THE OCEAN AND ITS WORK 



227 



(Fig. 220), for example, formerly extended across the continental 

 shelf into the deep sea, as is shown by its deep, submarine channel. 

 The St. Lawrence, Potomac, and other rivers also have submarine 



channels. The bays of the 

 Coastal Plain are the result of 

 a slight subsidence after the 

 newly made land had been cut 

 up to some extent by streams, 

 and are consequently merely 

 drowned valleys. Bays are 

 sometimes formed by the ele- 

 vation of the sea bottom on 



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Fig. 219. — Chesapeake and Delaware 

 bays are drowned river valleys, the 

 ancient submerged channels of which can 

 be traced out to sea. (After Dryer.) 



Fig. 220. — Map showing the sub- 

 merged channel of the Hudson River. 

 This channel can be traced about 125 

 miles beyond the present mouth of the 

 river. (After Dryer.) 



one or two sides of an area in which there was no such movement. 

 The Gulf of California had such an origin. Bays are made also by 

 the settling of great blocks (fault blocks, p. 267), as is true on the 

 coast of the Red Sea. 



Examples of Irregular Coasts. — The character of irregular coasts depends upon 

 several factors. 



Coasts of Folded Regions. — If the region is folded, with the axes of the folds parallel 

 to the coast, the bays and islands will have a like direction. A typical example of 

 such a coast is to be found on the northeast shore of the Adriatic Sea (Fig. 221), 

 with its elongated islands, its constricted straits, and narrow bays ; all of which are 

 parallel to the coast. When the folds are perpendicular to the shore, a rugged 

 coast with projecting points and deep indentations results (Finisterre, Spain). 



