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

 By H. T. De la BECHE, Esq. F.R., L. and G. S.S. etc. 



[Read November 21st, 1823.] 



In a former communication to the Geological Society I presented an out- 

 line 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 myformer paper upon this subject*: — And the annexed sketch 

 (PI. III. fig. I.) 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, Terebratulas, &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 beds of the inferior oolite are not exposed in the section at 

 Down CHff ; but they are found resting on the sands, in the continuation of 

 the same hill, on the northern side of the London Road, being there worked 

 at what are usually named the Chidiock Quarries, 



* Geological Transactions, second series, vol. i. PI. VIII. 



