110 Mr. H. T. De la Beche on the Chalk and Sands beneath it, 



is no difficulty in determining the order in which they occur. For the por- 

 tions of the cliffs composed of these rocks^ I must refer to my section of this 

 coast contained in the Geological Transactions^ vol. i. second series, PI. VIII.; 

 and for a detailed section of their relative position, to PI. XVI. which accom- 

 panies this paper. I shall in the first instance, for the sake of convenience, 

 notice the Chalk and the sands beneath it near Lyme Regis, and then proceed 

 to those near Beer. 



Chalk near Li/me Regis. (PI. XVI. fig. 1.) 



This Chalk may be divided into Chalk with flints. Chalk without flints, and 

 Chalk with quartz -grains ; and is, taken as a mass, about 190 or 200 feet thick, 

 where most developed at Pinhay and Dowlands cliffs. 



Chalk withjlints. — This, as usual, constitutes the upper part of the forma- 

 tion, and is about 150 feet thick at Dowlands. For about 100 feet from the 

 top, the flints are very numerous, and in layers, occasionally mixed with conti- 

 nuous seams of the same substance. In its lower part, the flints become more 

 rare, gradually losing the appearance of being distributed in layers, and finally 

 occur as detached pieces, without order, in the mass of chalk. The organic 

 remains that usually occur in this division of the Chalk, are so well known, that 

 it would be useless to enter into a detail of them ; they have not been found 

 very abundantly in this neighbourhood; but such as have been discovered, 

 correspond with those contained in the same division of the Chalk in the east 

 of England. 



Chalk without Jlints. — This division succeeds to the above, the flints 

 becoming gradually scarce, and in the end disappearing altogether : — in the 

 neighbourhood I am noticing, it is in general tolerably hard, and does not 

 exceed 30 or 40 feet in thickness. The most abundant organic remains con- 

 tained in it are the Caiillus Cuvieri of M. Brongniart, Env. de Paris*, PI. IV. 

 fig. 10, (the Inoceramus Cuvieri of Sowerby), and the Mytiloides labiatus of 

 M. Brongniart, Env. de Paris, PI. III. fig. 4, (the Inoceramus mi/tiloides of 

 Sowerby, tab. 442). The palates, scales, and teeth of fish are also found in 

 it, with Belemnites, and the Ostrea vesicularis of Lamarck. (Env. de Paris, 

 PI. III. fig. 5.) 



Chalk with quartz-grains. — This division gradually acquires small irregu- 

 gularly rounded grains of white quartz, and ends by becoming thickly studded 



* I use this abbreviation for the Description Geologique des Environs de Paris, par MM. 

 G. Cuvier et Alex. Brongniart, contained in the 2d part of the 2d vol. of Cuvier's Ossemens 

 Fossiles. 



