The BGS Lexicon of Named Rock Units — Result Details

Coat Walls Mudstone Member [Obsolete: use KRM]

Computer Code: CWMU Preferred Map Code: notEntered
Status Code: Full
Age range: Ladinian Age (TD) — Ladinian Age (TD)
Lithological Description: [Obsolete: use KRM] Mudstone, reddish-brown, structureless, interbedded with silty mudstone, greenish grey, laminated, mudstone breccias, halite and gypsum are common towards the base.
Definition of Lower Boundary: Conformable, at gradational upward transition from the halite of the underlying Preesall Halite Member to the predominantly greenish grey laminated mudstone at the base of the Coat Walls Mudstone Member.
Definition of Upper Boundary: Gradational and conformable transition from the laminated, reddish brown and greenish grey mudstone of the Coat Walls Mudstone Member to the dominantly reddish-brown, structureless mudstones of the Breckells Mudstone Member.
Thickness: Up to 130 m in the Blackpool district, Lancashire (Wilson and Evans, 1990).
Geographical Limits: Within the limits of the Preesall syncline, north Fylde peninsula, Lancashire.
Parent Unit: none recorded or not applicable
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Section  Coat Walls Borehole (SD34NE/30) northern Fylde peninsula, Lancashire, full sequence proved between 152.30 m and 281.46 m depth. Wilson and Evans (1990). 
Reference(s):
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. 
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. 
Wilson, A A and Evans, W B. 1990 Geology of the country around Blackpool. Memoir of the British Geological Survey, Sheet 66. (England and Wales). 
Jackson, D I, Johnson, H and Smith, N J P. 1997. Stratigraphical relationships and a revised lithostratigraphical nomenclature for the Carboniferous, Permian and Triassic rocks of the offshore East Irish Sea Basin. 11-32 in Petroleum Geology of the Irish Sea and Adjacent Areas. Meadows, N S, Trueblood, S P, Hardman, M and Cowan, G. (editors). Geological Society Special Publication, No.124. 
Wilson, A A. 1990. The Mercia Mudstone Group (Trias) of the East Irish Sea Basin. Proceedings of the Yorkshire Geological Society, Vol.48, 1-22. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
none recorded or not applicable