| Computer Code: |
SMG |
Preferred Map Code: |
SMg |
| Status Code: |
Full |
| Age range: |
Early Devonian Epoch (DL)
— Early Devonian Epoch (DL) |
| Lithological Description: |
[Obsolete: use FWW] Interbedded purple, brown and green sandstones and red mudstones with intraformational conglomerates containing calcrete clasts. |
| Definition of Lower Boundary: |
Placed at top of Bishop's Frome ('Psammosteus') Limestone Member of the Raglan Mudstone Formation. |
| Definition of Upper Boundary: |
At base of Brownstones and (locally) Senni Beds, where sandstone-dominated sequences begin. |
| Thickness: |
c.400-700m. |
| Geographical Limits: |
Welsh Borderland. |
| Parent Unit: |
none recorded or not applicable
|
| Previous Name(s): |
St Maughan's Group [Obsolete Name and Code: Use SMG]
(-1190)
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Reference Section |
M 50 Motorway section, near Ross-on-Wye (Allen and Dineley, 1976). |
| Type Area |
Vicinity of the village of St Maughan's, Gwent. |
| Reference(s): |
| Brandon, A. 1989. Geology of the country between Hereford and Leominster. Memoir for 1:50 000 Geological Sheet 198. |
| Pocock, R W, 1940. South Wales and Bristol district. "In" Summary of Progress for 1938, p.25-26. Geological Survey of Great Britain. (London: Her Majesty"s Stationery Office). |
| Allen, J R L, and Dineley, D L. 1976. The succession of the Lower Old Red Sandstone (Siluro-Devonian) along the Ross - Tewkesbury Spur Motorway (M50), Hereford and Worcester. Geological Journal, Vol. 11, 1-14. |
| Welch, F B A and Trotter, F M. 1961. Geology of the country around Monmouth and Chepstow. Explanation of one-inch geological sheets 233 and 250. Memoir of the Geological Survey of Great Britain. |
| Waters, C N, Smith, K, Hopson, P M, Wilson, D, Bridge, D M, Carney, J N, Cooper, A H, Crofts, R G, Ellison, R A, Mathers, S J, Moorlock, B S P, Scrivener, R C, McMillan, A A, Ambrose, K, Barclay, W J, and Barron, A J M. 2007. Stratigraphical Chart of the United Kingdom: Southern Britain. British Geological Survey, 1 poster. |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
|
E198
E216
E232
E263
E249
E233
E234
E230
E212
E197
E213
E214
E199
E181
E250
|
