The BGS Lexicon of Named Rock Units — Result Details

Townsend Tuff Bed

Computer Code: TWT Preferred Map Code: TWT
Status Code: Full
Age range: Pridoli Epoch (SO) — Lochkovian Age (DO)
Lithological Description: Composite unit of air-fall tuff with three recognisable tuff beds and intervening mudstones.
Definition of Lower Boundary: Drawn at base of crystal tuff at base of FALL A.
Definition of Upper Boundary: Drawn at top of dust tuff at top of FALL C.
Thickness: 3 - 4m
Geographical Limits: South Wales and Welsh Borders.
Parent Unit: Sandy Haven Formation (SAHA)
Previous Name(s): Townsend Tuff Member (-1881)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Section  Townsend, west side of Dale Roads, west of Milford Haven, Dyfed [SM 8126 0610] (Allen and Williams, 1978). 
Reference(s):
Allen, J R L and Williams, B P J. 1978. The sequence of the earlier Lower Old Red Sandstone (Siluro - Devonian) north of Milford Haven, southwest Dyfed (Wales). Geological Journal, Vol.13, 113-136. 
Allen, J R L and Williams, B P J. 1981. Sedimentology and stratigraphy of the Townsend Tuff Bed (Lower Old Red Sandstone) in South Wales and the Welsh Borders. Quarterly Journal of the Geological Society, Vol.138, 15-29. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E199 E181 E214