RINGSTEAD BAY. 391 



Gad Cliff (see p. 366), reappears in Ringstead 

 Bay, and a good section of the strata is exposed 

 in the cliff. Proceeding towards Weymouth, the 

 clays in the lower part of the series gradually 

 become sandy and calcareous, and pass insensibly 

 into the Oxford oolite. 



In Ringstead Bay, there is a striking example of 

 that kind of displacement, which is geologically 

 termed a fault ; signifying a vertical or diagonal 

 fissure through the strata, accompanied either by 

 a subsidence, or an upheaval, of one side of the 

 dislocated masses. In this instance the beds, con- 

 sisting of chalk, firestone, and oolite, on the south 

 side of the fissure, are thrown down much lower 

 than those from which they have been separated. 

 This phenomenon is connected with the displace- 

 ments which the districts we have passed over 

 have undergone. The line of disturbance we 

 traced through the Isle of Wight, forming the 

 anticlinal axis from east to west, continues through 

 the Isle of Purbeck from Swanage Bay to Lul- 

 worth Cove and the adjacent bays, and is pro- 

 longed westward through the vale of Weymouth, 

 to the Chesil Bank ; the strata dipping respectively 

 north and south, on each side the principal axis 

 of elevation. The transverse valleys which here 

 and there intersect the chains of hills, have no 

 doubt originated from fractures occasioned by the 



