The BGS Lexicon of Named Rock Units — Result Details

Beckley Sand Member

Computer Code: BYSA Preferred Map Code: BeS
Status Code: Full
Age range: Oxfordian Age (JO) — Oxfordian Age (JO)
Lithological Description: A grey, weathering brown to yellow, quartzose, fine- to medium-grained Sand in the east, becoming coarser in the west, with calcareous sandstone beds and doggers, and thin, sandy, shelly bioclastic limestone beds. It is moderately fossiliferous, containing bivalves and ammonites.
Definition of Lower Boundary: The lower boundary is gradational. East of Cumnor, there is an upward transition from the muddy and more finely sandy Temple Cowley Member or the spiculitic sandstone of the Arngrove Spiculite Member, into non-spiculitic sands and calcareous sandstone. West of Cumnor, there is a gradational change up from poorly fossiliferous fine-grained and sandy mudstone of the Hazelbury Bryan Formation, into medium- to coarse-grained sand and sandstone, with possibly some lateral passage.
Definition of Upper Boundary: East of Garford, Oxon, there is a sharp non-sequential boundary with fine- to medium-grained sand and sandstone, overlain by bioclastic limestones or grey calcareous mudstones of the Stanford Formation, commonly marked by a pebble bed. West of Garford, there is a change up from medium- to coarse-grained sand and sandstone into shelly ooidal limestone commonly with a basal pebble bed of the Highworth Limestone Member.
Thickness: Up to 20 m thick, measured as 11.15 m thick in the Cumnor borehole.
Geographical Limits: From Beckley south-westwards through Oxford and Abingdon at least as far as Faringdon. At the north-eastern limit it is overstepped by the Stanford Formation as seen in the inset map on 1:50 000 Sheet 237.
Parent Unit: Kingston Formation (KTON)
Previous Name(s): BECKLEY SANDS (BYSA)
BERKSHIRE OOLITE SERIES (BOS)
HIGHWORTH FORMATION
LOWER CORALLIAN (LCR)
LOWER CALCAREOUS GRIT (LCG)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  Benfield and Loxley's Quarry, Beckley, Oxon. 
Reference Section  Primary reference: BGS Cumnor (Henwood Farm) Borehole SP40SE/11, 20.35 - 31.50 m depth. 
Reference Section  Harwell No. 3 Borehole (SU48NE/92), c. 202.5 - 215.6 m depth. 
Reference Section  Dry Sandford Quarry near Abingdon, Oxon, also known as Cothill Quarry, shows the uppermost 7 m of the Beckley Sand. 
Reference(s):
Horton, A, Sumbler, M G, Cox, B M and Ambrose, K, 1995. Geology of the country around Thame. Memoir of the British Geological Survey, Sheet 237 (England and Wales). 
Arkell, W J. 1927. The Corallian rocks of Oxford, Berks and north Wilts. Philosophical Transactions of the Royal Society of London, Vol.B216, 67-181. 
Arkell, W J. 1936. The ammonite zones of the Upper Oxfordian of Oxford, and the horizons of the Sowerby's and Buckman's types. Quarterly Journal of the Geological Society of London, Vol. 92, 146-187. 
Arkell, W J. 1947. The Geology of Oxford. [Oxford: Clarendon Press.] 
Coe, A L. 1995. A comparison of the Oxfordian successions of Dorset, Oxfordshire and Yorkshire. 151-172 in Taylor, P D (Ed.) Field Geology of the British Jurassic. [Bath: The Geological Society.] 
Cox, B M and Wright, J K, 2001. British Upper Jurassic stratigraphy (Oxfordian to Kimmeridgian). Geological Conservation Review Series, No. 21. (Peterborough: Joint Nature Conservation Committee.) 
Gallois, R W and Worssam, B C. 1983. Stratigraphy of the Harwell boreholes. Institute of Geological Sciences Report FLPU 83-14. 
Wright, J K, and Cope, J C W. In press. Oxfordian Correlation Chart. In: A revised correlation of the Jurassic rocks of the British Isles. Cope, J C W (editor). Special report of the Geological Society of London. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E237 E236 E253