The BGS Lexicon of Named Rock Units — Result Details
Stanmore Gravel Formation
| Computer Code: | STGR | Preferred Map Code: | notEntered |
|---|---|---|---|
| Status Code: | Full | ||
| Age range: | Early Pleistocene (QPE) — Early Pleistocene (QPE) | ||
| Lithological Description: | Gravel and sand, clayey near base. Gravel mostly composed of flints, up to 150mm in diameter, with a little quartz, quartzite and Lower Greensand chert in the fine fractions. Matrix of orange-brown, pale grey, red mottled clay and sandy clay, with pockets of coarse sand. Locally with layers of silt, clay or peat. Interpreted as offshore or beach gravels (Ellison et al 2004), or possibly fluvial (Bridgland 1994). | ||
| Definition of Lower Boundary: | Rests unconformably on London Clay bedrock, base of deposit at 105-128 above O.D. | ||
| Definition of Upper Boundary: | Overlain in places by till of the (Anglian) Lowestoft Formation, but generally at surface. | ||
| Thickness: | To 7m; average 3m. A thickness of 4.8m is recorded in the BGS Stanmore Common borehole (TQ19SE102). | ||
| Geographical Limits: | Thames Valley and Colne and Lea valleys region; plateau cappings from Stanmore, Middlesex to Billericay, Essex, and Shooter's Hill, Kent. | ||
| Parent Unit: | Crag Group (CRAG) | ||
| Previous Name(s): | Pebble Gravel [Obsolete Name and Code: Use PBGR, STGR]
(-442)
Sand and gravel of unknown age [Obsolete Name and Code: Use SGAO] (SGU) Stanmore Pebble Gravel [Obsolete Name and Code: Use STGR] (-3054) Warley Gravel [Obsolete Name and Code: Use STGR] (-3055) Stanmore Member (-547) Plateau Gravel (PLG) Pebble Gravel Formation [Obsolete Name And Code: See NBED And STGR] (PBGR) Sand and gravel of unknown age [Obsolete Name and Code: Use SGAO] (SGU) |
||
| Alternative Name(s): | none recorded or not applicable | ||
| Stratotypes: | |||
| Type Area | Harrow Weald Common. Gibbard, 1999. | ||
| Partial Type Section | Stanmore Common, described in BGS (MAU) boreholes TQ19SE/5 (TQ 1550 9394), and TQ19SE/6 (TQ 1647 9360). 4.80m recorded in BGS Stanmore Common borehole (TQ19SE/102). Ellison et al., 2004. | ||
| Reference(s): | |||
| Gibbard, P L. 1999. The Thames Valley, its tributaries and their former courses. 45-58 in Bowen, D Q (Editor), A revised correlation of Quaternary deposits in the British Isles. [London: The Geological Society.] | |||
| 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. | |||
| Bromehead, C E N. 1925. The Geology of North London. Memoir of the Geological Survey of Great Britain. Sheet 256 (England and Wales). | |||
| Bridgland, D R. 1994. Quaternary of the Thames. Geological Conservation Review Series No.7. (Peterborough: Joint Nature Conservation Committee.) | |||
| 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). | |||
| Dines, H G and Edmonds, F H. 1925. The geology of the country around Romford. Memoir of the Geological Survey of Great Britain, Sheet 257 (England and Wales). | |||
| Dewey, H, Bromehead, C E N, Chatwin, C P and Dines, H G. 1924. The geology of the country around Dartford. Memoir of the Geological Survey, Sheet 271 (England and Wales). | |||
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: | |||
| E256 E257 | |||