OCEANOGRAPHY AND SEA-ICE 



freezes rapidly. On March i6th the sea was at a tem- 

 perature of 20° F. while the air was about 6° F. The 

 sea was covered with frost smoke "as though it had 

 been boiling." On March 19th the temperature fell to 

 —9° F., the surface froze rapidly, and a splendid crop 

 of ''flowers" resulted. Later as the temperature rose 

 the centers of the flowers melted, for they were formed 

 of saline solutions squeezed up from below, while the 

 ''tips" of the flowers persisted longer as they were due 

 in part to the frost smoke. Some of the "petals" of 

 the flowers were plates two inches across. 



The ice over MacMurdo Sound w^as nine to ten 

 inches thick during the early days of March, 1908, but 

 blew out with the blizzard mentioned above. The next 

 ice layer grew to a thickness of eighteen inches, when 

 it was removed early in April, except a patch which 

 held in near Cape Royds. A few days later the final 

 freezing occurred which persisted all the winter. The 

 sea-ice was about five feet thick at the end of July, and 

 grew to a thickness of six or seven feet by the end of 

 September. Thereafter the cold air had no great effect 

 on the water beneath the ice, which protected it from 

 further cooling. It stayed at a temperature of about 

 29° F. although the air only six feet above it was 

 at a temperature of —51° F., i.e. 80° colder. During 

 the winter I often thought that a diving-bell would be 

 a very comfortable dwelling place, at any rate as far as 

 temperature was concerned. 



165 



