The BGS Lexicon of Named Rock Units — Result Details

Breighton Sand Formation

Computer Code: BREI Preferred Map Code: BREI
Status Code: Full
Age range: Devensian Stage (QD) — Devensian Stage (QD)
Lithological Description: Dominantly yellow to pale brown and reddish yellow slightly clayey sand to silty sand with a variably developed very dusky red to black compressible peat to clayey sandy peat base. Typically composed of moderately well-sorted medium quartz grains with minor bands of finer, coarser or poorly sorted material, including finely comminuted flint and lithic clasts. Thin beds of clayey sandy peat and poorly developed fine- to medium-grained slightly gravelly clayey sand are noted towards the base of the formation.
Definition of Lower Boundary: Sharp to gradational (over several tens of cms) transition to underlying clay, silt or sand of the Hemingbrough Glaciolacustrine Formation, gravels of the Pocklington Gravel Formation, or directly to bedrock. A moderate to well developed basal dark brown peat (Skipwith or Bielby Peat Bed) is present in some localities. The presence of sparsley disseminated fine flint gravel is noted close to the lower boundary, particularly towards the Formation's eastern limits (Bielby Sand Member).
Definition of Upper Boundary: Typically exposed at surface beneath a thin (0.2 to 0.5m thick) sandy soil or locally overlain by alluvial and aeolian deposits.
Thickness: Average 1 to 2m but can exceed 6m in some cases.
Geographical Limits: The Breighton Sand Formation is known to extend across the Vale of York, from the River Ouse in the west, to beyond Holme-on-Spalding-Moor in the east, The sands are known to extend south and north beyond the Selby district.
Parent Unit: Yorkshire Catchments Subgroup (YKC)
Previous Name(s): Breighton Cover Sand Formation (-1384)
Sand Of 25-Foot Drift Of Vale Of York (-1385)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Partial Type Section  An extensive body of the Breighton Sand Formation is present in the vicinity of the disused Breighton Airfield. Locally the Formation forms a slight raised feature c.1m above the level of the surrounding clay-dominated ground. Auger holes into ridges and elevated ground in the area between the dismantled railway and the airfield prove relatively consistent thicknesses in excess of 1.2m of weakly laminated grey-brown, fine- to medium-grained clayey sand. Local auger holes pprove that the Breighton Formation directly overlies clays of the Hemingbrough Glaciolacustrine Formation. 
Reference(s):
1:50k geological map of Selby (Sheet 71) (in prep): Selby Sheet Explantion (in prep). 
British Geological Survey, 1973. Sheet 71 Selby solid and drift/compiled and draw in Leeds Office of the Institute of Geological Sciences - Solid and drft ed. Provisional ed. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E071