Computer Code: |
LIT |
Preferred Map Code: |
LiT |
Status Code: |
Full |
Age range: |
Caradoc Series (O4)
— Caradoc Series (O4) |
Lithological Description: |
White-weatherd, massive, crystal-rich (K-feldspar), welded rhyolitic tuff containing lithophysae-rich zones locally. |
Definition of Lower Boundary: |
Base of tuff; overlies volcaniclastic sandstones and andesite sheets of the Birker Fell Andesite Formation (undivided). |
Definition of Upper Boundary: |
Top of tuff; overlain by volcaniclastic sandstones of the Blisco Member or by the Great Whinscale Dacite. |
Thickness: |
7 - 27m; ponded at one locality to 60m |
Geographical Limits: |
West of Yoadcastle (SD 15 95) south of Devoke Water to Pike of Blisco (NY 27 04) and Seathwaite Tarn (SD 249 984), Cumbria. |
Parent Unit: |
Birker Fell Andesite Formation (BFA)
|
Previous Name(s): |
Tongue House Member [Obsolete Name: Replaced By LIT, GWD, GY]
(TNM)
|
Alternative Name(s): |
none recorded or not applicable
|
Stratotypes: |
Type Area |
Crags around Little Stand. |
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. 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. |
1:50K maps on which the lithostratigraphical unit is found, and map code used: |
E038
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