The BGS Lexicon of Named Rock Units — Result Details

Skegness Clay Formation

Computer Code: SKEG Preferred Map Code: SkC
Status Code: Full
Age range: Aptian Age (KP) — Aptian Age (KP)
Lithological Description: The Formation comprises grey and dark grey mudstone with Prodeshayesites bodei and iridescent fragments of other ammonites, some of which are partially pyritised and phosphatised. In the Wash borehole (72/78) the formation becomes brownish grey in its lower part, with scattered, cream-coloured phosphatic nodules. Burrows occur, some of them filled with limonite ooliths.
Definition of Lower Boundary: In the type section, the base is defined by a downward change from grey and dark grey mudstone with partially pyritised and phosphatised ammonites to black, pyritous upper Roach Formation. The boundary is apparently conformable, although the junction is bioturbated and the top of the underlying Roach is burrowed.
Definition of Upper Boundary: The upper boundary is defined by an upward change from medium and dark grey mudstone with ammonites, some of which are partially pyritised and phosphatised, to pale grey, calcareous, mudstone (Sutterby Formation).
Thickness: 1.98m in the type section.
Geographical Limits: Confined to The Wash and the southern part of Lincolnshire, but not known at outcrop. The formation occurs only in the Skegness Borehole and the Wash boreholes. It has not been recognised in Norfolk, but it appears to extend under The Wash to within two kilometres of Hunstanton (Wingfield et al., 1978). Swinnerton (1935), mentioned 1.83m of a similar lithology below the Sutterby Formation in the Alford and Maltby boreholes, and although he made no reference to the fauna, this deposit might be the Skegness Formation.
Parent Unit: Not Applicable (-)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Reference Section  Wash Borehole TF64SW1 between the depths 23.34 and 24.60m (situated within The Wash). Wingfield et al., 1978. 
Type Section  Skegness Borehole TF56SE9 between 44.58 and 46.56m depth. Gallois, 1975. 
Wingfield, R T R, Evans, C D R, Deegan, S E and Floyd, R. 1978. Geological and geophysical survey of The Wash. Report of the Institute of Geological Sciences, 78/18, 32pp. 
Swinnerton, H H. 1935. The rocks below the Red Chalk of Lincolnshire and their cephlopod fauna. Quarterly Journal of the Geological Society, London, 91, 1-46. 
Gallois, R W, 1994. The geology of the country around King's Lynn and The Wash. Memoir of the British Geological Survey, Sheet 145 and part of 129 (England and Wales). 
Gallois, R W. 1984. The Late Jurassic to Mid Cretaceous rocks of Norfolk. Bulletin of the Geological Society of Norfolk, Vol.34, 3-64. 
Gallois, R W. 1975. A boreal section across the Barremian-Aptian boundary (Lower Cretaceous) at Skegness, Lincolnshire. Proceedings of the Yorkshire Geological Society, Vol.40, 499-503. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E116 E129 E145