THE WILSON PIEDMONT GLACIER 101 



derived, in part at all events, from the huge outlet glaciers of the inland plateau 

 west of Ross Sea. But this ice was certainly confluent with that of the Ross Barrier. 



An examination of the map (Plate III.) shows that the eastern portions of all the 

 great glaciers entering Ross Sea along its west coast show a trend somewhat to the 

 north of east as far as Cape Irizar. Thus the East Fork of the Ferrar Glacier, the 

 North Fork and Dry Valley, the Mawson Glacier, and the Davis Glacier all have an 

 E.N.E. trend, whereas the trend of the coast-line is almost exactly north and south. 

 It is suggested that this deflection towards the noi'th is due to the shouldering 

 action of the Ross Barrier with its powerful thrust from the south. 



In regard to the second theory, that the piedmont is formed partly of local snow 

 which has fallen on the surface of the coastal plain, partly of snow drifted from the 

 inland plateau across the ranges, it may be stated that there can be no doubt that 

 vast quantities of snow are conveyed from inland seawards by the action of the 

 plateau wind. Where the plateau wind blows straight down the gateways in the 

 great horst formed by the outlet glaciers, such as the Ferrar, Mackay, and Mawson 

 Glaciers, &c., it carries with it a continuous stream of snow crystals, the air being as 

 thick as a hedge during blizzards on these glaciers, for four or five consecutive days 

 on occasions. Such snow when it reaches the coast is distributed far and wide over 

 the surface of the sea ice. It was this somewhat thick covering of snow with its high 

 sastrugi which prevented our taking the motor car more than about one-third of the 

 way across McMurdo Sound towards the mouth of the Ferrar Glacier. In the late 

 summer, when the sea ice has broken away from near the mouth of the glacier, any 

 snow carried from inland down the glacier by the plateau wind is of course blown 

 out to sea and quickly melts in the salt water. Where, however, the elongated 

 tabular mountains of the great horst, with their steep, almost precipitous, eastern 

 slopes form a lee to the westerly plateau wind, their snow-drifts must necessarily 

 accumulate on a grand scale. 



Professor Hobbs has already suggested that much of the Antarctic ice along the 



shore-line of the continental mass is formed from drift snow. There can be little 



doubt that such is the case. During the few days that the Northern Party were at 



or near the Backstairs Passage Glacier it was noticed that when the plateau wind 



was blowing at times with blizzard force it carried dense masses of drift snow down 



this pass in the range. Vast quantities of this snow were swejst out over the surface 



of the piedmont to the open sea about 15 miles distant, but a considerable amount of 



it must have lodged on the surface of this glacier. Whether or not any portion of 



the piedmont ice of to-day is actually the relic of the old ice mass, which was formerly 



an integral part of the Ross Barrier, is a question which cannot be proved, though it 



is by no means improbable that some of the ice is an actual survival of the former 



Ross Barrier sheet. It may be regarded as proved that a considerable portion of the 



nourishment of the piedmont glacier ice is received from blown snow, and the ice in 



some sense may therefore be considered a snow-dune ice. 



o 



