The BGS Lexicon of Named Rock Units — Result Details

Thornsgill Till Formation

Computer Code: THGTI Preferred Map Code: TH
Status Code: Full
Age range: Anglian Stage (QA) — Wolstonian Stage (QO)
Lithological Description: Extremely compact, silty sandy gravelly diamicton containing clasts mainly of slate. "Borrowdale Volcanic Group" lithologies and Threlkeld microgranite. Dark grey at base becoming increasingly weathered upwards to yellowish brown with olive brown, orange and white mottling where it has been cryoturbated. Most clasts are decomposed towards top and are commonly bleached. The deeply weathered zone of the unit is named formally as the Troutbeck Palaeosol.
Definition of Lower Boundary: Generally an uneven, unconformable boundary with slate bedrock, but locally a thin unit of weathered sand and gravel intervenes. Bedrock commonly decomposed.
Definition of Upper Boundary: Generally a sharp, planar, or gradational glacitectonic boundary with greyish brown stony clay diamicton (Threlkeld Till Formation).
Thickness: To 15m
Geographical Limits: Vale of Thelkeld, Cumbria.
Parent Unit: Central Cumbria (Albion) Glacigenic Subgroup (CCAG)
Previous Name(s): Thornsgill Formation (-2482)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Partial Type Section  River sections in the banks of the Mosedale Beck, 3km south of Wallthwaite, Cumbria. Boardman (1981, 1991, 2000). 
Partial Type Section  River cliff sections in the banks of the Thornsgill Beck, 1km south of Troutbeck Head, Cumbria. Boardman (1981, 1991, 2001) 
Reference(s):
Boardman, J, Lowe, J J, Holyoak, D T, and Wilson, P. 1981. Northeastern Lake District: The valleys of Mosedale and Thornsgill, 7-39 in Field Guide to Eastern Cumbria. J Boardman (ed.) Quaternary Research Association, London, 128pp. 
Boardman, J. 1991. Glacial deposits in the English Lake District, 231-260 in Glacial deposits in Great Britain and Ireland. Ehlers, J, Gibbard, P L and Rose, J (editors). (Rotterdam:Balkema.) 
Boardman, J. 2002. Thornsgill and Mosedale, 46-51 in Huddart, D and Glasser, N F (editors), Quaternary of Northern England. Geological Conservation Review Series, No.25. [Peterborough: Joint Nature Conservation Committee.] 745pp. 
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:
none recorded or not applicable