| Computer Code: |
FORCA |
Preferred Map Code: |
notEntered |
| Status Code: |
Full |
| Age range: |
Devensian Stage (QD)
— Holocene Epoch (QH) |
| Lithological Description: |
Includes the fluvial and related organic deposits of the catchments surrounding the Forth Estuary.
The deposits include alluvium and river terrace deposits comprising gravel, sand, silt and peat. Rock types are principally of Carboniferous and Devonian strata (sandstone, siltstone) with volcanic (basalt and andesite) and intrusive igneous rocks (microdiorite) of Midland Valley provenance. Variable but generally minor components of Dalradian metasedimentary and Caledonian igneous rocks derived from the Grampian Highlands are present.
A suite of fluvial (alluvium and river terrace deposits) and associated organic and lacustrine sediments that contain clasts derived from Palaeozoic rocks and glacigenic deposits cropping out in the catchment of the River Forth and other rivers flowing directly to the Firth of Forth, including the rivers Teith, Almond, Carron, Allan Water, and the rivers Esk and Tyne of the Lothians.
Late Devensian to Holocene (MIS 2-1). |
| Definition of Lower Boundary: |
Unconformable contact with units of the Midland Valley, Mearns and Central Grampian Glacigenic subgroups and bedrock. |
| Definition of Upper Boundary: |
Generally the ground surface, but units of the subgroup may be overlain locally by mass movement deposits or may locally interfinger with units of the British Coastal Deposits Group. |
| Thickness: |
Up to 25 m. |
| Geographical Limits: |
The present physical catchments of the River Forth and the Firth of Forth. The catchments extend across Stirlingshire, Clackmannanshire, south Fife and the Lothians. |
| Parent Unit: |
Britannia Catchments Group (BCAT)
|
| Previous Name(s): |
none recorded or not applicable
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| none recorded or not applicable |
| Reference(s): |
| 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. |
| McMillan, A A, Hamblin, R J O, and Merritt, J W. 2011. A lithostratigraphical framework for onshore Quaternary and Neogene (Tertiary) superficial deposits of Great Britain and the Isle of Man. British Geological Survey Research Report, RR/10/03. 343pp. |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
| none recorded or not applicable |
