On the occurrence of a Bed of Septaria, containing fresh-water Shells, in the series of Plastic Clay, at New Cross, Kent

Abstract

Having occasion, in the Spring of 1843, to travel along the South Eastern Railway, I observed at the distance of about 200 yards to the south of the New Cross Station, on the western side of the cutting which there lays bare the junction of the London and Plastic Clays, and at the very foot of that cutting, what seemed to be a continuous bed of stone, forming a part of the Plastic Clay series. I applied, in consequence, to Mr. Simms, a Fellow of our Society, (who, as one of the resident engineers, had ready access to every part of the line), to procure for me specimens of this bed; and he not only complied with this request, but also made a vertical section of the beds exposed in the cutting, extending from the base of the London Clay to the bed of stone in question. The specimens which Mr. Simms procured contain, imbedded in the substance of the stone, two fresh-water shells, a Paludina and a Unio, which Professor E. Forbes has examined and described. The stone proved, on examination, not to form a continuous stratum extending to any distance, but to occur at intervals only; and to be, in fact, a bed of Septaria, of a texture considerably more earthy than the Septaria of the London clay usually are.