The BGS Lexicon of Named Rock Units — Result Details

Duddon Hall Tuff Formation

Computer Code: DH Preferred Map Code: DH
Status Code: Full
Age range: Caradoc Series (O4) — Caradoc Series (O4)
Lithological Description: Bedded tuff and lapilli-tuff (air-fall) with some pyroclastic breccia, intercalated andesite and basaltic andesite lava.
Definition of Lower Boundary: Base of bedded tuff and lapilli-tuff (air-fall), unconformably overlying Airys Bridge Tuff Formation, (rhyodacitic tuff) and Waberthwaite Tuff Formation (dacitic tuff).
Definition of Upper Boundary: At base of overlying formations including Ulpha Formation (andesite), Holehouse Gill Formation (mudstone and sandstone) and Wallowbarrow Formation (andesitic lapilli-tuff).
Thickness: 200 to 450m
Geographical Limits: Ulpha Basin and Coniston Fells from Duddon Bridge (SD 19 88) via Ulpha (SD 19 93) to Wallowbarrow Heald (SD 21 97), Buck Pike (SD 261 972) to east of Birk Fell (NY 295 015), Cumbria.
Parent Unit: Borrowdale Volcanic Group (BVG)
Previous Name(s): Duddon Bridge Tuffs (-3351)
Duddon Hall Tuffs (-2750)
Lower Tilberthwaite Tuffs (-4605)
Alternative Name(s): none recorded or not applicable
Type Area  Wallowbarrow Heald (SD 21 97) to Hollin House Tongue (SD 22 96) area in the Duddon Valley. 
Mitchell, G H, 1940. The Borrowdale Volcanic Series of Coniston, Lancashire. Quarterly Journal of the Geological Society of London, Vol.96, p.301-319. 
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. 
Mitchell, G H, 1956. (Undivided Lickle Rhyolites). The Borrowdale Volcanic Series of the Dunnerdale Fells, Lancashire. Liverpool and Manchester Geological Journal, Vol.1, p.428-449. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E038 E048