Computer Code: |
PNT |
Preferred Map Code: |
PnT |
Status Code: |
Full |
Age range: |
Caradoc Series (O4)
— Caradoc Series (O4) |
Lithological Description: |
Felsic tuffs with siltstone intercalations. |
Definition of Lower Boundary: |
Conformable within the upper part of the Nant Ffrancon Subgroup. |
Definition of Upper Boundary: |
Conformable within the upper part of the Nant Ffrancon Subgroup. |
Thickness: |
To 10m |
Geographical Limits: |
Eastern central Snowdonia. |
Parent Unit: |
Nant Ffrancon Subgroup (NFR)
|
Previous Name(s): |
none recorded or not applicable
|
Alternative Name(s): |
Gwern Gof Tuff
|
Stratotypes: |
Type Section |
Head of Cwm Penamnen. Howells et al., 1978. |
Reference(s): |
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 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. |
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. |
1:50K maps on which the lithostratigraphical unit is found, and map code used: |
E119
|