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
Stratotypes:
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). 
Reference(s):
Smith, B. 1924. On the West Cumberland Brockram and its associated rocks. Geological Magazine, Vol.61, 289-308. 
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. 
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:
E048