The only DSL records obtained by the ATKA while crossing the 

 convergence are those for the Atlantic Antarctic Convergence. The 

 layer did not show major differences In depth. Crossing the Pacific 

 Antarctic Convergence, by the HENDERSON, the layer was observed to 

 drop from 300 fathoms to iiOO fathoms. A rise of about 135 fathoms by 

 the lay^r was noted as the COMt-IANDANT CHARCOT crossed the Subtropical 

 Convergence proceeding northward in the Indian Ocean, 



6, Recommendations 



From the above comparison of obsei^rations of the DSL by the three 

 expeditions, certain, features of the layer appear to warrant specific 

 observation on future Antarctic cruises. The f athogram shovild be 

 closely ;;atched through the mid-Pacific region to see if the DSL is 

 absent for one or more days. Special interest should also be paid 

 to the fathogram when traversing the regions of the Subtropical and 

 Antarctic Convergences, to note any change in prevailing depth or the 

 disappearance of the layer. The possible effect of heavy overcast or 

 fog upon the daj-iiijnie depth of the layer also should be observed, A 

 c3.ose watch should be maintained for the occurrence of the DSL in 

 Antarctic waters south of 60° S. If absent on the fathogram, aural 

 observations should ba riade possible. The use of the o,000~fathom 

 scale is preferred when bottom depths allow and when the day-night 

 cycle is in effect. 



It appears from this study that there is considerable difference 

 in the resolution factor between various fathometer instruments and 

 between scale settings of the same instrument. This suggests that 

 some atteirpt should be made to calibrate or evaluate fathometer 

 instruments on seme standard so that it v/ill be possible to relate 

 trace records to one another. 



G. Results From Snow and Ice Studies 



Snow pits were dug in the compacted snow of the shelf ice at 

 sex-eraJ. places on both sides of the continent, and ice cores w<ire 

 obtained from the fast ice where possible. Results from tests con- 

 ducted on snovj and ice are reported upon below. 



In the Little America area two snow pits were dug at or near the 

 site of Little Am.Grica III, a 1,9-meter pit over the emergency Quonset 

 radio hut ei'ected in 19h7 and a 2,0-raeter pit dug l/l2 mile to the east 

 of tna Ccurp, The snow surface was relatively smooth and soft; without 

 skis, a man would sink 2 or 3 inches into the surface, Lox-i and in- 

 frequent sastrugi crests vjere exposed throughout the surface drift. 

 There were few crevasses in the area and the general surface was flat 

 with imperceptible changes in elevation, A udnd cxTJ-st was observed 



61 



