| Computer Code: |
PCE |
Preferred Map Code: |
notEntered |
| Status Code: |
Full |
| Age range: |
Longvillian Substage (OL)
— Longvillian Substage (OL) |
| Lithological Description: |
Coarse rhyolitic tuff. |
| Definition of Lower Boundary: |
Impersistent basal Member of the Gelli-grin Calcareous Ash Formation. Conformably overlies mudstones of the Ceiswyn Formation, but base is extremely irregular. |
| Definition of Upper Boundary: |
Passes conformably and gradationally upwards into the main part of the Gelli-grin Calcareous Ash Formation. |
| Thickness: |
0 to 6m |
| Geographical Limits: |
Bala and Corwen districts, North Wales. |
| Parent Unit: |
Gelli-Grin Calcareous Ash Formation (GEL)
|
| Previous Name(s): |
Pont-Ceunant Ash [Obsolete Name and Code: Use PCE]
(-2969)
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Partial Type Section |
Basal section in quarry southeast of Y Garnedd Farm. Elles, 1922. |
| Type Area |
No stratotype defined, but the thickest development (6m) is in the area immediately south of Pont-y-ceunant, 1.5km east of Bala. |
| Reference(s): |
| Elles, G L. 1922. The Bala country: its structure and rock succession. Quarterly Journal of the Geological Society of London, Vol. 78, 132-175. |
| Bassett, D A, Whittington, H B, and Williams, A. 1966. The stratigraphy of the Bala district, Merionethshire. Quarterly Journal of the Geological Society of London, Vol. 122, 219-271. |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
| none recorded or not applicable |
