The BGS Lexicon of Named Rock Units — Result Details

Cautley Mudstone Formation

Computer Code: CMU Preferred Map Code: Cmu
Status Code: Full
Age range: Caradoc Series (O4) — Ashgill Series (OA)
Lithological Description: Calcareous mudstone with impersistent limestone beds; includes units of sandstone at the base and higher in the succession [Wilsey Beck Sandstone Member]; also of rhyolitic tuff [Cautley Volcanic Member].
Definition of Lower Boundary: Not exposed, but taken at the base of the lowest bed of mudstone overlying a small exposure of purple andesite, putatively belonging to the Borrowdale Volcanic Group.
Definition of Upper Boundary: Taken at the unconformity with the overlying Ashgill Formation.
Thickness: Up to 570m
Geographical Limits: Restricted to the Cautley and Dent districts of Cumbria.
Parent Unit: Dent Group (DNT)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Section  Wandale Beck [Murthwaite Inlier] and its tributaries on the western bank between the Odd Gill and the confluence with the River Rawthey, Cumbria 
Reference Section  Backside Beck, Westerdale Inlier, Cautley district, Cumbria 
Reference(s):
Ingham, J K, 1966. The Ordovician rocks in the Cautley and Dent districts of Westmorland and Yorkshire. Proceedings of the Yorkshire Geological Society, Vol.35, 455-505. 
Owen, A W and Rushton, A W A, 1999. Arenig to Ashgill of northern England. pp 259-292 in Rushton, A W A, Owen, A W, Owens, R M, and Prigmore, J K. British Cambrian to Ordovician stratigraphy. Geological Conservation Review, Vol. 18. Joint Nature Conservation Committee. Peterborough. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E040 E039 E049