The BGS Lexicon of Named Rock Units — Result Details

Shales With Beef Member

Computer Code: SHWB Preferred Map Code: ShwB
Status Code: Full
Age range: Sinemurian Age (JS) — Sinemurian Age (JS)
Lithological Description: Dark grey laminated organic-rich shaly mudstone and dark grey mudstones with sporadic concretionary and tabular limestone bands. Abundant vertically oriented fibrous calcite of diagenetic origin ('Beef').
Definition of Lower Boundary: Base of bed 50, of Lang, W D, et al, 1923. Taken at sharp lithological change from limestone-shale interbeds of the Blue Lias Formation, to predominantly shales. Conformable boundary.
Definition of Upper Boundary: Top of bed 75 (Birchi nodules) of Lang, W D, et al, 1923).
Thickness: 30-32m
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)
Shales-With-Beef (-1180)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Section  Foreshore and cliffs below Black Ven, west of Charmouth, Dorset. Lang, W D, et al, 1923. 
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, 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. 
Lang, W D, 1914. The geology of Charmouth cliffs, beach and fore-shore. Proceedings of the Geologists' Association, Vol.25, 293-360. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E327 E341 E342 E343