The BGS Lexicon of Named Rock Units — Result Details

St Bees Evaporite Formation

Computer Code: SBE Preferred Map Code: SBE
Status Code: Full
Age range: Guadalupian Epoch (PUG) — Lopingian Epoch (PUL)
Lithological Description: Anhydrite and/or gypsum, with subordinate dolomite and siltstone, interbedded in cyclical sequences.
Definition of Lower Boundary: Taken at the point where the "basal breccia" or brockram passes up into grey carbonate-rich siltstones.
Definition of Upper Boundary: Taken at the base of the overlying red clastic sequence (St. Bees Shales) where red mudstones become predominant over evaporites.
Thickness: 21m in the type section with general range of 0 - 100m in west and south Cumbria.
Geographical Limits: West and south Cumbria, north Lancashire and east Irish Sea Basin.
Parent Unit: Cumbrian Coast Group (CCO)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Reference Section  BGS Roosecote Borehole (SD 26NW/19) (Rose and Dunham, 1977; Smith and others, 1974). 
Type Section  Borehole NX91SE/190 (Sandwith S9) 1.4km southwest of Salton Bay, west Cumbria. Depth 160.9 to 181.7m (Arthurton and Hemingway, 1972). 
Smith, B. 1924. On the West Cumberland Brockram and its associated rocks. Geological Magazine, Vol.61, 289-308. 
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. 
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. 
1:50K maps on which the lithostratigraphical unit is found, and map code used: