31 



size and number with those in relatively rugged topography 

 of the irregular zone. 



The irregular zone consists mainly of mounds and ridges 

 which project 10 to 40 feet and occasionally 60 to 80 feet 

 above the sea floor. The flanks of many of these mounds and 

 ridges appear jagged, irregular, and steep on fathograms. 

 The slopes may be locally more than 15©, but generally are 

 less than 1° or 20. Some of the mounds are connected by low 

 ridges and these also have irregular and jagged sloping sides. 

 Individual mounds are 2,000 to 3,000 feet in diameter; some 

 are smaller or larger, but this appears to be the average 

 size. The area enclosed by the irregular zone is known to 

 have much gravel and some bedrock so that the relief evidently 

 is due to rock outcrops and patches of gravel. Because the 

 micro-relief chart is based only on fathometer traces and not 

 on bottom sampling, and because the fathometer does not 

 necessarily distinguish between bottom types, the limits of 

 the rock and gravel area differ slightly on the two charts 

 (Figs. S and 13). 



Redondo and Santa Monica Canyons 



The head of Redondo Canyon consists of an am phi the at er- 

 like bowl which is located a short distance from the shore. 

 The canyon has a relatively flat floor throughout most of its 

 length, has only a few bends, and has a wide terminal end at 

 a depth of approximately 2,200 feet. According to Shepard and 

 Emery (1941, p. 64, pi, 12), the gradient of Redondo Canyon 

 decreases along its course; being 8% at the head, 2.5% at the 



