The BGS Lexicon of Named Rock Units — Result Details

Sowerthwaite Formation

Computer Code: SOW Preferred Map Code: SowF
Status Code: Full
Age range: Rawtheyan Stage (OW) — Hirnantian Age (OH)
Lithological Description: Siltstone and mudstone with interbedded tuff (Dam House Bridge Tuff Member) and sandstone (Jop Ridding Sandstone Member). A 2m-thick conglomerate (Wharfe Conglomerate) lies towards the top of the succession.
Definition of Lower Boundary: Taken at the base of the volcaniclastic rocks of the Dam House Bridge Tuff Member or at the base of the tuffaceous sandstone of the Jop Ridding Sandstone Member.
Definition of Upper Boundary: Defined by the base of the overlying Silurian strata.
Thickness: To 300m
Geographical Limits: Restricted to the Craven inliers of North Yorkshire.
Parent Unit: Dent Group (DNT)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Section  Austwick Beck, north of Dam House Bridge Arthurton et al.,1988 
Reference(s):
Arthurton, R S, Johnson, E W and Mundy, D J C. 1988. Geology of the country around Settle. Memoir of the British Geological Survey, Sheet 60 (England and Wales). 
Kneller, B C, Scott R W, Soper N J, Johnson E W and Allen P M, 1994. Lithostratigraphy of the Windermere Supergroup, Northern England. Geological Journal, Vol. 29, 219-240. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E050 E060