The BGS Lexicon of Named Rock Units — Result Details

Scunthorpe Mudstone Formation

Computer Code: SMD Preferred Map Code: SMd
Status Code: Full
Age range: Rhaetian Age (TR) — Sinemurian Age (JS)
Lithological Description: Grey, variably calcareous and silty, blocky or fissile mudstone with thin beds of argillaceous limestone (bioclastic or micritic) and calcareous siltstone, particularly near base and in upper part, which is ferruginous in the type area.
Definition of Lower Boundary: Where lowest grey mudstone (may be laminated) of the Lias Group rests with sharp contact on bluish and greenish grey to (less commonly) reddish brown mudstone of the Cotham Member (Lilstock Formation, Penarth Group) or on grey porcellanous limestone of the Langport Member (Lilstock Formation, Penarth Group) where locally present.
Definition of Upper Boundary: In type area, at top of Frodingham Ironstone (Gaunt, G D, Fletcher, T P and Wood, C J, 1992); elsewhere, at erosive base of thin pebbly ferruginous oolite (Glebe Farm Bed), which marks the base of the Charmouth Mudstone Formation.
Thickness: To c.128m
Geographical Limits: East Midlands Shelf (north) (Leicester to Market Weighton).
Parent Unit: Lias Group (LI)
Previous Name(s): Scunthorpe Mudstones (-1189)
Ferruginous Limestone Series (-4887)
Scunthorpe Mudstones Formation (-3685)
Bucklandi Clays (-2431)
Angulata Clays (-2626)
Hydraulic Limestones [Obsolete Name And Code: See SMD, BNT, ELL] (HYDL)
Granby Limestones (-3440)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  North Lincolnshire and Humberside. Gaunt, G D, et al, 1992. 
Type Section  British Geological Survey Blyborough Borehole, Blyborough, Lincolnshire (SK99SW/79) c.51.57-139.5m depth. Gaunt, G D, Fletcher, T P and Wood, C J, 1992. 
Reference Section  Fulbeck Airfield Borehole F/B1 (SK85SE/25), depths 0 to 100.9m. 
Reference Section  Borehole F/B5, Fulbeck, Lincolnshire (SK95SW/17) 4.58-117.65m depth. Brandon, A, Sumbler, M G and Ivimey-Cook, H C, 1990. See also Cox, B M, et al, 1999 for additional reference sections. 
Reference(s):
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. 
Brandon, A, Sumbler, M G and Ivimey-Cook, H C, 1990. A revised lithostratigraphy for the Lower and Middle Lias (Lower Jurassic) east of Nottingham, England. Proceedings of the Yorkshire Geological Society, Vol.48, 121-141. 
Gaunt, G D, Fletcher, T P and Wood, C J. 1992. Geology of the country around Kingston upon Hull and Brigg. Memoir of the British Geological Survey, sheets 80 and 89 (England and Wales). 172pp. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E127 E080 E089 E126 E102 E142