| 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: |
Moor Cliffs Formation (MOCL)
|
| Previous Name(s): |
Townsend Tuff Member [Obsolete Name and Code: Use TWT]
(-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
|
