The BGS Lexicon of Named Rock Units — Result Details

Barton Clay Formation

Computer Code: BAC Preferred Map Code: BaC
Status Code: Full
Age range: Lutetian Age (GL) — Bartonian Age (GB)
Lithological Description: Olive grey and greenish grey shelly clays of varying sand content. Fine-grained clayey, commonly glauconitic, sands and flint pebble beds occur in the lower part of the sequence. Shelly in parts.
Definition of Lower Boundary: Lower boundary is marked by a bed of flint pebbles and the incoming of glauconitic sandy clays above both fine-to medium-grained sands of the Selsey Sand Formation in the east or the Boscombe Sand Formation in the west; both of the Bracklesham Group. This boundary is an interburrowed omission surface which marks a regional unconformity (Todd, 1990).
Definition of Upper Boundary: Overlain everywhere across its range by the Chama Sand Formation of the Barton Group at an abrupt upward change from silty clay to coarser-grained sediments.
Thickness: Between 38m and 83m.
Geographical Limits: Preserved over a wide area of the central Hampshire basin, S. England.
Parent Unit: Barton Group (BA)
Previous Name(s): Barton Clay (-1324)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Section  Cliffs between Highcliff Castle and Barton-on-Sea where up to 40 m of glauconitic sandy clay are seen intermitently in mainly obscured exposures. Edwards and Freshney (1987). 
Type Section  Type section of Elmore Member at Whitecliff Bay Isle of Wight. Gale et al. (1999). 
Reference(s):
Melville, R V and Freshney, E C. 1982. British Regional Geology: the Hampshire Basin and adjoining areas (4th Edition).(London ,HMSO for Institute of Geological Sciences). 
Hooker, J J. 1975. Reports of a field meeting to Hengistbury Head and adjacent areas, Dorset, with an account of published work and some new exposures. Tertiary Times, Vol.2, 109-121. 
Edwards, R A and Freshney, E C. 1987. Lithostratigraphical classification of the Hampshire Basin Palaeogene Deposits (Reading Formation to Headon Formation) Tertiary Research, Vol.8, 43-73. 
White, H J O. 1917. Geology of the country around Bournemouth (2nd edition). Memoir of the Geological Survey of Great Britain, Sheet 329 (England and Wales). 
Edwards, R A and Freshney, E C. 1987. Geology of the country around Southampton. Memoir of the British Geological Survey, Sheet 315 (England and Wales). 
Gardner, J S, Keeping, H and Monckton, H W, 1988. The Upper Eocene, comprising the Barton and Upper Bagshot Formations. Quarterly Journal of the Geological Society, Vol.44, p.578-635. 
King, C. In press. A correlation of Tertiary rocks in the British Isle and adjacent areas. Special Report of the Geological Society of London, No.12. 
Bristow, C R, Freshney, E C and Penn, I E. 1991. Geology of the country around Bournemouth. Memoir for 1:50 000 geological sheet 329 (England and Wales). HMSO, London. 
Curry, D, Adams, C G Boulter, M C, Dilley, F C, Eames, F E, Funnell, B M and Wells, M K. 1978. A Correlation of Tertiary rocks in the British Isles. Geological Society of London Special Publication , Vol.12, 1-72. 
Gale, A S, Jeffery, P A, Huggett, J M, and Connolly, P. 1999. Eocene inversion history of the Sandown Pericline, Isle of Wight, southern England. Journal of the Geological Society of London, Vol. 156, 327-339. 
Daley, B, and Balson, P. 1999. British Tertiary Stratigraphy. Geological Conservation Review Series Volume 15 Peterborough. (Joint Nature Conservation Committee) 
Todd, J. 1990. The stratigraphy and correlation of the Selsey Formation and Barton Clay Formation (Middle Eocene) of Studley Wood, Hampshire. Tertiary Research, Vol. 12, 37-50. 
Stinton, F C. 1975. Fish otoliths from the English Eocene. No. 1. (Palaeontological Society Monograph.) 
Kemp, D J, King, A, King, C, and Quayle, W J. 1979. Stratigraphy and biota of the Elmore Formation (Huntingbridge Division, Bracklesham Group) at Lee-on-the-Solent, Hampshire. Tertiary Research, Vol. 2, 93-103. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E314 E315 E329 E330