The BGS Lexicon of Named Rock Units — Result Details

Craghouse Tuff Member

Computer Code: CHT Preferred Map Code: ChT
Status Code: Full
Age range: Caradoc Series (O4) — Caradoc Series (O4)
Lithological Description: Lapilli-tuff; andesitic-dacitic, commonly eutaxitic, crystal-rich, ignimbrite.
Definition of Lower Boundary: Junction of lapilli tuff with underlying unnamed volcaniclastic sandstone, or andesite sheet/lava flow, or Seatallan Dacite.
Definition of Upper Boundary: Junction of lapilli-tuff with overlying volcaniclastic sandstone or andesite (Wrighthow Member).
Thickness: Highly variable - 30-800m
Geographical Limits: Wasdale area, Cumbria.
Parent Unit: Birker Fell Andesite Formation (BFA)
Previous Name(s): Craghouse Tuffs Member (-783)
Alternative Name(s): none recorded or not applicable
Type Area  Craghouse Park. Approximately 1km due north of Santon Bridge, Cumbria. 
Reference Section  Latterbarrow Crag, 2km north east of Santon Bridge. 
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 E037 E029