The BGS Lexicon of Named Rock Units — Result Details

London Clay Formation
Computer Code: LC Preferred Map Code: LC
Status Code: Full
Age range: Ypresian Age (GY) — Ypresian Age (GY)
Lithological Description: The London Clay mainly comprises bioturbated or poorly laminated, blue-grey or grey-brown, slightly calcareous, silty to very silty clay, clayey silt and sometimes silt, with some layers of sandy clay. It commonly contains thin courses of carbonate concretions (‘cementstone nodules’) and disseminated pyrite. It also includes a few thin beds of shells and fine sand partings or pockets of sand, which commonly increase towards the base and towards the top of the formation. At the base, and at some other levels, thin beds of black rounded flint gravel occurs in places. Glauconite is present in some of the sands and in some clay beds, and white mica occurs at some levels.
Definition of Lower Boundary: The base of the London Clay formation was redefined by Ellison et al. (1994) to correspond to the base of the Walton Member (Division A2) of King (1981). It is usually marked by a thin bed of well-rounded flint gravel or a glauconitic horizon, or both, typically resting on a sharply defined planar surface, although locally uneven. The London Clay Formation overlies the Harwich Formation or, where the Harwich Formation is absent, the Lambeth Group.
Definition of Upper Boundary: The top of the London Clay Formation is taken as the top of the Claygate Member, which 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: Up to 150m in eastern part of the London Basin (Essex).
Geographical Limits: The London Clay occurs in the London Basin, East Anglia and the Hampshire Basin.
Parent Unit: Thames Group (THAM)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Stratotypes:
Reference Section  Dowsetts Farm Borehole (TL32SE38) (for Hitchin district, BGS Sheet 221) Hopson et al. 1996. 
Reference Section  BGS Crystal Palace Borehole (TQ37SW671) [TQ 3379 7082], 5.16 to 128.97m depth Ellison et al., 2004, p.46. The BGS Crystal Palace Borehole cored most of the London Clay, from within the Claygate Member to the base. 
Reference Section  BGS Stanmore Common Borehole (TQ19SE102) Ellison et al., 2004, p.46 
Reference Section  BGS Stock Borehole (TL70SW1) Bristow, 1985; Ellison et al., 2004, p.46. 
Reference Section  BGS Bracknell Borehole (SU86NE42) 67.83 to 81.68m depth. Ellison and Williamson, 1999, fig. 6. 
Reference Section  Sheppey Cliffs, Isle of Sheppey, Kent, between Minster and Warden. This exposes the upper parts of the London Clay Formation and is well-known for as a fossil-collecting locality.(Daley, 1999b; King, 1984). 
Reference(s):
Prestwich, J. 1846. The Isle of Wight Tertiaries. Quarterly Journal of the Geological Society, Vol.2, 223-259. 
Smith, W, "In" Farey, J. 1811. General view of the agriculture and minerals of Derbyshire etc, Vol.1, p.111.(London: B. Macmillan.) 
Webster, T. 1814. Strata lying over the Chalk. Transactions of the Geological Society (1), Vol.2, p.187. 
Prestwich, J. 1847. London Clay. Quarterly Journal of the Geological Society, Vol.3, 354-377. 
Prestwich, J. 1850. The Lower Tertiary Strata. Quarterly Journal of the Geological Society, Vol.6, 252-281. 
Venables, E M. 1929. The London Clay of the Bognor District. Proceedings of the Geologists' Association, Vol.40, 41-51. 
Meyer, C J A. 1871. Lower Tertiary Deposits. Quarterly Journal of the Geological Society, Vol.27, 74-89. 
Wrigley, A G. 1924. Faunal Divisions of the London Clay. Proceedings of the Geologists' Association, Vol.35, 245-259. 
Wrigley, A G. 1940. Faunal Succession in the London Clay. Proceedings of the Geologists' Association, Vol.51, 230-245. 
Davis, A G and Elliot, G F. 1951. The London Clay of Coastal Suffolk and Essex. Geological Magazine, Vol.88, 329-338. 
Hewitt, R A. 1988. The London Clay Formation (Eocene) of the country around Southend (Essex, England). Tertiary Research, Vol.10, 83-86. 
King, C. 1984. The stratigraphy of the London Clay Formation and Virginia Water Formation in the coastal sections of the Isle of Sheppey, (Kent, England). Tertiary Research, Vol.5, 121-158. 
King, C. 1981. The stratigraphy of the London Clay and associated deposits. Tertiary Research Special Paper No.6. (Rotterdam: Backhuys.) 
ALDISS, D T. 2012. The stratigraphical framework for the Palaeogene successions of the London Basin, UK. British Geological Survey Open Report OR/12/004.  
BRISTOW, C R. 1985. Geology of the country around Chelmsford. Memoir of the British Geological Survey, Sheet 241 (England and Wales). 
DALEY, B. 1999. London Basin: eastern localities. 23-72 in British Tertiary Stratigraphy. DALEY, B, and BALSON, P (editors). Geological Conservation Review Series, No. 15. 
EDWARDS, R A, and FRESHNEY, E C. 1987. Lithostratigraphical classification of the Hampshire Basin Palaeogene deposits (Reading Formation to Headon Formation). Tertiary Research, Vol. 8, 43-73. 
ELLISON, R A, KNOX, R W O, JOLLEY, D W, and KING, C. 1994. A revision of the lithostratigraphical classification of the early Palaeogene strata of the London Basin and East Anglia. Proceedings of the Geologists' Association, Vol. 105, 187-197. 
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, WILLIAMSON, I T, and HUMPAGE, A. 2002. Geology of the Guildford district - a brief explanation of the geological map. Sheet Explanation of the British Geological Survey, 1:50 000 Sheet 285 Guildford (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) and 271 (Dartford) (England and Wales). 
HARRISON, C J O, and WALKER, C A. 1977. Birds of the British Lower Eocene. Tertiary Research Special Paper, Vol. 3, 1-52. 
HOPSON, P M, ALDISS, D T, and SMITH, A. 1996. The geology of the country around Hitchin. Memoir of the British Geological Survey, Sheet 221 (England and Wales). 
KING, C. 2006. Paleogene and Neogene: uplift and a cooling climate. 395-427 in The geology of England and Wales. BRENCHLEY, P J, and RAWSON, P F (editors). (The Geological Society, London.) 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E191 E206 E207 E208 E221 E222 E223 E225 E238 E239 E240 E241 E254 E255 E256 E257 E258 E259 E267 E268 E269 E270 E271 E272 E273 E274 E283 E284 E285 E298 E299 E314 E341 E342 E343 E162
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