The BGS Lexicon of Named Rock Units — Result Details

Pen Bwlch Tuff Member

Computer Code: PBT Preferred Map Code: notEntered
Status Code: Pending Upgrade
Age range: Soudleyan Substage (OY) — Soudleyan Substage (OY)
Lithological Description: Two thin units of lapilli tuff separated locally by 5m of mudstone and siltstone.
Definition of Lower Boundary: Conformable Member of the Teirw Siltstone Formation.
Definition of Upper Boundary: Conformably overlain by mudstones and siltstones of the Teirw Siltstone Formation.
Thickness: To 11m
Geographical Limits: none recorded or not applicable
Parent Unit: Teirw Siltstone Formation (TSI)
Previous Name(s): Pen Bwlch Tuff Formation (-2358)
Pen Bwlch Tuff (-1754)
Alternative Name(s): none recorded or not applicable
Stratotypes:
none recorded or not applicable
Reference(s):
Brenchley, P J, 1978. The Caradocian rocks of the North and West Berwyn Hills. Geological Journal, Vol.13, 137-164. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E136