The BGS Lexicon of Named Rock Units — Result Details

Gerrards Cross Gravel Member

Computer Code: GCGR Preferred Map Code: notEntered
Status Code: Full
Age range: Cromerian Stage (QC) — Anglian Stage (QA)
Lithological Description: Comprises 1 - 10 m of sand and gravel, locally with lenses of silt, clay or peat and organic material.
Definition of Lower Boundary: Rests unconformably on bedrock geology.
Definition of Upper Boundary: At surface.
Thickness: 1 - 10 m, average 4 m thick.
Geographical Limits: The unit occurs in the Colne valley near Watford up to about 90 m above OD (Ellison et al., 2004).
Parent Unit: Sudbury Formation (SBRY)
Previous Name(s): Gerrards Cross Gravel Formation [Obsolete Name and Code: Use GCGR] (-4058)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Section  Quarry face at Gerrards Cross Quarry (Gibbard, 1985). 
Reference(s):
Gibbard, P L, 1985. Pleistocene history of the Middle Thames Valley. (London: Cambridge University Press.) 
McMillan, A A, Hamblin, R J O, and Merritt, J W. 2011. A lithostratigraphical framework for onshore Quaternary and Neogene (Tertiary) superficial deposits of Great Britain and the Isle of Man. British Geological Survey Research Report, RR/10/03. 343pp. 
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). 
Whiteman, C A and Rose, J. 1992. Thames river sediments of the British Early and Middle Pleistocene. Quarterly Science Reviews, Vol.11, 363-375. 
Whiteman, C A. 1992. The palaeogeography and correlation of pre-Anglian-Glaciation terraces of the River Thames in Essex and the London Basin. Proceedings of the Geologists' Association, Vol.103, 37-56. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E256 E268