The BGS Lexicon of Named Rock Units — Result Details

Fernham Sand Member

Computer Code: FHMS Preferred Map Code: notEntered
Status Code: Full
Age range: Aptian Age (KP) — Aptian Age (KP)
Lithological Description: Reddish-brown, ferruginous, cross-bedded, shell-fragmental, medium- to coarse-grained, clean sandstone. There are scattered pebbles, bands of conglomeratic grit and minor horizons of mudstone.
Definition of Lower Boundary: Unconformable contact with the underlying Baulking Sand Member, marked by the upward facies change from the predominantly mudstone facies of the upper part of the Baulking Sand Member, to the ferruginous sandy facies of the Fernham Sand Member.
Definition of Upper Boundary: Not seen. The Fernham Sand Member occurs as hill-cappings in the Baulking area. The top of the formation is locally defined by the depth of the present-day weathered zone.
Thickness: 24m+ in the Furze Hill Borehole SU29SE/16 [2905 9281] (Poole et al., 1971).
Geographical Limits: Area around Little Coxwell and Fernham, Oxfordshire.
Parent Unit: Faringdon Sand Formation (FDNS)
Previous Name(s): Division 4 (Sands With Chert And Ironstone) (-3402)
Furze Hill Sandstone Formation (-3403)
Ferruginous Sands And Sandstones (-2801)
Red Sands Of Uffington (-248)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  In the vicinity of Furze Hill [SU 29 92] and Fernham [SU 293 919], Oxfordshire. 
Reference Section  Furze Hill Borehole SU29SE/16 [2905 9281] and boreholes F10 (SU29SE/5 [2982 9242]), F12 (SU29SE/7 [2925 9288]) and F13 (SU29SE/8 [2950 9305]) described in Poole et al. (1971), all located near Fernham, Oxfordshire. The Furze Hill Borehole contains the thickest development of the Fernham Sand Member. 
Reference(s):
Casey, R, 1961. The stratigraphical palaeontology of the Lower Greensand. Palaeontology, Vol.3, 487-621. 
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. 
Arkell, W J. 1947. The Geology of Oxford. 267pp. [Oxford: Clarendon Press.] 
Wilkinson, I P. 2006. The Holostratigraphy of the Albian Stage (Lower Cretaceous) of the United Kingdom and its continental shelf. British Geological Survey Research Report, RR/06/01. 
Meyer, C J A. 1864. Three days at Faringdon. Geologist, Vol.7, 5-11. 
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. 
Rawson, P F, Curry, D, Dilley, F C, Hancock, J M, Kennedy, W J, Neale, J W, Wood, C J and Worrsam, B C. 1978. A correlation of Cretaceous rocks in the British Isles. Geological Society of London, Special Report No.9. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
none recorded or not applicable