be the case. The concentration of these nodules increased to a maximum 

 and then decreased until a very fine-grained muddy bottom prevailed. 



Cores taken closest to the site of camera lowering number 1 were 

 either in deeper water in the Santa Cruz Basin or in about the same 

 depth as the camera lowering on the Santa Barbara slope. These cores 

 were dominantly fine-grained, green-gray muds with high organic content. 



Camera lowerings 2 and 3 were taken in the San Nicolas Basin 

 in depths of 1100 and 1370 meters, respectively. Figures 30 and 

 31 present two photographs from each lowering. On both lowerings, 

 fine-grained muds dominated the area. Numerous tracks and holes 

 made by burrowing organisms can be seen. Biological activity shown 

 in the lower photograph of Figure 30 illustrates the fine texture 

 of the bottom. Brittle stars, observed throughout lowering number 3, 

 are usually found in very fine-grained, soft, muddy bottoms. They 

 feed on organic material which indicates this area to be one of high 

 organic content. 



Cores taken in the San Nicolas Basin substantiate the above observations. 

 These cores, like the ones taken in the Santa Cruz Basin, were fine-grained, 

 green-gray muds with a high organic content . 



Camera lowering number A was taken on an elevation of the Santa 

 Rosa-Cortes Ridge at a depth of 86 meters. The photographs taken 

 on this lowering (Fig. 32) are not as clear as was desired. At this 

 shallow depth, a large amount of particulate matter probably caused 

 considerable diffusion of the strobe lights. The photographs from 

 this lowering were dominated by in situ weathered rocks. The area 

 appeared to be well-swept with bare bedrock visible in many photographs. 



No cores were taken in the area of camera lowering 4, but cores 

 taken on the San Clemente and Santa Rosa-Cortes Ridges were the 

 coarsest obtained on this survey. 



G. Biological Analysis. 



Vertical plankton hauls were made with a 1-meter net of unknown 

 mesh size while the ship was drifting on station (Fig. 2). Since 

 the quantity of water that passed through the net is unknown, the 

 population figures presented in the following paragraphs represent 

 relative abundance of the various plankters rather than density per 

 unit volume. 



Plankton haul number 1 was taken on 23 September, 2 weeks before 

 the other samples were collected. This haul, taken from a depth 

 of 700 meters, was the second deepest haul made on the survey. A 

 total of 55cc of plankton was obtained as compared to an average 

 plankton volume of 16.8cc per haul obtained during October. 



In a 3-week period between haul 1 and the October collection at 



35 



