| 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 150 m 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 128.97 m 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 81.68 m 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 as a fossil-collecting locality. Daley, 1999b; King, 1984. |
| Reference(s): |
| Daley, B. 1999. London Basin: eastern localities. 23-72 in British Tertiary Stratigraphy. Daley, B, and Balson, P (editors). Geological Conservation Review Series 15. |
| Ellison, R A, Knox R W O'B, 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. |
| King, C. 2006. Paleogene and Neogene: uplift and a cooling climate. 395-427 in Geology of England and Wales. Brenchley, P J, and Rawson, P F (editors). (London: The Geological Society.) |
| Waters, C N, Smith, K, Hopson, P M, Wilson, D, Bridge, D M, Carney, J N, Cooper, A H, Crofts, R G, Ellison, R A, Mathers, S J, Moorlock, B S P, Scrivener, R C, McMillan, A A, Ambrose, K, Barclay, W J, and Barron, A J M. 2007. Stratigraphical Chart of the United Kingdom: Southern Britain. British Geological Survey, 1 poster. |
| 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). |
| 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). |
| 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. |
| 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. 1981. The stratigraphy of the London Clay and associated deposits. Tertiary Research Special Paper No.6. (Backhuys: Rotterdam). |
| 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). |
| 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. |
| Harrison, C J O, and Walker, C A. 1977. Birds of the British Lower Eocene. Tertiary Research Special Paper, Vol. 3, 1-52. |
| 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
|
