The BGS Lexicon of Named Rock Units — Result Details

Lark Valley Formation

Computer Code: LKVY Preferred Map Code: notEntered
Status Code: Full
Age range: Mid Pleistocene Epoch (QPM) — Holocene Epoch (QH)
Lithological Description: Formation encompasses the fluvial, lacustrine and organic deposits of the River Lark and its tributaries. Five terraces are identified. The terrace deposits comprise well bedded to rather poorly bedded sands and sandy gravels, deposited by braided rivers in a preglacial environment. The pebbles are dominantly angular to rounded flints up to about 100mm across, with a few glacial erratics. The three higher terraces are cryoturbated. The floodplain alluvium comprises silts, clays and fine sands, with bodies of peat, overlying sands and gravels.
Definition of Lower Boundary: Unconformable on Mid Pleistocene glacial deposits and on bedrock (Kimmeridge Clay to Chalk Group).
Definition of Upper Boundary: Surface.
Thickness: To c.14m
Geographical Limits: The entire catchment of the River Lark and its tributaries, from near Bury St Edmunds, Suffolk to Littleport, Cambridgeshire.
Parent Unit: Ouse-Nene Catchments Subgroup (ONCA)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  Valley of the River Lark from near Bury St Edmunds to near Littleport. Clayton, 1983. 
Reference(s):
Clayton, A R. 1983. The sand and gravel resources of the country between Maidenhall and Barrow, Suffolk: description of 1:25000 Sheets TL76, TL77 and part of TL87. Mineral Assessment Report, 123, Institute of Geological Sciences, London. 
Worssam, B C and Taylor, J H. 1969. The geology of the country around Cambridge. Memoir of the Geological Survey of Great Britain, Sheet 188 (England and Wales). 
Gallois, R W. 1988. Geology of the country around Ely. Memoir of the British Geological Survey, Sheet 173 (England and Wales). 
Lewis, S G. 1999. Eastern England. 10-27 in Bowen D Q (editor), A revised correlation of Quaternary deposits in the British Isles. Geological Society Special Report, 23. [London: Geological Society.] 
Bristow, C R. 1990. Geology of the country around Bury St Edmunds. Memoir of the British Geological Survey, Sheet 189 (England and Wales). 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E173 E188 E189