The BGS Lexicon of Named Rock Units — Result Details
Lower Basic Volcanic Group
| Computer Code: | LBV | Preferred Map Code: | notEntered |
|---|---|---|---|
| Status Code: | Full | ||
| Age range: | Abereiddian Stage (O2) — Abereiddian Stage (O2) | ||
| Lithological Description: | Altered, pale green basic pillow lavas with intercalated bands of slate and acid and basic tuffs. | ||
| Definition of Lower Boundary: | Drawn at base of mainly tuff and slate of Lower Basic Volcanic Group which rests conformably on massive, agglomeratic ashes of the Cefn-Hir Ashes. | ||
| Definition of Upper Boundary: | Drawn at conformable upward passage from pillow lavas of the Lower Basic Volcanic Group to oolitic iron ore of the Llyn-y-Gader Mudstone and Ashes. | ||
| Thickness: | Approx. 450 metres. | ||
| Geographical Limits: | Mid-Wales and Marches. | ||
| Parent Unit: | Not Entered (?) | ||
| Previous Name(s): | The Lower Basic Spilitic Group [Obsolete Name and Code: Use LBV]
(-1641)
Llyn-Y-Gafr Spilitic Group [Obsolete Name and Code: Use LBV, LYG] (-4147) |
||
| Alternative Name(s): | none recorded or not applicable | ||
| Stratotypes: | |||
| Type Area | Llyn-y-Gafr, Cader Idris, Gwynedd. | ||
| Reference(s): | |||
| 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. | |||
| 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. | |||
| Cox, A H, and Wells, A K. 1927. The geology of the Dolgelley district, Merionethshire. Proceedings of the Geologists' Association, Vol.38, 265-318. | |||
| 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. | |||
| Jones, B, 1933. The geology of the Fairbourne-Llwyngwril district, Merioneth. Quarterly Journal of the Geological Society, Vol.89, 145-171. | |||
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: | |||
| none recorded or not applicable | |||