The BGS Lexicon of Named Rock Units — Result Details

Gryphite Grit Member

Computer Code: GRGR Preferred Map Code: notEntered
Status Code: Full
Age range: Bajocian Age (JB) — Bajocian Age (JB)
Lithological Description: Grey and brown hard, rubbly, shelly, coarsely shell-detrital, bioturbated, variably sandy peloid grainstones, packstones and wackestones with thin mudstone, sandstone and marl beds; bioturbated, some ferruginous peloids; characteristic fauna includes abundant Gryphaea spp and belemnites in upper part, and colonial worm Sarcinella and brachiopod Lobothyris buckmani (Davidson) in lower part.
Definition of Lower Boundary: Upward transition from less sandy, more finely shell-detrital and more ironshot limestones with Aulacothyris meriani (Oppel) (Lower Trigonia Grit Member) into limestone as described in lithology with L. buckmani.
Definition of Upper Boundary: Upward transition into sparsely shelly peloidal and ooidal grainstones (Notgrove Member), or hardground overlain by Salperton Limestone Formation.
Thickness: Typically 3 to 5m, maximum 7m. Type section (Leckhampton Hill); 6.6m (Richardson, L, 1906).
Geographical Limits: Cotswolds: north of North Cerney and west of Northleach, Cold Aston and Condicote. Absent between Birdlip and Cirencester (Barron, A J M, et al, 1997, fig.4).
Parent Unit: Aston Limestone Formation (ASLS)
Previous Name(s): Gryphaea Grit (-2833)
Gryphaea Bed (-4686)
Windrush Member (WNR)
Gryphite Grit (-4071)
Gryphite Grit And Buckmani Grit (-3443)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Section  Disused quarry, Leckhampton Hill. Wright, T, 1860; Buckman, J, 1893, p.512, beds 5-14; 1895; Richardson, 1906, pp.187-188, beds 5-22; Cox, B M, and Sumbler, M G. 2002. 
Type Area  North Cotswolds, Gloucestershire. For further reference sections see Barron et al., 1997. 
Reference Section  Tumulus railway cutting, Chedworth Woods, Gloucestershire. Sumbler, M G and Barron, A J M, (Cutting K of Woodward, H B, 1894, fig.42).1995, appendix 1, locality A, beds 10-15; Sumbler, M G, Barron, A J M and Morigi, A N, 2000. 
Reference(s):
Cox, B M and Sumbler, M G. 2002. British Middle Jurassic Stratigraphy. Geological Conservation Review Series No.26. [Peterborough: Joint Nature Conservation Committee.] 
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. 
Buckman, S S, 1887. The Inferior ooilte between Andoversford and Bourton-on-the-Water. Proceedings of the Cotteswold Naturalists' Field Club, Vol.9, 108-135. 
Parsons, C F, 1976. Ammonite evidence for dating some Inferior Oolite sections in the North Cotswolds. Proceedings of the Geologists' Association, 87, 45-63. 
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). 
Buckman, S S, 1895. The Bajocian of the mid-Cotswolds. Quarterly Journal of the Geological Society of London, Vol.51, 388-445; 458-462. 
Murchison, R I, 1834. Outline of the geology of the neighbourhood of Cheltenham. Cheltenham: Davies, 40 pp. 
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. 
Wright, T, 1856. On the palaeontological and stratigraphical relations of the so-called 'Sands of the Inferior Oolite'. Quarterly Journal of the Geological Society of London, 12, 292-325. 
Buckman, S S, 1893. The Bajocian of the Sherborne district: its relation to subjacent and superjacent strata. Quarterly Journal of the Geological Society of London. Vol.49, 479-522. 
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. 
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. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
none recorded or not applicable