| Computer Code: |
LLV |
Preferred Map Code: |
LlV |
| Status Code: |
Full |
| Age range: |
Caradoc Series (O4)
— Caradoc Series (O4) |
| Lithological Description: |
Acid ash-flow tuffs, with some basic and intermediate volcanic rocks. Note: see also the descriptions of the Capel Curig Volcanic, Conwy Rhyolite, Braich Tu Du, Gwern Gof, Foel Fras and Foel Grach formations. |
| Definition of Lower Boundary: |
Where one of the constituent formations rests on sediments of the undivided Nant Ffrancon Group; at base of the Capel Curig Volcanic Formation. |
| Definition of Upper Boundary: |
At top of Capel Curig Volcanic Formation. d tuffs of the Cwm Eigiau Formation. |
| Thickness: |
1400m approx. |
| Geographical Limits: |
Northern and central Snowdonia. |
| Parent Unit: |
Gwynedd Supergroup (GWYN)
|
| Previous Name(s): |
none recorded or not applicable
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Type Area |
Between Carnedd Dafydd and Conwy Mountain. Note: see also stratotypes for Capel Curig Volcanic, Conwy Rhyolite, Braich Tu Du, Gwern Gof, Foel Fras and Foel Grach formations. |
| Reference(s): |
| Smith, B and George, T N. 1961. North Wales. British Regional Geology. (London: H.M.S.O.). 97pp. |
| Ball, T K, and Merriman, R J. 1989. The petrology and geochemistry of Ordovician Llewelyn Volcanic Group, Snowdonia, North Wales. British Geological Survey Research Report, SG/89/1. |
| 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: |
|
E106
E119
E094
|
