THE ANTAECTIC ICE-FIELDS. 



45 



glaciers of tlie Antarctic lands farther into the open sea. Even at 

 the 50 th degree of south latitude, ships meet with ice-fields of a size 

 equal to those which on the other side of the earth are only found 

 within the polar circle. In the northern hemisphere the ice-rivers of 

 Greenland and Spitzbergen are not fed by a sufficient quantity of snow 

 to carry them completely out of the bays into which they flow, and 

 into the open sea. Retained in their course by steep lateral cliffs, 

 promontories, and rocky islets, they assume in consequence of all 

 these obstacles a much more irregular form than they would have 

 if they penetrated into the free ocean, like the glaciers of the South 



Figs. 14 and 15.— Icebergs of the Antarctic Ocean ; after Wilkes. 



Pole. The latter are drifted far out of the gulfs, beyond the capes 

 even, and they are only occasionally attached to the submarine base 

 of the continent. In front of this ice- sheet float innumerable 

 islands, through which ships can with difficulty find their way. 

 Thus during the exploring voyage of Wilkes, the Peacock had to 

 steer for a long time in a labyrinth of blocks which threatened to 

 crush her. 



The breaking up of the Antarctic ice occurs in spring and summer, 



