The BGS Lexicon of Named Rock Units — Result Details

Lochwinnoch Clay Member

Computer Code: LNCH Preferred Map Code: notEntered
Status Code: Full
Age range: Devensian Stage (QD) — Holocene Epoch (QH)
Lithological Description: The Lochwinnoch Borehole (Browne and McMillan, 1989, Figure 25) contains the standard section in the Lochwinnoch Clay Member (20.08 to 24.4m in depth). The typical lithological association is of silty clay with many layers of silt and locally of sand. Bands relatively rich in organic detritus also occur, typically about 20 units per metre. Grains and flecks of vivianite are common except in the lowest metre of the unit. In the basal 50cm or so the deposit is almost all minerogenic and thinly colour-laminated in shades of orange, brown and grey. In general the clays are dark brown, of a firm consistency and medium plasticity, locally displaying folded slumped bedding. The base of the unit is a 10cm-thick ripple-laminated sand. The lithofacies association is typical of lake bottom muds, the presence of vivianite supporting this interpretation. The presence of dark organic-rich bands perhaps suggests seasonal banding.
Definition of Lower Boundary: This laminated clay and silt member rests unconformably on the Wilderness Till Formation (at a depth of 24.4 m in the Lochwinnoch Borehole).
Definition of Upper Boundary: Unconformity below younger Quaternary strata including the Law Sand and Gravel Member.
Thickness: Veneer to over 4m
Geographical Limits: Known currently only in the Lochwinnoch area, southwest of Johnstone and Paisley in the upper valley of the Black Cart Water.
Parent Unit: Clyde Valley Formation (CLVY)
Previous Name(s): Lochwinnoch Formation (-4767)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Reference Section  BGS Lochwinnoch Borehole (Registered No.NS35NE/26). Browne and McMillan, 1989a. 
Reference(s):
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). 
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). 
Browne, M A E and McMillan, A A. 1989a. Quaternary geology of the Clyde valley. British Geological Survey Research Report, SA/89/1. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S022 S030