The BGS Lexicon of Named Rock Units — Result Details

Trefriw Tuff Formation

Computer Code: TRT Preferred Map Code: notEntered
Status Code: Pending Upgrade
Age range: Caradoc Series (O4) — Caradoc Series (O4)
Lithological Description: Highly weathered, medium to coarse basaltic tuff, hyaloclastite and agglomerate with interbedded volcaniclastic sediments.
Definition of Lower Boundary: Conformably overlies black mudstones of the Nod Glas Formation.
Definition of Upper Boundary: Overlain by grey mudstones and siltstones of the Conwy Mudstone Formation.
Thickness: To 70m
Geographical Limits: none recorded or not applicable
Parent Unit: Not Available (!)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
none recorded or not applicable
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: