| Computer Code: |
CCV |
Preferred Map Code: |
CCV |
| Status Code: |
Full |
| Age range: |
Soudleyan Substage (OY)
— Soudleyan Substage (OY) |
| Lithological Description: |
Acidic ash-flow tuffs. |
| Definition of Lower Boundary: |
Overlies unnamed sandstones of the Llewellyn Volcanic Group and siltstones of the Nant Ffrancon Subgroup. |
| Definition of Upper Boundary: |
Overlain by sandstones of the Cwm Eigiau Formation. |
| Thickness: |
Total up to 340 m. |
| Geographical Limits: |
Northern and central Snowdonia. |
| Parent Unit: |
Llewelyn Volcanic Group (LLV)
|
| Previous Name(s): |
none recorded or not applicable
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Reference Section |
Gallt yr Ogof [SH 693 597] (Howells, Reedman and Leveridge, 1985, p. 11). |
| Reference Section |
Craig yr Ysfa [SH 692 642] (Howells, Reedman and Leveridge, 1985, p. 11). |
| Reference(s): |
| Howells, M F and Leveridge, B E, 1980. The Capel Curig Volcanic Formation. Report of the Institute of Geological Sciences, No.80/6 |
| Howells, M F, Reedman, A J and Campbell, S D G, 1991. Ordovician (Caradoc) marginal basin volcanism in Snowdonia (north-west Wales). (London: HMSO for the British Geological Survey). |
| 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. |
| Howells, M F and Smith, M. 1997. Geology of the country around Snowdon. Memoir of the British Geological Survey, Sheet 119 (England and Wales). (London: The Stationery Office). 104pp. |
| Howells M F, Reedman A J and Leveridge B E. 1985. Geology of the country around Bangor: Explanation for 1:50 000 geological sheet 106 (England and Wales). British Geological Survey Sheet Explanation. [London: HMSO.] 34pp. |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
|
E106
E119
E094
E120
|
