The BGS Lexicon of Named Rock Units — Result Details

Cockermouth Volcanic Formation

Computer Code: CKML Preferred Map Code: CkmL
Status Code: Full
Age range: Courceyan Substage (CF) — Courceyan Substage (CF)
Lithological Description: Olivine-phyric basalt and tholeiitic andesite. Up to four sheets of massive to intensely amygdaloidal and scoriaceous rock, dark blue-grey to grey. Interpreted to be lavas. No intercalated pyroclastic or sedimentary rocks are present.
Definition of Lower Boundary: Taken at base of lowest basalt sheet that conformably overlies conglomerate of the Marsett Formation; the formation oversteps the eastwards, unconformably to overlie the Skiddaw and Eycott groups.
Definition of Upper Boundary: Conformably overlain by interbedded mudstone, sandstone and thin limestone of the Marsett Formation.
Thickness: 105m in the Cockermouth area, thinning to 30m near Sunderland; 67m thick in the type section.
Geographical Limits: Northern margin of Lake District Lower Palaeozoic massif, from just west of Cockermouth to Bothel (wholly on sheets E22 and E23). Intrusions of microgabbro ("dolerite") and lapilli-tuff on Little Mell Fell (E30 Appleby) may be intrusive equivalents of the Cockermouth Volcanic Formation (Macdonald and Walker, 1985).
Parent Unit: Ravenstonedale Group (RVS)
Previous Name(s): Cockermouth Lavas (-3933)
Cockermouth Lavas Formation (-3934)
Alternative Name(s): none recorded or not applicable
Reference Section  Bothel Craggs Quarry, on west side of A591, about 1.5km southsoutheast of Bothel, Cumbria. Millward and Williamson. 2003. 
Type Section  Gill Beck, immediately south of Blindcrake, about 4.5km northeast of Cockermouth, Cumbria. Millward and Williamson. 2003. 
Type Area  Outcrops between Wood Hall and Redrain Bridekirk. 
Millward, D and Williamson, I T. 2003. Dinantian volcanic rocks of the Northumberland, Solway and Tweed basins. 109-143, in Stephenson, D, Loughlin, S C, Millward, D, Waters, C N and Williamson, I T. Carboniferous and Permian igneous rock of Great Britain north of the Variscan Front. Geological Conservation Review Series. No.27. (Joint Nature Conservation Committee:Peterborough). 
Eastwood,T, Hollingworth, S E, Rose, W C C and Trotter, F M. 1968. Geology of the country around Cockermouth and Caldbeck. Memoir of the Geological Survey of Great Britain, England and Wales, Sheet 23. 
Eastwood, T. 1928. The Cockermouth Lavas, Cumberland - a Carboniferous volcanic episode. 15-22 in Summary of progress of the Geological Survey of Great Britain for 1927, Part 2. 
MacDonald, R and Walker, B H. 1985. Geochemistry and tectonic significance of the Lower Carboniferous Cockermouth Lavas, Cumbria. Proceedings of the Yorkshire Geological Society, Vol.45, 141-146. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E023 E022 E028