( 14 September 1969) 

 Figure 4-47. Growth of a spit into deep water, Sandy Hook, New Jersey. 



imbedded in the sea floor (Inman and Rusnak, 1956), but without extending the 

 survey beyond the boundary of the moving sand bed, it is difficult to deter- 

 mine net changes. 



e. Subma r i ne Ca ny o ns . In some coastal areas, an important sink for 

 littoral materials is submarine canyons. Shepard (1963) and Shepard and Dill 

 (1966) provide extensive description and discussion of the origin of submarine 

 canyons. The relative importance of submarine canyons in sediment budgets is 

 still largely unknown. 



Of 93 canyons tabulated by Shepard and Dill (1966), 34 appear to be 

 receiving sediment from the coast, either by longshore transport or by trans- 

 port from river mouths. Submarine canyons are thought to be especially 

 important as sinks off southern California. Herron and Harris (1966, p. 654) 

 suggest that Mugu Canyon, California, traps about 765,000 cubic meters (1 

 million cubic yards) per year of the local littoral drift. 



4-123 



