The BGS Lexicon of Named Rock Units — Result Details
Crayford Silt Member
Computer Code: | CFSI | Preferred Map Code: | notEntered |
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Status Code: | Full | ||
Age range: | Ipswichian Stage (QI) — Ipswichian Stage (QI) | ||
Lithological Description: | Generically it varies from silt to clay, commonly yellow-brown. Origin uncertain. Commonly includes a high percentage of wind-blown, silt-sized quartz (possibly loess). Locally represented by yellow to buff sand with shells at base passing up through brown, bedded sand with sandy silt to grey clay and shelly sand at the top. | ||
Definition of Lower Boundary: | Overlies Interglacial gravel and sand | ||
Definition of Upper Boundary: | At surface or overlain by floodplain gravel | ||
Thickness: | 2.4m (average) | ||
Geographical Limits: | Crayford, and Cray and Darent valleys. | ||
Parent Unit: | Maidenhead Formation (MNHD) | ||
Previous Name(s): | Crayford Brickearth [Obsolete Name and Code: Use CFSI]
(-2685)
Crayford Brickearth Formation (-769) Crayford Silt Formation [Obsolete Name and Code: Use CFSI] (CRAY) |
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Alternative Name(s): | none recorded or not applicable | ||
Stratotypes: | |||
Type Area | Crayford area (Greater London). Ellison et al., 2004. | ||
Reference(s): | |||
Bridgland, D R. 1994. Quaternary of the Thames. Geological Conservation Review Series No.7. (Peterborough: Joint Nature Conservation Committee.) | |||
Gibbard, P L. 1994. Pleistocene History of the Lower Thames Valley. (Cambridge University Press.) | |||
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). | |||
1:50K maps on which the lithostratigraphical unit is found, and map code used: | |||
E271 |