The BGS Lexicon of Named Rock Units — Result Details

Lackford Member

Computer Code: LFRD Preferred Map Code: notEntered
Status Code: Full
Age range: Quaternary Period (Q) — Quaternary Period (Q)
Lithological Description: Sand and gravel, but also with beds of interbedded clay and silt.Typically about 6 per cent 'fines', 65 per cent sand and 29 per cent gravel.
Definition of Lower Boundary: Generally unconformably overlying Chalk bedrock or chalky till, but also overlying glacial silt infilling buried valleys.
Definition of Upper Boundary: At surface
Thickness: Generally up to between about 4 and 5m but locally over 9m thick.
Geographical Limits: Within the valley of the River Lark especially Hawstead, Bury St Edmunds, Lackford and Mildenhall, and the Lark tributaries, the Kennet and the Black Bourn.
Parent Unit: Lark Valley Formation (LKVY)
Previous Name(s): none recorded or not applicable
Alternative Name(s): 1st Terrace Of River Lark (Bristow,1990)
Stratotypes:
Type Section  The stratotype is the north face of a gravel pit just south of the River Lark about 1km north-east of Lackford. Bristow,1990 
Reference(s):
Bristow, C R. 1990. Geology of the country around Bury St Edmunds. Memoir of the British Geological Survey, Sheet 189 (England and Wales). 
Bowen, D Q. 1999. A revised correlation of Quaternary deposits in the British Isles. Geological Society Special Report, No. 23. 
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. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E189