THE CONTINENTAL GLACIERS OF POLAR REGIONS 281 



vasses and so emerge at a level considerably above the glacial 

 floor. It may thus come about that the outwash plain is built 

 up about the nose of the glacier so as partially to bury it from 



/^r^^^, nu-t-^a^ P^ fn ^ m ~ - . 



^^^^^^Kii^^^y^ : * - :: ^ 



FIG. 309. Diagrams to show the manner of formation and the structure of an 

 outwash plain, and the position of the fosse between this and the moraine. 



sight. When now the ice front begins a rapid retirement, a de- 

 pression or fosse (Fig. 309 and Fig. 339, p. 314) is left behind the 

 outwash plain and in front of the moraine which is built up at the 

 next halting place. 



The continental glacier of Antarctica. In Victoria Land, upon 

 the continent of Antarctica, so far as exploration has yet gone, 

 the continental glacier is held back by a rampart of mountains, 

 as has been shown to be true of the inland ice of Greenland. The 

 same flat dome or shield has likewise been found to characterize 

 its upper surface (Fig. 310). 



The most noteworthy differences between the inland ice masses 

 of Greenland and Antarctica are to be ascribed to the greater 

 severity of the Antarctic climate and to the more ample nourish- 

 ment of the southern glacier measured by the land area which it 

 has submerged. There is here no marginal land ribbon as in Green- 

 land, but the glacier covers all the land and is, moreover, extended 

 upon the sea as a broad floating terrace the shelf ice (Fig. 311). 

 This barrier at its margin puts a bar to all further navigation, 

 rising as it does in some cases 280 feet above the sea and descend- 

 ing to even greater depths below (plate 15 B). 



In that portion of Antarctica which was explored by the German 

 expedition, the inland ice is not as in Victoria Land restrained 

 within walls of rock, but is spread out upon the continent so as to 

 assume its natural ice slopes, which are therefore much flatter 



