The BGS Lexicon of Named Rock Units — Result Details

Edwalton Member

Computer Code: EDW Preferred Map Code: Edw
Status Code: Full
Age range: Carnian Age (TC) — Carnian Age (TC)
Lithological Description: Mudstone and siltstone, red-brown and greenish grey, with beds of indurated, variably dolomitic siltstone and very fine-grained sandstone common in the lower half; finely disseminated gypsum common in upper half.
Definition of Lower Boundary: Conformable, at the abrupt or rapid upward transition from interbedded green mudstone and pale grey fine-grained sandstone of the Cotgrave Sandstone Member to reddish brown structureless mudstone at the base of the Edwalton Member.
Definition of Upper Boundary: Conformable, at the abrupt upward transition from structureless, reddish brown and greenish grey mottled, gypsiferous mudstone at the top of the Edwalton Member to the lowest fine to medium-grained sandstone bed of the Arden Sandstone Formation.
Thickness: 35 to 45m
Geographical Limits: Mapped at the surface in south Nottinghamshire and Leicestershire; recognisable in borehole core and geophysical logs in the subsurface throughout East Midlands and northeast England.
Parent Unit: Sidmouth Mudstone Formation (SIM)
Previous Name(s): Edwalton Formation (-228)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Reference Section  Surface section, in north bank of gullied trackway to west of Kneeton, Notts. exposes lowermost 12m of formation including base. 
Type Section  Cropwell Bridge Borehole (SK63NE/28), near Cropwell Bishop, Nottinghamshire, from 42.0 m to 84.2 m depth. Curated core held at the National Geosciences Records Centre, BGS Keyworth. Howard et al., in press. 
Reference Section  Fulbeck F/B1 Borehole (SK85SE/25), Fulbeck, Lincolnshire, between 158.8 m and 119.41 m depth. Curated core held at the National Geosciences Records Centre, BGS Keyworth. Berridge et al., 1999. 
Reference(s):
Howard, A S, Warrington, G, Carney, J N, Ambrose, K, Young, S R and Pharaoh, T C. 2009. Geology of the country around Nottingham. Memoir of the British Geological Survey, Sheet 126 (England and Wales). 
Berridge, N G, Pattison, J, Samuel, M D A, Brandon, A, Howard, A S, Pharaoh, T C and Riley, N J. 1999. Geology of the Grantham district. Memoir of the British Geological Survey, sheet 127 (England and Wales). 
Elliott, R E 1961. The stratigraphy of the Keuper Series in southern Notinghamshire. Proceedings of the Yorkshire Geological Society, Vol.33, 197-231. 
Charsley, T J, Rathbone, P A and Lowe, D J, 1990. Nottingham: A geological background for planning and development. British Geological Survey Technical Report WA/90/1. 
Warrington, G, Audley-Charles, M G, Elliott, R E, Evans, W B, Ivimey-Cook, H C, Kent, P E, Robinson, P L, Shotton, F W and Taylor, F M. 1980. A correlation of the Triassic rocks in the British Isles. Special Report of the Geological Society of London, No.13. 
Howard, A S, Warrington, G, Ambrose, K, and Rees, J G. 2008. A formational framework for the Mercia Mudstone Group (Triassic) of England and Wales. British Geological Survey Research Report, RR/08/04. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E126 E127 E142 E141