The BGS Lexicon of Named Rock Units — Result Details

Widmerpool Formation

Computer Code: WDF Preferred Map Code: WdF
Status Code: Full
Age range: Asbian Substage (CR) — Brigantian Substage (CX)
Lithological Description: Dark to pale brown or grey, calcareous and locally carbonaceous, pyritic, fissile mudstone, thinly interbedded with turbidite, argillaceous cherty limestone and thin beds of quartzose siltstone, calcareous or quartzose sandstone and tuff. The proportion of limestone to mudstone increases northwards, with the formation passing laterally into the Hopedale Limestone Formation of the Derbyshire Platform.
Definition of Lower Boundary: Seen only in the Ratcliffe-on-Soar and Long Eaton boreholes, where it is taken at the top of the uppermost thick bed of pale brown argillaceous to sandy limestone, of the Lockington Limestone Formation. Overlain by dark green mudstone of the Widmerpool Formation, which might locally be unconformable on other units, such as the Milldale Limestone Formation.
Definition of Upper Boundary: The base of dark grey fossiliferous, fissile mudstone of the Cravenoceras leion Marine Band, where present. Otherwise taken at the start of a dark grey mudstone and siltstone sequence, lacking limestones, of the Bowland Shale Formation, present above the top of the uppermost limestone bed of the Widmerpool Formation.
Thickness: Variable, from 741m in the Ratcliffe-on-Soar Borehole (SK52NW/72) at [SK 5081 2913], with attenuated development of 110-130m on the Hathern Shelf.
Geographical Limits: Crops out discontinuously northwestwards from Wardgate to Kniveton [SK 20 50], Grindonmoor Gate and Butterton [SK 07 56] in Derbyshire. Restricted to the Widmerpool half-graben [SK53] and Hathern Shelf [SK52].
Parent Unit: Craven Group (CRAV)
Previous Name(s): Mixon Limestone-Shales Formation [Obsolete Name And Code: Use WDF] (MX)
Longstone Mudstone Formation [Obsolete Name And Code: Use WDF] (LSM)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Reference Section  Stream section, southwest of Brookhouse Farm, Kniveton. 
Type Section  Duffield No.1 Borehole (SK34SW/5), Derbyshire. 
Reference Section  Lees Farm Borehole (SK15SE/12). 
Reference(s):
Aitkenhead, N. 1977. The Institute of Geological Sciences borehole at Duffield, Derbyshire. Bulletin of the Geological Survey of Great Britain, No.59, 1-38. 
Frost, D V and Smart, J G O, 1979. Geology of the country around Derby. Memoir of the Geological Survey of Great Britain, Sheet 125 (England and Wales). 
Aitkenhead, N and Chisholm, J I. 1982. A standard nomenclature for the Dinantian formations of the Peak District of Derbshire and Staffordshire. Report of the Institute of Geological Sciences, No.82/8. 
Carney, J N and Cooper, A H, 1997. Geology of the West Leake area: 1:10 000 Sheet SK52NW. British Geological Survey Technical Report WA/97/46. 
Carney, J N, Ambrose, K and Brandon, A. 2001. Geology of the country between Burton, Loughborough and Derby. Description of 1:50k Sheet 141 (England and Wales). 
Chisholm, J I, Charsley, T J and Aitkenhead, N. 1988. Geology of the country around Ashbourne and Cheadle. Memoir of the British Geological Survey, Sheet 124 (England and Wales). 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E124 E125 E141