The BGS Lexicon of Named Rock Units — Result Details

Black Ven Marl Member
Computer Code: BVM Preferred Map Code: BVM
Status Code: Full
Age range: Sinemurian Age (JS) — Sinemurian Age (JS)
Lithological Description: Dark grey thinly interbedded mudstones and organic-rich mudstone, with a few thin beds and doggers of muddy limestone.
Definition of Lower Boundary: Base of Birchi Tabular Limestone (bed 76 of Lang, W D, et al, 1923). Conformable on Shales-with-Beef Member.
Definition of Upper Boundary: Base of Belemnite Marl Member, at base of hummocky limestone, (Lang, W D, et al, 1922, bed 103).
Thickness: 43m
Geographical Limits: Southwest Dorset and southeast Devon, United Kingdom. Mapped on Sheets 326 (Sidmouth) and 327 (Bridport). Northern limit not yet proved.
Parent Unit: Charmouth Mudstone Formation (CHAM)
Previous Name(s): Black Ven Marls (-2650)
Black Marl (-3884)
Black Ven Beds (-96)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Section  Black Ven, Charmouth, Dorset. Continuous and complete exposure in cliffs. Hesselbo, S P and Jenkyns, H C A, 1995. 
Reference(s):
Hesselbo, S P and Jenkyns, H C A, 1995. A comparison of the Hettangian to Bajocian successions of Dorset and Yorkshire. 105-150 in Taylor, P D (Editor). Field geology of the British Jurassic (London Geological Society). 
Lang, W D, 1914. The geology of Charmouth cliffs, beach and fore-shore. Proceedings of the Geologists' Association, Vol.25, 293-360. 
Woodward, H B and Ussher, W A E, 1911. The geology of the country around Sidmouth and Lyme Regis. Memoir of the Geological Survey, England and Wales, Sheet 326. 
Cope, J C W and others, 1980. A correlation of Jurassic rocks in the British Isles. Part 1: Introduction and Lower Jurassic. Special Report of the Geological Society of London, No.14. 
Wilson, V, et al, 1957. Geology of the country around Bridport and Yeovil. Memoir of the Geological Survey of Great Britian, Sheets 327 and 312. 
Arkell, W J. 1933. The Jurassic System in Great Britain. [Oxford: Clarendon Press.] 
Lang, W D, Spath, L F and Richardson, W A, 1923. Shales-with-'Beef': a sequence in the Lower Lias of the Dorset coast. Quarterly Journal of the Geological Society, London, Vol.74, 47-99. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E327 E341 E342 E343
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