| Computer Code: |
SLN |
Preferred Map Code: |
Sln |
| Status Code: |
Full |
| Age range: |
Bolsovian Substage (CC)
— Asturian Substage (CAS) |
| Lithological Description: |
The formation is mainly sandstone with some interbedded mudstones. The sandstone is friable, fine- to coarse-grained, grey, cross-bedded and slightly micaceous. The mudstones are buff, purple and red-brown mottled. Locally, at the base of the formation is a loosely cemented, poorly sorted conglomerate about 10 m thick. The conglomerate has a red-brown sandy matrix and subrounded clasts of igneous rocks, quartzite, sandstone and limestone up to 15 cm diameter. |
| Definition of Lower Boundary: |
The grey sandstone of the Stallion Hill Sandstone Formation rests unconformably upon the red mudstones of the Raglan Mudstone Formation (RG). |
| Definition of Upper Boundary: |
There is a conformable passage from the grey sandstone of the Stallion Hill Sandstone Formation into the overlying grey mudstone with subordinate sandstone, seatearth and coal of the Grovesend Formation (GDB). |
| Thickness: |
Up to 80 m. Thinning to 0 within 2 km to northwest; cut out by faulting within 0.5 km to east of type locality. |
| Geographical Limits: |
Restricted to the Newent Coalfield, Gloucestershire. The formation crops out between Stallion Hill [SO 715 238] and Boulsdon Lea [SO 7083 2422]. |
| Parent Unit: |
Warwickshire Group (WAWK)
|
| Previous Name(s): |
none recorded or not applicable
|
| Alternative Name(s): |
Trenchard Group [Obsolete: use TRGP]
|
| Stratotypes: |
| Type Section |
Stallion Hill [SO 7151 2405]: 5.7 m thick sandstone. |
| Reference(s): |
| Waters, C N, Waters, R A, Barclay, W J, and Davies, J R. 2009. Lithostratigraphical framework for Carboniferous successions of Southern Great Britain (Onshore). British Geological Survey Research Report, RR/09/01. 184pp. |
| Worssam, B C, Ellison, R A and Moorlock, B S P. 1989. Geology of the country around Tewkesbury. Memoir of the British Geological Survey, Sheet 216 (England and Wales). |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
|
E216
|
