II.—On the Lias of the Coast, in the Vicinity of Lyme Regis, Dorset.

Abstract

In a former communication to the Geological Society I presented an outline of the features of the coast in the vicinity of Lyme Regis; but having there described the lias only in a general manner, it is my present purpose to offer a more detailed account of that formation, as I am not acquainted with any situation where its geological structure and composition, and the organic remains which it contains, can be better studied. The relative position of the cliffs referred to in the following description is represented in the section connected with my former paper upon this subject*:—And the annexed sketch (Pl. III. fig. 1.) represents the order of superposition of the inferior oolite sands, the lias formation, and the upper beds of the red marl, as they appear in the section between Down Cliff and Culverhole Point; the beds being supposed to be placed horizontally above each other, and the superincumbent chalk and green-sand removed. The uppermost beds of the lias rise from beneath the sands of the inferior oolite at Down Cliff, on the west of Bridport Harbour; where a section is afforded of about one hundred and eighty feet of sand, in which large flattened masses of limestone occur, containing Pectens, Belemnites, Terebratulæ, &c. These sands are calcareo-siliceous, their colour is a ferruginous yellow, and they contain an abundance of mica in their lower parts. A bed of grey marl occurs in them about one hundred feet above the commencement of the lias. The calcareous