The BGS Lexicon of Named Rock Units — Result Details
Lower Acid Volcanic Group [Obsolete: use OF]
| Computer Code: | LAV | Preferred Map Code: | notEntered |
|---|---|---|---|
| Status Code: | Full | ||
| Age range: | Arenig Series (OR) — Abereiddian Stage (O2) | ||
| Lithological Description: | [Obsolete: use OF] Tuffs and rhyolitic lavas (the latter may be recrystallized acid tuffs) interbedded slates also occur. | ||
| Definition of Lower Boundary: | Drawn at base of mainly tuffs of Lower Acid Volcanic Group which rest conformably on grits and sandy flags of the Basement Group. | ||
| Definition of Upper Boundary: | Drawn at conformable upward passage from mainly tuffs of Lower Acid Volcanic Group to the Moelyn Slates of the 'Bifidus' Beds. | ||
| Thickness: | Approx. 150 to 300 metres. | ||
| Geographical Limits: | Mid-Wales and Marches. | ||
| Parent Unit: | none recorded or not applicable | ||
| Previous Name(s): | Mynydd Y Gader Volcanic Group [Obsolete Name and Code: Use LAV]
(-4746)
Lower Acid Rhyolitic Group [Obsolete Name and Code: Use LAV] (-3512) Mynydd Y Gader Rhyolitic Group [Obsolete Name and Code: Use LAV] (-2281) |
||
| Alternative Name(s): | none recorded or not applicable | ||
| Stratotypes: | |||
| Type Area | Dolgellau-Cader Idris district, Gwynedd. | ||
| Reference(s): | |||
| Lake, P and Reynolds, S H. 1896. The Lingula Flags and igneous rocks of the neighbourhood of Dolgelly. Quarterly Journal of the Geological Society of London, Vol.52, 511-527. | |||
| Lake, P and Reynolds, S H, 1912. The geology of Mynydd-y-Gader, Dolgelly. Quarterly Journal of the Geological Society of London, Vol.68, 345-363. | |||
| Davies, R G, 1959. The Cader Idris Granophyre and its associated rocks. Quarterly Journal of the Geological Society, London. Vol.115, 189-216. | |||
| Wells, A K. 1925. The geology of the Rhobell Fawr district (Merioneth). Quarterly Journal of the Geological Society of London, Vol.81, 463-538. | |||
| Cox, A H. 1925. The geology of the Cadair Idris Range, (Merioneth). Quarterly Journal of the Geological Society of London, Vol.81, p.539-592. | |||
| Jones, B, 1933. The geology of the Fairbourne-Llwyngwril district, Merioneth. Quarterly Journal of the Geological Society, Vol.89, 145-171. | |||
| Cox, A H, and Wells, A K. 1921. The Lower Palaeozoic rocks of the Arthog-Dolgellau district (Merionethshire). Quarterly Journal of the Geological Society, London, Vol.76, p. 254-324. | |||
| Cox, A H, and Wells, A K. 1927. The geology of the Dolgelley district, Merionethshire. Proceedings of the Geologists' Association, Vol.38, 265-318. | |||
| Cox, A H, and Wells, A K. 1916. The Ordovician sequence in the Cader Idris district (Merioneth). British Association for the Advancement of Science Report for 1915 (Manchester), p.424. | |||
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: | |||
| none recorded or not applicable | |||