| Computer Code: |
MV |
Preferred Map Code: |
Mv |
| Status Code: |
Full |
| Age range: |
Caradoc Series (O4)
— Caradoc Series (O4) |
| Lithological Description: |
Volcaniclastic debris-flow deposits, felsic tuffs and tuffites. |
| Definition of Lower Boundary: |
Conformable within silty mudstones of the undivided Nant Ffrancon Subgroup. |
| Definition of Upper Boundary: |
Conformable within silty mudstones of the undivided Nant Ffrancon Subgroup. |
| Thickness: |
Upper up to 200mwith a Lower and Upper Member each up to 100m |
| Geographical Limits: |
South central Snowdonia. |
| Parent Unit: |
Nant Ffrancon Subgroup (NFR)
|
| Previous Name(s): |
Y Glog Volcanic Series [Obsolete Name and Code: Use MV]
(-1714)
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Partial Type Section |
Lower Member: screes behind Glan Y Morfa. |
| Partial Type Section |
Upper Member: Cefn Fedw. |
| Reference Section |
Moelwyn Mountains, above Tan y Grisiau Dam. |
| Reference(s): |
| 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. |
| Shackleton, R M. 1959. The stratigraphy of the Moel Hebog district between Snowdon and Tremadoc. Liverpool and Manchester Geological Journal, Vol.2, 216-252. |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
|
E119
|
