| Computer Code: |
BPGR |
Preferred Map Code: |
notEntered |
| Status Code: |
Full |
| Age range: |
Anglian Stage (QA)
— Anglian Stage (QA) |
| Lithological Description: |
Sand and gravel, with possible lenses of silt, clay or peat. [Generic description]. Horizontally stratified, matrix-supported gravel with thin tabular cross-bedded sand channels. Gravel assemblage is characterised by abundant angular flint (75-89%), sparse rounded flint (3-9%), sparse vein quartz (4-10%) and sparse quartzite (1-6%). |
| Definition of Lower Boundary: |
Rests unconformably on bedrock geology (London Clay on Sheet 256). |
| Definition of Upper Boundary: |
At surface. |
| Thickness: |
1-6m, average 3m |
| Geographical Limits: |
Thames Valley and associated tributaries. |
| Parent Unit: |
Maidenhead Formation (MNHD)
|
| Previous Name(s): |
none recorded or not applicable
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Type Area |
Black Park Country Park, Slough. Stratotype: up to 4m of gravel and sand. Gibbard, 1985. |
| Reference(s): |
| Gibbard, P L. 1979. Middle Pleistocene drainage in the Thames Valley. Geological Magazine, Vol. 116, 35-44. |
| Hare, F K, 1947. The geomorphology of a part of the Middle Thames. Proceedings of the Geologists' Association, Vol.58, 294-339. |
| Gibbard, P L. 1989. The geomorphology of part of the Middle Thames forty years on: a reappraisal of the work of F Kenneth Hare. Proceedings of the Geologists' Association, Vol. 100, 481-503. |
| 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. 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: |
|
E254
E256
E257
E268
|
