Bembridge Beds

Bembridge Beds, a division of the Oligocene or Upper Eocene strata, resting on the St Helen's, and capped by the Hempstead series, are principally developed in the Isle of Wight. Edward Forbes arranged them in four divisions: (1) The upper marls and laminated gray clays, which form the basement bed of the 'black band,' the lowest member of the Hempstead series. They are distinguished by the abundance of Melania turrettissima. (2) Unfossiliferous mottled clays, alternating with fossiliferous marls and clays, whose characteristic organisms are Cerithium mutabile and Cyrena pulchra. (3) The oyster-bed, consisting of greenish marl, and containing immense quantities of a species of oyster (Ostrea vectensis), accompanied with Cerithia, Mytili, and other marine mollusca. (4) The Bembridge limestone, generally a compact, pale-yellow, or cream-coloured limestone, but sometimes vesicular and concretious, and containing occasionally siliceous or cherty bands. This is interstratified with shales and friable marls. All the beds are fossiliferous, containing numerous land and fresh-water shells. One bed is composed almost entirely of the remains of a little globular Paludina. Shells of Lymnea and Planorbis are abundant, and are accompanied with the spirally striated nucules of two species of Chara, water-plants which have been well preserved because of the large quantity of lime which enters into their composition. In this division have been found the mammalian remains of the species of Paleotherium (q.v.) and Anoplotherium (q.v.), which characterise the gypseous deposits of Montmartre.