The BGS Lexicon of Named Rock Units — Result Details

Corallian Group

Computer Code: CR Preferred Map Code: Cr
Status Code: Full
Age range: Oxfordian Age (JO) — Oxfordian Age (JO)
Lithological Description: Complex succession of interdigitating limestones, marls, sandstones, sands, siltstones, silts, spiculites, mudstones.
Definition of Lower Boundary: First appearance of medium- or coarse-grained sand above the Oxford Clay Formation. In some areas, this also defines the top of that Formation but elsewhere, there is an intervening silty unit (West Walton Formation).
Definition of Upper Boundary: In the Dorset reference area, at the base of the Inconstans Bed (Kimmeridge Clay Formation), which also marks the Oxfordian-Kimmeridgian stage boundary, but elsewhere at the base of the thick mudstone succession that spans that stage boundary (ie Ampthill Clay and equivalents, and Kimmeridge Clay).
Thickness: To c.100m
Geographical Limits: Dorset to Oxfordshire, and North Yorkshire.
Parent Unit: Not Applicable (-)
Previous Name(s): CORALLIAN BEDS
CORALLIAN ROCKS
CORALLIAN FORMATION
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  Coast between Weymouth and Ringstead, Dorset, England 
Reference Section  Coastal cliffs and foreshore between Weymouth and Ringstead Bay, Dorset. 
Reference Section  Filey Brigg to the Hambleton Hills (inclusive), North Yorkshire (quarry and natural sections). 
Reference Section  Howardian Hills, North Yorkshire (quarry and natural sections). 
Reference(s):
Johnson, A L A, 1983. Field meeting on the Corallian of Oxfordshire, 16th May 1982. Proceedings of the Geologists' Association, Vol 94, P. 177. 
Wright, J K, 1986. A new look at the stratigraphy, sedimentology and ammonite fauna of the Corallian Group (Oxfordian) of south Dorset. Proceedings of the Geologists' Association, Vol.97, p.1. 
Melville, R V and Freshney, E C, 1982. The Hampshire Basin and adjoining areas. British Regional Geology. 
Arkell, W J. 1933. The Jurassic System in Great Britain. [Oxford: Clarendon Press.] 
Sherlock, R L, 1960. London and Thames Valley. British Regional Geology. 
Hallam, A, 1975. Jurassic Environments, p.79,82-82,165. Cambridge. 
Cope, J C W, 1980. A Correlation of Jurassic rocks in the British Isles, Part Two: Middle and Upper Jurassic. Geological Society of London Special Report No 15. 
Wright, J K, 1981. The Corallian rocks of north Dorset. Proceedings of the Geologists' Association, Vol 92, p.17. 
Blake, J F and Hudleston, W H, 1877. The Corallian rocks of England. Quarterly Journal of the Geological Society, Vol.33, p.260-405. 
Sun, S Q, 1989. A new interpretation of the Corallian (Upper Jurassic) Cycles of the Dorset Coast, Southern England. Geological Journal, Vol 24, p. 139. 
Horton, A, Sumbler, M G, Cox, B M and Ambrose, K, 1995. Geology of the country around Thame. Memoir of the British Geological Survey, Sheet 237 (England and Wales). 
Arkell, W J, 1927. The Corallian rocks of Oxford, Berkshire and north Wiltshire. Philosophical Transactions of the Royal Society of London, Vol.B216, 67-181. 
Arkell, W J, 1936. The Corallian Beds of Dorset. Proceedings of the Dorset Natural History and Archaeological Society, Vol.57, 59-93. 
Wright, J K, 1972. The stratigraphy of the Corallian. Proceedings of the Yorkshire Geological Society, Vol.39, 225-266. 
Fursich, F T, 1976. The use of macroinvertebrate associations in interpreting Corallian (Upper Jurassic) environments. Palaeogeography, Palaeoclimatology, Palaeoecology, Vol.20, 235-256. 
Wright, J K, 1980. Oxfordian Correlation Chart. "In" Cope, C J W, (Editor). A correlation of Jurassic rocks in the British Isles, Part two: Middle and Upper Jurassic. Geological Society of London Special Report No.15. (p.61-76 in Correlation Chart). 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E253 E254 E265 E266 E268 E281 E343 E341 E342 E237 E313 E252 E052 E282 E327 E055 E065 E064 E158 E187 E188 E204 E220