The BGS Lexicon of Named Rock Units — Result Details

Dufton Shale Formation

Computer Code: DNSH Preferred Map Code: DnSh
Status Code: Full
Age range: Caradoc Series (O4) — Ashgill Series (OA)
Lithological Description: Dark grey, partly calcareous, siltstone and mudstone, with thin beds, lenticles or nodules of silty limestone. Poorly fossiliferous sandier beds occur near the top and base; at the base these include debris from the Borrowdale Volcanic Group with the commonly occuring brachiopod Trematis corona ['corona facies']
Definition of Lower Boundary: Taken at the base of sandstones and siltstones of the 'corona facies', overlying volcaniclastic rocks of the Harthwaite Formation [Borrowdale Volcanic Group]
Definition of Upper Boundary: Overlain by limestones of the Swindale or Keisley limestone formations, or where these are absent, the Ashgill Formation
Thickness: About 400m
Geographical Limits: Restricted to the Cross Fell Inlier, Cumbria
Parent Unit: Dent Group (DNT)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Type Section  Swindale Beck, Cross Fell Inlier, Cumbria 
Reference Section  Harthwaite Sike, Cross Fell, Cumbria 
Reference Section  Melmerby Road, Cross Fell Inlier, Cumbria 
Reference Section  Pus Gill, Cross Fell Inlier, Cumbria 
Burgess, I C and Holliday, D W. 1979. Geology of the country around Brough-under-Stainmore. Memoir for 1:50 000 geological sheet 31 and parts of sheets 25 and 30. Geological Survey of Great Britain (England and Wales). [London: HMSO.] 131pp. 
Owen, A W and Rushton, A W A, 1999. Arenig to Ashgill of northern England. pp 259-292 in Rushton, A W A, Owen, A W, Owens, R M, and Prigmore, J K. British Cambrian to Ordovician stratigraphy. Geological Conservation Review, Vol. 18. Joint Nature Conservation Committee. Peterborough. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E024 E031 E030