o90 



KAPLAN AND RITTRNBEK(; 



[CHAP. 23 



C. Composition and Distrihitlion 

 a. Grain size 



This parameter shows a verj^ clear tendency in most recent basins. In inland 

 seas or land-locked basins the picture may be more complicated because a 

 inimber of sources for the sediment may exist. The trend, however, is for a 

 continual decrease in grain size with distance from the source. Thus, in land- 

 locked l)a8ins such as the Black Sea, Baltic Sea or Lake Maracaibo, the deposits 

 in the center are fine-grained silts and clays, those along the shores are coarse- 

 grained sands or pebbles. This tendency was also observed by Kuenen (1943) in 



PPM HYDROCARB. 



PPM PHEOPHYTIN % ORG. MATTER 



% CaCOj 



Md-MiCRONS 



MAINLAND 

 BEACHES 



LOS ANGELES 

 BASIN 



MAINLAND 

 SHELVES 



NEARSHORE 

 BASINS 



ISLAND 

 SHELVES 



MIDDLE 

 BASINS 



BANK TOPS 



OFFSHORE 

 BASINS 



CONTINENTAL 

 SLOPE 



DEEP-SEA 



FLOOR 



Fig. 2. Curves showing variation with facies or generaHzed distance from shore of several 

 components of the sediments of southern CaHfornia basins. (From Emery, I960, 

 fig. 203.) 



the Moluccan basins, but is probably most dramatically illustrated in the series 

 of basins extending seaward on the continental borderland ojEf southern Cali- 

 fornia. 



Here it is possible to draw seven roughly parallel stri])s, which are also 

 parallel to the coast, each strip containing a number of basins (Emery, 1960, 

 \). 220). The Los Angeles Basin, now completely filled with sediment and 

 wholly exposed, can be considered the first basin. Fig. 2 illustrates the decrease 

 in grain size in going from the nearshore basins to the offshore basins. This 



