The BGS Lexicon of Named Rock Units — Result Details

Penfro Till Formation

Computer Code: POTI Preferred Map Code: notEntered
Status Code: Full
Age range: Pleistocene Epoch (QP) — Pleistocene Epoch (QP)
Lithological Description: Sand and gravel and red and purple stony clay diamicton (till) with distinctive igneous clasts of western provenance (Bowen p. 147 in Lewis and Richards, 2005). Erratic boulders include tuff (at Pentre), quartz felsite (at Newton and St Athan).
Definition of Lower Boundary: Unconformable contact with bedrock of Silurian to Carboniferous age
Definition of Upper Boundary: Ground surface or overlain by Glamorgan Glacigenic Formation, as at Pencoed (Griffiths, 1940)
Thickness: 5m at type section; up to 9.5m at Pencoed (Strahan and Cantrill, 1904)
Geographical Limits: Highly dissected in Pembrokeshire and western Carmarthenshire. Widespread in south Pembrokeshire.
Parent Unit: Albion Glacigenic Group (ALBI)
Previous Name(s): Penfro Formation (-1766)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Partial Type Section  Llandre Gravel Quarry, Pembrokeshire Glacial gravels with local clasts and erratics from North Pembrokeshire (Bowen, 1999) 
Partial Type Section  West Angle Bay, Milford Haven Stiff purplish stony clay with igneous clasts (till), overlain by raised beach deposits (Dixon, 1921; West Angle Member of Bowen, 1999) 
Reference(s):
Bowen, D Q. 1994. Late Cenozoic of Wales and South-West England. Proceedings of the Ussher Society, Vol. 8, 209-213. 
Dixon, E E L, 1921. The Geology of the South Wales Coalfield, Part XIII , the country around Pembroke and Tenby, being an account of the region comprised in sheets 244 and 245. Memoir of the Geological Survey of Great Britain (HMSO). 
Griffiths, J C. 1940. The glacial deposits west of the Taff. Unpublished PhD thesis, University of London. 
Strahan, A, and Cantrill, T C. 1904. The geology of the South Wales Coalfield, Part VI, the country around Bridgend. Memoir of the Geological Survey of Great Britain (London: HMSO). 
Bowen, D Q. 1999. A revised correlation of Quaternary deposits in the British Isles. Geological Society Special Report, No. 23. 
Campbell, S and Bowen, D Q. 1989. Quaternary of Wales. Geological Conservation Review. (Peterborough: Nature Conservancy Council.) 
Bowen, D Q. 2005. South Wales. In Lewis, C A and Richards, A E (editors), The glaciations of Wales and adjacent areas. (Logaston Press.) 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
none recorded or not applicable