The BGS Lexicon of Named Rock Units — Result Details

Chudleigh Group

Computer Code: CHUD Preferred Map Code: notEntered
Status Code: Full
Age range: Tournaisian Age (CT) — Namurian Stage (CN)
Lithological Description: Thin bedded cherts and siliceous mudstones, black mudstones and limestones passing up into thick-bedded to massive sandstones with subordinate conglomerate and mudstone.
Definition of Lower Boundary: In the Chudleigh area the lower boundary is taken at the incoming of black sooty and siliceous mudstones of the Chudleigh Group (Winstow Chert Formation) above the purple, green and grey mudstones of the underlying Tamar Group (Whiteway Mudstone Formation). The contact is generally sharp. In the Plymouth area it is taken at the incoming of dark grey cherts and siliceous mudstones of the Chudleigh Group (Winstow Chert Formation) above the mid grey silty mudstones of the Tamar Group (Saltash Formation).
Definition of Upper Boundary: The upper boundary is taken at an angular unconformity where fine-grained glauconitic sandstone of the Upper Greensand Formation rests upon thick-bedded to massive, locally pebbly to conglomeratic sandstone of the Ugbrooke Sandstone Formation.
Thickness: Not known but probanly about 550m+
Geographical Limits: In the Chudleigh (SX 870 784) and East Ogwell (SX 845 695) areas, south Devon and in the middle Tamar valley (SX 43 61) in the Plymouth area, on the Devon/Cornwall border.
Parent Unit: Culm Supergroup (CU)
Previous Name(s): Culm [Obsolete Name and Code: Use CHUD, CU] (-3928)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  Area between Chudleigh and Kingsteignton, south Devon. The entire exposed Group is seen in the limbs of several recumbent folds. Exposure is poor but critical Group and Formational contacts have been investigated by trenching. Selwood et al. (1984); House and Butcher (1973). 
Reference(s):
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. 
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). 
Waters, C N, Barclay, W J, Davies, J R and Waters, R A. In press. Stratigraphical framework for Carboniferous successions of Southern Great Britain (Onshore). British Geological Survey Research Report, RR/05/06. 
House, M R and Butcher, N E, 1973. Excavations in the Devonian and Carboniferous Rocks near Chudleigh, south Devon. Transactions of the Royal Geological Society of Cornwall, Vol.20, p.199-220. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
none recorded or not applicable