The BGS Lexicon of Named Rock Units — Result Details

Grangemouth Silt Member

Computer Code: GMSI Preferred Map Code: notEntered
Status Code: Full
Age range: Holocene Epoch (QH) — Holocene Epoch (QH)
Lithological Description: Clayey silt and silty clay, finely laminated and crudely stratified with silt and very fine- to medium-, locally coarse-grained sand (gravelly at base of member); grey, black and brownish grey, finely micaceous, sulphur-rich, contains shells and shell fragments. Massive where bioturbated. Contains some thin peat beds (maximum 9cm). Cross bedded sands represent tidal channel deposits. The member is an estuarine tidal flat complex formed after the time of highest Holocene sea-level (Main Post-Glacial Shoreline).
Definition of Lower Boundary: Unconformable on the Claret Clay Member (Carse Clay Formation), and on older Holocene and late Devensian units including the Wilderness Till Formation.
Definition of Upper Boundary: Upper boundary at the land surface or the sea bed.
Thickness: Veneer to perhaps as much as 18m.
Geographical Limits: Lower Forth valley from Stirling eastwards to near the Forth estuary in the Falkirk area; area of the estuarine deposits of the modern estuary and also under reclaimed land.
Parent Unit: Carse Clay Formation (CARCL)
Previous Name(s): Grangemouth Beds (-289)
Alternative Name(s): Grangemouth Formation
Type Section  Grangemouth Docks No.103 Bore, BGS Ref. NS98SW/126, 1.0m to 6.71m depth. 
Francis, E H, Forsyth, I H, Read, W A and Armstrong, M. 1970. The geology of the Stirling district. Memoir of the Geological Survey of Great Britain, Sheet 39 (Scotland). 
Paul, M A, Peacock, J D and Barras, B F. 1995. Flandrian Stratigraphy and Sedimentation in the Bothkennar-Grangemouth area, Scotland. Quaternary Newsletter, February 1995, No.75, 22-35 
Browne, M A E, Graham, D K and Gregory, D M 1984. Quaternary estuarine deposits in the Grangemouth area, Scotland. Report of the Institute of Geological Sciences, No.16/3. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S039 S031