| Computer Code: |
TYFV |
Preferred Map Code: |
TF |
| Status Code: |
Full |
| Age range: |
Caradoc Series (O4)
— Caradoc Series (O4) |
| Lithological Description: |
Basalt lavas and pillow breccias with hyaloclastite, basaltic tuff; mudstone intercalations. |
| Definition of Lower Boundary: |
Rests on mudstones associated with the Lower Crafnant Volcanic Formation. |
| Definition of Upper Boundary: |
Overlain by part of the Nod Glas (= Cadnant Shales). |
| Thickness: |
500m |
| Geographical Limits: |
Restricted to the area of Tal y Fan, 5km north west of Dolgarrog. |
| Parent Unit: |
Snowdon Volcanic Group (SV)
|
| Previous Name(s): |
none recorded or not applicable
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Reference Section |
Tal y Fan. |
| Reference(s): |
| 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, 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
E094
|
