The BGS Lexicon of Named Rock Units — Result Details

Seatallan Dacite Member

Computer Code: STAD Preferred Map Code: STaD
Status Code: Full
Age range: Caradoc Series (O4) — Caradoc Series (O4)
Lithological Description: Dacite lava flow. Porphyritic, flow laminated, white to pink-weathered.
Definition of Lower Boundary: Junction with underlying unnamed andesite sheets in the Birker Fell Andesite Formation.
Definition of Upper Boundary: Junction with overlying tuffs or ignimbrites of the Craghouse Member.
Thickness: 200m
Geographical Limits: Seatallan - Haycock area, west of Wasdale, Cumbria.
Parent Unit: Birker Fell Andesite Formation (BFA)
Previous Name(s): Dacite Group (-4344)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  Seatallan 4.5km west of Wasdale Head. 
Reference Section  Between summit of Haycock and Scoat Tarn. 
Reference(s):
Petterson, M G, Beddoe-Stephens, B, Millward, D and Johnson, E W, 1992. A pre-caldera plateau-andesite field in the Borrowdale Volcanic Group of the English Lake District. Journal of the Geological Society, London, Vol. 149, 889-906. 
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. 
Clark, L, 1964. The Borrowdale Volcanic Series between Buttermere and Cumberland. Proceedings of the Yorkshire Geological Society, Vol.34, p.343-356. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E038 E037 E029