The BGS Lexicon of Named Rock Units — Result Details

West Wales Catchments Subgroup

Computer Code: WWACA Preferred Map Code: notEntered
Status Code: Full
Age range: Devensian Stage (QD) — Holocene Epoch (QH)
Lithological Description: Alluvial silt, sand, clay and gravel with some peat. Associated river terraces are dominated by sand and gravel, gravelly sand or sandy gravel with rare clay and silt.
Definition of Lower Boundary: Unconformable and in places strongly incised into lithologically highly variable sediments of the Caledonia Glacigenic Group or bedrock.
Definition of Upper Boundary: Ground surface or overlain unconformably by artificial deposits.
Thickness: Highly variable depending upon the relative stratigraphical positions of each of the component units. In the major river valleys the thickness may vary between 2 and 5m, but probably does not exceed 10m. For deposits flanking the major river valleys, the thickness probably varies between 1 and 3m.
Geographical Limits: Catchments of West and South Wales
Parent Unit: Britannia Catchments Group (BCAT)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Type Area  Catchments of rivers draining West Wales to Cardigan Bay and South Wales to the Bristol Channel, including the valleys and tributaries of the Prysor, Wnion, Afon Dyfi (River Dovey), Rheidol, Ystwyth, Afon, Tywi, Afon Teifi and Afon Nedd (River Neath). 
McMillan, A A, Hamblin, R J O and Merritt, J W. 2005. An overview of the lithostratigraphical framework for the Quarternary and Neogene deposits of Great Britain (onshore). British Geological Survey Research Report RR/04/04. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
none recorded or not applicable