250 ANNUAL REPOBT SMITHSONIAN INSTITUTION, 1932 



surveys. These did not include accurate latitude measurements of 

 the shelf -ice front to see whether it had advanced or receded. They 

 did, however, show many changes in outline along the portion west- 

 ward from Discovery Inlet. "Wliere Scott had found indentations 

 there were now none, and again new indentations had formed where 

 there were none before. 



It is of interest here to return to the observations made by the 

 geological party. The very direction of the ice flow along the foot 

 of the mountains mapped indicates a maximum outward push in the 

 western portion of the shelf ice, to say nothing, of course, of the great 

 amount of ice flowing out from Beardmore and the other outlet 

 glaciers west of Liv. Furthermore, the crevasses between latitudes 

 81° and 82° indicate that the shelf ice is here held back by land or a 

 submerged reef of some sort which definitely obstructs the direct 

 northward flow of ice. Again, the great hill south of Little America 

 further blocks a northward movement of the shelf ice; and finally 

 Commander Byrd found crevasses in latitude 80° 45' S-, longitude 

 173° W., west of the crevassed region we crossed. These observa- 

 tions but further substantiate David's studies that from Discovery 

 Inlet eastward the slielf-ice front has not undergone great changes in 

 recent years. 



COMPOSITION OF THE SHELF ICE 



The presence of numerous crevasses about Little America as well 

 as the exposed face of the shelf ice gave us abundant opportunity 

 to study its composition. Everywhere above sea level it is made up 

 of snow. The top few inches to 3 or 4 feet is made up of ordinary 

 snow. The remainder down to sea level is composed of granular 

 snow. Nowhere could we make out a systematic arrangement 

 of layers of this granular snow. Sufficient melting to form crusts 

 is rare, and there seems little or no way to distinguish between sea- 

 sonal amounts of precipitation. The speed with which this gran- 

 ular snow accommodates itself by flowage was a surprise to all of us. 

 Haines and Harrison, the meteorologists, made a snow house for 

 storing their kites ; and at a depth of about 5 feet below the surface 

 level they dug caves horizontally into the walls to make additional 

 storage room. Within four months the roofs of these small caves 

 had sagged as much as 6 to 8 inches across a span of 4 feet. All this 

 happened under the severest temperature conditions of the year. 

 The caves were made in the late fall, and the measurements were 

 taken in the spring. 



Particularly where the crevasses go down to the sea the rising 

 moist air has left along the walls and pendant from the roofs an 

 array of ice crystals prodigious in size and infiuitely varied in form 

 while always of the hexagonal system. It was common to find 

 individual crystals from 5 to 10 inches across. 



