IV-12 



The large ocean waves lose much of their energy in the relatively 

 shallow water depths over the continental shelves, thus reducing the 

 force with which they strike the shore (Figure IV. 1.2). Where the 

 continental shelf is wide, waves reach the shore with greatly 

 decreased power and tend to move existing sediments around rather 

 than cutting the shoreline to produce new ones. 



Along the Atlantic and Gulf coasts of the continental United States 

 the continental shelf is generally about 50 to 100 miles wide and 

 terminates at depths ranging from 300 to 900 feet. Within this 

 regime four significant differences in conditions on the shelf are 

 reflected in the estuarine zone: 



(1) The Gulf of Maine forms an embayment between Cape 

 Cod and Nova Scotia, and the general configuration of deep 

 basins close to shore with broad banks seaward of them is 

 unique to this part of the coast (Figure IV. 1.3). While 

 the shoal waters on the shelf serve to protect the New 

 England coast from the full force of the ocean swells, the 

 deep embayment near shore and the narrow trough which 

 connects it to the ocean cause the great tide ranges and 

 strong currents characteristic of the region. These 

 currents tend to reduce deposition of sediments close 

 inshore, particularly along the Maine coast where the tide 

 range is greatest and the currents strongest. 



