The BGS Lexicon of Named Rock Units — Result Details

Gourock Sand Member

Computer Code: GOSA Preferred Map Code: notEntered
Status Code: Full
Age range: Holocene Epoch (QH) — Holocene Epoch (QH)
Lithological Description: The parent Clydebank Clay Formation consists of four members (qv): from oldest to youngest, the Buchanan Clay, Longhaugh Sand and Gravel, Erskine Clay and Gourock Sand. The Gourock Sand Member is named from Gourock No.2 Borehole [NS 244 777] in the inner Firth of Clyde. Here, the main lithology is grey, fine- to coarse-grained sand. In the Bridgeton Borehole in east Glasgow (Browne and McMillan, 1989a, Figure 18), the uppermost metre consists of brown silt and clay with thin bands and wisps of peat. The basal part is of sandy fine gravel. At Shieldhall [NS 536 664] (ibid, Figure 19), temporary sections showed trough and parallel cross-bedded sands with gravel units. Dark coloured beds rich in organic detritus were about 50cm thick. The lithological association is compatible with an estuarine origin, the range varying from fluvial processes in the east to almost fully marine in the west. The sediments were deposited along very shallow channels probably linked in a anastomosing pattern isolating low lying islands and forming a complex with extensive intertidal flats in the estuary. The stratigraphical relationships and its geographical distribution are illustrated in ibid (Figure 2f, and 3A, B, and C).
Definition of Lower Boundary: The Gourock Sand Member of the Clydebank Clay Formation rests, possibly by passage, on the underlying Erskine Formation where developed, and with angular unconformity on older Quaternary sediments or bedrock.
Definition of Upper Boundary: The Gourock Sand Member of the Clydebank Clay Formation is exposed at surface in the lower Clyde valley and in lower Strathendrick.
Thickness: Ranges from a thin veneer to more than 5m.
Geographical Limits: The Gourock Sand Member of the Clydebank Clay Formation is recognised in the lower Clyde valley, in the estuary of the Clyde, and in the Loch Lomond area (lower Strathendrick).
Parent Unit: Clydebank Clay Formation (CBCL)
Previous Name(s): Gourock Sand Formation (-291)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  Lower Clyde valley, Clyde Estuary and Loch Lomond. The NGR values provided are the southwest and northeast corners of a conceptual rectangle that approximates to the Type Area, and should be considered a rough guide only to the lateral extent of the Member. 
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. 
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 Aidrie district. Memoir of the British Geological Survey, Sheet 31W (Scotland). 
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). 
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. 
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. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
none recorded or not applicable