The BGS Lexicon of Named Rock Units — Result Details

Wardour Formation

Computer Code: WAR Preferred Map Code: War
Status Code: Full
Age range: Tithonian Age (JI) — Tithonian Age (JI)
Lithological Description: Sequence of siltstone, variably-cemented sandstone/sand and mudstone. Glauconite is present in many of the sandstone beds. Thin layers of black chert pebbles, strongly bioturbated beds and shelly beds occur at some levels. There are also unconfirmed reports of palaeosols and evaporitic pseudomorphs at some localities. Higher intervals, comprising bioclastic, lime mud-rich limestones and glauconitic limestones, previously considered as forming part of the Portland Sand Formation (Wimbledon, 1976, 1980), were classified with the Portland Stone Formation by Bristow et al. (1999). Vale of Pewsey, Wiltshire: Sand and variably cemented sandstone, very well sorted fine- to medium-grained, quartzose and moderately glauconitic, green where unweathered, bioturbated, shells and shell debris in parts.
Definition of Lower Boundary: Upward change from dark grey, slightly sandy mudstone of the Kimmeridge Clay Formation to clayey sand and sandy mudstone; boundary taken at the base of a glauconitic sand forming the top to a coarsening-upward cycle. Springs commonly mark the base.
Definition of Upper Boundary: Upward change from sandy mudstone and clayey sand and sandstone to fine-grained bioclastic sandstone and sandy limestone (Vale of Pewsey; undivided Portland Stone Formation) or (Vale of Wardour) shelly lime-mudstone of the Tisbury Member (Portland Stone Formation).
Thickness: Vale of Wardour up to 24m; Vale of Pewsey up to 20m; 30m in Urchfont borehole (SU05NW 18 [SU 0444 5816]).
Geographical Limits: Vale of Wardour and Vale of Pewsey, south Wiltshire. Overstepped to north and south by Cretaceous strata. Equivalent to Portland Sand Member of north Wiltshire, Oxfordshire and Buckinghamshire, and lower part of Portland Sand Formation of south Dorset. Location of eastward/southward passage into Weald/Dorset sequence uncertain.
Parent Unit: Portland Group (PL)
Previous Name(s): Basement Beds (-3812)
Portland Sand (-2373)
Lower Portland Beds (-3115)
Wardour Member (-3116)
Portland Sand Formation (POSA)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Section  Tisbury Borehole (BGS) ST92NW 2. 13.0-36.7m depth. (Bristow et al. 1999). 
Type Area  Vale of Wardour, Wiltshire. (Bristow et al. 1999)(Hopson et al., 2007). 
Reference(s):
Wimbledon, W A and Cope, J C W. 1978. The ammonite faunas of the English Portland Beds and the zones of the Portlandian Stage. Journal of the Geological Society of London, Vol.135, 183-190. 
Bristow, C R, Barton, C M, Freshney, E C, Wood, C J, Evans, D J, Cox, B M and Woods, M A. 1999. The Wincanton district - a concise account of the geology. Memoir of the British Geological Survey, Sheet 297 (England and Wales). 
Wimbledon, W A. 1976. The Portland Beds (Upper Jurassic) of Wiltshire. Wiltshire Archaeological and Natural History Magazine, Natural History, Vol.71, 3-11. 
Arkell W J, 1933. The Jurassic System in Great Britain [Oxford: Clarendon Press.] 
Wimbledon, W A. 1980. Portlandian correlation chart. 85-93 in Cope, J C W (Editor), A correlation of the Jurassic rocks of the British Isles. Part Two: Middle and Upper Jurassic. Geological Society of London Special Report, No.15. 
Hudleston W H, 1883 (for 1881). On the geology of the Vale of Wardour. Proceedings of the Geologists' Association. Vol.7, 161-185. 
Reid C. 1903, Geology of the country around Salisbury. Memoir of the Geol. Survey of Great Britain. 
Hopson, P M, Farrant, A R, Newell, A J, Marks, R J, Booth, K A, Bateson, L B, Woods, M A, Wilkinson, I P, Brayson, J, and Evans, D J. 2007. Geology of the Salisbury district - a brief explanation of the geological map. Sheet Explanation of the British Geological Survey. 
Booth, K A, Hopson, P M, Farrant, A R, Newell, A J, Marks, R J, Bateson, L B, Woods, M A, Wilkinson, I P, and Evans, D J. in press. Geology of the Devizes district - a brief explanation of the geological map. Sheet Explanation of the British Geological Survey. 
Woodward, H B. 1895. the Jurassic Rocks of Britain. The Middle and Upper Oolitic rocks of England (Yorkshire excepted). Vol.5. Memoir or the Geological Survey of the United Kingdom. 
Blake, J F. 1880. On the Portland Rocks of England. Quarterly Journal of the Geological Society of London, Vol.36, 189-236. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E282 E297 E298