| Computer Code: |
UPSCL |
Preferred Map Code: |
notEntered |
| Status Code: |
Full |
| Age range: |
Ypresian Age (GY)
— Ypresian Age (GY) |
| Lithological Description: |
The Upper Shelly Clay mainly comprises brown and dark grey to black shelly clay, sandy clay and muddy limestone with fossil oysters. It appears to become more sandy towards the south-east and east (Ellison et al., 2004, fig. 19) although King (in prep.) suggests that these occurrences may be partly incised channel-filling units that post-date the Upper Shelly Clay.
The Upper Shelly Clay includes a distinctive bed of grey argillaceous shelly limestone with a conchoidal fracture, typically about 0.2 m thick but locally up to 1 m (Ellison, 1983), containing the fossil shells of freshwater molluscs. This is known as the 'Paludina Limestone', the Paludina Bed (or Band) (Curry, 1958; Rickman, 1861) or the Woolwich Freshwater Bed (Dewey and Bromehead, 1921).
The Upper Shelly Clay was deposited in marginal marine lagoons with freshwater incursions.
Earliest Eocene (Ypresian). |
| Definition of Lower Boundary: |
The Upper Shelly Clay rests on a burrowed erosive surface overlying either the Reading Formation or the Laminated Beds or the Lower Shelly Clay of the Woolwich Formation. The contact with the Laminated Beds may be a rapid gradation. The 'Paludina Limestone' acts as a marker horizon, which has been used to show that the Upper Shelly Clay rests directly on the Lower Shelly Clay in south-east London in the vicinity of Petts Wood and St Mary Cray [TQ 45 68] (Ellison et al., 2004, p. 29 and fig. 14; Whitaker, 1872, p. 116). |
| Definition of Upper Boundary: |
The Upper Shelly Clay underlies the Harwich Formation (Thames Group) at a channelled erosion surface. This marks a change in lithology from shelly clay, sandy clay and muddy limestone of the Upper Shelly Clay to glauconite-bearing sands, silts or clays with a basal rounded flint gravel bed and a marine fauna, or sandy flint gravels of the Harwich Formation. |
| Thickness: |
Up to 5 m. |
| Geographical Limits: |
The Upper Shelly Clay is of relatively restricted extent in central and south-east London but has also been recorded at Leytonstone, in north-east London. Other apparently outlying occurrences have been found in south-west Essex and north-west Kent (Ellison et al., 2004, fig. 19).
Knox (1996b, p. 216) notes that a very thin representative is present at Bradwell in north Essex, where shelly gravelly clays rest on the Reading Formation. |
| Parent Unit: |
Woolwich Formation (WL)
|
| Previous Name(s): |
Woolwich Shell Bed(s) [Obsolete Name and Code: Use LSCL, UPSCL]
(-5087)
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Reference Section |
Jubilee Line Extension Borehole 404T (TQ37NW 2118), Bermondsey, London, 24.11 to 25.05 m depth (Ellison et al., 1994; Ellison et al., 2004, p. 32). |
| Reference Section |
BGS Crystal Palace Borehole (TQ37SW 671), 129.33 to 134.65 m depth (Ellison et al., 2004, p.32). |
| Reference(s): |
| 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. |
| Curry, D. 1958. Part 3a XII Palaeogene. Lexique Stratigraphique International. Whittard, W F, and Simpson, S (editors). Vol. 1 Europe (Paris: Centre Nationale de la Research Scientifique.) |
| Dewey, H, and Bromehead, C E N. 1921. The geology of the South London. Memoir of the British Geological Survey, Sheet 270 (England and Wales). |
| 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. |
| 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). |
| Ellison, R A, 1983. Facies distribution in the Woolwich and Reading Beds of the London Basin, England. Proceedings of the Geologists' Association, Vol. 94, 311-319. |
| King, C. in prep. A revised correlation of Palaeogene and Neogene deposits in the British Isles. Geological Society of London Special Report. |
| 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. |
| Whitaker, W. 1872. The geology of the London Basin, Part I. The Chalk and the Eocene beds of the southern and western tracts. Memoir of the Geological Survey of England and Wales, Vol. IV. |
| Rickman, C. 1861. On the sections of strata exposed in the excavations for the South High-Level Sewer at Dulwich; with notices of the fossils found there and at Peckham. Quarterly Journal of the Geological Society, Vol. 17, 6. |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
| none recorded or not applicable |
