2 INTRODUCTION. 



the Biscnvenj, thirty-nine years later, was able to explore this ice barrier more thoroughly 

 than had been done by any other explorer. He found that the ice-cliff extended from 

 Cape Crozier almost due east to the new land which he discovered and named King 

 Edward VII Land. The height of the Barrier varies between a few feet and 240 feet, but 

 the general height is between 50 and 100 feet. Scott was unable to proceed to the east of 

 King Edward VII Land owing to thick ice. With Scott's first expedition what may be called 

 the permanent extent of the Ross Sea on its western and southern sides was fixed. 



The extent of the Ross Sea on the east is not known. Every explorer has had his 

 progress in this direction stopped by thick, impassable sea ice. It is obvious that the edge 

 of this ice varies from year to year. In 1842 Ross sailed up the east of the Ross Sea along 

 a course almost due north-west from near King Edward VII Land, and he found ' compact 

 hummock}^ ice ' to the east of him. 



In 1912 Evans in the Term Nova sailed somewhat to the east of Ross's track, and he 

 had the greatest difficulty in forcing his way through the pack ice. There can be little 

 doubt that the sea to the east of 165° W. longitude is permanently covered with ice, and 

 that this meridian may be considered to limit the open water of the Ross Sea on the east. 



Looking now at the map we see that the Ross Sea on the north opens into the Antarctic 

 Ocean in about latitude 70° S., and is bounded on the west by the coast of the high 

 tableland, on the south by the Great Ice Barrier, and on the east by an undefined mass of ice 

 or land which is probably at or very near sea-level, in any case the probabilities are against its 

 being high land similar to that on the west. 



For our discussion of the meteorology of the region it is essential to have some knowledge 

 of the varying ice conditions of the Ross Sea. Unfortunately the data available are very few, 

 and they chiefly refer to the three summer months, December, January, and February. 



During January the Ross Sea is nearly free from ice between the coast of South Victoria 

 Land and the heavy sea ice near longitude 165° W. There are, however, isolated patches of 

 pack ice and floating bergs to be met with in all parts, and probably these occur more fre- 

 quently in the eastern than in the western half. These floating masses of ice are indicated 

 by lozenge-shaped areas in figure 1. North of the Ross Sea there is an almo.st constant stream 

 of pack ice which has broken oft' from the coast of the Antarctic Continent and is slowly 

 drifting from east to west. The Terra Nova, in 1910, entered this stream in latitude 65|-° S. 

 and took nearly three weeks to force her way through, which she did not do until she was in 

 latitude 71|-° S. 



In March the sea commences to freeze, but the wind is a great obstacle to the formation 

 of a peimanent coat of ice. During March 1910 the sea in McMurdo Sound froze over as 

 far as the eye could see several times, only to have every bit of ice removed by a subse- 

 quent blizzard. In April the ice along the coast gradually became sufficiently thick not to 

 be removed by the wind, and afterwards daily increased in thickness and so became more 

 and moie able to withstand subsequent gales. It was not until the end of May that the 

 Sound was completely frozen over. During the winter of 1912 the gales were so frequent 

 that the Sound never became properly frozen over, and open water extended right up to 

 Cape Evans for the greater part of the winter. 



The wind must play a similar part in the freezing of the Ross Sea, and as there is very 

 much more wind over the western half of the sea than over the eastern half it is almost 

 certain that the ice will form earlier and grow much thicker in the east than in the west. 



By the middle of the winter it is probable that the ice conditions over the Ross Sea 

 are somewhat as follows. The greater part of the eastern half of the sea is firmly frozen 



