The BGS Lexicon of Named Rock Units — Result Details

Combe Shale Formation [Obsolete Name And Code: Use CMMU]

Computer Code: CMSH Preferred Map Code: CmSh
Status Code: Index Level
Age range: Courceyan Substage (CF) — Chadian Substage (CI)
Lithological Description: Highly fissile bluish-black or black shales and slates, locally characterised by white, silty laminations and closely spaced vertical joints, particularly in higher horizons.
Definition of Lower Boundary: Base taken at change from grey micaceous and green shales of the Trusham Shale to the typical black shales of the Combe Shale.
Definition of Upper Boundary: Top taken at bottom of the lowest bedded chert of Teign Chert.
Thickness: 90 - 150m (Middle Teign Valley); 45m (Ilsington area).
Geographical Limits: Middle Teign Valley, Devon, and Ilsington area.
Parent Unit: Not Entered (?)
Previous Name(s): Combe Formation (-144)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Reference Section  Road cutting from Ilsington to Woodhouse shows lower boundary with Trusham Shale. 
Type Section  Road cutting immediately north of Lower Ashton, Devon. 
Reference(s):
Chesher, J A, 1968. The succession and structure of the Middle Teign Valley. Proceedings of the Ussher Society, Vol.2, 15-17. 
Selwood, E B, Edwards, R A, Simpson, S, Chesher, J A, Hamblin, R J O, Henson, M R, Riddolls, B W and Waters, R A. 1984. Geology of the countryside around Newton Abbot. Memoir of the British Geological Survey, Sheet 339 (England and Wales). 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E339