The BGS Lexicon of Named Rock Units — Result Details
Great Whinscale Dacite Member
| Computer Code: | GWD | Preferred Map Code: | GWD |
|---|---|---|---|
| Status Code: | Full | ||
| Age range: | Caradoc Series (O4) — Caradoc Series (O4) | ||
| Lithological Description: | Extensive white-weathered aphyric, dacitic lava flow, platy-foliated with marginal autobreccias. | ||
| Definition of Lower Boundary: | Base of distinctive lava flow; underlain by thin un-named units of volcaniclastic sandstone or by the Little Stand Tuff. | ||
| Definition of Upper Boundary: | Top of distinctive lava flow; overlain by volcaniclastic sandstone sequence of the Blisco Member, or by the Grey Friar Tuff, or by un-named andesite lava flows of the Birker Fell Andesite Formation. | ||
| Thickness: | Generally 75 - 85m; locally 20 - 65m. | ||
| Geographical Limits: | Yoadcastle (SD 15 95) south of Devoke Water to Little Stand (NY 25 03), Harter Fell (SD 218 997) and around Seathwaite Tarn (SD 249 984), Cumbria. | ||
| Parent Unit: | Birker Fell Andesite Formation (BFA) | ||
| Previous Name(s): | Great Whinscale Rhyolite [Obsolete Name and Code: Use GWD]
(-300)
Tongue House Member [Obsolete Name: Replaced By LIT, GWD, GY] (TNM) |
||
| Alternative Name(s): | none recorded or not applicable | ||
| Stratotypes: | |||
| Type Area | Crook Crag, Great Whinscale, (Ulpha Fell, south of Eskdale). | ||
| Reference(s): | |||
| Millward, D. 2004. A stratigraphical framework for the Upper Ordovician and Lower Devonian volcanic and intrusive rocks in the English Lake District and adjacent areas. British Geological Survey, Research Report: RR/01/007. | |||
| 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. | |||
| Firman, R G J, 1957. The Borrowdale Volcanic Series between Wastwater and Duddon Valley, Cumberland. Proceedings of the Yorkshire Geological Society, Vol.31, p.39-64. | |||
| Kanaris-Sotiriou R, Millward, D and Rundle, C C, 1991. The Great Whinscale Dacite - an enigmatic lava flow from the Borrowdale Volcanic Group, English Lake District. Proceedings of the Yorkshire Geological Society, Vol.48, p.393-408. | |||
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: | |||
| E038 | |||