THE ANTARCTIC REGIONS. 51 



solid state ; the surface is always at a very low temperature ; snow 

 does not melt as it falls, and the sea is thus sometimes covered with 

 a continuous sheet of frozen snow ; sometimes with enormous floating 

 blocks of ice which are driven by the currents. Meeting with these 

 floating masses of ice is one of the dangers of polar navigation. 

 Captain Scoresby has given a very detailed description of the different 



Fig. 8. Mounts Erebus. and Terror. 



kinds of ice met with in the Arctic Seas. The ice-fields of this writer 

 are extensive masses of solid water, of which the eye often cannot 

 trace the limits ; some of them have been met with thirty-five leagues 

 in length and ten broad, with, a thickness of from seven to eight 

 fathoms ; but generally these ice-fields rise only four to six feet above 

 the water, and reach from three to four fathoms beneath its surface. 

 Scoresby has seen these ice-fields forming in the open sea. When 

 the first crystals appear, the surface of the ocean is cold enough to 



