The Belemnite Marls of Charmouth, a Series in the Lias of the Dorset Coast

Abstract

Anyone standing on the beach between Charmouth and Lyme, and looking up at the bluffs and precipices of Black Ven, is struck by the contrast between the pale, blue-grey colour of the third, and highest, Lias precipice and the deeper shade of the underlying Black Marl. These pale marls, about 75 feet thick, soon pass off the eastern shoulder of Black Ven, but are readily picked up again as the eye follows the line of stratification eastwards, and across the valley, to Stonebarrow Cliff. There the pale marls make the second precipice, but soon dip to the beach to form most of the long, low cliff reaching from Westhay to the Ridge fault. These 75 feet of the pale marls are the Belemnite Beds of Day and of the Geological Survey. No adequate mention of them is made before 1863, when Day wrote his classic account of the Middle and Upper Lias of the Dorset Coast. although they are included in the ‘Upper Lias Marls’ of De la Beche's earlier account, and form the middle part of the eighth bed from the bottom of the section there described. In De la Beche's later account they occupy the middle of the lower part of his bed ‘a’: ‘Marls and slaty marls with several beds of indurated marl and earthy limestone in the lower part, micaceous in the higher—350 ft.’ In both accounts De la Beche particularly notes that belemnites are numerous, and other fossils occur in ‘marls on the shore, between

Phylogeny and systematics of the Coleoidea

“…Pseudohastites is a passaloteuthid (type species, Belemnites scabrosus Simpson, 1866) closely related to the genus Passaloteuthis (see Doyle, 1990c, p. 23). The hastitid form of B. junceus was recognized by Lang (1928) and later workers (e.g., Schwegler, 1962;Jeletzky, 1966;Schumann, 1974), and therefore erection of the new genus is warranted. Bairstowius differs from Hastites Mayer in its extreme elongation and in its spicular or only feebly subhastate form.…”

“…The type species of Trachyteuthis is usually said to be Sepia hastiformis Rfippell (e.g., Bülow-Trummer, 1920, p. 248 ;Engeser, 1988, p. (Lang, 1928); B. longissimus (Miller, 1826); B. charmouthensis (Mayer, 1866); B. arundineus (Lang, 1928).…”

“…-Lang's (1928) interpretation of the genus Pseudohastites (Naef, 1922) to include forms typified by the species Belemnites junceus is erroneous. Pseudohastites is a passaloteuthid (type species, Belemnites scabrosus Simpson, 1866) closely related to the genus Passaloteuthis (see Doyle, 1990c, p. 23).…”

Eight belemnite biohorizons in the Cenomanian of northwest Europe and their importance

“…the Pleinsbachian Belemnite Marls of Dorset; the Toarcian Whitby Mudstone Formation of Yorkshire; the Callovian-Oxfordian Oxford Clay of Dorset, Wiltshire and Cambridgeshire; and the Lower Cretaceous Speeton Clay of Yorkshire) and sandstones (e.g. the Upper Toarcian Bridport Sands of Dorset; the Blea Wyke Sands of Yorkshire; and the Kellaways Sandstone of Wiltshire) (Phillips 1865(Phillips -1909Lang 1928;Doyle 1990Doyle , 1992bPage and Doyle 1991;Swinnerton 1936Swinnerton -1955. They also occur commonly in condensed ironstone and carbonate facies (e.g.…”

Use of palynofacies analysis to define Lower Jurassic (Sinemurian to Pliensbachian) genetic stratigraphic sequences in the Wessex Basin, England

“…The studied section comprises some 260m of predominantly finegrained, marine siliciclastic sediments with occasional limestone horizons. Lithostratigraphic nomenclature for the Lower Jurassic Dorset section follows that of Cope et al (1980), based on almost two centuries of work by various authors (de la Beche 1826, Day 1863, Woodward 1893, Lang 1914) (see Fig. 2).…”