122 



vicinity of Redondo and Clifton and indicate a convergence 

 of littoral currents in this area. 



Therefore, the sediment within the bay probably represents 

 all sediment contributed by local stream drainage plus littoral 

 drift contributions from the north minus the loss of fine 

 grained sediments to the offshore area, and the loss of coarser 

 sediment down the submarine canyons to the basins. Some losses, 

 although very minor, also can be charged to wind drift from the 

 beaches inland » 



Drainage Tributary to Santa Monica Bay 



Figure 3 shows the boundaries of the drainage areas and 

 the streams bordering Santa Monica Bay, Table IV lists the 

 areas and characteristics of the various zones. It can be 

 seen that the Santa Monica Mountains comprise the major 

 element. The area southeast of Santa Monica Harbor is mainly 

 coastal plain, while that northwest of the harbor is primarily 

 mountainous. 



Inland from Malibu several water supply dams have been 

 built which cut off much of the coarser sediment from the bay. 

 As this watershed alone constitutes 58% of the drainage in 

 this area, the remaining smaller watersheds have been lumped 

 together. 



Rate of Sedimentation 



It is difficult to calculate the rate of sedimentation 

 in Santa Monica Bay for several reasons. A number of the 

 problems concerned with source areas are obvious. The volumes 



