The BGS Lexicon of Named Rock Units — Result Details

Kirkbean Sand And Gravel Formation

Computer Code: KN Preferred Map Code: notEntered
Status Code: Full
Age range: Devensian Stage (QD) — Devensian Stage (QD)
Lithological Description: Sand and gravel, with cobbles and pebbles of Ordovician, Silurian, Devonian and Carboniferous rocks in a matrix of medium- to coarse-grained sand; typically pale yellow to palebrown. Granitic clasts are commonly a major component. Esker deposits are typically poorly sorted, cobbly and bouldery,well-bedded with high-angle cross-bedding, involutions and slumps. Some interbeds of coarse sand. Kame and kettle deposits are poorly exposed, but appear to be typically moderately sorted, silty, sandy, clast-supported gravel with rounded to subrounded cobbles and pebbles. Glaciofluvial Sheet deposits are poorly exposed but appear to be typically well-sorted sandy gravel, with interbeds of coarse- to medium-grained sand.
Definition of Lower Boundary: Unconformable on older glacigenic sediments, such as till of the Gretna Till Formation; locally rests directly on bedrock.
Definition of Upper Boundary: Locally overlain by Holocene alluvium and peat, and by Holocene and Lateglacial raised marine deposits. Some exposures are capped by gravelly friable pale brown to reddish brown diamicton (supraglacial flow till) typically 0.3-0.7m in thickness).
Thickness: Variable, typically 4-10m, esker deposits may be > 12m thick; moundy ice-contact deposits and sheet deposits are typically 2-8m thick.
Geographical Limits: Northern margin of the Solway Firth, principally southwest of Dumfries; isolated spreads north of Canonbie and Langholm.
Parent Unit: Southern Uplands Glacigenic Subgroup (SUDR)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Type Section  Kirkbean Quarry. Exposure in large esker ridge shows up to 10m of interbedded sand and gravel capped in places by sandy, silty, moderate brown diamicton, up to 0.8m thick. Sand and gravel thickly bedded, with involutions, slumps and channels in upper part of unit. Interbeds of moderate brown [5YR 4/4] laminated sandy silt and coarse quartzofeldspathic sand thoroughout. Gravel clasts: mainly cobbles and coarse gravel, rounded to subangular; white granodiorite, greywacke, pink granite, metamudstone, red mudstone and feldsparphyic porphyry. Steeply arched bedding dips away from axis of esker ridge. Base of unit not seen 
none recorded or not applicable
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S010 S010 S011 S009