3l6 POLAR PROBLEMS 



Antarctic continental shelf is the existence upon the land of a great 

 sheet of continental ice, but, as will be indicated later in this paper, 

 in Weddell Sea there is evidence that faulting also has probably played 

 its part. 



Paucity of Rock Exposures for Geological Evidence 



The great central plateau (8000-11,000 feet) is covered with ice 

 to an unknown depth and is known to descend more or less gradually 

 to low levels in the Adelie Land sector of the continent. It is perhaps 

 a reasonable assumption that similar conditions hold for the rest 

 of the western portion of the Australian Quadrant and the quadrant 

 facing Africa. Only a very small proportion of the land surface is 

 exposed to view. Where the glaciers have cut deep troughs through 

 the coastal ranges or horst, steep rock cliffs, often several thousands 

 of feet in height, stand on either side with their feet buried in mighty 

 screes of debris lying at or about the angle of repose. The peaks of 

 the higher mountain ridges project above the sheets of continental 

 ice, or highland ice, and often have steep slopes on which snow and ice 

 can obtain no hold. Here and there along the coast line comparatively 

 new areas of dark volcanic rock are kept clear by the combined action 

 of insolation and the blizzard winds. All these are, however, excep- 

 tions almost negligible as regards extent, though of supreme importance 

 to the geologist and the explorer. Geological data are fortunately, 

 however, not limited to the evidence acquired from the scant 

 areas thus laid bare to direct observation. Much priceless informa- 

 tion has been gleaned from transported morainic debris drawn from 

 wide areas, to appear in time at the surface of ice sheet or glacier. 



As in the past, so in the future, the evidence which, when pieced 

 together, provides the solution of many of the geological problems of 

 Antarctica must inevitably be in large measure won from erratic 

 material of this kind. 



Australian Quadrant 



Of the quadrants, that facing Australia is by far the best known, 

 both geographically and geologically. This sector of the continent 

 is bounded on the east by Ross Sea and extends westward to Queen 

 Mary Land. A belt of mountainous country forms the western rim 

 of Ross Sea and extends from Cape Adare to the southeastern limit 

 of the quadrant (in 85° S.) where the chain is continued in the Queen 

 Maud Range. The mountains rise abruptly from the sheet of shelf 

 ice known as the Ross Barrier, or from the sea, to heights ranging from 

 8000 to 15,000 feet and thus form a containing buttress to the vast 

 snow plateau of the hinterland. The eastern edge of this range is 

 situated on a meridional zone of stupendous fractures with a displace- 



