The BGS Lexicon of Named Rock Units — Result Details

Potts Ghyll Tuff Formation

Computer Code: POG Preferred Map Code: PoG
Status Code: Full
Age range: Caradoc Series (O4) — Caradoc Series (O4)
Lithological Description: Massive vitroclastic and lithic-rich lapilli tuff and tuff of acid andesite/dacite composition.
Definition of Lower Boundary: Lower boundary not exposed in detail; taken at upward change from dominantly andesite to volcaniclastic deposits, within the Eycott Volcanic Group
Definition of Upper Boundary: Overlain unconformably by Carboniferous strata
Thickness: 800m+
Geographical Limits: Northern flanks of Caldbeck Fells from Branthwaite Beck (NY301 367) to just west of Birket (NY329 363)
Parent Unit: Eycott Volcanic Group (EVG)
Previous Name(s): Potts Ghyll Formation (-4262)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Section  Gill Beck, 500m upstream from Potts Ghyll (2.5 km SSW of Caldbeck) 
Reference(s):
Millward, D, Carruthers, R M, Marriner, G F, Molyneux S G and Beddoe-Stephens, B. 1999. The Eycott Volcanic Group. British Geological Survey Technical Report, WA/99/68. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E023