The BGS Lexicon of Named Rock Units — Result Details
Faringdon Sponge Gravel Member
| Computer Code: | FSG | Preferred Map Code: | FSG |
|---|---|---|---|
| Status Code: | Full | ||
| Age range: | Aptian Age (KP) — Aptian Age (KP) | ||
| Lithological Description: | Cross-bedded pebbly sands and highly fossiliferous gravels comprising predominantly the remains of calcareous sponges, but also including common brachiopods, echinoderms and bryozoa. Bored mudstone and limestone clasts and phosphatised fossils, derived from underlying Kimmeridge Clay and Corallian Group strata, occur at the base of the member and at higher levels within the succession. Two subdivisions, comprising lower 'yellow gravel' and upper (iron-oxide stained) 'red gravel', have previously been recognised, separated by a non-sequence. According to Poole et al. (1971), cross-bedding diminishes upwards from the 'yellow gravel' into the 'red gravel', and there is a change in current direction as indicated by apparent dips. | ||
| Definition of Lower Boundary: | Unconformable, channelled, at the basal contact of the 'yellow gravel' with underlying Kimmeridge Clay mudstones, or locally, Corallian Group limestones. | ||
| Definition of Upper Boundary: | The upper boundary of the member is the upward facies change from gravelly, fossiliferous sandstone to non-pebbly, poorly fossiliferous sandstone and mudstone containing horizons of chert and ironstone of the Baulking Sand Member. | ||
| Thickness: | About 50 m. | ||
| Geographical Limits: | Faringdon area, Oxfordshire. | ||
| Parent Unit: | Faringdon Sand Formation (FDNS) | ||
| Previous Name(s): | Faringdon Sponge Gravels [Obsolete Name and Code: Use FSG]
(-263)
The Sponge Gravels Of Farringdon (-916) Sands and gravels of Faringdon [Obsolete Name and Code: Use FSG] (-4659) |
||
| Alternative Name(s): | none recorded or not applicable | ||
| Stratotypes: | |||
| Type Section | Faringdon Pit Arkell, 1947; Krantz, 1972. | ||
| Reference Section | Baulking No.1 Borehole. Poole and Kelk, 1971. | ||
| Reference Section | Baulking No.2 Borehole. Poole and Kelk, 1971. | ||
| Reference Section | Little Coxwell Pit. Meyer, 1864; Arkell, 1947; Krantz, 1972. | ||
| Reference Section | Wicklesham Pit. Meyer, 1864; Arkell, 1947; Krantz, 1972. | ||
| Reference Section | Fernham No.1 Borehole. Poole et al., 1971. | ||
| Reference Section | Fernham Borehole No.13. Poole et al., 1971. | ||
| Reference Section | Baulking No.4 Borehole. Poole and Kelk, 1971. | ||
| Reference(s): | |||
| Ruffell, A H and Wignall, P B. 1990. Depositional trends in the Upper Jurassic-Lower Cretaceous of the northern margin of the Wessex Basin. Proceedings of the Geologists' Association, Vol.101, 279-288. | |||
| Mantell, G 1839. The wonders of Geology, volume 2. | |||
| Sharpe, D 1854. On the age of the fossiliferous sands and gravels of Faringdon and its neighbourhood. Quarterly Journal of the Geological Society, London, 10, 176-198. | |||
| Casey, R, 1961. The stratigraphical palaeontology of the Lower Greensand. Palaeontology, Vol.3, 487-621. | |||
| Golding, R, Layer, M G, Magyari, A, Palotas, K and Dexter, J. 1998. Facies variation in the Corallian Group (U. Jurassic) of the Faringdon-Shellingford area (Oxfordshire) and the rockground base to the Faringdon Sponge Gravels (L. Cretaceous). Proceedings of the Geologists' associatio;n, Vol. 109, p. 115-125. | |||
| Krantz, R. 1972. Die Sponge-Gravels von Faringdon (England). Neues Jahrbuch fur Geologie und Palaontologie Abhandlungen, 140, 207-231. | |||
| Poole, E G, and Kelk, B. 1971. Calcium montmorillonite (fuller's earth in the Lower Greensand of the Baulking area, Berkshire. Institute of Geological Sciences Report 71/4. | |||
| Poole, E G, Kelk, B, Bain J A, and Morgan, D J. 1971. Calcium montmorillonite (fuller's earth) in the Lower Greensand of the Fernham area, Berkshire. Report of the Institute of Geological Sciences, 71/12, 64pp. | |||
| Hopson, P M, Wilkinson, I P and Woods, M A. 2008. A stratigraphical framework for the Lower Cretaceous of England. British Geological Survey. British Geological Survey Research Report, RR/08/03. | |||
| Austen, R A C. 1850. On the age and position of the fossiliferous sand and gravel of Farringdon. Quarterly Journal of the Geological Society of London, Vol. 6, 454-478. | |||
| Meyer, C J A. 1864. Three days at Faringdon. Geologist, Vol.7, 5-11. | |||
| Arkell, W J. 1947. The Geology of Oxford. 267pp. (Oxford: Clarendon Press.) | |||
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: | |||
| E253 | |||