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 |
Craig yr Ysfa [SH 692 642] (Howells, Reedman and Leveridge, 1985, p. 11). |
Reference Section |
Gallt yr Ogof [SH 693 597] (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
|