The BGS Lexicon of Named Rock Units — Result Details

Three Tarns Sandstone Member

Computer Code: TTA Preferred Map Code: Tta
Status Code: Full
Age range: Caradoc Series (O4) — Caradoc Series (O4)
Lithological Description: White-weathered laminated and thinly bedded fine-grained volcaniclastic sandstone and siltstone
Definition of Lower Boundary: Taken at the sharp base of bedded volcaniclastic sedimentary rocks where these overlie pyroclastic rocks of the Lingmell Formation, and locally, the Airy's Bridge Tuff Formation and Scafell Dacite. The contact is gradational and arbitrary where the upper part of the Lingmell Formation has been reworked subaqueously
Definition of Upper Boundary: Defined by the base of overlying volcaniclastic rocks including the Cam Crags and Bell Crags members
Thickness: Up to 80m
Geographical Limits: Bell Crags, Thirlmere to Seathwaite (Borrowdale) Fell, and from Pike de Bield to the Langdale Pikes, Cumbria
Parent Unit: Seathwaite Fell Sandstone Formation (SET)
Previous Name(s): Three Tarns Member (-1241)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  Pike O'Stickle to Harrison Stickle, Langdale, Cumbria Kneller and McConnell, 1993 
Reference(s):
Millward, D, Johnson, E W, Beddoe-Stephens, B, Young, B, Kneller, B C, Lee, M K, Fortey, N J, Allen, P M, Branney, M J, Cooper, D C, Hirons, S, Kokelaar, B P, Marks, R J, McConnell, B J, Merritt, J W, Molyneux, S G, Petterson, M G, Roberts, B, Rundle, C C, Rushton, A W A, Scott, R W, Soper, N J and Stone, P. 2000. Geology of the Ambleside district. Memoir of the British Geological Survey, England and Wales, Sheet 38. 
Kneller B C and McConnell, B J . 1993. The Seathwaite Fell Formation in the central Fells. British Geological Survey Technical Report WA/93/43 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
none recorded or not applicable