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):
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. 
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. 
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