The BGS Lexicon of Named Rock Units — Result Details

Porth Maen Melyn Volcanic Formation

Computer Code: PMV Preferred Map Code: PMV
Status Code: Pending Upgrade
Age range: Abereiddian Stage (O2) — Abereiddian Stage (O2)
Lithological Description: Rhyolitic and dacitic lavas, tuffs and agglomerates, locally with interbedded sediments and debris flows.
Definition of Lower Boundary: Not defined.
Definition of Upper Boundary: Not defined.
Thickness: 80-100 metres.
Geographical Limits: 1:50,000 Sheet 209 (St.Davids) and adjacent Sheet 210.
Parent Unit: Fishguard Volcanic Group (FIV)
Previous Name(s): Lower Rhyolitic Division (-4841)
Alternative Name(s): none recorded or not applicable
Stratotypes:
none recorded or not applicable
Reference(s):
Thomas, G E and Thomas, T M. 1956. The volcanic rocks of the area between Fishguard and Strumble Head, Pembrokeshire. Quarterly Journal of the Geological Society, Vol.112, 291-314. 
Bevins, R E, and Roach, R A. 1980. Early Ordovician Volcanism in Dyfed, south-west Wales. "In" Harris, A Land others. The Caledonides of the British Isles Reviewed. Geological Society Special Publication, No.8, p.603-609. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E209