The BGS Lexicon of Named Rock Units — Result Details

Whitby Mudstone Formation

Computer Code: WHM Preferred Map Code: WhM
Status Code: Full
Age range: Toarcian Age (JT) — Toarcian Age (JT)
Lithological Description: Medium and dark grey fossiliferous mudstone and siltstone, laminated and bituminous in part, with thin siltstone or silty mudstone beds and rare fine-grained calcareous sandstone beds; dense, smooth argillaceous limestone nodules very common at some horizons; phosphatic nodules at some levels. Nodular and fossiliferous limestones occur at the base in some areas.
Definition of Lower Boundary: In Cleveland Basin, base of mudstone resting upon ooidal limestone or sideritic mudstone nodules of the Cleveland Ironstone (see Cox, B M, et al, for more details). Elsewhere, at base of mudstone overlying ironstone of the Marlstone Rock Formation.
Definition of Upper Boundary: In most areas, sharp, eroded boundary with limestones or sandstones of the Inferior Oolite Group (East Midlands Shelf) or the Ravenscar Group or Dogger Formation (Cleveland Basin). In Ravenscar area, and in much of Worcester Basin arbitrary boundary in transition to sandy sediments of the Blea Wyke Formation or Bridport Sand Formation respectively
Thickness: To c.120m
Geographical Limits: Cleveland Basin, East Midlands Shelf and Worcester Basin (i.e. Yorkshire coast to Mendip).
Parent Unit: Lias Group (LI)
Previous Name(s): Upper Lias [Obsolete Name And Code: See WHM] (ULI)
Upper Lias Clay Formation [Obsolete Name And Code: Use WHM] (ULC)
Coleby Mudstones [Obsolete Name And Code: Use CHAM Or WHM] (CLM)
Coleby Mudstone Formation (-2531)
Upper Lias Clay (-3760)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Section  Coastal exposures from Hawsker Bottoms to Whitby Harbour. Howarth, M K, 1962, 1973, 1992. 
Reference Section  Copper Hill Borehole. Depths 17.31 - 63.70m. Powell, 1984; Ivimey-Cook and Powell, 1991. 
Type Area  North Yorkshire Coast. 
Reference Section  BGS Stowell Park Bore, Gloucs (Reg. No. SP01SE/1) 122.28 - 220m depth (Green, G W and Melville, R V, 1956; Melville, R V, 1956; Spath, L F, 1956; Ivimey-Cook, H C, 1993; Sumbler, M G and Barron, A J M, 1995; Sumbler, M G, Barron, A J M and Morigi, A N, 2000. See also Cox, B M, et al, 1999, for additional reference sections. 
Reference(s):
Ivimey-Cook, H C and Powell, J H. 1991. Late Triassic and early Jurassic biostratigraphy of the Felixkirk Borehole, North Yorkshire. Proceedings of the Yorkshire Geological Society, Vol.48, 367-374. 
Green, G W and Melville, R V. 1956. The stratigraphy of the Stowell Park Borehole (1949-1951). Bulletin of the Geological Survey of Great Britain, No.11, p.1-66. 
Howarth, M K, 1992. The ammonite family Hildoceratidae in the Lower Jurassic of Britain. Part 1. Monograph of the Palaeontographical Society London: 1-106, pls.1-16. (Publication No.586, part of Vol.145 for 1991). 
Powell, J H, 1984. Lithostratigraphic nomenclature of the Lias Group in the Yorkshire Basin. Proceedings of the Yorkshire Geological Society, Vol.45, p.51-57. 
Berridge, N G, Pattison, J, Samuel, M D A, Brandon, A, Howard, A S, Pharaoh, T C and Riley, N J. 1999. Geology of the Grantham district. Memoir of the British Geological Survey, sheet 127 (England and Wales). 
Cox, B M, Sumbler, M G and Ivimey-Cook, H C, 1999. A Formational framework for the Lower Jurassic of England and Wales (Onshore Area). British Geological Survey Research Report No. RR/99/01. 
Howarth, M K, 1973. The stratigraphy and ammonite fauna of the Upper Liassic Grey Shales of the Yorkshire coast. Bulletin of the British Museum (Natural History), Geology Series, Vol.29, 235-288. 
Howarth, M K, 1962. The Jet Rock Series and the Alum Shales Series of the Yorkshire coast. Proceedings of the Yorkshire Geological Society, Vol.33, 381-422. 
Ivimey-Cook, H C, 1993. The biostratigraphy of the Lower Jurassic of the Stowell Park Borehole. British Geological Survey Technical Report WH/93/174R. 
Melville, R V, 1956. Stratigraphical palaeontology, ammonites excluded, of the Stowell Park Borehole. Bulletin of the Geological Survey of Great Britain, No.11, 67-139. 
Spath, L F, 1956. The Liassic ammonite faunas of the Stowell Park Borehole. Bulletin of the Geological Survey of Great Britain, No.11, 140-164. 
Sumbler, M G and Barron, A J M, 1995. Geological notes and local details for 1: 10 000 Sheet SP01SE (Chedworth). British Geological Survey Technical Report, WA/95/73. 
Sumbler, M G, Barron, A J M and Morigi, A N, 2000. Geology of the Cirencester district. Memoir of the British Geological Survey, Sheet 235 (England and Wales). 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E052 E034 E043 E127 E062 E035 E044 E042 E054 E072 E235 E199 E102 E055 E065 E064 E080 E114 E143 E144 E157 E158 E159 E170 E171 E203 E172 E185 E186 E187 E201 E202 E204 E217 E218 E142 E220 E236 E251 E252 E253 E264 E265 E219 E279 E280