| Computer Code: |
GLMD |
Preferred Map Code: |
notEntered |
| Status Code: |
Full |
| Age range: |
Wenlock Epoch (SW)
— Wenlock Epoch (SW) |
| Lithological Description: |
Calcareous silty mudstones and siltstones, with limestone nodules, localised thin bentonitic clays, and very fossiliferous containing a diverse shelly fauna, mainly of brachiopods. |
| Definition of Lower Boundary: |
Not seen. |
| Definition of Upper Boundary: |
At the base of sandstone-dominated beds of the Ton Siltstone Formation. |
| Thickness: |
At least 220 m thick. |
| Geographical Limits: |
The central part of the (Silurian) Usk Inlier, South Wales. |
| Parent Unit: |
Not Applicable (-)
|
| Previous Name(s): |
Wenlock Shales
(-933)
|
| Alternative Name(s): |
Coalbrookdale Formation
|
| Stratotypes: |
| Type Section |
Railway cutting by the Royal Ordnance Factory, near Bryn Farm, Glascoed, 3 km north-west of Usk. Barclay, 1989; Walmsley, 1882, p.5. |
| Reference(s): |
| Walmsley, V G. 1982. In: The Silurian inliers of the south-eastern Welsh Borderland. Lawson, J D, Curtis, M L K, Squirrell, H C, Tucker, E V and Walmsley, V G. Geologists' Association Guide No. 5. |
| Barclay, W J, Jackson, D I, Mitchell, M, Owen, B, Riley, N J, White, D E, Strong, G E, and Monkhouse, R A. 1989. Geology of the South Wales Coalfield, Part II, the country around Abergavenny. Memoir of the British Geological Survey. |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
|
E232
|
