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 Ingham, 1966 
Reference Section  Backside Beck, Westerdale Inlier, Cautley district, Cumbria Ingham, 1966 
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:
E039 E049 E040