| Computer Code: |
CFF |
Preferred Map Code: |
notEntered |
| Status Code: |
Full |
| Age range: |
Aurelucian Stage (OJ)
— Burrellian Stage (OK) |
| Lithological Description: |
Acidic ash-flow tuff. |
| Definition of Lower Boundary: |
Overlies siltstone and basalt at the top of the Benglog Formation. |
| Definition of Upper Boundary: |
Overlain by the Pistyllion Formation and the Aran Fawddwy Formation. |
| Thickness: |
To 212 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 |
Craig y Ffynnon [SH 832 195]. |
| 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. |
| Allen, P M, and Jackson, A A. 1985. Geology of the country around Harlech. Memoir of the British Geological Survey, Sheet 135 with part of Sheet 149 (England and Wales). (London: HMSO.) 112 pp. |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
|
E136
E135
|
