The BGS Lexicon of Named Rock Units — Result Details

Belemnite Marl Member
Computer Code: BM Preferred Map Code: BM
Status Code: Full
Age range: Pliensbachian Age (JE) — Pliensbachian Age (JE)
Lithological Description: Pale grey and dark grey interbedded calcareous mudstones with abundant belemnites at many levels.
Definition of Lower Boundary: Base of hummocky limestone (base of bed 103 of Lang, W D, et al, 1922). Pale grey colour of Belemnite Marl Member contrasts strongly in cliffs with darker underlying Black Ven Marl Member. Non sequence at base between Sinemurian and Pliensbachian stages.
Definition of Upper Boundary: Top of Belemnite Stone (top of bed 121 of Lang, W D, et al, 1923). Conformable junction with Green Ammonite Member.
Thickness: 20 to 27m in coastal sections.
Geographical Limits: Southwest Dorset; mapped on sheet 327 (Bridport). Northern Limit not yet proved.
Parent Unit: Charmouth Mudstone Formation (CHAM)
Previous Name(s): Stomebarrow Beds (-2622)
Belemnite Marls (-4475)
Belemnite Beds (-1997)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Section  Cliffs below Stonebarrow, east of Charmouth, Dorset. Lang, W D, et al, 1928. 
Reference(s):
Lang, W D, 1914. The geology of Charmouth cliffs, beach and fore-shore. Proceedings of the Geologists' Association, Vol.25, 293-360. 
Lang, W D, Cox, L R and Muir Wood, H M, 1928. The Belemnite Marls of Charmouth. A series in the Lias of the Dorset coast. Quarterly Journal of the Geological Society of London, Vol.84, 179-257. 
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). 
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
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