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 |