The BGS Lexicon of Named Rock Units — Result Details

Loveden Gryphaea Bed

Computer Code: LDGR Preferred Map Code: LG
Status Code: Full
Age range: Pliensbachian Age (JE) — Pliensbachian Age (JE)
Lithological Description: Grey mudstone beds with numerous Gryphaea maccullochii. Locally includes a thin shelly limestone bed. Fauna also includes corals, brachiopods, many other bivalve species, and belemnites. No feature, but Gryphaea conspicuous in clay soil.
Definition of Lower Boundary: Change up from mudstone with large argillaceous limestone nodules and small phosphatic nodules at some levels, of the undifferentiated Charmouth Mudstone Formation, into mudstone with abundant Gryphaea (as described under Lithology). In type section Copper Hill Borehole (SK94SE/56), base lies at change up from poorly fossiliferous sandstone, siltstone and mudstone beds at 147.30m depth.
Definition of Upper Boundary: Change up from mudstone with numerous Gryphaea (as described under Lithology) into mudstone with thin (0.02m) limestone beds of undifferentiated Charmouth Mudstone Formation; at 145.08m depth in type section Copper Hill Borehole (SK94SE/56).
Thickness: 1.5 to 2.2m; 2.22m 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 part of the mudstone-dominated Charmouth Mudstone Formation. An assertion by Berridge et al, (1999) that the Loveden Bed (Raricostatum Zone) may correlate with the '70 Marker' (Jamesoni Zone) (Horton and Poole, 1977) of the Charmouth Mudstone Formation of the south Midlands is at odds with the biostratigraphy.
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). 
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). 
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. 
Horton, A and Poole, E G, 1977. The lithostratigraohy of three geophysical marker horizons in the Lower Lias of Oxfordshire. Bulletin of the Geological Survey of Great Britain, Vol.62, 13-33. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E127 E142 E126