The BGS Lexicon of Named Rock Units — Result Details

Po House Tuff Formation

Computer Code: PHT Preferred Map Code: PHT
Status Code: Full
Age range: Caradoc Series (O4) — Caradoc Series (O4)
Lithological Description: Thin and medium parallel bedded andesitic tuff and lapilli-tuff.
Definition of Lower Boundary: Base of Dog Crag Tuff Member - a thin pyroclastic flow deposit - which rests on a non-sequence that occurs at the top of the Whinney Bank Formation (an interbedded succession of siltstone and andesitic lapilli-tuff).
Definition of Upper Boundary: Base of Waberthwaite Formation (dacitic tuff and lapilli-tuff).
Thickness: Up to c.400m
Geographical Limits: Whicham Valley:- between Park Head (SD 172 834) and Lacra Bank (SD 145 815).
Parent Unit: Borrowdale Volcanic Group (BVG)
Previous Name(s): Mottled Shale Of Dog Crag Type (-4839)
Po House Tuffs (-2370)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  Pohouse Bank, Whicham Valley, Cumbria. 
Reference(s):
Mathieson, N A, 1986 Geology, structure and geochemistry of the Ordovician volcanic succession in south west Cumbria. Unpublished Ph.D. thesis, University of Sheffield. 
Johnson, E W, Soper, N J, Burgess, I C, Ball, D F, Beddoe-Stephens, B, Carruthers, R M, Fortey, N J, Hirons, S, Merritt, J W, Millward, D, Roberts, B, Walker, A B and Young, B. 2001. Geology of the country around Ulverston. Memoir of the British Geological Survey, England and Wales, Sheet 48. 
British Geological Survey 1994a. Silecroft, SD18SW solid and drift 1:10,000 (Keyworth, Nottingham, British Geological Survey). 
Green, J F N, 1913. The older Palaeozoic succession of the Dudden Estuary. London, 23pp. 
British Geological Survey, 1994(b). Millom Park, SD18SE, Solid and Drift, 1:10,000 (Keyworth, Nottingham, British Geological Survey). 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E048