IV-55 



The Middle Atlantic and Gulf estuarlne regions have about equal 

 amounts of tidal shoreline and estuarlne water areas per mile of 

 ocean coastline, but 1n the Middle Atlantic region the estuarlne 

 zone consists primarily of a few large drowned river valley embay- 

 ments (e.g. New York Harbor, Delaware Bay, and Narragansett Bay) 

 and some small marsh amd barrier beach systems receiving only 

 coastal fresh-water runoff. The estuarine zone of the Gulf region 

 on the other hand, consists mainly of moderate sized embayments 

 with barrier beaches and extensive marshes, but receiving river 

 flow from upland drainage areas and representing an Intermediate 

 state 1n the evolution of drowned river valleys into coastal marshes 

 in the Gulf region. 



The North Atlantic 1s unlike any of the other regions in overall 

 structure, but 1s similar to Puget Sound and Southeast Alaska. 

 Characteristic of the North Atlantic region are very Irregular, 

 hilly coastlines with deep water close Inshore and long, narrow 

 embayments with open access to the sea. 



The South Atlantic region has two dominant types of estuarine 

 structure. From Cape Hatteras to about Jacksonville, there is a 

 general input of uDland river drainage to the estuarlne zone and 

 the estuarine systems are typical drowned river valleys in the 

 later stages of evolution represented by barrier beaches or 

 coastal marshes backed by extensive swamps. South of Jacksonville 

 fresh-water runoff comes primarily from local coastal drainage, 



