Mainland Shelf 



203 



Santa Barbara, 95; off Santa Monica, 53; 

 off San Pedro, 87; and off San Diego, 

 78. These detrital sediments consist mostly 

 of sands and silts which form seaward 

 continuations of the beaches. They can 



be recognized by their seaward decrease 

 in grain size, their low content of calcium 

 carbonate, and the fresh unstained ap- 

 pearance of the grains. They consist chiefly 

 of quartz and feldspar with an average ratio 



BOTTOM MATERIALS OFF 

 SAN DIEGO. CALIFORNIA 



-200 METER CONTOUR 



>: 



Figure 179. Classification and distribution of sediments off San Diego. From Emery, Butcher, Gould, and Shepard 

 (1952, Fig. 7). 



