The BGS Lexicon of Named Rock Units — Result Details

Signet Member

Computer Code: SI Preferred Map Code: Si
Status Code: Full
Age range: Bathonian Age (JN) — Bathonian Age (JN)
Lithological Description: Typically brownish grey sandy or clayey peloidal wackestone, commonly with shell-fragments and lignite, associated with green and brown mudstone/clay; also shell-fragmental ooidal grainstones, brown sandy limestone and white carbonate mudstone and coralliferous marl.
Definition of Lower Boundary: Base of rock types as described in lithological description, resting on (generally) hardground or eroded surface of white carbonate mudstone or wackestone at top of underlying Ardley Member of White Limestone Formation.
Definition of Upper Boundary: Generally sharp, erosive boundary with cross-bedded shell-fragmental ooidal limestone, or mudstone of Forest Marble Formation.
Thickness: 0 - 11m
Geographical Limits: Churn Valley west of Cirencester area of Gloucestershire (westwards of which the member cannot be recognised consistently) eastwards to Shilton, near Burford, Oxon (eastwards of which it passes into the Bladon Member of the White Limestone Formation).
Parent Unit: White Limestone Formation (WHL)
Previous Name(s): Signet Beds (-526)
Kemble Beds [Obsolete Name And Code: See BLAD And SI] (KEB)
Kemble Beds Units I And II (-4326)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Reference Section  Primary Reference Section. Wiggold Railway Cutting. Richardson, L, 1911, beds 3 and 4; Sumbler, M G, Barron, A J M and Morigi, A N, 2000. 
Type Area  Signet area, south of Burford, Oxon. 
Type Section  Banks of Job's Lane, Signet. Sumbler, M G, 1991, p.62, based on Worssam, B C and Bisson, G, 1961 
Reference(s):
Sumbler, M G, 1991. The Fairford Coral Bed: new data on the White Limestone Formation (Bathonian) of the Gloucestershire Cotswolds. Proceedings of the Geologists' Association, Vol.102, 55-62. 
Sumbler, M G, 1984. The stratigraphy of the Bathonian White Limestone and Forest Marble formations of Oxfordshire. Proceedings of the Geologists' Association, Vol.95, 51-64. 
Worssam, B C and Bisson, G, 1961. The geology of the country between Sherborne, Gloucestershire and Burford, Oxfordshire. Bulletin of the Geological Survey of Great Britain, No.17, 75-115. 
Woodward, H B, 1894. The Jurassic Rocks of Britain, Vol.4. The Lower Oolitic Rocks of England (Yorkshire excepted). Memoir of the Geological Survey of the United Kingdom. 
Richardson, L. 1911. On the sections of the Forest Marble and Great Oolite on the railway between Cirencester and Chedworth, Gloucestershire. Proceedings of the Geologists' Association, Vol.22, 95-115. 
Sumbler, M G, Barron, A J M and Morigi, A N, 2000. Geology of the Cirencester district. Memoir of the British Geological Survey, Sheet 235 (England and Wales). 
Richardson, L. 1933. The Country around Cirencester. Memoir of the Geological Survey of Great Britain, Sheet 235 (England and Wales). 
Cox, B M and Sumbler, M G. 2002. British Middle Jurassic Stratigraphy. Geological Conservation Review Series No.26. [Peterborough: Joint Nature Conservation Committee.] 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E235 E252