The BGS Lexicon of Named Rock Units — Result Details

Kentmere Pike Tuff Formation

Computer Code: KMR Preferred Map Code: Kmr
Status Code: Full
Age range: Caradoc Series (O4) — Caradoc Series (O4)
Lithological Description: A dacitic lapilli-tuff, with flow joints, localised breccia and some interbeds of tuff, lapilli-tuff and volcaniclastic sandstone. It is laterally impersistent, possibly filling hollows in an erosion surface, interpreted as a densely welded, rheomorphic high-grade ignimbrite.
Definition of Lower Boundary: Taken at the abupt change from volcaniclastic sedimentary rocks of the Seathwaite Fell Sandstone Formation to dacitic lapilli-tuff indicating an erosion surface, which is usually obscured by later, syn-BVG andesite intrusions.
Definition of Upper Boundary: Overlain by eutaxitic lapilli-tuff of the Lincomb Tarns Tuff Fomration, but the relationships are obscured by later syn-BVG andesite intrusions.
Thickness: To 350m
Geographical Limits: The east side of Kentmere Valley [NY 468 081], via Hallow Bank Quarter and Kentmere Pike [NY 465 078] to the west side of Longsleddale [NY 471 079].
Parent Unit: Borrowdale Volcanic Group (BVG)
Previous Name(s): Kentmere Pike Formation (-2270)
Kentmere Pike Rhyolites (-943)
Kentmere Formation (-2218)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  Kentmere Pike and Hallow Bank Quarter, Kentmere, Cumbria. Johnson, E W (In prep.) 
Reference(s):
Mitchell, G H, 1929. The succession and structure of the Borrowdale Volcanic Series in Troutbeck, Kentmere and the western part of Long Sleddale (Westmorland). Quarterly Journal of the Geological Society of London, Vol. 85, 9-44. 
Soper, N J and Numan, N M S, 1974. Structure and stratigraphy of the Borrowdale Volcanic Rocks of the Kentmere area, English Lake District. Geological Journal, Vol. 9, 147-166. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E030 E039