| Computer Code: |
THMU |
Preferred Map Code: |
notEntered |
| Status Code: |
Full |
| Age range: |
Anisian Age (TA)
— Anisian Age (TA) |
| Lithological Description: |
[Obsolete: use KRM]
Mudstone and siltstone, interlaminated, with rhythmic alternation between reddish brown and greenish grey intervals. Halite occurs at base and top. |
| Definition of Lower Boundary: |
Conformable, at the gradational upward transition from predominantly structureless reddish brown mudstones (Sidmouth Mudstone Formation, undifferentiated) to the laminated reddish brown and greenish grey mudstones of the Thornton Mudstone Member. |
| Definition of Upper Boundary: |
Conformable, at the gradational upward transition from the laminated reddish brown and greenish grey mudstones of the Thornton Mudstone Member to the halite of the Preesall Halite Member. |
| Thickness: |
71 m to 112 m (Wilson and Evans, 1990). |
| Geographical Limits: |
North Fylde peninsula, Lancashire. |
| Parent Unit: |
none recorded or not applicable
|
| Previous Name(s): |
Thornton Mudstone [Obsolete Name and Code: Use KRM, THMU]
(-2880)
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Type Section |
Thornton Clevelys Borehole (SD34SW/15), Fylde, Lancashire, full sequence proved between 87.85 m and 209.00 m depth. Curated core held at the National Geosciences Records Centre, BGS Keyworth. Wilson and Evans (1990). |
| Reference(s): |
| 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. |
| 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. |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
| none recorded or not applicable |
