The BGS Lexicon of Named Rock Units — Result Details

Exmoor Group

Computer Code: EXM Preferred Map Code: notEntered
Status Code: Full
Age range: Emsian Age (DE) — Tournaisian Stage (CT)
Lithological Description: Grey mudstones with subordinate thin- to medium-bedded siltstones, sandstones and a few limestones. The Group is punctuated by three sandstone-dominated formations. The lower two are predominantly red, purple green and grey sandstones with minor conglomerates and trace mudstones. The upper one is interbedded grey to buff sandstones, siltstones and mudstones.
Definition of Lower Boundary: Not seen.
Definition of Upper Boundary: The upper boundary is taken at the incoming of hard black finely laminated unfossiliferous and silty mudstones of the Teign Valley Group (Doddiscombe Formation) above the soft mid to dark grey mudstones with scattered very thin fossiliferous limestones, siltstones and sandstones of the underlying Exmoor Group (Pilton Mudstone Formation).
Thickness: c.7000m
Geographical Limits: North Devon and west Somerset. (SS 80 40).
Parent Unit: Not Applicable (-)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  Exmoor, north Devon and Somerset. Complete sequence, apart from top and base is exposed on the coast between Croyde and Minehead. Edmonds et al. 1985. 
Reference(s):
Waters, C N, Brown, M A E, Dean, M T and Powell, J H. In press. Lithostratigraphical framework for Carboniferous successions of Great Britain (Onshore). British Geological Survey Research Report, RR/05/06. 
Edmonds, E A, Whittaker, A, and Williams, B J. 1985. Geology of the country around Ilfracombe and Barnstaple. Memoir of the British Geological Survey, Sheets 277 and 293 (England and Wales). 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
none recorded or not applicable