The BGS Lexicon of Named Rock Units — Result Details

Minffordd Formation

Computer Code: MINF Preferred Map Code: notEntered
Status Code: Pending Upgrade
Age range: Comley Series (EC) — Comley Series (EC)
Lithological Description: Coarse- to fine-grained epiclastic rocks intercalated with pyroclastic and mixed pyroclastic and epiclastic rocks, comprising laminated siltstones, felsic air-fall tuffs and tuffites, volcanogenic sandstones and conglomerates (particularly in the lower part) and thin ash-flow tuffs.
Definition of Lower Boundary: Unconformably overlies rocks of the Padarn Tuff Formation.
Definition of Upper Boundary: Unconformably overlain by rocks of the Bangor Formation.
Thickness: 1600m
Geographical Limits: Snowdonia, North Wales.
Parent Unit: Arfon Group (ARN)
Previous Name(s): none recorded or not applicable
Alternative Name(s): Minfordd Formation
Stratotypes:
Partial Type Section  Track between Pant-caerhun and Tai'r-ffynnon, near Caerhun. Howells, M F, Reedman, A J and Leveridge, B E. 1985. 
Partial Type Section  Roadcuts on Bangor By-Pass (A55) near Caerhun. Howells, M F, Reedman, A J and Leveridge, B E. 1985. 
Reference(s):
Rushton, A W A and Howells, M F. 1998. Stratigraphical framework for the Ordovician of Snowdonia and the Lleyn Peninsula. British Geological Survey Research Report, RR/99/08. 
Reedman, A J, Leveridge, B E and Evans, R B. 1984. The Arfon Group (Arvonian?) of North Wales. Proceedings of the Geologists' Association, Vol.95, 313-321. 
Howells M F, Reedman A J and Leveridge B E. 1985. Geology of the country around Bangor: Explanation for 1:50 000 geological sheet 106 (England and Wales). British Geological Survey Sheet Explanation. [London: HMSO.] 34pp. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E106 E118