The BGS Lexicon of Named Rock Units — Result Details
Harford Member
| Computer Code: | HFD | Preferred Map Code: | Hf |
|---|---|---|---|
| Status Code: | Full | ||
| Age range: | Aalenian Age (JA) — Aalenian Age (JA) | ||
| Lithological Description: | Interbedded yellow silty fine-grained sand, cemented in parts ('Harford Sands'), grey and brown mudstone, shelly and sandy in parts ('Snowshill Clay' and 'Naunton Clay') and variably sandy and ooidal limestone ('Tilestone'). The succession is characterised by rapid lateral facies transitions and a mix of fully marine and quasi-non-marine facies. | ||
| Definition of Lower Boundary: | Upward change or passage from peloidal and ooidal packstones and grainstones (Scottsquar Member) to lithologies as described in Lithological Description. Locally a non-sequence marked by a hardground (Buckman, J, 1901; Cave, R and Penn, I E, 1972). | ||
| Definition of Upper Boundary: | Sharp contact, generally a hardground, overlain by Aston Limestone Formation, or hardground overlain by Salperton Limestone Formation. | ||
| Thickness: | Up to 14m. Type section (Harford Cutting); 3.05m+ (Parsons, C F, 1976). Thickens northward. | ||
| Geographical Limits: | Cotswold Hills, Gloucestershire: north of Chedworth, west of Bourton-on-the-Water and Moreton-in-Marsh (Barron, A J M, et al, 1997, fig.4). | ||
| Parent Unit: | Birdlip Limestone Formation (BLPL) | ||
| Previous Name(s): | Grouping of Harford Sands [Obsolete Name and Code: Use HFD]
(-3464)
Harford Sands Member [Obsolete Name and Code: Use HFD] (-3465) Snowshill Clay [Obsolete Name And Code: Use HFD] (SHC) Naunton Clay (-956) Stanway Hill Formation [Obsolete Name and Code: Use HFD] (-313) Tilestone [Obsolete Name and Code: Use HFD] (-314) |
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| Alternative Name(s): | none recorded or not applicable | ||
| Stratotypes: | |||
| Reference Section | Jackdaw Quarry SSSI, Stanway, Gloucestershire. Parsons, C F, 1976; Mudge, D C, 1978a; 1978b; Cox, B M, and Sumbler, M G. 2002. For further reference sections see Barron, A J M, et al, 1997. | ||
| Type Area | North Cotswolds, Gloucestershire. | ||
| Type Section | Harford railway cutting SSSI, Gloucestershire. Buckman, J, 1887, section 4; Woodward, H B, 1894, fig.43, cutting Q; Richardson, L, 1929, p.79; Beds 1 to 2b of Parsons, C F, 1976; Barron, A J M, 1999; Cox, B M, and Sumbler, M G. 2002. | ||
| Reference(s): | |||
| Richardson, L. 1929. The Country around Moreton in Marsh. Memoir of the Geological Survey of Great Britain, Sheet 217 (England and Wales). | |||
| Barron, A J M. 1999. Geology of the Naunton area. British Geological Survey Technical Report WA/98/27. | |||
| 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. | |||
| 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. | |||
| 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. | |||
| 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. | |||
| Cave, R and Penn, I E, 1972. On the classification of the Inferior Oolite of the Cotswolds. Bulletin of the Geological Survey of Great Britain, No.38, 59-65. | |||
| 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. | |||
| 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. | |||
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: | |||
| E235 E217 | |||