The BGS Lexicon of Named Rock Units — Result Details

Skipwith Sand Member

Computer Code: SKIS Preferred Map Code: notEntered
Status Code: Full
Age range: Devensian Stage (QD) — Devensian Stage (QD)
Lithological Description: Dominantly yellow to pale brown slightly clayey sand. 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 laminae of clayey sandy peat and poorly developed fine to medium slightly gravelly clayey sand are noted towards base of the member.
Definition of Lower Boundary: Sharp to gradational transition (over several tens of cms) to underlying sands and clays of Hemmingbrough Glaciolacustrine Formation. A moderate to well developed dark brown peat (Skipwith Peat Bed) is present at some localities.
Definition of Upper Boundary: The Skipwith Sand Member is largely exposed at surface, beneath a thin (0.2-0.6m) development of well drained light brown sandy soil. This unit is also present beneath alluvial and aeolian deposits.
Thickness: Maximum thickness in excess of 2.4m, as proven in borehole SE64NE/14 [466220 439530].
Geographical Limits: Skipwith Common Sand Member is known to extend across the Vale of York from the River Ouse in the west to beyond the River Derwent in the east. The northern limit is marked by the Escrick Moraine [SE 595 396]. The sands are known to extend beyond Selby. Lateral boundaries vary from a gradual thinning over several hundred metres, to an abrupt thinning of the sands giving rise to a strong topographic feature.
Parent Unit: Breighton Sand Formation (BREI)
Previous Name(s): Sand Of 25 Foot Drift Of The Vale Of York (-4886)
Skipwith Common Sand Member (-2425)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Partial Type Section  Temporary exposure in partially collapsed drainage ditch to east of track, close to Nightingale Wood, 1300m northwest of Skipwith. Approximately 1m of vertical exposure on the south side of the ditch shows weakly bedded pale yellow to pale grey, very slightly gravelly, clayey, medium-grained sand with centimetre-scale clay and sandy peat beds; includes sparse sub-rounded fine gravel clasts of comminuted quartzite and flint. 
Reference(s):
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 geological map of Selby (Sheet 71) (in prep): Selby Sheet Explantion (in prep). 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
none recorded or not applicable