The BGS Lexicon of Named Rock Units — Result Details

Red Down Sand Member

Computer Code: RDDI Preferred Map Code: RDS
Status Code: Pending Upgrade
Age range: Oxfordian Age (JO) — Oxfordian Age (JO)
Lithological Description: Sand and sandstone, fine- to medium-grained, reddish brown to yellow, ferruginous.
Definition of Lower Boundary: Base is taken at change up from mottled grey, yellow and brown mudstone of undifferentiated Ampthill Clay Formation or grey, shelly, ferru-ooidal mudstone or ironstone of the Marston Ironstone Member (where present) into fine- to medium-grained, ferruginous sand or sandstone.
Definition of Upper Boundary: Top marked by change up from fine- to medium-grained ferruginous sandstone or sand into mudstone of the undifferentiated Ampthill Clay Formation.
Thickness: 0 to 4.5m (Swindon-Faringdon area); 0-1.5m (Lyneham area).
Geographical Limits: Area between Hillmarton and Lyneham, Wiltshire and Swindon, Wiltshire and Faringdon, Oxfordshire. Pinches out laterally into undifferentiated Ampthill Clay. May be lateral equivalent of the Red Down Sand of Westbury, Wiltshire. (not defined here).
Parent Unit: Ampthill Clay Formation (AMC)
Previous Name(s): Red Sand In Upper Calcareous Grit (-4290)
Red Down Ironsand (-2995)
Red Down Ironsand Member (-1137)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  Red Down, near Highworth, Wiltshire. Arkell, 1951. 
Partial Type Section  Red Down Borehole SU19SE/4. Surface to 0.9 m in depth. Arkell, 1941, fig 4. 
Reference(s):
Wright, J K. 2003. New exposures of the Ampthill Clay near Swindon, Wiltshire, and their significance within the succession of the Oxfordian/Kimmeridgian boundary beds in southern England. Proceedings of the Geologists' Association, Vol.114, 97-121. 
Arkell, W J. 1951. The geology of the Corallian ridge between Wootton Bassett and Lyneham, Wiltshire. Wiltshire Archaeological and Natural History Magazine, Vol.54, 1-18. 
Arkell, W J. 1941a. Map of the Corallian Beds around Highworth, Wiltshire. Proceedings of the Geologists' Association, Vol.52, 79-109. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E252 E253 E266