The BGS Lexicon of Named Rock Units — Result Details
Belemnite Marl Member
Computer Code: | BM | Preferred Map Code: | BM |
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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): | Belemnite Marls [Obsolete Name and Code: Use BM, PLMA]
(-4475)
Belemnite Beds [Obsolete Name and Code: Use BM] (-1997) Stomebarrow Beds [Obsolete Name and Code: Use BM] (-2622) |
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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): | |||
Arkell, W J. 1933. The Jurassic System in Great Britain (Oxford: Clarendon Press.) | |||
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). | |||
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 |