The BGS Lexicon of Named Rock Units — Result Details

Blengdale Tuff Formation

Computer Code: BGD Preferred Map Code: Bgd
Status Code: Full
Age range: Caradoc Series (O4) — Caradoc Series (O4)
Lithological Description: Rheomorphic, parataxitic tuff, rhyolitic in composition and locally autobrecciated. At top coarse breccia largely composed of clasts of tuff.
Definition of Lower Boundary: Not exposed, but taken at the base of the parataxitic silicic tuff resting on dominantly lithic-rich lithic-tuff of the Lowcray Formation.
Definition of Upper Boundary: Not exposed, removed by recent erosion (overlain unconformably by Permian strata).
Thickness: Estimated minimum preserved thickness c.250m
Geographical Limits: Main exposures in Blengdale Forest to Ponsonby Fell, near Gosforth, Cumbria.
Parent Unit: Borrowdale Volcanic Group (BVG)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  Blengdale Forest. Small quarries exposed north west side of forestry track, c.220m, south west of Gait Kirk, Blengdale Forest, near Gosforth, West Cumbria. 
Reference Section  Ponsonby Fell. Small exposures on north west flanks of Ponsonby Fell, c.600m, east north east of Farmery, Gosforth area, West Cumbria. 
Reference(s):
none recorded or not applicable
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E037