374 GEOLOGY OF THE ISLE OF PURBECK. 



Wealden clays, and sands. Thus the northern 

 barrier of the coves consists of precipitous chalk 

 cliffs, the entrance is formed by rocks of the Port- 

 land and Purbeck limestone, and between these, 

 is a low coast, composed of the less durable strata 

 of the Wealden. These bays expose, in fact, trans- 

 verse sections of the hills of Portland and Purbeck 

 strata — of the clays and sands of the Wealden — 

 and at their back, chalk precipices of great height, 

 formed by the destruction of the southern face of 

 the Downs. 



LIGN. ."2. — PLAN OF Till; STRATIFICATION OF THE COVES ON THE SOUTH- 

 WESTERN COAST OF THE ISLF. OF PUHBECK. 



a, Chalk, b. Chalk-marl. r, Firestone, rf, Gait. e, Wealden. 

 /, Purbeck. g, Portland oolite. 



The plan of the stratification, lign. 32, given by 

 Mr. Conybeare,* affords a clear illustration of this 

 structure. The Portland and Purbeck beds (g,f,) 

 dipping inland, in an angle of from 45° to 60°, 



Geolog] of Km. land and Wales, p. 1S3. 



