The BGS Lexicon of Named Rock Units — Result Details

Cayton Clay Formation

Computer Code: CAYC Preferred Map Code: Cay
Status Code: Full
Age range: Callovian Age (JC) — Callovian Age (JC)
Lithological Description: Dark grey, soft clay and mudstone, laminated in part, becoming silty at the top and passing up gradationally into the Osgodby Formation (Redcliff Rock Member). The clay contains numerous small grey phosphatic nodules which may enclose the shrimp Meyeria or the ammonite Macrocephalites spp. and bivalves Meleagrinella aff. braamburiensis, Modiolus bipartus, and Nuculana sp.
Definition of Lower Boundary: Generally a sharp, conformable boundary between bioclastic, berthierine (chamosite) ooid-rich, sandy limestone of the underlying Cornbrash Formation and the dark grey, silty mudstone (locally shelly) of the Cayton Clay Formation.
Definition of Upper Boundary: Conformable boundary where the soft, grey mudstone of the Cayton Clay Formation passes gradationally up to the pale yellow, clayey sandstone of the overlying Osgodby Formation (Redcliff Rock Member).
Thickness: Up to 3m (Wright 1968a; 1977); locally absent in the west of the Cleveland Basin.
Geographical Limits: The Cleveland Basin (Northeast Yorkshire), but locally absent in the west (Powell, 2010) and south of the basin (Page, 1989).
Parent Unit: Not Applicable (-)
Previous Name(s): Clays-of-the-Cornbrash [Obsolete Name and Code: Use CAYC] (-3277)
Shales-of-the-Cornbrash Member [Obsolete Name and Code: Use CAYC] (-3278)
Shales-Of-The-Cornbrash (-752)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Section  Red Cliff [TA 076 840], Cayton Bay, North Yorkshire (Wright, 1977, p.339). The formation is often poorly exposed at beach level; where fully exposed it is 2.53 m thick and comprises of dark grey, shelly silty mudstone with very fine-grained sandstone laminae; small phosphatic nodules are also present. The boundaries with the underlying Cornbrash Formation and overlying Osgodby Formation (Redcliff Rock Member) are conformable. 
Reference Section  Havern Beck [SE 847 948] Newtondale, near the Saltersgate Hotel; where fully exposed about 2.4 m thick (Wright 1968a, 1977, 1978; Riding and Wright, 1989; Cox and Sumbler 2002 pp. 343-345). Grey, fissile clay, bituminous in part, with traces of small bivalves (Douglas and Arkell, 1932) underlain by sandy limestone of the Cornbrash Formation, and overlain conformably by sandstone of the Osgodby Formation (Redcliff Rock Member). 
Reference(s):
Cox, B M, and Sumbler, M G. 2002. British Middle Jurassic Stratigraphy. Geological Conservation Review Series No.26. [Peterborough: Joint Nature Conservation Committee.] 
Douglas, J A and Arkell, W J. 1932. The Stratigraphical Distribution of the Cornbrash II. The northeastern area. Quarterly Journal of the Geological Society, Vol.88, 112-170. 
Waters, C N, Smith, K, Hopson, P M, Wilson, D, Bridge, D M, Carney, J N, Cooper, A H, Crofts, R G, Ellison, R A, Mathers, S J, Moorlock, B S P, Scrivener, R C, McMillan, A A, Ambrose, K, Barclay, W J, and Barron, A J M. 2007. Stratigraphical Chart of the United Kingdom: Southern Britain. British Geological Survey, 1 poster. 
Fox-Strangways, C. 1892. Jurassic rocks of Britain, Vols 1 and 2, Yorkshire. Memoir of the Geological Survey of Great Britain. 
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). 
Wright, T, 1860. On the subdivisions of the Inferior Oolite of the south of England, compared with the equivalent beds of that formation on the Yorkshire coast. Quarterly Journal of the Geological Society of London, 16, 1-48. 
Riding, J B and Wright, J K. 1989. Palynostratigraphy of the Scalby Formation (Middle Jurassic) of the Cleveland Basin, north-east Yorkshire. Proceedings of the Yorkshire Geological Society, Vol.47, 349-354. 
Powell, J.H. 2010. Jurassic sedimentation in the Cleveland Basin: a review. Proceedings of the Yorkshire Geological Society, 58, 21-72. 
Wright, J K. 1968a. The stratigraphy of the Callovian Rocks between Newtondale and the Scarborough Coast, Yorkshire. Proceedings of the Geologists' Association, 79, 363-399. 
Wright, J K. 1977. The Cornbrash Formation (Callovian) in North Yorkshire and Cleveland. Proceedings of the Yorkshire Geological Society, Vol.41, 325-346. 
Page, K N. 1989. A stratigraphic revision for the English Lower Callovian. Proceedings of the Geologists' Association, Vol.100, 363-382. 
Rawson, P F and Wright, J K. 2000. The Yorkshire Coast. Geologists' Association Guide No.34. (London: The Geologists' Association.) 130pp. 3rd Edition. 
Wright, J.K. 1978. The Callovian succession (excluding Cornbrash) in the western and northern parts of the Yorkshire Basin. Proceedings of the Geologists' Association, 89, 259-261. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E054