The BGS Lexicon of Named Rock Units — Result Details

Slea Valley Formation

Computer Code: SLVY Preferred Map Code: notEntered
Status Code: Full
Age range: Mid Pleistocene Epoch (QPM) — Holocene Epoch (QH)
Lithological Description: The formation encompasses the fluvial, lacustrine and organic deposits of the River Slea and its tributaries. It includes floodplain alluvium, river terrace deposits, and the Sleaford Sands and Gravels of Berridge et al (1999). The floodplain comprises soft clays, silts and fine sands, with bodies of peat, overlying sands and gravels. The terrace deposits comprise sands, gravelly sands and sandy gravels, deposited by braided rivers in a periglacial environment. The pebbles include much buff ooidal limestone from the Lincolnshire Limestone Formation, and flint, ironstone and sandstone, and are up to c.40mm in diameter.
Definition of Lower Boundary: Unconformable on Middle Pleistocene glacial deposits, and on Jurassic bedrock.
Definition of Upper Boundary: Surface.
Thickness: To c.7m
Geographical Limits: The entire catchment of the River Slea and its tributaries, Lincolnshire.
Parent Unit: Ouse-Nene Catchments Subgroup (ONCA)
Previous Name(s): Sleaford Sands And Gravels (-2430)
Alternative Name(s): none recorded or not applicable
Type Area  Valley of River Slea from Grantham to Sleaford, Lincolnshire. Berridge et al., 1999. 
Berridge, N G, Pattison, J, Samuel, M D A, Brandon, A, Howard, A S, Pharaoh, T C and Riley, N J. 1999. Geology of the Grantham district. Memoir of the British Geological Survey, sheet 127 (England and Wales). 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E127 E128