The BGS Lexicon of Named Rock Units — Result Details

Mardale Sandstone Formation

Computer Code: MRL Preferred Map Code: Mrl
Status Code: Full
Age range: Caradoc Series (O4) — Caradoc Series (O4)
Lithological Description: A mixed succession of predominantly bedded volcaniclastic rocks, comprising detritus mainly of andesitic composition with bedded volcaniclastic sandstone as the main lithofacies, and subsidiary units of volcaniclastic breccia, tuff and lapilli-tuff, of which significant units of volcaniclastic breccia and pyroclastic rocks are given member status, the whole intruded by many contemporaneous andesite sills.
Definition of Lower Boundary: Taken at the abrupt change from silicic tuff and lapilli-tuff of the Whelter Knotts Formation, to generally well bedded volcaniclastic rocks.
Definition of Upper Boundary: Defined by the sharp base of tte Froswick Tuff Formation.
Thickness: Probably up to 980m, but much faulted and greatly inflated by sills.
Geographical Limits: Between Ullswater and Haweswater, and Nan Bield Pass to Wet Sleddale, northeastern Lake District.
Parent Unit: Borrowdale Volcanic Group (BVG)
Previous Name(s): Mardale Tuff Formation (-4204)
Keasgill Tuffs (-3563)
Mardale Formation (-3564)
Nan Bield Formation (-3565)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  The fellside on the south-east side of Swindale, near Shap, Cumbria. 
Reference(s):
Nutt, M J C, 1970. The Borrowdale Volcanic Series and associated rocks around Haweswater, Westmorland. Unpublished PhD thesis, University of London (Queen Mary College). 
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. 
Beddoe-Stephens, B, 2000. The Borrowdale Volcanic Group between Haweswater and eastern Ullswater. British Geological Survey Technical Report WG/00/04. 
Woodhall, D G. 2000. The geology of the Haweswater and Martindale areas of the north-eastern Lake District. British Geological Survey Technical Report WA/00/55. 
Millward, D, 2002. Geology of the area between Haweswater and Shap. British Geological Survey Research Report RR/02/02 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E030 E039