The BGS Lexicon of Named Rock Units — Result Details

Westmill Gravel Member

Computer Code: WLGR Preferred Map Code: notEntered
Status Code: Full
Age range: Anglian Stage (QA) — Anglian Stage (QA)
Lithological Description: Gravel and sand, locally with lenses of silt, clay or peat and organic material. Gravel is 80 to 90% flint with relatively high percentage (10 to 15%) of quartz, and 1.5 to 6% chalk.
Definition of Lower Boundary: Rests unconformably on chalk bedrock of the Chalk Group or sands and clays of the Palaeogene formations.
Definition of Upper Boundary: Overlain by till of the (Anglian) Lowestoft Formation in places; otherwise at surface. Cut by till at Aldenham [TQ 133 981].
Thickness: To 5m
Geographical Limits: Colne Valley, near Watford, at 60-70m OD; course of Proto-Thames (ancestral Thames) through the Vale of St Albans.
Parent Unit: Colchester Formation (CCHR)
Previous Name(s): Westmill Gravel Formation (-2536)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Section  Westmill Quarry, northeast of Westmill Farm, Herts. One of several local gravel pits: see Bridgland and Cheshire, 1994. 
Reference(s):
Bridgland, D R and Cheshire, D A. 1994. Westmill Quarry. 121-129 in: Bridgland, D R (Editor), The Quaternary of the Thames. [London: Chapman and Hall.] 
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). 
Strange, P J, 1992. A new nomenclature for the River Terrace Deposits of North London. British Geological Survey Technical Report, WA/92/52. 
Gibbard, P L, 1977. Pleistocene history of the Vale of St. Albans. Philosophical Transactions of the Royal Society of London. Vol.B280, 445-483. 
Gibbard, P L, 1985. Pleistocene history of the Middle Thames Valley. (London: Cambridge University Press.) 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E256