The BGS Lexicon of Named Rock Units — Result Details

Nothe Clay Member

Computer Code: NOC Preferred Map Code: NoC
Status Code: Full
Age range: Oxfordian Age (JO) — Oxfordian Age (JO)
Lithological Description: Grey mudstone and sandy mudstone, containing scattered ooids, interbedded with about eight limestone horizons. The limestones are variously iron-rich, ooidal, sandy and bioclastic, and there is a distinctive white-weathering shelly micrite, with extensive borings, near the base of the succession. Locally abundant bivalves.
Definition of Lower Boundary: Base is a gradational boundary with medium-grained calcareous sandstone of the uppermost 1.5m of the Nothe Grit (=Preston Grit Member of Wright, 1986) passing to sandy mudstone of the basal Nothe Clay Member.
Definition of Upper Boundary: The top is a gradational boundary marked by an increase in quartz sand in the mudstones of the topmost part of the Nothe Clay Member, passing into the argillaceous sandstone of the Bencliff Grit Member. Crushed specimens of the bivalve Modiolus are common at this horizon.
Thickness: 12m at Osmington; 13.5m at Rodwell (Sandsfoot).
Geographical Limits: South Dorset.
Parent Unit: Redcliff Formation (RECF)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Stratotypes:
Partial Type Section  Cliffs near Osmington Mills, Dorset. Upper beds exposed. 
Partial Type Section  Wave cut platform on south side of Nothe Point, Weymouth. Lowest 8m of member exposed. Wright (1986) 
Reference(s):
Blake, J F and Huddleston, W H 1877. On the Corallian rocks of England. Quarterly Journal of the Geological Society of London, Vol.33, 260-405. 
Wright, J K. 1986. A new look at the stratigraphy, sedimentology and ammonite fauna of the Corallian Group (Oxfordian) of south Dorset. Proceedings of the Geologists' Association, Vol. 97, 1-21. 
Wright, J K, and Cox, B M. 2001. British Upper Jurassic Stratigraphy (Oxfordian to Kimmeridgian). Geological Conservation Review Series. No. 21. (Peterborough: Joint Nature Conservation Committee/Chapman and Hall.) 
Arkell, W J. 1947. Geology of the country around Weymouth, Swanage, Corfe and Lulworth. Memoir of the British Geological Survey. Sheets 341, 342, 343 and small portions of sheets 327, 328 and 329 (England and Wales). 
Coe, A L. 1995. A comparison of the Oxfordian successions of Dorset, Oxfordshire and Yorkshire. 151-172 in Taylor, P D (Ed.) Field Geology of the British Jurassic. [Bath: The Geological Society.] 
Newall, A J. 2000. Fault activity and sedimentation in a marine rift basin (Upper Jurassic, Wessex basin, UK). Journal of the Geological Society, London, Vol.157, 83-92. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E341 E342 E343