The BGS Lexicon of Named Rock Units — Result Details

Crayford Silt Member

Computer Code: CFSI Preferred Map Code: notEntered
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 Formation (-769)
Crayford Silt Formation [Duplicate Code: Use CFSI] (CRAY)
Crayford Brickearth (-2685)
Alternative Name(s): none recorded or not applicable
Type Area  Crayford area (Greater London). Ellison et al., 2004. 
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). 
Bridgland, D R. 1994. Quaternary of the Thames. Geological Conservation Review Series No.7. (Peterborough: Joint Nature Conservation Committee.) 
1:50K maps on which the lithostratigraphical unit is found, and map code used: