The BGS Lexicon of Named Rock Units — Result Details

Inferior Oolite Group
Computer Code: INO Preferred Map Code: InO
Status Code: Full
Age range: Aalenian Age (JA) — Bathonian Age (JN)
Lithological Description: Varied sucession of ooidal, peloidal, marly, sandy, ferruginous and shelly limestones, with subordinate sandstone, calcareous mudstone and mudstone beds.
Definition of Lower Boundary: Disconformity: change upwards from Lias Group (mudstone with or without sand, ironshot marl and limestone beds) into predominantly limestone succession as described in the lithology. Locally (in Mendips area and at depth on the London Platform) unconformably overlies older beds including lower Lias, Triassic, Carboniferous and Devonian strata.
Definition of Upper Boundary: In Dorset-Somerset, change from ooidal limestones upward into Fuller's Earth Formation mudstone with beds of finer-grained limestone. In Cotswolds, change from predominantly ooidal limestone (Salperton Limestone Formation) into mudstone (Fuller's Earth Formation) or into sandy fine-grained ooidal limestone (Chipping Norton Limestone Formation) where present, of Great Oolite Group. Generally transitional, but locally an erosive non-sequence marked by hard ground. In North Oxfordshire to Lincolnshire, sharp upward change (unconformity) from fine-grained sandstone (Grantham Formation) or ooidal limestone (Lincolnshire Limestone Formation; where present) into mudstone, siltstone, limestone and sandstone succession of Great Oolite Group (Rutland Formation).
Thickness: 0-106m at outcrop. Dorset-Somerset; up to 30m (but thickens rapidly in subcrop). South Cotswolds; 10-20m. North Cotswolds; 20-106m. Oxfordshire-Northamptonshire; up to 30m. Lincolnshire; up to 50m. Present at depth in Wessex-Weald Basin where up to 120m thick (Kingsclere No.1 Borehole).
Geographical Limits: Outcrop: Dorset, Somerset, Avon, Gloucestershire, Oxfordshire, Northamptonshire, Lincolnshire and Yorkshire (south of Market Weighton High). Subcrop: southern England, apart from interior of London Platform (Parsons, C F, 1980; Sumbler, M G, 1996).
Parent Unit: Not Applicable (-)
Alternative Name(s): none recorded or not applicable
Type Area  Cotswold Hills: Bath to Moreton-in-Marsh. 
Reference Section  Quarries at Cleeve Common SSSI, Cleeve Hill, Gloucester. 
Reference Section  British Geological Survey Stowell Park Borehole, Gloucester, 160' 10" (49.02m) to 401' 2" (122.28m). 
Reference Section  Nettleton Bottom Borehole (TF19NW/54), Lincolnshire, c.346m to c.392m. 
Reference Section  Purse Caundle Borehole (ST71NW/7), Dorset, 89.99m to c.134.19m. 
Jones, L E and Sellwood, B W, 1989. Palaeogeographic significance of clay mineral distributions in the Inferior Oolite Group (Mid-Jurassic) of southern England. Clay Minerals, Vol.24, No.1. p.91. 
Penn, I E and others, 1980. The Inferior Oolite (Bajocian) sequence from a borehole in Lyme Bay, Dorset. Institute of Geological Sciences, Report No. 79/3. 
Woodward, H B, 1887. The Geology of England and Wales, 2nd edition, p.255, 284-285, 308, 317. (London: George Philip). 
Richardson, L, 1910. The Inferior Oolite and contiguous deposits of the South Cotteswolds. Proceedings of the Cotteswolds. NFC, Vol.17, p.75. 
Arkell, W J. 1947. The Geology of Oxford. [Oxford: Clarendon Press.] 
Hollingworth, S E, Taylor, J H and others, 1951. The Northampton Sand Ironstone. Stratigraphy, structures and reserves. Memoirs of the Geological Survey of Great Britain, p.3. 
Pringle, J, 1908. On a boring in the Fullonian and Inferior Oolite at Stowell, Somerset. Summary of the Progress of the Geological Survey of Great Britain, for 1908. 
Cave, R and Penn, I E, 1971. On the classification of the Inferior Oolite of the Cotswolds. Bulletin of the Geological Survey of Great Britain, No.38, p.59. 
Woodward, H B, 1894. The Jurassic Rocks of Britain, Vol.4. The Lower Oolitic Rocks of England (Yorkshire excepted). Memoir of the Geological Survey of the United Kingdom. 
Townsend, J, 1813. The character of Moses established for veracity as a historian, recording events from the creation to the deluge. (Bath: Gye; London: Longman.) 
Arkell, W J. 1933. The Jurassic System in Great Britain. [Oxford: Clarendon Press.] 
Fox-Strangeways, C, 1892. The Jurassic Rocks of Britain, Vol.1. Yorkshire. Memoir of the Geological Survey of the United Kingdom. 
Barron, A J M, Sumbler, M G and Morigi, A N, 1997. A revised lithostratigraphy for the Inferior Oolite Group (Middle Jurassic) of the Cotswolds, England. Proceedings of the Geologists' Association. 
Parsons, C F, 1980. In Cope, J C W (editor). A correlation of the Jurassic rocks of the British Isles. Part Two: Middle and Upper Jurassic. Geological Society of London Special Report, No.15. 
Barron, A J M, 1995. Geological notes and local details for 1: 10 000 Sheet SO91NE (Seven Springs). British Geological Survey Technical Report WA/94/14. 
Barron, A J M, 1999. Geology of the Bishop's Cleeve area (1:10 000 Sheet SO92NE). British Geological Survey Technical Report WA/99/01. 
Buckman, S S, 1897. Deposits of the Bajocian age in the northern Cotswolds: the Cleeve Hill Plateau. Quarterly Journal of the Geological Society of London, Vol.53, 607-629. 
Cox, B M, and Sumbler, M G. 2002. British Middle Jurassic stratigraphy. Geological Conservation Review Series, Vol.26. (Peterborough: Joint Nature Conservation Committee.) 
Gaunt, G D, Fletcher, T P amd Wood, C J. 1992. Geology of the country around Kingston upon Hull and Brigg. Memoir of the British Geological Survey, sheets 80 and 89 (England and Wales). 
Green, G W and Melville, R V, 1956. The stratigraphy of the Stowell Park Borehole (1949-1951). Bulletin of the Geological Survey of Great Britain, No.11, p.1-66. 
Murray, J W, 1968. The Inferior Oolite of the Cotswold scarp, Wotton-under-Edge to Leckhampton. Proceedings of the Bristol Naturalists' Society, Vol.31, 535-549. 
Mudge, D C, 1978. Stratigraphy and sedimentation of the Lower Inferior Oolite of the Cotswolds. Journal of the Geological Society of London, Vol.135, 611-627. 
Richardson, L, 1906. Half-day excursion to Leckhampton Hill, Cheltenham. Proceedings of the Cotswold Naturalists' Field Club, Vol.15, 182-189. 
Richardson, L, 1929. The Country around Moreton in Marsh. Memoir of the Geological Survey of Great Britain, Sheet 217, (England and Wales). 
Smith, W, 1815. A memoir to the map and delineation of the strata of England and Wales, with part of Scotland. (London: J Cary). 
Sumbler, M G, 1996. British regional geology; London and the Thames Valley. (4th edition). (London: HMSO for the British Geological Survey). 
Sumbler, M G and Barron, A J M, 1995. Geological notes and local details for 1: 10 000 Sheet SP01SE (Chedworth). British Geological Survey Technical Report, WA/95/73. 
Sumbler, M G, Barron, A J M and Morigi, A N, 2000. Geology of the Cirencester district. Memoir of the British Geological Survey, Sheet 235 (England and Wales). 
Wright, T, 1860. On the subdivisions of the Inferior Oolite of the south of England, compared with the equivalent beds of that formation on the Yorkshire coast. Quarterly Journal of the Geological Society of London, 16, 1-48. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E280 E234 E102 E103 E172 E199 E200 E217 E235 E237 E251 E265 E264 E270 E271 E281 E296 E297 E312 E313 E327 E279 E081 E127 E144 E157 E161 E170 E171 E185 E186 E201 E202 E218 E142 E236 E252 E253 E268 E341 E342 E343
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