The BGS Lexicon of Named Rock Units — Result Details

Cumbrian Coast Group

Computer Code: CCO Preferred Map Code: CCO
Status Code: Full
Age range: Permian Period (P) — Permian Period (P)
Lithological Description: Comprises a basal sequence of grey siltstones and dolomites overlain by evaporites (St Bees Evaporite Formation), overlain by red siltstones, silty mudstones and calcareous sandstones (St Bees Shale Formation), which locally pass laterally into halite.
Definition of Lower Boundary: Point in sequence where there is a sharp upwards change from either Brockram or red sandstone, to grey siltstones or dolomites.
Definition of Upper Boundary: Tends to be gradational therefore taken arbitrarily where sandstone (St Bees Sandstone Formation) becomes predominent over siltstone (St Bees Shale Formation).
Thickness: Ranges from 36m in type section to 300m+ in Irish Sea grabens.
Geographical Limits: North and east Irish Sea and bordering land areas west of the Pennines including west Cumbria, Vale of Eden, south Cumbria, Lancashire and north-east Cheshire, ie the 'Bakevellia Sea Basin' of Smith and others (1974); see also Jackson and others, 1987.
Parent Unit: Not Applicable (-)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Stratotypes:
Reference Section  Details published by Rose and Dunham (1977, figure 10 and p126) Haverigg Haws Borehole, SD17NW/2 between depths of 265.79m (top) and 515.11 (base). 
Reference Section  Details published by Arthurton and Hemingway, 1972. Borehole NX91SE/190, 1.4km south west of Salton Bay, between depths of 99.0m (top) and 181.7m (base). 
Type Section  Details of section published by Smith (1924), at Salton Bay on the Cumbrian coast south-west of Whitehaven. 
Reference(s):
Arthurton, R S and Hemingway, J E, 1972. The St Bees Evaporites - a carbonate evaporite formation of Upper Permian age in west Cumberland, England. Proceedings of the Yorkshire Geological Society, Vol.38, p 565-591. 
Pattison, J, 1970. A review of the marine fossils from the Upper Permian Rocks of Northern Ireland and north-west England. Bulletin of the Geological Survey of Great Britain, Vol.32, p.123-165. 
Smith, B. 1924. On the West Cumberland Brockram and its associated rocks. Geological Magazine, Vol.61, 289-308. 
Jackson, D I, Mulholland, P, Jones, S M and Warrington, G, 1987. The geological framework of the East Irish Sea Basin. 191-203 in Brooks J and Glennie, K (editors), Petroleum Geology of North West Europe. [Graham and Trotman.] 
Smith, D B, Brunstrom, R G W, Manning, D I, Simpson, S and Shotton, F W. 1974. A correlation of Permian rocks in the British Isles. Geological Society of London Special Report No. 5. 
Rose, W C C. 1977. Geology and Hematite deposits of South Cumbria. Economic Memoir for 1:50,000 Sheet 58 and southern part of Sheet 48. Memoir of the geological Survey of Great Britain. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E059 E058 E048