, K O and Watkins, C A. 2005. The Ravenscar Group: a coeval analogue for the Middle Jurassic reservoirs of the North Sea and offshore Mid-Norway. 43-53 in Powell, A J and Riding, J B (eds), Recent Developments in Applied Biostratigraphy. The Micropalaeontological Society, Special Publications. 
Hemingway, J E and Knox, R W O'B. 1973. Lithostratigraphical nomenclature of the Middle Jurassic strata of the Yorkshire Basin of north-east England. Proceedings of the Yorkshire Geological Society, Vol.39, 527-535. 
Hemingway, J E. 1974. Jurassic. 161-233 in Rayner, D H and Hemingway, J E (eds), The geology and mineral resources of Yorkshire. (Leeds: Yorkshire Geological Society.) 
Frost, D V. 1998. Geology of the country around Northallerton. Memoir of the British Geological Survey, Sheet 42 (England and Wales). 
Cope, J C W, Duff, K L, Parsons, C F, Torrens, H S, Wimbledon, W A and Wright, J K. 1980. A correlation of Jurassic rocks in the British Isles. Part 2: Middle and Upper Jurassic. Geological Society of London Special Report, 15, 73pp. 
Knox, R W O'B, Howard, A S, Powell, J H and van Buchem, F S P. 1991. Lower and Middle Jurassic sediments of the Cleveland Basin N.E. England: Shallow marine and paralic facies seen in their sequence stratigraphic context. Field Excursion Guide, No.5; 13th International Sedimentological Congress, Nottingham, UK. 1990. 66pp. 
Powell, J H and Rathbone, P A. 1983. The stratigraphical relationship of the Eller Beck Formation and the supposed Blowgill Member (Middle Jurassic) of the Yorkshire Basin. Proceedings of the Yorkshire Geological Society, Vol.44, 365-373. 
Lott, G K and Knox, R W O'B. 1994. 7. Post-Triassic of the Southern North Sea. In: Knox, R W O'B and Cordey, W G (eds.) Lithostratigraphic nomenclature of the UK North Sea. British Geological Survey, Nottingham. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E033 E034 E035 E042 E043 E044 E052 E053 E054 E063