The BGS Lexicon of Named Rock Units — Result Details

Kesgrave Catchment Subgroup

Computer Code: KGCA Preferred Map Code: notEntered
Status Code: Full
Age range: Pleistocene Epoch (QP) — Pleistocene Epoch (QP)
Lithological Description: Mainly gravels characterised by quartz and quartzite from the Triassic, Carboniferous and Devonian rocks of the West Midlands, Welsh Borderland and possibly south-western Pennines, and by felsic volcanic rocks from northern Wales. The members comprise bodies of cross-bedded and massive, moderately sorted sand and gravel. The upper part of the gravels which dominate the subgroup are commonly affected by pedogenesis. The Valley Farm Soil is a rubified and clay-enriched horizon affecting the top 1.0 - 1.5 m and indicating warm interglacial conditions. The Barham Arctic Structure Soil is a complex pedogenic horizon affecting the topmost 1.0 - 1.5 m of the subgroup and of the Valley Farm Soil (Rose and Allen 1977; Rose et al., 1985).
Definition of Lower Boundary: Unconformable on bedrock (Cretaceous - Palaeogene) and Crag Group. The deposits are generally entrenched into bedrock with a difference in surface elevation of at least 5 m. Differentiation from the Crag Group can be difficult where the latter is reworked, and the distinction must be made on the basis of sedimentological structures: the Crag Group is of shallow marine to estuarine origin, the Kesgrave Catchment Subgroup is fluvial.
Definition of Upper Boundary: Commonly overlain by mid-Pleistocene glacigenic deposits. The upper boundary may be difficult to determine where overlain by glaciofluvial sand and gravel, but the presence of more angular clasts, chalk, and poorer sorting in the over-lying beds is usually helpful. The uppermost 1.0 - 1.5 m of the subgroup is commonly marked by the pedogenic Valley Farm Soil and/or the Barham Arctic Structure Soil.
Thickness: About 21.3 m aggregate thickness with individual terrace aggradations typically 5 - 12 m thick.
Geographical Limits: The unit is restricted to the Thames Valley, Essex and Suffolk. BGS 1:50 000 Sheets E206-208, 221-225, 239-242, 255-257. It does not extend into Norfolk.
Parent Unit: Dunwich Group (DUNW)
Previous Name(s): Essex White Ballast (-3284)
Kesgrave Formation (B) [Obsolete Name And Code: See KGCA] (KES)
Kesgrave Formation (A) [Obsolete Name And Code: See KGCA] (KESF)
Kesgrave Sands And Gravels [Obsolete Name And Code: See KGCA] (KGSG)
Kesgrave Formation [Obsolete Code: Use KES] (-1621)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Section  Gravel pit at Kesgrave. Rose and Allen, 1977. 
Reference(s):
Hamblin, R J O, and Moorlock, B S P. 1995. The Kesgrave and Bytham Sands and Gravels of eastern Suffolk. Quaternary Newsletter, No.77, 17-31. 
Kemp, R A. 1987. Genesis and environmental significance of a buried Middle Pleistocene soil in eastern England. Geoderma, Vol.41, 49-77. 
Whiteman, C A and Rose, J. 1992. Thames river sediments of the British Early and Middle Pleistocene. Quarterly Science Reviews, Vol.11, 363-375. 
Rose, J. 1994. Major river systems of central and southern Britain during the Early and Middle Pleistocene. Terra Nova, Vol.6, 435-443. 
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. 
Rose, J, Allen, P and Hey, R W, 1976. Middle Pleistocene stratigraphy in Southern East Anglia. Nature, Vol.236, p.492-494. 
Rose, J and Allen, P, 1977. Middle Pleistocene stratigraphy in south-east Suffolk. Quarterly Journal of the Geological Society of London, Vol.133, p.83-102. 
Whiteman, C A. 1992. The palaeogeography and correlation of pre-Anglian-Glaciation terraces of the River Thames in Essex and the London Basin. Proceedings of the Geologists' Association, Vol.103, 37-56. 
Rose, J, Whiteman, C A, Allan, P and Kemp, R A. 1999. The Kesgrave Sands and Gravels: 'pre-glacial' Quaternary deposits of the River Thames in East Anglia and the Thames Valley. Proceedings of the Geologists' Association, Vol.110, 93-116. 
Rose, J, Allen, P, Kemp, R A, Whiteman, C A and Owen, N. 1985. The early Anglian Barham Soil in southern East Anglia. 197-229 in Boardman, J (editor), Soils and Quaternary landscape evolution. [Chichester: Wiley.] 
Kemp, R A. 1985. The Valley Farm Soil in southern East Anglia. 179-196 in Boardman, J (editor), Soils and Quaternary landscape evolution. [Chichester: Wiley.] 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
none recorded or not applicable