The BGS Lexicon of Named Rock Units — Result Details

Lebberston Member

Computer Code: LEBB Preferred Map Code: notEntered
Status Code: Full
Age range: Bajocian Age (JB) — Bajocian Age (JB)
Lithological Description: Heterolithic marine lithologies best described as three informal lithofacies (below). In the west of the Cleveland Basin it is represented by the "Whitwell Oolite", which consists of pale grey, shelly ooidal cross-bedded limestone with bivalves, gastropods, bryozoa and coral fragments, interbedded with yellow fine- to medium-grained, calcareous cross-bedded sandstone and grey calcareous mudstone. In the east of the Cleveland Basin it is represented, in ascending order, by the "Millepore Bed", which consists of yellow, fine- to medium-grained calcareous sandstone passing up to shelly ooidal, cross-bedded limestone and siderite mudstone; shelly fauna includes abundant bryozoa, Haploecia (=Millepora) straminea, and the overlying "Yons Nab Beds", consisting of grey, calcareous mudstone and yellow fine- to medium-grained calcareous sandstone and pale grey, sideritic mudstone; abundant shelly fauna includes crinoid ossicles, bivalves and ostracods, together with plant fragments.
Definition of Lower Boundary: The lower boundary is conformable, taken at the abrupt transition from sandstone, siltstone and mudstone with plant remains (Sycarham Member; Cloughton Formation) to marine strata comprising pale grey, shelly ooidal limestone ("Whitwell Oolite" lithofacies; Howardian Hills [SE 72 65]) or yellow, shelly calcareous sandstone with bivalves ("Millepore Bed" lithofacies; Yons Nab [TA 084 844], south of Scarborough).
Definition of Upper Boundary: The upper boundary is conformable or disconformable, taken at the abrupt transition from marine strata, comprising pale grey, shelly ooidal limestone ("Whitwell Oolite" lithofacies; Howardian Hills [SE 72 65]) or yellow, shelly calcareous sandstone with bivalves ("Yons Nab Bed" lithofacies at Yons Nab [TA 084 844]), south of Scarborough or calcareous mudstone at Cloughton Wyke [TA 021 958] or sideritic mudstone at Common Cliff [NZ 993 008], south of Ravenscar, to non-marine, yellow, medium- to coarse-grained, cross-bedded sandstone, mudstone and siltstone, commonly with plant fragments, of the Gristhorpe Member.
Thickness: About 9m in the Howardian Hills [SE 734 672] ("Whitwell Oolite"); c. 11m in the Fordon Borehole [TA 058 758]; 8m on the Yorkshire coast at Yons Nab [TA 084 844]; thinning to 1.5m in the Hambleton Hills at Hood Hill [SE 500 812]. Not traceable, probably absent, in the north of the Cleveland Basin.
Geographical Limits: North Yorks Moors and Howardian Hills; well exposed in several coastal cliff sections between Ravenscar (Peak Cliff) [NZ 981 019] and Yons Nab [TA 084 844], south of Scarborough. Offshore, the formation is equivalent, in part, to the Wroot Formation of the West Sole Group (Lott and Knox, 1994). South of the Market Weighton High the member is equivalent to the Cave Oolite (Bate, 1964; 1967). Three informal units, the "Millepore Bed", "Yons Nab Beds" and the "Whitwell Oolite" (Hemingway, 1974) are present in the Cleveland Basin (see details below). The member thins northwards, and cannot be traced over much of the northern part of the Cleveland Basin.
Parent Unit: Cloughton Formation (CLH)
Previous Name(s): Millepore Series (-2895)
Cayton Bay Formation (-3518)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Section  Proposed by Hemingway and Knox (1973) after Sylvester-Bradley (1949) at Yons Nab [TA 085 842], south of Scarborough. The section was described by Bate (1967, 128-129). It consists of yellow, fine- to medium-grained calcareous sandstone (c. 1.5m) overlain by grey, shelly ooidal limestone (c.1.2m), cross-bedded in part, capped by a siderite nodule band, the top of which marks the top of the informal "Millepore Bed". The latter is overlain by grey, calcareous mudstone and calcareous siltstone, with thin beds of yellow-grey, fine-grained sandstone with thin sideritic ironstone, which comprise the overlying informal "Yons Nab Beds", in total 4m thick. 
Reference Section  In the west and southwest of the Cleveland Basin the Lebberston Member is represented by the "Whitwell Oolite lithofacies" consisting of pale grey, shelly ooidal, cross-bedded limestone, locally interbedded with thin beds of yellow-orange, fine- to medium-grained shelly cross-bedded calcareous sandstone. It was partially exposed near Mount Pleasant Farm [SE 733 672] (Hemingway, 1974) where marine calcareous mudstone (1.2m) passes up to grey, shelly ooidal limestone (c. 8m), sandy at the base. Partial exposures in this area at Jamie's Crags Caravan Park [SE 733 670] comprise grey, cross-bedded, shelly ooidal limestone, sandy at the base. Hemingway and Knox (1973) proposed the section described by Bate (1967, 126-127) from the Seamer Lime and Sand Co. Quarry at Whitwell [SE 733 670] as the type section of the Whitwell Oolite; this is the same locality as Jamie's Crags Caravan Park noted above. 
Reference(s):
Whyte, M A and Romano, M. 2006. Middle-Upper Jurassic sequence between Cayton Bay and Yons Nab. 174-182 in Scrutton, C T and Powell, J H (eds), Yorkshire Rocks and Landscapes - A Field Guide, 3rd Edition. (Leeds: Yorkshire Geological Society.) 
Hemingway, J E and Knox, R W O'B. 1973. Lithostratigraphical nomenclature of the Middle Jurassic strata of the Yorkshire Basin of north-east England. Proceedings of the Yorkshire Geological Society, Vol.39, 527-535. 
Cope, J C W, Duff, K L, Parsons, C F, Torrens, H S, Wimbledon, W A and Wright, J K. 1980. A correlation of Jurassic rocks in the British Isles. Part 2: Middle and Upper Jurassic. Geological Society of London Special Report, 15, 73pp. 
Richardson, L. 1912. The Lower Oolitic Rocks of Yorkshire. Proceedings of the Yorkshire Geological Society, Vol.17, 184-215. 
Hemingway, J E. 1974. Jurassic. 161-233 in Rayner, D H and Hemingway, J E (eds), The geology and mineral resources of Yorkshire. (Leeds: Yorkshire Geological Society.) 
Fox-Strangways, C. 1892. The Jurassic Rocks of Britain, Vol.1. Yorkshire. Memoir of the Geological Survey of the United Kingdom. 
Bate, R H. 1967. Stratigraphy and palaeoecology of the Yorkshire Oolites and their relationships with the Lincolnshire Limestone. Bulletin of the British Museum (Natural History), Geology, Vol.14, 111-141. 
Lott, G K and Knox, R W O'B. 1994. 7. Post-Triassic of the Southern North Sea. In: Knox, R W O'B and Cordey, W G (eds.) Lithostratigraphic nomenclature of the UK North Sea. [British Geological Survey, Nottingham]. 
Bate, R H. 1964. Middle Jurassic ostracoda from the Millepore Series, Yorkshire. Bulletin of the British Museum, Natural History (Geology), Vol.10, 1-33. 
Powell, J H, Cooper, A H C and Benfield, A C. 1992. Geology of the country around Thirsk. Memoir of the British Geological Survey, Sheet 52 (England and Wales). 
Frost, D V. 1998. Geology of the country around Northallerton. Memoir of the British Geological Survey, Sheet 42 (England and Wales). 
Rawson, P F and Wright, J K. 1995. Jurassic of the Cleveland Basin, North Yorkshire. 173-208 in Taylor, P D (Ed.) Field Geology of the British Jurassic. (London: Geological Society.) 
Sylvester-Bradley, P C. 1949. Revised nomenclature for Yorkshire Estuarine Series. Geological Magazine, Vol.86, 263. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E035 E044 E052 E053 E054 E063