The BGS Lexicon of Named Rock Units — Result Details

Cullivait Silts Formation

Computer Code: CUS Preferred Map Code: notEntered
Status Code: Full
Age range: Devensian Stage (QD) — Devensian Stage (QD)
Lithological Description: Interbedded silty clay, sandy silt, and silty sand, forming upward coarsening flat-lying units; generally moderate reddish brown to brown or greyish brown. Sandy silts and silty clays are typically thinly bedded in finely-laminated to massive beds; silty sands display planar lamination, ripple lamination and small-scale tabular cross-bedding. Rounded greywacke dropstone cobbles disrupt the lamination in silt and clay units at the Partial Type Section.
Definition of Lower Boundary: Either overlies Bedrock or red-brown diamicton of the Gretna Till Formation. Base of unit is not exposed at the Partial Type Section.
Definition of Upper Boundary: Taken at the base of the Kilblane Sand and Gravel Formation at the Partial Type Section; overlain by red-brown diamicton of the Gretna Till Formation in the Reference Section.
Thickness: Typically 3-5m, but >10m proved in boreholes south of Canonbie.
Geographical Limits: Northern margin of the Solway Firth, principally between Dumfries and Gretna, but extending inland to Dalswinton and Canonbie. These deposits also occur concealed beneath the alluvial sediments of the River Esk between Gretna and Carlisle.
Parent Unit: Irish Sea Coast Glacigenic Subgroup (ISCG)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Stratotypes:
Reference Section  BGS Registered Borehole NY 37NE1, c 1km southsoutheast of Canonbie, Dumfriesshire. A7 Improvement-Canonbie Site Investigation Record SE 1054, Borehole 4. 10.3m of laminated silt and clay, occuring beneath 6.2m of red-brown till and resting on 3m of red-brown till of the Gretna Till Formation. 
Partial Type Section  Section in Locharbriggs Sand and Gravel Pit. BGS Registered Section CA1320 c 250m southeast of Cullivait House, Dumfriesshire. Section in interbedded moderate reddish brown fine-sand and laminated clayey silt with dropstone cobbles, beneath kettled kame terrace gravel (Kilblane Sand and Gravel Formation), exposed in working face in August 1999. 
Reference(s):
British Geological Survey. 2005. Solway East. Scotland Special sheet. Superficial Deposits and Simplified Bedrock. 1:50 000 Geology Series. 
British Geological Survey. 2005. Solway West. Scotland Special sheet. Superficial Deposits and Simplified Bedrock. 1: 50 000 Geology Series. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E017 S010 S010 S009