The BGS Lexicon of Named Rock Units — Result Details

Dersingham Formation

Computer Code: DEB Preferred Map Code: DeB
Status Code: Full
Age range: Hauterivian Age (KH) — Barremian Age (KB)
Lithological Description: The Formation comprises a rhythmic succession of thinly interbedded, fine-grained sands, ferruginous sandstones, silts and clays. The Formation varies laterally from ferruginous fine-grained sands and sandstones around Dersingham and Roydon Common, to silts in the Hunstanton Borehole. Clay (Snettisham Clay Member) is present at the top of the Formation, such as in the Hunstanton Borehole, at Dersingham and at Snettisham. It passes laterally into the Tealby Formation under The Wash.
Definition of Lower Boundary: The lower boundary is marked by an upward change from unconsolidated, fine- to medium-grained, cross-bedded, generally clean, pale quartz sands of the Leziate Member of the Sandringham Sands Formation into the ferruginous, fine-grained sandstone of the formation.
Definition of Upper Boundary: Around Dersingham and Snettisham, mudstone of the Snettisham Clay Member (Dersingham Formation) is overlain by ferruginous, generally pebbly, medium-grained sand, of the Carstone Formation (locally clayey at the base). At Hunstanton, silty, pebbly clays at the base of the Roach Formation overlie and are separated by an interburrowed erosion surface from a rhythmic succession of brown and red clay and clayey silt of the Dersingham Formation.
Thickness: To c.16m.
Geographical Limits: Crops out at Heacham to Babingley River and Roydon to Ashwicken, and outliers occur at Rising Lodge and East Winch. It is cut out by the overstepping Carstone in the vicinity of East Winch. Boreholes at Gayton and Hunstanton penetrated the Formation.
Parent Unit: Not Applicable (-)
Previous Name(s): Dersingham Beds (-3355)
Sandringham Sands [Duplicate Code: Use SAS] (SNDS)
Dersingham Beds/Snettisham Clay [Obsolete Code: See DEB And SNC] (DESC)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  Dersingham Common. Gallois, 1994. 
Reference Section  Warren Farm Stone pit. The most complete section through the formation is in the extended stone pit, on the southeastern face, where about 11m of the formation rests on the Leziate Member of the Sandringham Sand Formation. Gallois (1994, p.89). 
Reference Section  Dersingham Sand pit. Basal part of the succession; see Gallois (1994, p.88). 
Reference Section  Hunstanton Borehole TF64SE/12. The Dersingham Formation is cored between 53.42 and 65.02m depth. Gallois (1994, 90-91). 
Reference Section  South western end of Roydon Common. The basal part of the succession is exposed in several pits, see Gallois (1994, p.89). 
Reference(s):
Whitaker, W and Jukes-Browne, A J. 1899. The geology of the borders around The Wash: including Boston and Hunstanton. Memoir of the Geological Survey of England and Wales. 
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). 
Casey, R and Gallois, R W. 1973. The Sandringham Sands of Norfolk. Proceedings of the Yorkshire Geological Society, Vol.41, 1-22. 
Gallois, R W. 1984. The Late Jurassic to Mid Cretaceous rocks of Norfolk. Bulletin of the Geological Society of Norfolk, Vol.34, 3-64. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E129 E145 E146