| Computer Code: |
GGP |
Preferred Map Code: |
notEntered |
| Status Code: |
Full, pending ratification |
| Age range: |
Longvillian Substage (OL)
— Longvillian Substage (OL) |
| Lithological Description: |
[Obsolete: use GAFA] Greenish micaceous grits with some shales. |
| Definition of Lower Boundary: |
Drawn at the base of the Gaerfawr Group where green micaceous grit conformably rests upon shales of the Pwll-y-Glo Group. |
| Definition of Upper Boundary: |
Drawn at the conformable upward passage of micaceous grit to black phosphate shales of the Gwern-y-Brain Group. |
| Thickness: |
330 metres approx. |
| Geographical Limits: |
Gaerfawr Hill, north-west of Welshpool, Powys. |
| Parent Unit: |
none recorded or not applicable
|
| Previous Name(s): |
none recorded or not applicable
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Type Area |
Gaerfawr Hill, north west of Welshpool. |
| Reference(s): |
| Bancroft, B B. 1933. Correlation Tables of the stages Costonian - Onnian in England and Wales. Published by the author, Blakeney, Glos. |
| Wade, A, 1911. The Llandovery and associated rocks of north-eastern Montgomeryshire. Quarterly Journal of the Geological Society of London. Vol.67, p.419,428-431. |
| Shackleton, R M, 1938. The geology of the district around Llansantffraid Ym Mechain, Montgomeryshire. Quarterly Journal of the Geological Society of London. Vol.94, p.455. |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
| none recorded or not applicable |
