The BGS Lexicon of Named Rock Units — Result Details

Spilsby Sandstone Formation

Computer Code: SYS Preferred Map Code: SyS
Status Code: Full
Age range: Tithonian Age (JI) — Valanginian Age (KV)
Lithological Description: The Formation comprises two members that are further divided: Upper Spilsby Sandstone Member. Thin, coarse-grained, grey or brown pebble sandstone with iron ooliths [Ferruginous Grit of Swinnerton, 1937]. Underlain by fine-to medium-grained, buff, yellow and white sands with sparse calcareous "doggers" [the upper part of Swinnerton's 1937, "Glauconitic Sands"]. The latter sands become coarser and greener towards the base of the Member. A bed of phosphatic nodules and small [generally chert] pebbles occurs at the base [the Mid Spilsby Nodule Bed of Casey [1963, 1973]. Lower Spilsby Sandstone Member. Coarse-grained, pebbly, glauconitic sands and sandstones with calcareous "doggers" and sporadic phosphatic nodules towards the Top [this unit equates with the lower part of Swinnerton's, 1937, "Glauconitic Sands"]. The base of the Member comprises a thin grey sandstone with phosphatic nodules [the "Basement Beds" of Swinnerton, 1937, and Beds A and D of Swinnerton, 1935.
Definition of Lower Boundary: A downsection change from grey sandstone with phosphatic nodules [the "Basement Beds" of the Lower Spilsby Sandstone Member] to mudstone of the Kimmeridge Clay Formation.
Definition of Upper Boundary: Down-section change from purple-grey and brown mottled mudstones with sporadic iron ooliths [Hundlsby Clay Member, Claxby Ironstone Formation] or argillaceous oolitic ironstone [Claxby Ironstone Formation] to pale yellow, medium-grained sand and sandstone [Upper Spilsby Sandstone Member]. Offshore in the Southern North Sea Basin, the upper boundry is recognised by a down-section change from calcareous mudstones [Valhall Formation] to sandstones. It corresponds to a reduction in gamma-ray values and increase in sonic log.
Thickness: To c.24m
Geographical Limits: Onshore, the Spilsby Sandstone Formation is restricted to the southern part of Lincolnshire. It extends offshore into The Wash, but its extent is unknown as within a short distance it passes laterally into the lower part of Sandringham Sand Formation [Wingfield et al., 1978]. Offshore in the Southern North Sea, the Formation has been recognized in quadrants 47, 48, and 51-54. In the offshore region it forms the basal part of the Cromer Knoll Group [Lott and Knox, 1994]. It is not clear how the Spilsby Sandstone Formation [offshore] relates to the Spilsby Sandstone Formation and the Sandringham Sand Formation [onshore].
Parent Unit: Cromer Knoll Group (CRKN)
Previous Name(s): Spilsby Sandstone (-3066)
Spilsby Beds Of Spilsby Series (-4915)
Lower Sand And Sandstone (*596)
Greensand And Sandstone (-556)
Alternative Name(s): Lower Sand And Sandstone
Stratotypes:
Reference Section  Boston Corporation Waterworks, Fordington, boreholes, 8km north of Spilsby. Swinnerton, 1935, emended by Casey, 1973. 
Reference Section  Railway cutting between Benniworth and Donnington-on-Bain Casey, 1973 
Reference Section  Nettleton Top Barn, southwest of Caistor. Casey, 1973 
Reference Section  Skegness Borehole between the depths 107.37 and 116.8m. 
Reference(s):
Casey, R 1973. The ammonite succession at the Jurassic-Cretaceous boundary in Eastern England. In Casey, R and Rawson, P F [editors], The Boreal Lower Cretaceous [Liverpool: Seel House Press.] 
Dikes, W H and Lee, J W. 1837. Outlines of the Geology of Nettleton Hill, Lincolnshire. The Magazine of Natural History, I [No.11], 562-566. 
Swinnerton, H H. 1937 (for 1936). A monograph of British Cretaceous Belemnites, Part 11. Monograph of the Palaeontographical Society. 
Judd, J W 1867. On the strata which form the base of the Lincolnshire Wolds. Quarterly Journal of the Geological Society, London, 23, 227-251. 
Strahan, A. 1886. Notes on the relations of the Lincolnshire Carstone. Quarterly Journal of the Geological Society, London, 42, 481-493. 
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. 
Jukes-Browne, A.J. 1887. The Geology of part of east Lincolnshire. Memoir of the Geological Survey of the United Kingdom, 181pp. 
Lott, G K and Knox, R W O'B. 1994. 7. Post-Triassic of the Southern North Sea. In: Knox, R W O'B and Cordey, W G (eds.) Lithostratigraphic nomenclature of the UK North Sea. [British Geological Survey, Nottingham]. 
Casey, R. 1963. The dawn of the Cretaceous period in Britain. Bulletin of the South East Union of Scientific Societies, 117, 1-15. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E129 E103 E081 E089 E090 E091 E115