The BGS Lexicon of Named Rock Units — Result Details

Glaramara Tuff

Computer Code: GMT Preferred Map Code: Gmt
Status Code: Full
Age range: Caradoc Series (O4) — Caradoc Series (O4)
Lithological Description: A widespread package of dacitic pyroclastic rocks including coarse lithic-rich lapilli-tuff and pyroclastic breccia, bedded tuff with beds containing accretionary lopilli, and nodular eutaxitic lapilli-tuff. The uppermost part comprises massive to bedded pebbly sandstone with accumulations of broken accretionary lapilli in channels and scours.
Definition of Lower Boundary: The base is taken at the sharp contact at the base of dacitic pyroclastic rocks overlying sandstones with an overall andesitic composition. In places the contact is an erosion surface of low relief.
Definition of Upper Boundary: Defined by the overlying sandstones of the uppermost part of the Sprinkling Tarns Member or, where not distinguished, by the uppermost part of the Seathwaite Fell Sandstone Formation.
Thickness: About 20m in type area.
Geographical Limits: Discontinous outcrop within the uppermost part of the Seathwaite Fell Sandstone Formation and beneath the Lincomb Tarns Formation, throughout the central Lake District, Cumbria.
Parent Unit: Sprinkling Tarn Sandstone Member (SPR)
Previous Name(s): Glaramara Tuff Member (-3437)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  Glanamara, south of Borrowdale, 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:
E029