4 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 27 



three border islands: Santa Cruz, Catalina and San Clemente canyons; 

 and one, Tanner, borders submarine banks. Some of those along shore 

 dissect almost the entire mainland shelf ; such are Hueneme, Mugu, 

 Dume, Redondo, Newport and La Jolla canyons. Three others, Santa 

 Monica, San Pedro and Coronado canyons, cross only an outer end 

 of the shelf lands. Most of those bordering the mainland have their 

 axes at right angles to the mainland or curve counter clock-wise in a 

 southeasterly direction, from head to mouth ends. Because of their 

 proximity to the shelf, their faunal assemblages might be expected to 

 resemble those in shallower bottoms ; this expectation has been only 

 partly realized, as shown below. 



Typically a canyon consists of head, or upper, and mouth, or lower 

 ends, with walls of varying steepness, an axis, and a fan where it 

 adjoins the basin or trough adjacent to it. The degree of slope varies 

 so that there is a gradual decrease downward. 



The biological samples were taken at pre-selected sites along the 

 lengths of the canyons, which range in length from 4 to 15 miles. 

 Their lengths are approximately : Mugu, 4 miles ; Dume and San 

 Pedro, each 5; Newport, 6; Hueneme and Catalina, each 7; Tanner, 8; 

 Santa Monica and Redondo, each 9; Coronado, 10; San Clemente, 11; 

 Santa Cruz, 14; and La Jolla, 15. Their depths, at the heads, vary 

 from 15 to 950 meters, as follows, from shallowest to deepest: Mugu, 

 15 meters; Newport, 16 m; Redondo, 57 m; La Jolla, 79 m; Catalina, 

 88 m; Santa Cruz, 89 m; Hueneme, 98 m; Santa Monica, 116 m; 

 Coronado, 123 m; San Pedro, 187 m; Tanner, 298 m; Dume, 299 m, 

 and San Clemente, 950 meters. 



Their depths at the lower ends range from 621 to 1624 meters, as 

 follows, from shallowest to deepest: Hueneme, 621 meters; Newport, 

 624 m; San Pedro, 716 m; Mugu, 792 m; Redondo, 853 m; 

 Santa Monica, 873 m ; Dume, 905 m ; La Jolla, 976 m ; Coronado, 

 1265 m; Catalina, 1272 m; Tanner, 1298 m; San Clemente, 1620 m, 

 and Santa Cruz, 1624. 



Submarine canyons are known to exist throughout the world and 

 their origins have been the subject of considerable interest, chiefly to 

 geologists. The organisms existing in their sediments have not been 

 studied quantitatively, neither has the possible effect of their presence 

 on the physical aspects been explored. A study of life existing in 

 the upper rims of La Jolla canyon, was made by Limbaugh and 

 Shepard (1957, p. 637) whose reports on the fauna were based 



