The BGS Lexicon of Named Rock Units — Result Details

Sand Beck Nodule Bed

Computer Code: SBNB Preferred Map Code: SNB
Status Code: Full
Age range: Sinemurian Age (JS) — Sinemurian Age (JS)
Lithological Description: Grey mudstone beds with numerous ovoid sideritic ironstone nodules 0.05 to 0.1m across, weathering to reddish brown. Fauna includes gastropods, bivalves (Gryphaea), ammonites and belemnites.
Definition of Lower Boundary: Change up from mudstone with sparse argillaceous limestone nodules of undifferentiated Charmouth Mudstone Formation into mudstone with ironstone nodules (as described under Lithology); at 181.5m depth in type section Copper Hill Borehole (SK94SE/56).
Definition of Upper Boundary: Change up from mudstone with ironstone nodules (as described under Lithology) into mudstone with sparse limestone nodules of undifferentiated Charmouth Mudstone Formation; at c 177.2m depth in type section Copper Hill Borehole (SK94SE/56).
Thickness: 3 to 5m; c 4.0m in type section.
Geographical Limits: East Midlands: north Leicestershire to Linclonshire. Not recognised in the Charmouth Mudstone Formation of north Lincolnshire, or south Leicestershire, where it passes south into the mudstone-dominated Charmouth Mudstone Formation.
Parent Unit: Charmouth Mudstone Formation (CHAM)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Section  BGS Copper Hill Borehole (SK94SE/56). 
Reference(s):
Carney, J N, Ambrose. K and Brandon A, 2002. Geology of the Melton Mowbray district - a brief explanation of the geological map. British Geological Survey Sheet Explanation, Sheet 142 (England and Wales). 
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. 
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). 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E127 E126