Computer Code: |
PNF |
Preferred Map Code: |
notEntered |
Status Code: |
Full |
Age range: |
Aurelucian Stage (OJ)
— Burrellian Stage (OK) |
Lithological Description: |
Basaltic and andesitic lavas, with mudstone, mudflow breccias and crystal tuffs. |
Definition of Lower Boundary: |
Oversteps the Craig y Ffynnon Formation northwards and rests on the Allt Lwyd Formation. |
Definition of Upper Boundary: |
Overlain by the Aran Fawddwy Formation. |
Thickness: |
To 300 m. |
Geographical Limits: |
none recorded or not applicable
|
Parent Unit: |
Aran Volcanic Group (AVG)
|
Previous Name(s): |
none recorded or not applicable
|
Alternative Name(s): |
none recorded or not applicable
|
Stratotypes: |
Type Section |
Pistyllion to Bwlch y Fign [SH 8225 1900 to 8220 1855] (Allen and Jackson, 1985, p. 43). |
Reference(s): |
Rushton, A W A and Howells, M F. 1998. Stratigraphical framework for the Ordovician of Snowdonia and the Lleyn Peninsula. British Geological Survey Research Report, RR/99/08. |
British Geological Survey. 1986. Bala. England and Wales, Sheet 136. Provisional Solid Geology. 1:50 000 Series. (Keyworth, Nottingham: British Geological Survey.) |
1:50K maps on which the lithostratigraphical unit is found, and map code used: |
E136
E135
|