| Computer Code: |
GT |
Preferred Map Code: |
notEntered |
| Status Code: |
Full |
| Age range: |
Soudleyan Substage (OY)
— Soudleyan Substage (OY) |
| Lithological Description: |
White weathering, primary felsic ash-flow tuff. |
| Definition of Lower Boundary: |
Highly discordant on mudstones of the Nant Ffrancon Subgroup. |
| Definition of Upper Boundary: |
Conformably overlain by silty mudstones and fine grained sandstones of the Capel Curig Volcanic Formation. |
| Thickness: |
40 m. |
| Geographical Limits: |
none recorded or not applicable
|
| Parent Unit: |
Capel Curig Volcanic Formation (CCV)
|
| Previous Name(s): |
none recorded or not applicable
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| none recorded or not applicable |
| 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. |
| Howells, M F, Francis, E H, Leveridge, B E and Evans, C D R, 1978. Classical areas of British Geology. Capel Curig and Betws-y-Coed. Description of 1:25 000 Sheet SH75. London: HMSO for Institute of Geological Sciences. |
| 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). |
| 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. |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
|
E120
|
