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 nourishment of the southern glacier measured by the land area which it has submerged. There is here no marginal land ribbon as in Greenland, 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 descending to even greater depths below ([plate 15 B]).
Fig. 310.—Map showing the inland ice of Victoria Land bordered by the shelf ice of the Great Ross Barrier. The arrows show the direction of the prevailing winds (based on maps by Scott and Shackleton).
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 than those examined in Greenland and Victoria Land. Here in Kaiser Wilhelm Land the ice rises at its sea margin in a cliff which is from 130 to 165 feet in height, then upon a fairly steeply curving slope to an elevation of perhaps a thousand feet. Here the grades have become relatively level, and on ever flatter slopes the surface appears to continue into the distant interior ([plate 14]). Near the ice margin numerous fissures betray a motion within the mass which exact measurements indicate to be but one foot per day, and at a distance of a mile and a quarter from the margin even this slight value has diminished by fully one eighth. It can hardly be doubted that at moderate distances only within the ice margin, the glacier is practically without motion.
Plate 14.
View of the margin of the Antarctic continental glacier in Kaiser Wilhelm Land (after E. v. Drygalski).