The BGS Lexicon of Named Rock Units — Result Details

Crockey Hill Esker Member

Computer Code: CRHE Preferred Map Code: CRHE
Status Code: Full
Age range: Devensian Stage (QD) — Devensian Stage (QD)
Lithological Description: Pale brown, reddish brown and browish yellow, slightly silty, slightly to very gravelly fine to coarse sand. Gravel is subangular to subrounded and comprises a mixed lithology of sandstone, limestone and quartz with rare igneous clasts. Generally thinly bedded (<20mm). Bedding weakens, becoming disturbed, towards the upper surface, with evidence of cryoturbation. Rare laterally impersistant clay lenses.
Definition of Lower Boundary: Not observed but interpreted to rest discontinuously over older till and/or may interdigitate laterally with interbedded glaciofluvial and glaciolacustrine sand and clay.
Definition of Upper Boundary: Exposed at surface. In places overlain by thin aeolian sands.
Thickness: Known to be a minimum of 7m in a temporary excavation at Crockey Hill.
Geographical Limits: The Crockey Hill Esker Member is restricted to a narrow north-south to northwest-southeast trending belt to the south of York from Escrick to Fulford.
Parent Unit: Vale Of York Formation (VYORK)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Partial Type Section  Temporary excavation south of Crockey Hill, 460m south of Naburn Hill Farm, at side of A19. 1.2m section exposing 0.2m of plae brown, slightly gravelly, fine sand overlying 0,15m of brownish yellow, weakly bedded gravelly sand with rare cobbles, overlying 0.25m of reddish brown, slightly clayey, gravelly, thinly bedded (<20mm) medium to coarse sand, with clay dominating towards its base, where the bedding is discontinuous and deformed, over 0.6m of medium sand with distinct coars sand lenses to 150mm in length and 20-50mm in thickness. 
Reference Section  At Crockey Hill, 85m northwest of Crockey Hill Farm. Temporary exposure in a disused gravel pit showed 2m of pale brown, slightly silty, gravelly fine to coarse sand, with rare clay pods to 200mm in diameter. Gravel is subangular to subrounded. 
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