IV-56 



and there are uniform and extensive barrier beaches or coastal 

 marshes backed by extensive swamps. South of Jacksonville fresh- 

 water runoff comes primarily from local coastal drainage, and the 

 there are uniform and extensive barrier island beaches with long 

 narrow embayments behind them. Continuous but generally narrow 

 strips of marsh lie along the embayments. This structure fades 

 Into the extensive swamplands of the Everglades farther down the 

 Florida peninsula. 



Both the Pacific Northwest and Pacific Southwest regions have few 

 estuaries. The estuarlne systems of the Northwest Pacific region 

 tend to be the mouths of rivers which have cut their way through 

 coastal mountain ranges, either of their own accord of aided by 

 glaciers as 1n the case of Puget Sound. Shallow coastal embayments 

 with little and sporadic river flow are characteristic of the few 

 estuarlne systems of the Southwest, except for San Francisco Bay, 

 which receives fresh water runoff from much of central California. 



Alaska Dresents the greatest variety 1n estuarlne form and struc- 

 ture of any of the estuarlne regions. Nearly all kinds of systems 

 typical of other regions are found there. In addition, Alaska has 

 the only glaciated coast and most of the fjords found in the United- 

 States. 



The rivers entering the estuarlne zone drain nearly 90 percent of 

 the U. S. land area. They carry to the sea sediments eroded from 

 this vast expanse and deposit much of 1t in the narrow band of 274 



