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
|