The BGS Lexicon of Named Rock Units — Result Details

Gonerby Member [Obsolete Name And Code: See DYS]

Computer Code: GO Preferred Map Code: GoM
Status Code: Index Level
Age range: Pliensbachian Age (JE) — Pliensbachian Age (JE)
Lithological Description: Interbedded silty, micaceous grey mudstones and fine-grained flaggy sandstones and noduler ironstones; sandstone defines base locally.
Definition of Lower Boundary: Generally gradational boundary with non-silty mudstones of remainder of Brant Mudstone Formation. Locally, base is defined by a sandstone that forms a slight topographical feature.
Definition of Upper Boundary: Sharp contact with basal sandstones of Marlstone Rock Formation.
Thickness: c. 15 to 25m
Geographical Limits: Mid Lias age silts and silty clays are mapped in southern part of 1:50k sheet 127 (Grantham) southwards and southwestwards through parts of Lincolnshire, Leicestershire (including former Rutland) and Northamptonshire. May be equivalent of Dyrham Siltstone Formation.
Parent Unit: Brant Mudstone Formation [Obsolete Name And Code: Use CHAM] (BMN)
Previous Name(s): Middle Lias Mudstone And Siltstones (-4681)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  Around Great Gonerby, Grantham 
Reference(s):
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