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: |
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. |
Partial Type Section |
Basal section in quarry southeast of Y Garnedd Farm. Elles, 1922. |
Reference(s): |
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. |
Elles, G L. 1922. The Bala country: its structure and rock succession. Quarterly Journal of the Geological Society of London, Vol.78, 132-175. |
1:50K maps on which the lithostratigraphical unit is found, and map code used: |
none recorded or not applicable |