153 

 Submarine Topography 



The major submarine topographic features in Santa Monica 

 Bay are the shelf, Redondo and Santa Monica Canyons, the Basin 

 Slope, and Santa Monica Basin, 



The shelf is generally smooth and grades gently from shore 

 to a depth of approximately 270 feet. The surface shows several 

 distinct types of minor "micro-relief". Nearshore there are 

 bars and troughs, farther offshore are areas of smooth topo- 

 graphy with no micro-=relief , and near its edges the shelf shows 

 variable micro'=relief with small terraces and notches locally 

 present. On the portion of the shelf projecting between the 

 two submarine canyons irregular micro-relief consists of low 

 mounds and ridges and corresponds to the major rock and gravel 

 area. 



The two submarine canyons are incised into the shelf and 

 create the lobate outer projection of the shelf. These canyons 

 are V-shaped with relatively steep walls. Redondo Canyon is 

 cut through the shelf to within a few hundred feet of shore, 

 whereas Santa Monica Canyon has its head about 3y miles from 

 shore. 



At the edge of the shelf the gradient increases markedly 

 and the slope grades into an offshore basin. These slopes 

 appear to be smooth, but a few notches or terraces are known 

 to occur. 



The floor of Santa Monica Basin, starting at a depth of 

 approximately 2,700 feet is relatively smooth, but slopes 

 slightly in a seaward direction. 



