the center were noted, but there was no evidence of a bio- 

 logical inhabitant. 



Upon landing, sediment was elevated into suspension 

 by the displaced water. The majority of the heavy material 

 remained in a suspended state only a matter of seconds and 

 then settled. The remaining material offered an index to 

 the prevailing water current velocity. The current was 

 measured visually to be less than 1 cm per second moving 

 parallel to the ridges of exposed bedrock. The water 

 immediately above the sea floor was clear and virtually 

 devoid of marine life and suspended particles. 



A coil of material that had formed a 6- foot double S 

 was noted on the bottom. It was apparently a piece of 

 cable. 



Visual observations of the sea floor at this location 

 were comparable to those made at 18, 150 feet (Dive No. 

 61). A definite sea floor slope of about 1 degree with 

 discontinuities involving abrupt breaks in the slope expos- 

 ing bedrock were present. Bedrock covered with a thin 

 mantle of whitish sediment was noted in both dives. The 

 mantle gave all appearances of being relatively thin. 

 Bearing strength, however, was again adequate to sustain 

 the weight of the bathyscaph and only a modest penetration 

 of the sphere was experienced. 



DIVE NO. 75 



The sea floor at 8530 feet revealed coarse sediment 

 cover of at least several inches. Here well- developed 

 ripple marks were observed. The average crest-to- 

 crest distance of all the ripple marks was estimated to 

 be 18 inches with an amplitude of 0. 75 to 1 inch (from 

 motion picture footage and fig. 11). Water current at 

 that time was 0. 7 cm per second. It appeared that the 

 water current flow rate, which was not oscillatory, would 

 be too slow to form such ripple marks, which were con- 

 tinuous and parallel. They showed no signs of cross- 

 rippling and were well formed, as though of recent origin. 

 No thin layer of dark material was present on the surface. 

 Some dark pebble- like particles on the bottom were 

 scattered at random about 2 to 3 inches apart. The par- 

 ticle size was only slightly larger than the ballast (i. e. , 

 estimated to be 4 to 5 mm in maximum width). 



28 



