20 A TEXTBOOK OF OCEANOGRAPHY 



Two theories have been put forward to account for the 

 origin of the continental shelf. According to the first, it is 

 due solely to the denudation of the land ; but if that were the 

 case we should expect the sediments to exhibit a progressive 

 diminution of size of the component particles as we recede 

 from the land to the open sea. This is, however, by no means 



the case. 



The second theory accounts for the origin of the contmer 

 shelf by ascribing it exclusively to the effects of marine erosion. 



FIG. 3.-THE BRITISH ISLES AND THE CONTINENTAL SHELF. 



On this theory we should expect the widest shelf areas to be 

 found where storms and waves are at their maximum, 

 is not the case, since land breezes prevail off the east coast , 

 North America from the Straits of Belle Isle southwards 

 Cape Hatteras, where the continental shelf is wide an< 



marked. 



The British Continental Shelf. Off the south of Irelan 

 and at the entrance to the English Channel the banks run 

 parallel to one another in a direction roughly from north-east 



