The BGS Lexicon of Named Rock Units — Result Details

Dolgarrog Volcanic Formation

Computer Code: DV Preferred Map Code: DV
Status Code: Full
Age range: Caradoc Series (O4) — Caradoc Series (O4)
Lithological Description: Basalt, hyaloclastite, basaltic tuffs and pillow breccias.
Definition of Lower Boundary: Overlies Upper Crafnant Volcanic Formation. Characterized by ill-sorted pyroclastic deposits with much included argillaceous debris.
Definition of Upper Boundary: Underlies the Nod Glas (= Cadnant Shales).
Thickness: 400m
Geographical Limits: South and west of Dolgarrog.
Parent Unit: Snowdon Volcanic Group (SV)
Previous Name(s): Part Of Crafnant Volcanic Group (-2771)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Reference Section  Afon Porth-Llwyd. 
Reference(s):
Howells, M F, Leveridge, B E, Evans, C D R and Nutt, M J C, 1981. Classical areas of British Geology. Dolgarrog. Description of 1:25 000 Sheet SH76. London: HMSO for Institute of Geological Sciences. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E106