The BGS Lexicon of Named Rock Units — Result Details

Culm Supergroup
Computer Code: CU Preferred Map Code: notEntered
Status Code: Full
Age range: Famennian Age (DA) — Bolsovian Sub-age (CC)
Lithological Description: The lower part predominantly comprises euxinic black mudstones, bedded cherts, siliceous mudstones, thin limestones and local basaltic tuffs and lavas. Local shallow water quartzites, greenish mudstones and limestones and dark grey mudstones with thin sandstones are developed in the south. There are local small-scale turbidite systems comprising interbedded sandstones, conglomerates and mudstones or interbedded limestones and mudstones. The upper part comprises large scale turbidite and delta systems of thin- to thick-bedded sandstone, siltstones and mudstones. The delta systems contain rare thin coals.
Definition of Lower Boundary: In north Devon and west Somerset, the lower boundary is taken at the incoming of black, locally siliceous mudstones of the Culm Supergroup (Teign Valley Group) 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), In south Devon, it is taken at the incoming of black, locally siliceous mudstones of the Culm Supergroup (Teign Valley Group) above the olive green and pale grey mudstones of the Trusham Mudstone Formation. Elsewhere in the south the base is thrust out.
Definition of Upper Boundary: Not seen.
Thickness: 3600 to 4750m
Geographical Limits: Devon, north and east Cornwall and west Somerset, southwest England.
Parent Unit: Not Applicable (-)
Previous Name(s): Culm Measures (-3967)
Culm (-3928)
Culm Group (-1465)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  Devon, north and east Cornwall and west Somerset, southwest England. Waters et al. (in press). 
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. 
Sedgwick, A and Murchison, R I. 1840. On the physical structure of Devonshire, and on the subdivisions and geological relations of its older stratified deposits. Transactions of the Geological Society of London, Vol.5, 633-705. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
none recorded or not applicable
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