The BGS Lexicon of Named Rock Units — Result Details

Treginnis Group

Computer Code: PVT Preferred Map Code: notEntered
Status Code: Full, pending ratification
Age range: Neoproterozoic Era (AZ) — Neoproterozoic Era (AZ)
Lithological Description: Fragments of vesicular trachyte, augite andesite and quartz rhyolite in red matrix as well as fragments of reddish trachyte in green gritty matrix.
Definition of Lower Boundary: Drawn at base of green grit with trachyte fragments where it rests conformably on feldspathic grit of the Penrhiw Group.
Definition of Upper Boundary: Drawn at conformable upward passage from red grit of the Treginnis Group to green grit and clegyr conglomerate of the Caerbwdy Group.
Thickness: 180 - 220m approx.
Geographical Limits: South-west Wales.
Parent Unit: Pebidian Supergroup (PN)
Previous Name(s): Treginnis Series (-4278)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  Treginnis-Uchaf Farm, St. David's, Dyfed, Wales. 
Reference(s):
Green, J F N. 1908. The geological structure of the Saint David's area (Pembrokeshire). Quarterly Journal of the Geological Society of London, Vol.64, 363-383. 
Cox, A H, Green, J F N, Jones, O T and Pringle, J. 1930. The Geology of the St David's district, Pembrokeshire. Proceedings of the Geologists' Association, Vol.41, 241-273. 
Harris, A L and others, 1973. A correlation of the Pre-Cambrian rocks in the British Isles. Geological Society of London Special Report No 6. 
Pringle, J and George, T N, 1948. South Wales. British Regional Geology. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
none recorded or not applicable