The BGS Lexicon of Named Rock Units — Result Details

Bytham Catchments Subgroup

Computer Code: BYCA Preferred Map Code: notEntered
Status Code: Full
Age range: Early Pleistocene Epoch (QPE) — Mid Pleistocene Epoch (QPM)
Lithological Description: The subgroup encompasses all the fluvial, lacustrine and organic deposits of the Proto-Soar and Bytham rivers. Deposits of four separate river terrace levels are recognised as members of the Ingham Formation. Commonly a basal sandy gravel is overlain by pebbly sands, with few clay and silt beds. The gravels of all contain a high proportion of rounded pebbles of grey and purple "Bunter" quartzite of Triassic derivation, and of vein quartz, Jurassic and Cretaceous rocks are local important constituents. Sedimentary structures indicate deposition by braided rivers.
Definition of Lower Boundary: Unconformable on bedrock of Carboniferous to Pleistocene age.
Definition of Upper Boundary: Commonly overlain by Middle Pleistocene glacigenic deposits. 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 latter is generally helpful.
Thickness: c.18m
Geographical Limits: Deposits of the subgroup follow the course of the pre-Glacial Proto-Soar and Bytham rivers, from Snitterfield near Stratford-upon-Avon in the west, to Croft and Huncote, Leicester, Castle Bytham and Witham-on-the-Hill, towards the Fen edge south of Bourne, through Shouldham Thorpe, south along the eastern margin of Fens to High Lodge, Middenhall, along the valleys of the Lark, Little Ouse, and Waveney, to the North Sea coast at Pakefield and Kessingland.
Parent Unit: Dunwich Group (DUNW)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Section  Thunderbolt Pit, 800m east of Castle Bytham. Rose, 1989b; Lewis, 1993. 
Reference(s):
Rose, J. 1994. Major river systems of central and southern Britain during the Early and Middle Pleistocene. Terra Nova, Vol.6, 435-443. 
Lewis, S G. 1993. The status of the Wolstonian glaciation in the English Midlands and East Anglia. PhD Thesis, University of London. 
Rose, J. 1989. Tracing the Baginton-Lillington Sand and Gravel from the West Midlands to East Anglia. 102-110 in Keen, D H (editor), The Pleistocene of the West Midlands: Field Guide [Cambridge: Quaternary Research Association.] 
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. 
Rose J. 1989b. Castle Bytham. 117-122 in Keen, D H (editor), The Pleistocene of the West Midlands: Field Guide. [Cambridge: Quaternary Research Association.] 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
none recorded or not applicable