Beyond the reef, the depth increases very abruptly. 

 Whrn soiling along the edge of the shelf, it was not im- 

 coramon to see the greenish color of shallov^ wt.t^.v on one 

 side of the vessel rnd the mrrine blue of deep \iet:-.v on 

 the other even though her bee m a7Cs on]y twelve rnd a half 

 feet. 



The sea^/f:rd edge of th- shelf is generally about 

 25 to 30 meters deep, the base of the steep cliff is rt 

 about 150 to 200 meters. Only three times WcS it possible 

 to find bottom betv'een 30 end 150 meters, once the sound- 

 ing lefd struck rt 130 end again at 137 meters and the 

 Ewing camera struck what appears to be a roclcy ledpe at 

 132 meters (fig. 9). A few samples of e limestone rock 

 containing fossils were torn off the brse of the cliff with 

 the dfadfie. These were turned over to Dr. Newell for study. ■ 



Photographs of the bottom beyond the cliff (figs.lO- 

 14.) show bare rock down to 230 meters. /, photcgrrph (fig. 15) 

 taken at 383 meters shows some sand and grr-vel which fpperrs 

 to lie as a covering over the rock, ^^.t 450 .aeters, (fig. 16) 

 a photograph shows bare grtvel. This gravel appeared in 

 dredge samples rnd w&s found to consist ;lmost entirely of 

 dead segaients of Ha limed a . This genus of coralline algae is 

 common in shallow wrter throughout the warm seas. The 

 dredged mrterial h:d, however, very oiuch larger fnd coarser 

 fronds than rnj^^ now living along the .Andres coest end ac- 

 cording to Dr. Harold J. Piumm, the cf Icification appears 



