The BGS Lexicon of Named Rock Units — Result Details

Birdlip Limestone Formation

Computer Code: BLPL Preferred Map Code: BpL
Status Code: Full
Age range: Aalenian Age (JA) — Aalenian Age (JA)
Lithological Description: Predominantly white, pale grey and yellow ooidal limestones of varying types; ferruginous and sandy (Leckhampton Member), pisoidal and shelly (Crickley Member) at the base, unfossiliferous and cross bedded in the middle (Cleeve Cloud Member), shelly and carbonate-muddy in the upper part (Scottsquar Member), uppermost beds include sand and clay (Harford Member).
Definition of Lower Boundary: Disconformity: upward change into predominantly ooidal limestone sequence as in Lithology above from noncalcareous mudstone in the north-east of its range (Whitby Mudstone Formation) and sandstone, in the centre and south (Bridport Sand Formation). Locally, bioclastic, ferru-ooidal calcareous mudstone and muddy limestone (the Cotswold Cephalopod Bed Member of the Bridport Sand Formation, (Simms et al., 2004)) underlies the formation.
Definition of Upper Boundary: Disconformity, generally a hardground: ooidal limestone, sand or clay overlain by shelly, ooidal, sandy, shell-detrital and bioturbated limestone of the Aston Limestone Formation where present; or members of the Salperton Limestone Formation, i.e. very shelly and coarsely shell-detrital ooidal grainstone and packstone (Upper Trigonia Grit Member, where present) or rubbly, fine- to coarse-grained ooidal, peloidal and finely shell-detrital packstone to grainstone (Clypeus Grit Member). The capping hardground is not well developed where the uppermost beds are the weak mudstones or sandstones of the Harford Member.
Thickness: Typically 40 to 46m; type section c.45m, maximum c.74m (Cleeve Hill area).
Geographical Limits: Cotswolds Hills from north Oxfordshire (near Chipping Norton) to northeast South Gloucestershire District. Only its lowest (Leckhampton) member is present to the east of the Vale of Moreton Axis, passing east into the Northampton Sand Formation near Chipping Norton. Absent due to overstep by Salperton Limestone Formation in south Cotswolds and in Vale of Moreton area. (See Barron et al, 1997, fig.4).
Parent Unit: Inferior Oolite Group (INO)
Previous Name(s): Lower Inferior Oolite Formation (-705)
Lower Inferior Oolite [Obsolete Name And Code: See BLPL] (LINO)
Combined Cheltenham And Stanway Hill Formations (-3228)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Section  Limekiln and Devil's Chimney quarries at Leckhampton Hill SSSI, Cheltenham, Gloucestershire. (Mudge, D C, 1978b, beds 1-60). See also Brodie (1850, 1851); Wright, (1860); Woodward (1894); Richardson (1904, 1906); Gray (1924); Murray (1968); Ager (1969); Mudge (1995); Sumbler and Barron (1996); Cox, B M, and Sumbler, M G. 2002. 
Type Area  Cotswold Hills, Gloucestershire. 
Reference Section  Disused quarries on face of Cleeve Cloud, Cleeve Hill, Gloucestershire. Mudge, D C, 1978a, 1978b; Barron, A J M, 1999. for further reference sections see Barron, A J M, et al, 1997. 
Reference(s):
Brodie, P B, 1850. On certain beds in the Inferior Oolite, near Cheltenham. Quarterly Journal of the Geological Society of London, Vol.6, 239-249. 
Brodie, P B, 1851, On the basement beds of the Inferior Oolite in Gloucestershire. Quarterly Journal of the Geological Society of London, Vol.7, 208-212. 
Cox, B M and Sumbler, M G. 2002. British Middle Jurassic Stratigraphy. Geological Conservation Review Series No.26. [Peterborough: Joint Nature Conservation Committee.] 
Ager, D V, 1969. The Lower and Middle Jurassic rocks of the Cotswold Escarpment and the Vale of Worcester. In (Torrens, H S, ed). Guide for north Somerset and Gloucestershire. International field symposium on the British Jurassic, Excursion No.2, B27-B43. 
Parsons, C F, 1980. Aspects of the statigraphy and ammonite faunas of the Aaenian-Bajocian stages in Great Britain. Unpublished PhD thesis, University of Keele. 
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. 
Mudge, D C, 1995. The Middle Jurassic of the Cotswolds. In (Taylor, P D; ed). Field Geology of the British Jurassic. Geological Society, London, 31-50. 
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. 
Barron, A J M, Lott, G K, and Riding, J B. 2012. Stratigraphical framework for the Middle Jurassic strata of Great Britain and the adjoining continental shelf. British Geological Survey Research Report RR/11/06. 
Simms, M J, Chidlaw, N, Morton, N, and Page, K N. 2004. British Lower Jurassic Stratigraphy. Geological Conservation Review Series. No. 30. (Peterborough: Joint Nature Conservation Committee/Chapman and Hall.) 
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, Vol.108, 269-285. 
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, 1901. Bajocian and contiguous deposits in the north Cotswolds: the main hill-mass. Quarterly Journal of the Geological Society of London, Vol.57, 126-155. 
Sumbler, M G and Barron, A J M, 1996. Day Excursion to the Cotswolds. Mercian Geologist, Vol.14, 34-37. 
Gray, J W, 1924. Leckhampton Hill, Gloucestershire: the Wellington Quarry and other sections. Proceedings of the Cotswold Naturalists' Field Club, Vol.22, 33-42. 
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. 
Richardson, L, 1904. Handbook to the geology of Cheltenham and neighbourhood (Cheltenham: Norman, Sawyer and Co). 
Richardson, L, 1906. Half-day excursion to Leckhampton Hill, Cheltenham. Proceedings of the Cotswold Naturalists' Field Club, Vol.15, 182-189. 
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. 
Buckman, S S, 1905. A monograph of the ammonites of the Inferior Oolite Series, Pt.13, Supplement pp.clxix-ccix. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E216 E234 E235 E251 E217