The BGS Lexicon of Named Rock Units — Result Details

Hamstead Member

Computer Code: HM Preferred Map Code: notEntered
Status Code: Full
Age range: Priabonian Age (GI) — Rupelian Age (GR)
Lithological Description: Predominantly red, green and grey clays, silts and sands with a fauna of freshwater molluscs, silty clays are locally laminated and carbonaceous. Includes thin blue and black clays with a marine influence.
Definition of Lower Boundary: Marked by the base of a 0.5m thick carbonaceous black clay with rootlets, locally known as the 'Black Band'. The basal contact is an omission surface, overlying a paleosol at the top of the Bembridge Marls Member (Hooker et al., 2004).
Definition of Upper Boundary: Top is a sharp but apparently conformable (King, in press) contact beneath the shelly brown clays of the Cranmore Member.
Thickness: Between 58m and 69m on the eastern and western sides of the Isle of Wight respectively. King (in press) gives a total of 78m for this member in the cliffs and on the foreshore between Bouldnor and Hamstead Ledge, Isle of Wight.
Geographical Limits: Isle of Wight, Hampshire, England.
Parent Unit: Bouldnor Formation (BOUL)
Previous Name(s): Lower Hamstead Beds (-5236)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Section  Cliff section and foreshore between Hamstead and Bouldnor. White (1921). 
Reference(s):
Gale, A S, Huggett, J M, Pälike, H, Laurie, E, Hailwood, E A, and Hardenbol, J. 2006. Correlation of Eocene-Oligocene marine and continental records: orbital cyclicity, magnetostratigraphy and sequence stratigraphy of the Solent Group, Isle of Wight, UK. Journal of the Geological Society of London, Vol. 163, 401-415. 
White, H J O. 1921. A short account of the geology of the Isle of Wight. Memoir of the Geological Survey of Great Britain, (1994 reprint). 
Hooker, J J, Collinson, M E, and Sille, N P. 2004. Eocene-Oligocene mammalian faunal turnover in the Hampshire Basin, UK: calibration to the global time scale and the major cooling event. Journal of the Geological Society, London, Vol. 161, 161-172. 
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). 
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. 
Reid, C, and Strahan, A. 1889. Geology of the Isle of Wight. Mem. Geol. Surv. G.B., (2nd edition). (Geological Survey of England and Wales.) 
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. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E330 E331