| Computer Code: |
GY |
Preferred Map Code: |
Gy |
| Status Code: |
Full |
| Age range: |
Caradoc Series (O4)
— Caradoc Series (O4) |
| Lithological Description: |
Massive, dacitic lapilli-tuff; contains significant quantities of lithic clasts, mainly of siltstone and sandstone derived from the subvolcanic, Skiddaw Group, basement. |
| Definition of Lower Boundary: |
Base of dacitic lapilli tuff. Unconformable, locally overlies Great Whinscale Dacite and elsewhere un-named basaltic andesite and andesite in the Birker Fell Andesite Formation. |
| Definition of Upper Boundary: |
Overlying parts of Birker Fell Andesite Formation, usually volcaniclastic sandstone or andesite. |
| Thickness: |
0 - 50m |
| Geographical Limits: |
Cockley Beck Fell - Grey Friar - Seathwaite Tarn - Troutal Fell, 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 |
Grey Friar - Seathwaite 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. |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
|
E038
|
