30 



three types of micro-relief were outlined: smooth, variable, 

 and irregular. 



A wide belt of smooth topography extends from nearshore 

 to varying distances out on the shelf (Fig. 8). The only 

 distinguishable irregularities within this area are isolated 

 mounds a few feet high. Depressions are conspicuously absent 

 within the zone. Near the edge of the shelf, occasional well- 

 defined terraces or flat areas can be seen on the fathograms, 

 some of which can be seen on the topographic map of the bay 

 (Tig, 5 ), but little micro-relief is evident. An especially 

 well-defined terrace is present at the boundary between the 

 smooth and irregular zones and extends a short distance north 

 towards Santa Monica Canyon. 



The zone of variable topography is generally seaward of 

 the smooth areas. The offshore limit could not be determined 

 accurately because of the transitory nature of the boundary 

 and the lack of fathograms in this region. Within this zone 

 are broad areas of no micro-relief and smaller sections having 

 low mounds, undulations, and small steps or terraces. Also 

 included in this zone is the sudden steepening at the shelf 

 break and the irregular topography associated with the sub- 

 marine canyons. Along the edge of the shelf and the upper 

 part of the basin slope, are numerous notches, steps, and 

 small terraces. Closer to shore, north of Santa Monica 

 Canyon, are several gullies 20 to 30 feet deep which are, 

 perhaps, similar to those described by Buffington (1951), 

 and Emery and Terry (1956). Although there are many mounds 

 and irregularities within this general area, none compare in 



