| Computer Code: |
GDGP |
Preferred Map Code: |
notEntered |
| Status Code: |
Index Level |
| Age range: |
Wenlock Epoch (SW)
— Ludlow Epoch (SU) |
| Lithological Description: |
[Obsolete] Slates, slates with thin silty sandstone-bands, alternating bands of cleaved mudstone and uncleaved laminated siltstone, fairly thinly bedded shales and perfectly cleaved silty mudstones. |
| Definition of Lower Boundary: |
Drawn at the base of the Pentre-Dwfr Slates where it rests conformably upon the Pen-y-Glog Group, namely the Pen-y-Glog Slates. |
| Definition of Upper Boundary: |
Drawn at conformable upward passage of the Glyn Dyfrdwy Group; thin-bedded shales, silty mudstones almost perfectly cleaved to fine-grained uncleaved sandstones and roughly cleaved sandy shales of the Nant-y-Bache Group. |
| Thickness: |
304 metres approx. |
| Geographical Limits: |
Llangollen, North Wales. |
| Parent Unit: |
none recorded or not applicable
|
| Previous Name(s): |
none recorded or not applicable
|
| Alternative Name(s): |
Nantglyn Mudstone Formation
|
| Stratotypes: |
| Type Area |
Llangollen area. |
| Reference(s): |
| Cocks, L R M, Holland, C H, Rickards, R B, and Strachan, I. 1971. A correlation of Silurian rocks in the British Isles. Geological Society of London, Special Report No. 1. |
| Wills, L J and Smith, B, 1922. The Lower Palaeozoic Rocks of the Llangollen district with special reference to Tectonics. Quarterly Journal of the Geological Society, Vol.78, p.176-226. |
| Wedd, C B, Smith, B and Wills, L J. 1927. The geology of the country around Wrexham, Part 1. Lower Palaeozoic and Lower Carboniferous rocks. Memoir of the Geological Survey of Great Britain. [London: HMSO.] 179pp. |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
| none recorded or not applicable |
