The BGS Lexicon of Named Rock Units — Result Details
Claygate Member
| Computer Code: | CLGB | Preferred Map Code: | CLGB |
|---|---|---|---|
| Status Code: | Full | ||
| Age range: | Ypresian Age (GY) — Ypresian Age (GY) | ||
| Lithological Description: | The Claygate Member comprises dark grey clays with sand laminae, passing up into thin alternations of clays, silts and fine-grained sand, with beds of bioturbated silt. Ferruginous concretions and septarian nodules occur in places. Fossils from the Claygate Member at Willesden Green are recorded by Wrigley (1921). | ||
| Definition of Lower Boundary: | The Claygate Member is distinguished from the underlying Sheppey Member by the laminated character and relative abundance of sand in the Claygate Member. The boundary is drawn at the base of the lowest sand bed, conformable on silty clay with common sandy clayey silt interbeds. In practical terms, it is taken at the ‘lowest sandy horizon mappable in the field’ (Lake et al., 1986). In London, and further to the west, sand beds appear lower in the sequence and here the base of the Claygate Member is based on other criteria including grain size and glauconite content (Ellison et al., 2004). | ||
| Definition of Upper Boundary: | Drawn at conformable upward passage from silt and fine-grained sand of the Claygate Member to the Bagshot Formation. The Claygate Member is distinguished from the overlying Bagshot Formation by containing finer sand without cross-bedding, and in the relative abundance of clay and silt in the Claygate Member. | ||
| Thickness: | Average thickness of 16m in London area; 17m to 25m in Essex. | ||
| Geographical Limits: | The Claygate Member occurs in the axial zone of the London Basin, where preserved from erosion | ||
| Parent Unit: | London Clay Formation (LC) | ||
| Previous Name(s): | Claygate Beds [Obsolete Name and Code: Use CLGB]
(-4549)
Passage Beds [Obsolete Name and Code: Use BOOC, SGBK, CLGB, MCH, UND, YED, MYS] (-3236) |
||
| Alternative Name(s): | none recorded or not applicable | ||
| Stratotypes: | |||
| Type Area | Clay-pits at Claygate, near Esher, Surrey. These exposures (Curry, 1958) are probably now no longer available. | ||
| Reference(s): | |||
| Ellison, R A and Williamson, I T. 1999. Geology of the Windsor and Bracknell district - a brief explanation of the geological map. Sheet Explanation of the British Geological Survey. 1:50 000 Sheet 269 Windsor (England and Wales). | |||
| Ellison, R A, Woods, M A, Allen, D J, Forster, A, Pharaoh, T C and King, C. 2004. Geology of London. Memoir of the British Geological Survey, Sheets 256 (North London), 257 (Romford), 270 (South London), 271 (Dartford) (England and Wales). | |||
| Wooldridge, S.W., 1924. The Bagshot Beds of Essex. Proceedings of the Geologists' Association 35, 359-383. | |||
| Aldiss, D T. 2012. The stratigraphical framework for the Palaeogene successions of the London Basin, UK. British Geological Survey Open Report OR/12/004. | |||
| King, C. 1981. The stratigraphy of the London Clay and associated deposits. Tertiary Research Special Paper No.6. (Backhuys: Rotterdam). | |||
| King, C. 1982. Comments on 'The nomenclature of the Claygate Beds and Bagshot Beds of London and Essex' (Bristow, 1982) and 'The Claygate Beds of Essex' (Bristow and others, 1980). Tertiary Research, Vol.4, p.47-52. | |||
| Bristow, C R, Ellison, R A, and Wood, C J. 1980. The Claygate Beds of Essex. Proceedings of the Geologists' Association, Vol. 91, 261-277. | |||
| Dewey, H. "In" Leach, A L, 1912. On the geology of Shooters Hill, Kent. Proceedings of the Geologists' Association, Vol.23, p.116. | |||
| Wrigley, A G, 1921. The Claygate Beds at Willesden Green. Proceedings of the Geologists' Association, Vol.32, p.139. | |||
| Dewey, H, 1923. Excursion to Claygate and Oxshott. Proceedings of the Geologists' Association, Vol.34, p.324. | |||
| Bristow, C R. 1982. The nomenclature of the Bagshot Beds and Claygate Beds of London and Essex. Tertiary Research, Vol. 4, 7-8. | |||
| Cooper, J, 1976. British Tertiary stratigraphical and rock terms, formal and informal, additional to Curry, 1958. Lexique Stratigraphique International. Tertiary Research Special Paper No.1, Tertiary Research Group. | |||
| Dewey, H, 1912. Report of an excursion to Claygate and Oxshott, Surrey. Proceedings of the Geologists' Association, Vol.23, p.239. | |||
| Curry, D. 1958. Part 3a XII Palaeogene. Lexique Stratigraphique International. Whittard, W F, and Simpson, S (editors). Vol. 1 Europe (Paris: Centre Nationale de la Research Scientifique.) | |||
| Lake, R D, Ellison, R A, Henson, M R, and Conway, B W. 1986. Geology of the country around Southend and Foulness. Memoir of the British Geological Survey, Sheet 258 and 259 (England and Wales). | |||
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: | |||
| E240 E241 E256 E257 E258 E259 E269 E270 E271 E272 E273 E285 | |||