kilometers or 36,940 miles), about 19,550 kilometers (12,150 miles) (33 

 percent) has beaches; the remaining 39,900 kilometers (24,790 miles) is rocky 

 or otherwise lacks the typical beach characteristics described in Figure 1- 

 1. Likewise the coast along shorelines varies. In New England, it is 

 frequently rocky promontories while the south Atlantic and gulf coasts are 

 generally low, dotted with backbays, wide estuaries, and marshes. Southern 

 California with a history of a rising landmass has coastal cliffs of 

 conglomerate material, some of which were at one time beaches. The coast of 

 the north Pacific and Alaska is dominated by the basaltic deposits of 

 postvolcanic activity, weathered by the action of water. Even on a more local 

 scale, beaches and coasts can vary widely reflecting their differences in 

 geologic history and recent wave and current action. 



Where the land meets the ocean at a sandy beach, the shore has natural 

 defenses against attack by waves, currents, and storms. The first of these 

 defenses is the sloping nearshore bottom that causes waves to break offshore, 

 dissipating their energy over the surf zone. The process of breaking often 

 creates an offshore bar in front of the beach that helps to trip following 

 waves. The broken waves re-form to break again, and may do this several times 

 before finally rushing up the beach foreshore. At the top of wave uprush a 

 ridge of sand is formed. Beyond this ridge, or crest of the berm, lies the 

 flat beach berm that is reached only by higher storm waves. 



During the early days of the United States, natural beach processes molded 

 the shore as in ages past. As the country developed, shore activity was con- 

 fined principally to harbor areas, and development along the shore progressed 

 slowly as small, isolated fishing villages. As the national economy grew and 

 transportation improved, more people began to use the beaches. Gradually, 

 extensive housing and commercial, industrial, recreational, and resort devel- 

 opments replaced the fishing villages as the predominant coastal manmade 

 features. Examples of this development are Atlantic City, Miami Beach, 

 Honolulu, and Imperial Beach south of San Diego. 



Numerous factors control the growth of development at beach areas, but 

 undoubtedly the beach environment is the development's basic asset. The 

 desire of visitors, residents, and industries to find accommodations as close 

 to the ocean as possible has resulted in man's encroachment on the sea. In 

 their eagerness to be as close as possible to the water, developers and prop- 

 erty owners often forget that land in the coastal area comes and goes, and 

 that land which nature provides at one time may later be reclaimed by the 

 sea. Once the seaward limit of a development is established, this boundary 

 between land and sea is perceived as fixed and must be held if large invest- 

 ments are to be preserved. Whether the problem is one of natural erosion 

 processes working on the coastal land that threatens man's presence there, or 

 erosion induced by man's encroachment on the sea, the results are similar. 

 Erosion generally leads to either great monetary losses due to storm damage or 

 even larger expenditures for shore protection to prevent the loss. 



Another problem in the coastal area is the need for inland waterborne 

 commerce on rivers and bays which must pass through the coastal area to reach 

 deep water. Inlets which once migrated to suit the water and wave forces 

 acting on them are now being pinned in place by jetties, creating accretion 

 and erosion problems on their flanks. 



1-3 



