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:
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 Section  Surface section, in north bank of gullied trackway to west of Kneeton, Notts. exposes lowermost 12m of formation including base. 
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). 
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. 
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). 
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