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.] 112pp. |
1:50K maps on which the lithostratigraphical unit is found, and map code used: |
E136
E135
|