IV-19 



are typical of the estuarine zone. 



The southern coast of Alaska is the only part of the United States 

 with glaciers existing in the estuarine zone. Glacier-fed estuaries 

 have much floating ice, usually in the form of small icebergs, and 

 very steep sides. The water is icy cold and often milky with sedi- 

 ment from earth and rock ground to a fine flour by the movement of 

 the ice across the land (Figure IV. 1.11). 



RIVER FLOW 



The estuarine zone is also shaped through erosion and sediment trans- 

 port by fresh water making its way to the sea. Along the coastlines 

 of the continental shelf of the United States are streams and rivers 

 carrying water from land runoff to the sea. These waterways range 

 from the Mississippi River down to the tiniest stream tricklinq 

 across the sands of a beach. 



Figure IV. 1.12 illustrates typical seasonal variation in river flow 

 into the estuarine zones of the United States. Everywhere there is 

 a pronounced annual cycle; neaking sharply in the snrinq in Alaska 

 and New England, neaking from early summer to early fall alono the 

 Atlantic and Gulf coasts, and reaching a maximum in late winter 

 alona the Pacific coast. 



