176 GLACIOLOGY 



snow above, leave behind the vertical wall of the ice-foot. Obviously the tendency 

 is, in rough weather, for nearly all the sea ice to break away right up to the edge 

 of the rocky shore-line, and it is the cliff which is finally left which constitutes the 

 ice-foot. This cliff is attacked by the sea surface below, which mechanically erodes 

 it, as well as by the warm sea water which causes it to thaw, the combined result 



Cape Royds 



Ho 



Prismatic Sea Ice 



Drin Snow 



TideCrack 



5 10 



Scale of Metres 



Fig. 57 



being that the ice-foot cliff is hollowed out in a series of caves, or is eroded back 

 below right to the rocky cliff face. Meanwhile thaw above removes a great deal 

 of the superincmiibent old snow-drifts. Thus, as the summer advances, the ice-foot 

 cliff is constantly dwindling. With the heaving of the waves and rise and fall of 

 the tide the roofs of the caverns of the ice-cliffs are subjected to a constant drip 

 of salt water, and this forms a beautiful set of icicles. The general appearance of 

 the ice-foot, when the thaw has advanced as late in February as the 18th, the time 

 the photograph was taken, is shown on the second sketch. 



