DIVE NO. 53 



The sea floor at 4100 feet (the San Diego Trough) 

 appears to be a grey- green clay- silt, Microtopographic 

 relief features are predominantly the result of biological 

 burrowings and digging activities. Small holes, small 

 cones of discharged sediments, brittle stars, fish trails 

 and sculpturing of the upper 0. 2 5 inch of sediments pre- 

 dominate throughout the area (fig, 2 and 3). 



Upon landing, a small amount of material was brought 

 into suspension. The bearing strength of the sea floor was 

 adequate to sustain the weight of the bathyscaph. Suspended 

 sediment was carried rapidly out of the viewing area by the 

 water current. Water current velocity was estimated to be 

 less than 0, 75 knot. Living forms in the water immediately 

 above the sea floor were abundant and apparently involved 

 a myriad of invertebrate forms. During a horizontal 

 traverse over the bottom using the bathyscaph propulsion 

 system, a half- pint milk carton, numerous brittle starfish, 

 and several sea cucumbers were observed. 



Ocean dives to the sea floor in the vicinity of Guam 

 were made in the basin west of Apra Harbor and in the 

 Marianas Trench east and southwest of Guam (fig, 4). In 

 contrast to the Mediterranean dive locations and those off 

 San Diego, the sea floor off Guam was observed to be pre- 

 dominantly exposed bedrock with only a thin layer of sedi- 

 ment. 



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