| 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 [Obsolete Name and Code: Use WLGR]
(-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): |
| 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. |
| Bridgland, D R, and Cheshire, D A. 1994. Westmill Quarry. 121-129 in The Quaternary of the Thames. Bridgland, D R (editor). (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). |
| 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
|
