The BGS Lexicon of Named Rock Units — Result Details

Capel Curig Volcanic Formation

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