The BGS Lexicon of Named Rock Units — Result Details

Pylle Clay Member

Computer Code: PYC Preferred Map Code: notEntered
Status Code: Full
Age range: Sinemurian Age (JS) — Pliensbachian Age (JE)
Lithological Description: Dark grey shaly mudstone.
Definition of Lower Boundary: Upward change from alternating thin limestones and mudstones, to a thick mudstone sequence.
Definition of Upper Boundary: Upward change to micritic limestones, or, where absent, to silty and fine-grained sandy clay.
Thickness: To 20m
Geographical Limits: From at least as far west as Pylle (limit of current mapping on 1:50k sheets 296 and 297)in an arc southeastward to just west of Milton Clevedon [ST 655 370]
Parent Unit: Charmouth Mudstone Formation (CHAM)
Previous Name(s): Lower Lias Shales (-3628)
Lower Lias Marls (-473)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  Around the hamlet of Pylle, Somerset 
Reference(s):
Hollingworth N T J, Ward D J, Simms, M J and Clothier, P, 1990. A temporary exposure of Lower Lias (Late Sinemurian) at Dimmer Camp, Castle Cary, Somerset, south-west England Mesozoic research, Vol.2, 163-180 
Donovan, D T, Bennett, R, Bristow, C R, Carpenter, S C, Green, G W, Hawkes, C J, Prudden, H C and Stanton W I, 1989. Geology of a gas pipeline from Ilchester (Somerset) to Pucklechurch (Avon), 1985. Proceedings of the Somerset Archaeological and Natural History Society for 1988, Vol.132, 297-317. 
Bristow, C R and Westhead R K, 1993. Geology of the Evercreech-Batcombe area (Somerset). British Geological Survey Technical Report WA/93/89. 
Duff K L, McKirdy A P and Harley M J [Eds], 1985. New Sites for Old. A Student's Guide to the Geology of the East Mendips. Nature Conservancy Council. 
Kellaway, G A and Wilson, V. 1941. An outline of the geology of Yeovil, Sherborne and Sparkford Vale. Proceedings of the Geologists' Association, Vol.52, 131-174. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
none recorded or not applicable