PLATEAU AND MOUNTAINS 287 



undoubtedly given rise to a permanent refrigerating system of 

 winds which has made Antarctic coasts much more inclement than 

 they would have been with a less elevated interior. 



There is practically no trace of pre-glacial topography such 

 as might be shown by a moulding of the inland ice cap. We may 

 picture the rock surface like that of upland Norway, as a gently 

 rolling plateau. As the ice mantle covered Antarctica, occupying 

 the more pronounced swellings first, and then spreading in lobes 

 of ice down the broad depressions, we may imagine that a very 

 little difference in the contour might determine the position of 

 the great outlet glaciers where the ice cap drained away to the 

 sea. In other words, the glacier valleys do not appear to owe 

 much to pre-glacial topography. 



Let us now survey the marginal mountain range and the ice 

 plateau more closely. The plateau seems to rise to 11,000 feet 

 near the South geographic Pole, and decreases gradually to the 

 north, being about 7000 feet at the South magnetic Pole. The 

 mountain ranges have peaks, such as Markham and Lister, rising 

 to 15,000 and 13,000 feet respectively, but the average height 

 is perhaps about 9000 or 10,000 feet, while for considerable 

 stretches near Granite Harbour they are only 6000 or 8000 feet 

 high. Every 20 or 30 miles this fairly continuous range is broken 

 by a huge ' outlet ' glacier. Many of these are now well known, 

 such as the Beardmore, which "is .over 100 miles long and 30 

 miles wide, the Ferrar, Mackay, David, &c. They form the 

 only routes from the coast to the interior, and were it not for 

 the ice falls where the glacier covers some irregularity in its rock 

 floor, or the more dangerous crevassed areas, where it sweeps 

 round a corner, or receives the thrust of a large tributary, they 

 would not be difficult to traverse with sledges. The grade is not 

 very steep, and they are to some extent sheltered from the bliz- 

 zard drift which is the great obstacle to Barrier and plateau 

 journeys. Their detailed topography is however very different 

 from that of an area subjected to ' normal ' erosion. 



The regions more especially investigated in the two sledge 

 journeys of the Western Geological Parties in 1911 and 1912 

 were the following: 



(a) The Ferrar and Taylor outlet glaciers (77 40'). 



(b) The Koettlitz ice delta and its hinterland (78 20'). 



(c) Granite Harbour and the Mackay outlet glacier (77). 



