The BGS Lexicon of Named Rock Units — Result Details
Upnor Formation
| Computer Code: | UPR | Preferred Map Code: | UPR |
|---|---|---|---|
| Status Code: | Full | ||
| Age range: | Thanetian Age (GT) — Thanetian Age (GT) | ||
| Lithological Description: | The Upnor Formation is typically composed of variably but commonly abundant glauconitic fine- to coarse-grained sand with variable clay and silt content, and with beds, lenses and stringers of well-rounded, black flint gravel, and minor thin clays, commonly interbedded with glauconitic sand laminae and lenses. When fresh, the sands are dark grey-brown to dark green depending on proportion of glauconite grains which may be more than 25%. In south-east London there is a persistent pebble bed at the top. The sands weather pale grey-brown to yellow-brown but the glauconite remains dark green. In the central and northern London Basin pedogenic processes during deposition of the overlying Reading Formation modified the sands, resulting in development of carbonate concretions, clay enrichment and colour mottling that exceptionally extend through the formation. Oysters are common in unweathered sections. The Upnor Formation represents proximal marine sedimentation in predominantly high energy, partly tidally influenced environments. In contrast to that of the Thanet Formation, the heavy mineral content of the sands suggests a provenance from the south (Morton, 1982). Paleocene: Late Thanetian (NP9), based on calcareous nannofossil assemblages, dinoflagellate cysts and magnetostratigraphy (Ali and Jolley, 1996; Ellison et al., 1996; King, in prep.; Knox, 1996). | ||
| Definition of Lower Boundary: | In the eastern part of the London Basin, the Upnor Formation rests on silty fine-grained sand at a burrowed contact with the Thanet Formation, with burrows extending as much as 0.5 m into the Thanet Formation, or on a channelled erosion surface (King, in prep). The Upnor Formation is likely to be composed of medium to coarse-grained sand that is greener and commonly more gravelly than that of the Thanet Formation but in places has a confusingly similar lithology, especially where, as in the far east of the London Basin, bioturbation has produced a gradational junction (Ellison et al., 1994). According to Morton (1982), the top of the Thanet Formation has been leached during a period of exposure, probably with some erosion, prior to deposition of the Upnor Formation. In the west of the London Basin, to the west of the Thanet Formation outcrop and subcrop, the Upnor Formation rests on a burrowed contact with chalk and flints of the Chalk Group, commonly modified by karstic dissolution. In East Anglia, the Upnor Formation rests on a burrowed contact with the clay of the Ormesby Clay Member. | ||
| Definition of Upper Boundary: | In general, marked by an upwards change from green glauconitic sand or sandy gravel to colour-mottled clays of the Reading Formation, or dark shelly clay or lignitic sand of the Woolwich Formation. Commonly however the Upnor Formation has been affected by contemporary pedogenic alteration associated with the mid-Lambeth Group Hiatus. Its original character may then be obscured and the contact with the overlying Reading Formation unclear. In north and east Kent, the Lambeth Group (including the top of the Upnor Formation) was eroded prior to deposition of the Harwich Formation (Oldhaven Member). | ||
| Thickness: | Up to 15 m in the east of the London Basin. Typically 5 to 8 m in central London but locally as little as 2 m, generally decreasing westwards to less than 2 m. | ||
| Geographical Limits: | The Upnor Formation occurs throughout most of the London and Hampshire basins but thins markedly to the west of London. It also occurs in north Essex and in Suffolk. In north Kent the top was removed by erosion prior to deposition of the Oldhaven Member. | ||
| Parent Unit: | Lambeth Group (LMBE) | ||
| Previous Name(s): | Hales Clay Member [Obsolete Name and Code: Use UPR]
(HAC)
Bottom Bed [Obsolete Name and Code: Use UPR] (-5097) Reading Bottom Bed [Obsolete Name and Code: Use UPR] (BBD) Reading Formation Basement Bed [Obsolete Name and Code: Use UPR] (RFBB) Woolwich Bottom Bed [Obsolete Name and Code: Use UPR] (-5099) |
||
| Alternative Name(s): | none recorded or not applicable | ||
| Stratotypes: | |||
| Reference Section | Jubilee Line Extension Borehole 404T. BGS Registration No. TQ37NW 2118. Ellison et al., 1994. | ||
| Type Section | Lower Upnor Pit, north of Chatham, north Kent. Daley, 1999; Ellison et al., 1994; Kennedy and Sellwood, 1970. | ||
| Reference Section | Charlton Pit (or Gilbert's Pit), just south-west of Maryon Park, Charlton, London Borough of Greenwich. Daley, 1999; Ellison et al., 1994; Whitaker, 1889. | ||
| Reference Section | BGS Crystal Palace Borehole (TQ37SW 671), 141.95 to 145.10 m depth. Ellison et al., 2004, p.32. | ||
| Reference Section | Staines 5 Borehole (TQ07SW 156), 129.74 to 130.11 m depth. Ellison and Williamson, 1999, fig. 6. | ||
| Reference Section | Old Cement Works, Harefield, London Borough of Hillingdon. Cooper, 1976; Daley, 1999; King, 1981, fig. 32. This locality exposes a thin development of the Upnor Formation in the west of the London Basin. | ||
| Reference Section | Pincent's Kiln, Theale, Berkshire. Crane and Goldring, 1991; Daley, 1999. | ||
| Reference(s): | |||
| King, C. in prep. A revised correlation of Palaeogene and Neogene deposits in the British Isles. Geological Society of London Special Report. | |||
| Daley, B. 1999. London Basin: eastern localities. 23-72 in British Tertiary Stratigraphy. Daley, B, and Balson, P (editors). Geological Conservation Review Series 15. | |||
| King, C. 1981. The stratigraphy of the London Clay and associated deposits. Tertiary Research Special Paper No.6. (Backhuys: Rotterdam). | |||
| Whitaker, W., 1889. The geology of London and part of the Thames Valley (Explanation of Sheets 1, 2 and 7). Memoir of the Geological Survey of the United Kingdom Vol. 1. Descriptive geology. | |||
| Ellison, R A, Knox R W O'B, Jolley, D W, and King, C. 1994. A revision of the lithostratigraphical classification of the early Palaeogene strata of the London Basin and East Anglia. Proceedings of the Geologists' Association, Vol. 105, 187-197. | |||
| Ali, J R, and Jolley, D W. 1996. Chronostratigraphic framework for the Thanetian and lower Ypresian deposits of southern England. Geological Society, London, Special Publications, Vol. 101, 129-144. | |||
| Cooper, J. 1976. Report of a field meeting to Harefield, Middlesex. Tertiary Research, Vol. 1, 31-36. | |||
| Daley, B. 1999. London Basin: western localities. 73-84 in British Tertiary Stratigraphy. Daley, B, and Balson, P (editors). Geological Conservation Review Series, No. 15. | |||
| Ellison, R A, Ali, J R, Hine, N M, and Jolley, D W. 1996. Recognition of Chron C25n in the upper Paleocene Upnor Formation of the London Basin, UK. Geological Society special publication, Vol. 101, 185-193. | |||
| Knox, R W O. 1996. Tectonic controls on sequence development in the Palaeocene and earliest Eocene of southeast England: implications for North Sea stratigraphy. 209-230 in Sequence Stratigraphy in British Geology. Hesselbro, S P, and Parkinson, D N (editors). Geological Society of London Special Publication, No. 103. | |||
| Morton, A C. 1982. The provenance and diagenesis of Palaeogene sandstones of southeast England as indicated by heavy mineral analysis. Proceedings of the Geologists’ Association, Vol. 93, 263-274. | |||
| Kennedy, W.J., Sellwood, B.W., 1970. Ophiomorpha nodosa Lundgren, a marine indicator from the Sparnacian of south-east England. Proceedings of the Geologists' Association 81, 99-110. | |||
| Edwards, R A, and Freshney, E C. 1987. Lithostratigraphical classification of the Hampshire Basin Palaeogene Deposits (Reading Formation to Headon Formation) Tertiary Research, Vol. 8, 43-73. | |||
| Hester, S W. 1965. Stratigraphy and palaeogeography of the Woolwich and Reading Beds. Bulletin of the Geological Survey of Great Britain No. 23, 117-137. | |||
| Crane, P R, and Goldring, R. 1991. The Reading Formation (late Palaeocene to early Eocene) at Cold Ash and Pincent's Kiln (Berkshire) in the western London Basin. Tertiary Research, Vol. 12, 147-158. | |||
| Ellison, R A, and Williamson, I T. 1999. Geology of the Windsor and Bracknell district - a brief explanation of the geological map. Sheet Explanation of the British Geological Survey. 1:50 000 Sheet 269 Windsor (England and Wales). | |||
| Aldiss, D T. 2014. The stratigraphical framework for the Palaeogene successions of the London Basin, UK. British Geological Survey Open Report OR/14/008. 95 pp. | |||
| Waters, C N, Smith, K, Hopson, P M, Wilson, D, Bridge, D M, Carney, J N, Cooper, A H, Crofts, R G, Ellison, R A, Mathers, S J, Moorlock, B S P, Scrivener, R C, McMillan, A A, Ambrose, K, Barclay, W J, and Barron, A J M. 2007. Stratigraphical Chart of the United Kingdom: Southern Britain. British Geological Survey, 1 poster. | |||
| 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). | |||
| Hull, E, and Whitaker, W. 1861. The geology of parts of Oxfordshire and Berkshire. Memoir of the Geological Survey of Great Britain, Sheet 13 (Old Series). | |||
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: | |||
| E256 E257 E268 | |||