116 



bed, and (2) there appears to be no relationship between the 

 observed current velocities and the type of bottom. For 

 example, the strongest current was fovind on the slope off 

 Palos Verdes Hills where the bottom is covered with mud. 

 Cores showed that mud was deposited to a considerable thick- 

 ness in several localities where currents were relatively 

 high. In addition, two water samples taken about 3 feet above 

 the bottom during the time of mgiximum observed currents failed 

 to show any traces of suspended sediment. In both cases, the 

 bottom was covered by silt and fine sand. 



Mud flows and Submarine Landslides 



Shepard (1941) points out the importance of submarine 

 slides as a cause for nondeposition on some surfaces. While 

 these slides may be important in some localities, such as the 

 head of submarine canyons, the relatively horizontal surface 

 of the outer shelf in Santa Monica Bay probably cannot have 

 significant slumping. Perhaps the exception to this is along 

 the northern boundary of the rock and gravel area where it 

 borders the southern part of Santa Monica Canyon. Parts of 

 this sediment cover may possibly slide periodically off into 

 Santa Monica Canyon, Sliding also takes place along the 

 basin slope, but the study made by Emery and Terry (1956) 

 along the Palos Verdes Slope indicates that considerable 

 thicknesses of sediment can accumulate before the sediment 

 becomes unstable and slides take place. 



