The BGS Lexicon of Named Rock Units — Result Details

Base Bed Member

Computer Code: BSBD Preferred Map Code: notEntered
Status Code: Full
Age range: Thanetian Age (GT) — Thanetian Age (GT)
Lithological Description: The Base Bed Member comprises glauconitic, very fine-grained sand and silt, some clayey, with scattered flint gravel, and with a layer (about 1m thick) of glauconite-coated, pitted and fractured angular flint gravel and cobbles at the base. Dispersed volcanic ash occurs in this unit. The basal gravel corresponds to the Bullhead Bed (BLHB).
Definition of Lower Boundary: The base of the Base Bed Member (the base of the Thanet Formation) is the base of the basal sandy, clayey flint gravel bed, which rests on the Chalk Group, often on an irregular, karstic surface modified by dissolution in groundwater.
Definition of Upper Boundary: The top of the unit is placed at the change from very fine-grained sands and silts of the Base Bed Member to the silts and silty clays of the overlying Stourmouth Silt Member (STMH).
Thickness: none recorded or not applicable
Geographical Limits: Kent and eastern Essex.
Parent Unit: Thanet Formation (TAB)
Previous Name(s): Thanet Base-Bed (-5081)
Alternative Name(s): none recorded or not applicable
Type Section  Cliffs near Little Cliffsend, Pegwell Bay, Kent. Curry, 1981; Daley, 1999; Ward, 1977 
Daley, B. 1999. London Basin: eastern localities, In: Daley, B., Balson, P. (Eds.), British Tertiary Stratigraphy. Geological Conservation Review Series 15, pp. 23-72. 
Jolley, D W, 1992. Palynofloral association sequence stratigraphy of the Palaeocene Thanet Beds and equivalent sediments in eastern England. Review of Palaeobotany and Palynology, Vol.74, p.207-237. 
Whitaker, W. 1866. On the "Lower London Tertiaries" of Kent. Quarterly Journal of the Geological Society London, Vol.22, 404-435. 
Ward, D J, 1977. The Thanet Beds exposure at Pegwell Bay, Kent. Tertiary Research, Vol.1, p.69-76. 
Aldiss, D.T., 2012. The stratigraphical framework for the Palaeogene successions of the London Basin, UK. British Geological Survey Open Report OR/12/004. Available from 
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. 
Ellison, R A, and Lake, R D. 1986. Geology of the country around Braintree. Memoir of the British Geological Survey, Sheet 223 (England and Wales). 
Knox, R W O. 1979. Igneous grains associated with zeolites in the Thanet Beds of Pegwell Bay, Northeast Kent. Proceedings of the Geologists' Association, Vol. 90, 55-59. 
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. 
Knox, R W O, Hine, N M, and Ali, J R. 1994. New information on the age and sequence stratigraphy of the type Thanetian of southeast England. Newsletters on Stratigraphy, Vol. 30, 45-60. 
Knox, R W O, and Morton, A C. 1983. Stratigraphical distribution of Early Palaeogene pyroclastic deposits in the North Sea Basin. Proceedings of the Yorkshire Geological Society, Vol. 44, 355-363. 
Powell, A J, Brinkhuis, H, and Bujak, J P. 1996. Upper Paleocene-Lower Eocene dinoflagellate cyst sequence biostratigraphy of southeast England. 145-183 in Correlation of the Early Palaeogene in Northwest Europe. Knox, R W O, Corfield, R M, and Dunay, R E (editors). Geological Society Special Publication, No. 101. 
Siesser, W G, Ward, D J, and Lord, A R. 1987. Calcareous nannoplankton biozonation of the Thanetian Stage (Palaeocene) in the type area. Journal of Micropalaeontology, Vol. 6, 85-102. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
none recorded or not applicable