The BGS Lexicon of Named Rock Units — Result Details

Frog Hall Member

Computer Code: FRHA Preferred Map Code: notEntered
Status Code: Full
Age range: Pleistocene Epoch (QP) — Pleistocene Epoch (QP)
Lithological Description: Predominantly cold phase sands and gravels that infill a channel incised, to a level several metres below the Dunsmore Gravel "plateau", into the Wolston Formation and underlying Triassic bedrock and grade southwards into the valley of the River Leam (a principal Avon tributary). Lithologically similar to the Dunsmore Gravel Member (Wolston Formation), being dominated by clasts of Triassic ("Bunter") lithologies and flint, but compositionally more mature, and also containing clasts of ironpan (ferricrete) derived from Dunsmore Gravel. At the type locality it includes organic peaty deposits ("Frog Member") assigned to MIS 9 at base. Probably contemporaneous with the Pershore Member (Avon Valley Formation).
Definition of Lower Boundary: Unconformable, channelled base on Wolston Formation or Triassic bedrock.
Definition of Upper Boundary: Ground surface.
Thickness: 0 to c 9m.
Geographical Limits: Confined to immediate vicinity of Stretton-on-Dunsmore, Warwickshire [SP 41 73], largely within a minor un-named tributary of the River Leam ("Alluvial fan gravels" of BGS Sheet 184).
Parent Unit: Warwickshire Avon Valley Formation (AVON)
Previous Name(s): Dunsmore Gravel (DMG)
Alluvial Fan Deposits (ALF)
Frog Hall Sand And Gravel (-262)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Section  Frog Hall Quarry. Sand and gravel pit 300m northeast of Frog Hall near Stretton-on-Dunsmore. Still exposed. Sumbler, 1989. 
Reference(s):
Keen, D H, Coope, G R, Jones, R L, Field, M H, Griffiths, H I, Lewis, S G and Bowen, D Q. 1997. Middle Pleistocene deposits at Frog Hall Pit, Stretton-on-Dunsmore, Warwickshire, English Midlands, and their implication for the age of the type Wolstonian. Journal Quaternary Science, Vol.12, 183-208. 
Old, R A, Sumbler, M G and Ambrose, K, 1987. Geology of the country around Warwick. Memoir of the British Geological Survey, Sheet 184 (England and Wales). 
Shotton, F W. 1953. The Pleistocene deposits of the area between Coventry, Rugby and Leamington and their bearing on the topographic development of the Midlands. Philosophical Transactions of the Royal Society of London, Vol.B237, 209-260. 
Sumbler, M G. 1989. The Frog Hall Sand and Gravel: a post "Wolstonian" fluvial deposit near Coventry. Quaternary Newsletter, No.58, pp.3-8. 
Bowen, D Q. 1999. A revised correlation of Quaternary deposits in the British Isles. Geological Society Special Report, No. 23. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E184