AND OTHER WATER WAVES 197 



but in the last 2 miles it is doubled every 

 J-mile. 



Most of the beach is, in fact, composed of small 

 shingle, but close under the eastern shelter of Port- 

 land Bill the shingle is large. At the Chesilton 

 end the beach receives new material from the steep 

 shore of Portland. It mostly consists of large stones 

 of the Portland stone, which is derived partly from 

 the waste of the steep shore but not a little largely 

 from the foot of the tips of the stone from the great 

 quarries on the summit. It is the larger frag- 

 ments chiefly which reach the foot of the tips. 

 A glance at the map shows that large waves can 

 travel towards Chesilton, not only from the direc- 

 tion of Bridport Harbour, but from the direction 

 of Portland Bill. I found many very large pebbles 

 of Portland stone on the beach at and near Chesil- 

 ton, which must have been driven there from the 

 coast of the promontory by these large waves. 

 But an examination of length of fetch on the map 

 shows at once that there can be no large waves to 

 drive these great pebbles far along the beach to 

 the westward. At Chesilton, or Chesil Cove, the 

 direction of the shore changes through nearly a 

 right angle. The corner is open directly to the 

 south-west. The Cove is a focus towards which 

 large breakers can and do come in winds from 



11 



