THE WORK OF SNOW AND ICE. 



295 



form of cliffs above it. As a result, the surfaces of ice-caps are com- 

 paratively clean, except at their edges where the ice is thin. 



Fig. 269. — Side view of end of a glacier on the south side of Olriks Bay, North Green- 

 land. 



Fig. 270. — Closer view of a part of the ice shown in Fig. 269. 



Englacial material may become superglacial by surface ablation. In 

 this case the drift does not rise, but melting brings the surface of the 

 ice down to its level. This occurs chiefly at the end or edge of the ice, 



