The BGS Lexicon of Named Rock Units — Result Details

Sharp's Hill Formation

Computer Code: SHHB Preferred Map Code: ShH
Status Code: Full
Age range: Bathonian Age (JN) — Bathonian Age (JN)
Lithological Description: Varied sequence of greenish grey, silty, moderately shelly and calcareous mudstones, pale greenish grey shelly marls and fine-grained shelly limestones with marine and freshwater faunas. Rootlets are common, and some mudstones display seatearth textures and more variegated colours, also indicating shallow, proximal conditions. Subordinate siltstone and sandstone beds are present near the base of the formation.
Definition of Lower Boundary: Non-sequential, on the Chipping Norton Limestone Formation, where present or the Horsehay Sand Formation. The base, which may be marked by an uneven junction, is taken as the first mudstone (commonly carbonaceous), marl, sand or micritic limestone (commonly richly fossiliferous or pebbly), above the ooidal limestones of the Chipping Norton Limestone Formation (Horton, 1987, p.74), or the barren sands of the Horsehay Sand Formation.
Definition of Upper Boundary: Conformably overlain by ooidal and shelly detrital limestones of theTaynton Limestone Formation, where present, otherwise, the formation is difficult to distinguish from the lithologically similar Rutland Formation.
Thickness: Up to 5 m thick.
Geographical Limits: North Oxfordshire north-east of Milton-under-Wychwood and Minster Lovell, where it passes south-west (on BGS 1:50000 sheet 236) into the marine mudstones of the Fuller's Earth Formation; north-west Buckinghamshire; Northamptonshire south-west of Eydon and Wappenham (on BGS 1:50000 sheet 202) where the overlying Taynton Limestone Formation is succeeded to the north-east by the Wellingborough Member of the Rutland Formation (unpublished BGS data), and the Sharp's Hill Formation is undifferentiated, passing into lithologically similar unnamed mudstone beds of the Rutland Formation.
Parent Unit: Great Oolite Group (GOG)
Previous Name(s): Neaeran Beds (-3673)
Sharp's Hill Beds (-523)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Section  Sharp's [or Sharps] Hill Quarry, Sibford Ferris, Oxfordshire. [Horton et al. 1987, p. 57 - 58; Cox, B M, and Sumbler, M G. 2002]. 
Reference Section  Horsehay Quarry, Dun's Tew, Oxfordshire. [Horton et al. 1987, p. 57 - 58; Cox, B M, and Sumbler, M G. 2002]. 
Reference(s):
Bradshaw, M J. 1978. A facies analysis of the Bathonian of eastern England. (University of Oxford: Unpublished PhD thesis.) 
Richardson, L. 1911. The Inferior Oolite and contiguous deposits of the Chipping Norton district, Oxfordshire. Proceedings of the Cotteswold Naturalists' Field Club, Vol. 17, 195 - 231. 
Walford, E A. 1906. On some new Oolitic strata in north Oxfordshire. (Buckingham: printed privately.) 
McKerrow, W S and Kennedy, W J. 1973. The Oxford district. Geologists' Association Guide No.3. 
Arkell W J, 1933. The Jurassic System in Great Britain [Oxford: Clarendon Press.] 
Horton, A, Poole, E G, Williams, B J, Illing, V C and Hobson, G D. 1987. Geology of the country around Chipping Norton. Memoir of the British Geological Survey, Sheet 218 (England and Wales). 
Cox, B M and Sumbler, M G. 2002. British Middle Jurassic Stratigraphy. Geological Conservation Review Series No.26. [Peterborough: Joint Nature Conservation Committee.] 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E218 E236 E237