The BGS Lexicon of Named Rock Units — Result Details

Lower Basic Volcanic Group

Computer Code: LBV Preferred Map Code: notEntered
Status Code: Full, pending ratification
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): Llyn-Y-Gafr Spilitic Group (-4147)
The Lower Basic Spilitic Group (-1641)
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, 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. 
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, 1916. The Ordovician sequence in the Cader Idris district (Merioneth). British Association for the Advancement of Science Report for 1915 (Manchester), p.424. 
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