The BGS Lexicon of Named Rock Units — Result Details

Hambleton Oolite Member

Computer Code: HAO Preferred Map Code: HaO
Status Code: Full
Age range: Oxfordian Age (JO) — Oxfordian Age (JO)
Lithological Description: Ooidal limestone, white to grey, variably bioclastic; high-energy facies generally an ooid-grainstone or packstone, medium- to coarse-grained, thick- and cross-bedded, lower energy facies variably shelly, finely sandy, thin- to medium-bedded and bioturbated, with fine-grained calcareous sandstone beds. Fauna notably of ammonites, bivalves, gastropods, echinoids, serpulids and brachiopods.
Definition of Lower Boundary: Non-sequence: shelly, sandy, variably ooidal limestone, with abundant bivalves, serpulids and coral debris, with a sharp, locally encrusted top (Yedmandale Member), or where latter is absent, generally on well-cemented calcareous fine-grained sandstone, locally spicule-rich (Lower Calcareous Grit Formation), overlain by ooidal limestone (Hambleton Oolite Member).
Definition of Upper Boundary: Conformable: sharp change upwards from sandy ooidal limestone into calcareous fine-grained sandstone (Middle Calcareous Grit Member), or where this is locally absent (Wright, 1972), it may be distinguished from the ooidal limestone of the Malton Oolite Member by its finer grain size and poorer sorting (Wright, 2009).
Thickness: Up to about 35m: Tabular Hills 20 to 35m; Hambleton Hills 0 to 34m (Powell et al., 1992); Howardian Hills about 30m (excluding median Birdsall Calcareous Grit Member, Wright, 2009); Spiker's Quarry 16.2m (Wright and Cox, 2001, pp 157-161).
Geographical Limits: Cleveland Basin, North Yorkshire: Tabular Hills, Hambleton Hills, Howardian Hills as far south as Kennythorpe.
Parent Unit: Coralline Oolite Formation (COO)
Previous Name(s): Hambleton Oolites (-3455)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Reference Section  Spikers Hill Quarry, West Ayton, North Yorkshire. Exposes full thickness of Hambleton Oolite Member, comprising white, sparsely fossiliferous, thick-bedded ooid-limestone overlain by variously shelly, non-ooidal and sandy limestone, totalling 16.2m thick; underlain by Yedmandale Member, overlain by Middle Calcareous Grit Member Wright and Cox, 2001, pp 157-161. 
Reference Section  Rock platform and low cliffs at Filey Brigg, Filey, North Yorkshire. Exposes the Hambleton Oolite Member, in two leaves, enclosing approximately 7 m of beds of the Birdsall Calcareous Grit Member. The lower leaf comprises 3.7 to 4m of bioturbated shelly sandy ooidal limestone and calcareous sandstone, about 1.5m of the upper leaf are seen comprising muddy, shelly sandy limestone with ammonites, the top is not seen. Wright, 1983; Coe, 1995 
Type Section  Cold Kirby Quarry, Thirsk, North Yorkshire, exposed in 1979-1980: Oolite, white, shelly, thinly bedded with bivalves; channel cross-bedding 4.5m Blake and Hudleston, 1877, p. 351. Section description from J H Powell field slip SE58SW/NW, held in BGS NGDC. 
Reference(s):
Powell, J H, Cooper, A H C and Benfield, A C. 1992. Geology of the country around Thirsk. Memoir of the British Geological Survey, Sheet 52 (England and Wales). 
Frost, D V. 1998. Geology of the country around Northallerton. Memoir of the British Geological Survey, Sheet 42 (England and Wales). 
Wright, J K. 1983. The Lower Oxfordian (Upper Jurassic) of North Yorkshire. Proceedings of the Yorkshire Geological Society, Vol. 44, 249-281. 
Coe, A L. 1995. A comparison of the Oxfordian successions of Dorset, Oxfordshire and Yorkshire. 151-172 in Taylor, P D (Ed.) Field Geology of the British Jurassic. [Bath: The Geological Society.] 
Blake, J F and Huddleston, W H 1877. On the Corallian rocks of England. Quarterly Journal of the Geological Society of London, Vol.33, 260-405. 
Wright, J K. 1972. The stratigraphy of the Yorkshire Corallian. Proceedings of the Yorkshire Geological Society, Vol. 39, 225-266. 
Wright, J K. 2009. The geology of the Corallian ridge (Upper Jurassic) between Gilling East and North Grimston, Howardian Hills, North Yorkshire. Proceedings of the Yorkshire Geological Society, Vol. 57, 193-216. 
Wright, J K, and Cox, B M. 2001. British Upper Jurassic Stratigraphy (Oxfordian to Kimmeridgian). Geological Conservation Review Series. No. 21. (Peterborough: Joint Nature Conservation Committee/Chapman and Hall.) 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E042 E043 E044 E052 E053 E054 E063