| Computer Code: |
CTM |
Preferred Map Code: |
Ctm |
| Status Code: |
Full |
| Age range: |
Rhaetian Age (TR)
— Rhaetian Age (TR) |
| Lithological Description: |
Grey and grey-green calcareous mudstones and shales and laminated and lenticular calcareous siltstones with beds of coarse-grained oolitic sandstone. |
| Definition of Lower Boundary: |
Placed at sharp, commonly channelled base, resting on underlying Westbury Formation. |
| Definition of Upper Boundary: |
Placed at base of porcellanous limestones of overlying Langport Member. |
| Thickness: |
1-2m |
| Geographical Limits: |
Present throughout England. |
| Parent Unit: |
Lilstock Formation (LTK)
|
| Previous Name(s): |
Cotham Beds [Obsolete Name and Code: Use CTM]
(-2131)
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Reference Section |
Lilstock, west Somerset. |
| Type Area |
West Somerset and South Glamorgan. |
| Reference Section |
Immediately north of Lavernock Point, South Glamorgan. |
| Reference(s): |
| 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. |
| Waters, R A and Lawrence, D J D. 1987. Geology of the South Wales Coalfield - Part III: the country around Cardiff. Memoir of the British Geological Survey, Sheet 263. (England and Wales). |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
|
E183
E199
E127
E202
E142
E141
E279
|
