The BGS Lexicon of Named Rock Units — Result Details

Bridgeton Sand Member

Computer Code: BRON Preferred Map Code: notEntered
Status Code: Full
Age range: Devensian Stage (QD) — Devensian Stage (QD)
Lithological Description: The two typical lithofacies are beds of very fine- to medium-grained sand, and fine to coarse gravel and boulders with a sandy matrix. The deposit is loose to dense. At Shieldhall (Browne and McMillan, 1989a, Figure 19), west Glasgow, the Member showed a gross upward-fining succession of about 20m thickness. The sands and silts showed flat bedding, ripple-lamination and climbing ripple-lamination, and planar and trough cross-bedding (westward transport). There were indistinct channels filled with massive sand, and two discrete ones up to 2m thick (width not known) containing framework-supported fine to very coarse gravel. Microfaulting was rarely seen and consisted of small reversed faults. There was evidence of soft sediment deformation, in that these deposits and the overlying laminated clays, originally flat-lying, dipped centroclinally into basins at angles up to as much as 80 degrees. This member forms the basal part of the Clyde Clay Formation.
Definition of Lower Boundary: The Bridgeton Sand Member rests with angular unconformity on bedrock or older Quaternary sediments. It commonly rests on the Wilderness Till Formation of the Caledonia Glacigenic Group (Midland Valley Glacigenic Subgroup).
Definition of Upper Boundary: The Bridgeton Sand Member is overlain unconformably or disconformably by younger Quaternary sediments, normally the Paisley Clay Member of the British Coastal Deposits Group or the Clyde Valley Formation of the Britannia Catchments Group (Clyde Catchment Subgroup). It is almost always concealed below younger sediments throughout its area of occurrence.
Thickness: Veneer to over 20 metres.
Geographical Limits: The Bridgeton Sand Member of the Clyde Clay Formation is recognised in the lower Clyde valley west of Hallside/Greenoakhill (NS 670 600) downriver at least to near Erskine Bridge (NS 460 720).
Parent Unit: Clyde Clay Formation (CLYD)
Previous Name(s): Bridgeton Formation [Obsolete Name and Code: Use BRON] (-2022)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  Around Bridgeton in the Clyde valley in central Glasgow. 
Reference(s):
Browne, M A E and McMillan, A A. 1989a. Quaternary geology of the Clyde valley. British Geological Survey Research Report, SA/89/1. 
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. 
Bowen, D Q. 1999. A revised correlation of Quaternary deposits in the British Isles. Geological Society Special Report, No. 23. 
Forsyth, I H, Hall, I H S and McMillan, A A. 1996. Geology of the Airdrie district. Memoir of the British Geological Survey, Sheet 31W (Scotland). 
Paterson, I B, McAdam, A D and MacPherson, K A T. 1998. Geology of the Hamilton district. Memoir of the British Geological Survey, Sheet 23W (Scotland). 
Browne, M A E and McMillan, A A. 1989b. Geology for land use planning: drift deposits of the Clyde valley Volume 1: Planning Report. British Geological Survey Technical Report, WA/89/78. 
Hall, I H S, Browne, M A E and Forsyth, I H. 1998. Geology of the Glasgow district. Memoir of the British Geological Survey, Sheet 30E (Scotland). 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
none recorded or not applicable