The BGS Lexicon of Named Rock Units — Result Details

Nettle Crags Tuff Member

Computer Code: NCT Preferred Map Code: NCT
Status Code: Full
Age range: Caradoc Series (O4) — Caradoc Series (O4)
Lithological Description: Massive, eutaxitic to parataxitic dacitic lapilli-tuff.
Definition of Lower Boundary: Base of dacitic lapilli-tuff above dacite lavas (and/or sills) within the Birker Fell Andesite Formation.
Definition of Upper Boundary: Non-sequence at top of dacitic lapilli-tuff. Overlain by dacite and volcaniclastic sandstone in the Birker Fell Andesite Formation.
Thickness: 60-220m
Geographical Limits: Nettle Crags - Bootle Fell in the Borrowdale Volcanic Group outcrop between the Skiddaw Group and Eskdale Granodiorite.
Parent Unit: Birker Fell Andesite Formation (BFA)
Previous Name(s): Part Of Nettle Crags Tuffs And Lavas (-2334)
Nettle Crags Tuff Formation (-1722)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  Nettle Crags, 1km east north east of Bootle, Cumbria. 
Reference(s):
British Geological Survey, 1994. Black Combe and Bootle, SD18NW, Solid and Drift 1:10,000 (Keyworth, Nottingham, British Geological Survey). 
Mathieson, N A, 1986 Geology, structure and geochemistry of the Ordovician volcanic succession in south west Cumbria. Unpublished Ph.D. thesis, University of Sheffield. 
Johnson, E W, Soper, N J, Burgess, I C, Ball, D F, Beddoe-Stephens, B, Carruthers, R M, Fortey, N J, Hirons, S, Merritt, J W, Millward, D, Roberts, B, Walker, A B and Young, B. 2001. Geology of the country around Ulverston. Memoir of the British Geological Survey, England and Wales, Sheet 48. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E048