Computer Code: |
UCV |
Preferred Map Code: |
UCV |
Status Code: |
Full |
Age range: |
Woolstonian Substage (OS)
— Woolstonian Substage (OS) |
Lithological Description: |
Massive, acidic, grey, muddy, crystal tuffite. |
Definition of Lower Boundary: |
Rests on mudstone and siltstone of the Middle Crafnant Volcanic Formation. |
Definition of Upper Boundary: |
Overlain by Nod Glas (= Cadnant Shales). |
Thickness: |
60-150m |
Geographical Limits: |
Eastern Snowdonia, around Betws-y-Coed. Farther north it is not readily separated from the Middle Crafnant Volcanic Formation. |
Parent Unit: |
Snowdon Volcanic Group (SV)
|
Previous Name(s): |
Upper Tuff Bed [Obsolete Name and Code: Use UCV]
(-1251)
|
Alternative Name(s): |
none recorded or not applicable
|
Stratotypes: |
Reference Section |
Gwydir Forest. |
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, Leveridge, B E, Evans, C D R and Nutt, M J C, 1981. Classical areas of British Geology. Dolgarrog. Description of 1:25 000 Sheet SH76. London: HMSO for Institute of Geological Sciences. |
1:50K maps on which the lithostratigraphical unit is found, and map code used: |
E106
E107
|