﻿66 



MB. H. DEWEY ON THE ORI&IN OF SOME 



[vol. lxxii, 



The most conspicuous features in these gorges are the numerous 

 potholes or marmites, and it is not too much to say that they were 

 instrumental in drilling out the chasms where now the rivers flow 

 as cascades and torrents. Of these gorges the most characteristic 

 in Cornwall are near Tintagel and Boscastle, and, inland, those 

 at Lydford, Luxulyan, and the Bovey Valley. 



The following descriptions are arranged geographically, com- 

 mencing in North Cornwall and following the coast southwards, 

 and thence to inland localities. 



Fig. L 



The base of the degraded line of cliffs runs nearly parallel with, and between, 

 the 400- and the 500-foot contours. The cliff is marked by the crowding- 

 together of the contours above 400 feet. 



The plateau (see map, fig. 1) near Boscastle covers an area of 

 some 10 square miles, with a coast-line 6 miles long and much 

 indented with bays, havens, and coves. There are five valleys 

 dissecting this plateau, and, although they are several hundred feet 



