In the Chukchi Sea a unique set of records was obtained: 

 there were to 5 feet of sediment overlying folded, tilted, 

 and truncated rock; bedding planes in the rock were quite 

 distinct. 



b. Detailed topography along the track was obtained 

 either by traces on the Marine Sonoprobe record, or with 

 the Precision Depth Recorder; these traces, plus the thick- 

 ness information previously mentioned, show that, because 

 of smoothing by sedimentation, these areas are among the 

 flattest places known on earth. 



c. Sediments 



Figure 1 shows the sediment distributions in parts 

 of the shallow Bering Sea as established by the expedition 

 and by previous work in the area. The exact track lines 

 are classified. 



Fifty-three sediment samples were taken by snapper, 

 corer, or by diver. The sediments of the Bering Sea were 

 dominantly fine and very-fine sand in the eastern portions, 

 and sandy silt and silt in the outer (or western) areas. In 

 the Chukchi Sea the sediment was apt to be a mixture of 

 sand-silt-clay, and gravel. Portions of these sediments 

 were examined in the laboratory for median grain diameter, 

 sediment type, density, porosity, shear strength, and 

 sound velocity and attenuation. 



d. Bottom photography 



A shallow-water lowered camera devised by C. 

 J. Shipek of NEL was used to make 21 lowerings for photo- 

 graphs of the sea floor. Owing to the turbidity of the bottom 

 water (observed by divers) most of these photographs were 

 not usable. 



15 



