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 Marl (-3884)
Black Ven Beds (-96)
Black Ven Marls (-2650)
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):
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. 
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). 
Wilson, V, Welch, F B A, Robbie, J A, and Green, G W. 1958. Geology of the country around Bridport and Yeovil. Memoir of the Geological Survey of Great Britain, Sheets 327 and 312 (England and Wales). 
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. Sidmouth and Lyme Regis. Memoir of the Geological Survey, Sheets 326 and 340 (England and Wales). 
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 of London, Vol.79, 47-99. 
Arkell, W J. 1933. The Jurassic System in Great Britain. [Oxford: Clarendon Press.] 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E327 E341 E342 E343