The BGS Lexicon of Named Rock Units — Result Details

Oakley Marl Member

Computer Code: OKY Preferred Map Code: Oky
Status Code: Full
Age range: Tithonian Age (JI) — Tithonian Age (JI)
Lithological Description: Variable, but dominantly marls or clays, with thin beds of micritic limestone.
Definition of Lower Boundary: Upward change from either dominantly micritic limestones of the Wockley Member, or fine-grained oolites of the Chilmark Member, to marls and clays. In sections, base taken below lowest "Dirt Bed"; in the field, micritic limestone above the Dirt Bed is probably mapped with the underlying Member.
Definition of Upper Boundary: Upward change fron a dominantly marly sequence to micritic limestones of the "Middle Purbeck".
Thickness: c.5m
Geographical Limits: Fonthill Gifford [ST 923 316] eastwards to beyond Chilmark [ST 980 310] (limit of current mapping).
Parent Unit: Purbeck Group (PB)
Previous Name(s): Lower Purbeck (-2963)
Lulworth Beds [Obsolete Name And Code: Use LULW] (LWB)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Section  Old Oakley (or Wockley, or Shavers Bridge) Quarry, southeast of Tisbury. 
Reference(s):
Andrews W R and Jukes-Browne A J, 1894. The Purbeck Beds of the Vale of Wardour. Quart. Jnl. Geol. Soc. of London. Vol.50. 44-71. (In particular, see section on p.49). 
Reid C. 1903, Geology of the country around Salisbury. Memoir of the Geol. Survey of Great Britain. 
Woodward, H B. 1895. the Jurassic Rocks of Britain. The Middle and Upper Oolitic rocks of England (Yorkshire excepted). Vol.5. Memoir or the Geological Survey of the United Kingdom. 
Wimbledon, W A. 1980. Portlandian correlation chart. 85-93 in Cope, J C W (Editor), A correlation of the Jurassic rocks of the British Isles. Part Two: Middle and Upper Jurassic. Geological Society of London Special Report, No.15. 
Wimbledon, W A and Cope, J C W. 1978. The ammonite faunas of the English Portland Beds and the zones of the Portlandian Stage. Journal of the Geological Society of London, Vol.135, 183-190. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
none recorded or not applicable