DIVE NO. 60 



The sea floor at 4900 feet on the steep slope just west 

 of Apra Harbor, Guam, was a unique area for bathyscaph 

 operations because of water currents and the magnitude of 

 the rugged outcrops. Outcrops were identified as the pre- 

 dominantly exposed bedrock of a regular size and form. 

 Interspersed among the outcrops was an off-white sediment. 



A conspicuous feature was the ubiquitous distribution 

 of unidentified "black pebbles" that were strewn about the 

 sea floor (fig. 5); The mantle of sediment overburden 

 appeared to be thin and sub] ect to transfer by water cur- 

 rent. Although not clearly defined, the sediment appeared 

 to be banked against the north (?) slope of the rock piles 

 (fig. 6). The exposed bedrock varied from eroded and 

 partially dissolved masses of bedrock (fig. 7) to relatively 

 unaltered materials, possibly of igneous origin. Although 

 the sediment yielded all appearances of being skeletal 

 remains of deceased animals, it is possible that a portion 

 of it was from terrigenous sources, particularly the coral 

 fringing reef of Guam. 



Although landing conditions were obviously hazardous, 

 a bottoming was accomplished among significant rock out- 

 crops (fig. 6). Sediment brought into suspension by the 

 landing rapidly settled to the sea floor or was carried out 

 of the viewing area. The bearing strength of the sea floor 

 was adequate to sustain the weight of the bathyscaph well 

 above the bottom. The penetration of the sphere was esti- 

 mated to be no more than 3 inches. A rock outcrop 4 or 5 

 feet high of varied form was seen through the observation 

 window (fig. 6). The outcrop material appeared to be 

 pillow lava covered with a thin layer of recently deposited 

 sediments. The crustal bedrock (of igneous origin?) had 

 undergone some chemical and physical erosion (fig. 7). 

 As the bathyscaph drifted across the sea floor, photographs 

 were taken using the external 35- mm camera and electronic 

 strobe light. 



Biological activity was at a minimum. However, 

 three eels about 3 feet long were observed swimming 4 or 

 5 feet above the rocky outcrops. They showed little 

 response to the high- intensity lamp illuminating the area. 

 During the bathyscaph cruise across the sea floor, scour- 

 ing was noted to be minimal. A few depressions and the 

 perimeter of 0. 5- inch holes were obviously of biological 

 origin, but their occupants were not observed. A single, 

 living "whip coral" was noted to be attached to an exposed 

 sheet of bedrock (fig. 8). 



