66 DYNAMICAL GEOLOGY. 



irregular, assuming often striking forms of mountains, 

 castles, cathedrals, etc. (.Fig. 33). 



In Antarctic regions the development of ice is even 



greater. Whatever of land exists there, is completely 



covered with a universal ice-mantle, which pushes out 



ten miles to sea as a continuous ice-barrier. From the 

 margin of this barrier break off regular prismatic blocks 

 of enormous size and thickness (Fig. 34) 



PIG. 34. 



Icebergs as a Geological Agent. 



Erosion. Since icebergs are floating bodies, they do 

 not erode unless they ground. In places like the Banks 

 of Newfoundland, where icebergs ground in great num- 

 bers, they doubtless disturb the bottom. But, when we 

 remember the irregularity of their movements, under the 

 action of waves and tides, and also that the sea-bottom is 

 deeply covered with ooze, we may safely assert that no 

 smooth, striated, moutonneed rocks, such as are produced 

 by glaciers, would be found there. 



Transportation and Deposit. But, in the trans- 

 portation and distribution of materials very widely over 

 the sea-bottom, the agency of icebergs is very important. 

 The Greenland ice-sheet, since it is universal, can carry 

 no moraines atop, but it everywhere pushes seaward its 



