The BGS Lexicon of Named Rock Units — Result Details

Upper Basic Volcanic Group [Cf Pen-Y-Gader Group]

Computer Code: UBV Preferred Map Code: notEntered
Status Code: Full, pending ratification
Age range: Abereiddian Stage (O2) — Caradoc Series (O4)
Lithological Description: Spilitic pillow lavas with subordinate pyroclastic bands to the east and central parts of the Cader Idris Range and dominantly pyroclastic rocks to the west. (Correlative of Upper Basic Volcanic Group = Pen-y-Gader Group).
Definition of Lower Boundary: Drawn at base of Upper Basic Volcanic Group where it rests conformably on pyroclastics of the Llyn-y-Gader Mudstones Group.
Definition of Upper Boundary: Drawn at conformable upward passage from spilitic lavas, mudstone, ash and chert of the Upper Basic Volcanic Group to mudstones of the Llyn Cau Mudstones Group.
Thickness: Approx. 120 to 150 metres.
Geographical Limits: Mid-Wales.
Parent Unit: Not Entered (?)
Previous Name(s): Pen-Y-Gader Group [Cf Upper Basic Volcanic Group] (PYGA)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  Pen-y-Gader, Cader Idris, Gwynedd. 
Reference(s):
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 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. 
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. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
none recorded or not applicable