5. Occurrence of Littoral Materials on U.S. Coasts . 



Littoral materials on U.S. coasts vary from consolidated rock to clays, 

 but sand with median diameters between 0.1 and 1.0 millimeter (3.3 and phi) 

 is most abundant. General information on littoral materials is in the reports 

 of the U.S. Army Corps of Engineers National Shoreline Study; information on 

 certain specific geological studies is available in Shepard and Wanless 

 (1971); and information on specific engineering projects is published in 

 Congressional documents and is available in reports of the Corps of Engineers. 



a. Atlantic Coast . The New England coast is generally characterized by 

 rock, headlands separating short beaches of sand or gravel. Exceptions to this 

 dominant condition are the sandy beaches in northeastern Massachusetts and 

 along Cape Cod, Martha's Vineyard, and Nantucket. 



From the eastern tip of Long Island, New York, to the southern tip of 

 Florida, the littoral materials are characteristically sand with median 

 diameters in the range of 0.2 to 0.6 millimeter (2.3 to 0.7 phi). This 

 material is mainly quartz sand. In Florida, the percentage of calcium 

 carbonate in the sand tends to increase going south until, south of the Palm 

 Beach area, the sand becomes predominantly calcium carbonate. Size 

 distributions for the Atlantic coast, compiled from a number of sources, are 

 shown in Figure 4-11 (Bash, 1972). Fine sediments and organic sediments are 

 common minor constituents of the littoral materials on these coasts, especial- 

 ly in South Carolina and Georgia. Beach rock and coquina are common at 

 shallow depths along the Atlantic coast of Florida. 



b. Gulf Coast . The Gulf of Mexico coast along Florida, Alabama, and 

 Mississippi is characterized by fine white sand beaches and by stretches of 

 swamp. The swampy stretches are mainly in Florida, extending from Cape Sable 

 to Cape Romano and from Tarpon Springs to the Ochlockonee River (Shepard and 

 Wanless, 1971, p. 163). 



The Louisiana coast is dominated by the influence of the Mississippi 

 River, which has deposited large amounts of fine sediment around the delta 

 from which wave action has winnowed small quantities of sand. This sand has 

 been deposited along barrier beaches offshore of a deeply indented marshy 

 coast. West of the delta is a 120-kilometer (75-mile) stretch of shelly sand 

 beaches and beach ridges. 



The Texas coast is a continuation of the Louisiana coastal plain extending 

 about 128 kilometers (80 miles) to Galveston Bay; from there a series of long, 

 wide barrier islands extends to the Mexican border. Littoral materials in 

 this area are predominantly fine sand, with median diameters between 0.1 and 

 0.2 millimeter (3.3 and 2.3 phi). 



c. Pacific Coast . Sands on the southern California coast range in size 

 from 0.1 to 0.6 millimeter (3.3 to 0.7 phi) (Emery, 1960, p. 190). The 

 northern California coast becomes increasingly rocky, and coarser material 

 becomes more abundant. The Oregon and Washington coasts include considerable 

 sand (Bascom, 1964) with many rock outcrops. Sand-sized sediment is con- 

 tributed by the Columbia River and other smaller rivers. 



d. Alaska. Alaska has a long coastline (76,120 kilometers (47,300 miles) 



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