The sediment charts (figs. 2 and 5) utilize the data ob- 

 tained from the USS NEREUS samples, from the bottom no- 

 tations on the U. S. Navy Hydrographic Office charts Nos. 0068, 

 10639-1, and 10639-15, and from a few ALBATROSS samples 

 as noted by Trask. 1 ^ For the purpose of the chart, the sedi- 

 ments were classified as rocky, stony (includes bottoms 

 marked as gravel, pebbles, and hard on H. O. chart No. 0068), 

 sand, sand with mud, mud with sand, and mud. As the charts 

 are based on only a relatively few bottom samples, the ac- 

 curacy is not great; however it is believed that the sediment 

 distribution indicated on the charts is correct in a general way. 



By comparing the bottom samples with the fathometer 

 bottom traces at the various stations, it was found that gravel 

 or rock bottom is invariably irregular and hummocky and that 

 soft bottoms are flat and featureless. Thus, the nature of the 

 bottom sediments along the entire track of the USS NEREUS 

 was determined with some certainty by correlating the fath- 

 ometer trace with the bottom samples obtained at intervals 

 of many miles. An attempt was also made to obtain bottom 

 sediment information by studying the nature of the bottom 

 echo itself, but this was not successful. 



Bottom Cores. Twenty cores were obtained by plunging 

 into the bottom a device similar to that described by Emery 

 and Dietz 3 and consisting of a 2f-inch core tube weighted 

 with lead. Because the small size (0.25 inch) of the wire used 

 to lower the coring device necessitated limiting the weight of 

 the sampler to less than 150 pounds, only short cores were 

 obtained (minimum length = 8.5 inches, maximum length = 70 

 inches, average length = 30 inches). 



Since most of the cores taken in the Bering Sea were very 

 short, sandy cores, the nature of the sediment is known for 

 only an unfortunately short distance below the sea bottom. 

 These Bering Sea cores suggest a change in sedimentation 

 in comparatively recent times. The appearance of the upper 

 1 to 3 inches of the core is usually higher in color and more 

 loosely packed. Other texture changes from silty sand to 

 silt take place at varying distances below the bottom in a 

 number of cores. In core NEL 502 (54 fathoms), the change 

 occurs at about 30 inches below the bottom; in core NEL 508 

 (32 fathoms), the change takes place gradually at about 7 inches; 

 and in core NEL 513 (19 fathoms), a sharp change occurs at 

 10 inches. Core NEL 504 is probably too short to show any 

 change, and core NEL 506 shows very little change. The cores 

 taken at the entrance to Norton Sound show changes to coarser 

 sediment at about 10 to 12 inches below the bottom, then to 

 finer sediment below 14j inches. 



