The BGS Lexicon of Named Rock Units — Result Details

Froswick Tuff Formation

Computer Code: FSW Preferred Map Code: Fsw
Status Code: Full
Age range: Caradoc Series (O4) — Caradoc Series (O4)
Lithological Description: Eutaxitic to parataxitic, andesitic to dacitic lapilli-tuff, locally lithic rich with minor tuff-breccia and bedded tuff and lapilli-tuff.
Definition of Lower Boundary: Marked by the abrupt change from bedded volcaniclastic rocks of the Mardale Formation to massive pyroclastic rocks.
Definition of Upper Boundary: Defined by the base of the overlying Woundale or Seathwaite Fell Sandstone formations.
Thickness: To 640m
Geographical Limits: Northeastern Lake District, from Kentmere to Place Fell, southeast Ullswater; Hart Fell, Haweswater; Bampton Common, Mardale Common and Wet Sleddale.
Parent Unit: Borrowdale Volcanic Group (BVG)
Previous Name(s): Froswick Tuffs (-264)
Froswick Formation (-2808)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Reference Section  Eastern slopes of Froswick, west of the River Kent, Kentmere. 
Type Area  Swindale Common, from Fewling Stones to High Wether Howe. 
Reference(s):
Woodhall, D G. 2000. The geology of the Haweswater and Martindale areas of the north-eastern Lake District. British Geological Survey Technical Report WA/00/55. 
Millward, D, 2002. Geology of the area between Haweswater and Shap. British Geological Survey Research Report RR/02/02 
Beddoe-Stephens, B, 2000. The Borrowdale Volcanic Group between Haweswater and eastern Ullswater. British Geological Survey Technical Report WG/00/04. 
Mitchell, G H, 1929. The succession and structure of the Borrowdale Volcanic Series in Troutbeck, Kentmere and the western part of Long Sleddale (Westmorland). Quarterly Journal of the Geological Society of London, Vol. 85, 9-44. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E030 E039