ANTARCTIC CRUISE. 349 



than iii others. The icy barrier retreats several degrees to the south 

 of the Antarctic Circle to the west of Cape Horn, while to the east- 

 ward it in places advances to the northward of that line, which is no" 

 doubt owing to the situation of the land. From the great quantities 

 of ice to be found drifting in all parts of the ocean in high southern 

 latitudes, I am induced to believe that the formation of the ice-islands 

 is much more rapid than is generally supposed. The manner of their 

 formation claimed much of my attention while among them, and I 

 think it may be explained satisfactorily and without difficulty. In 

 the first place, I conceive that ice requires a nucleus, whereon the 

 fogs, snow, and rain, may congeal and accumulate; this the land 

 affords. Accident then separates part of this mass of ice from the 

 land, when it drifts off, and is broken into many pieces, and part of 

 this may again join that which is in process of formation. The sketch 

 in Chapter IX. has already given the reader some idea of its appear- 

 ance in this state. 



From the accumulation of snow, such a mass speedily assumes a 

 flat or table-topped shape, and continues to increase. As these layers 

 accumulate, the field-ice begins to sink, each storm (there of frequent 

 occurrence) tending to give it more weight. The part which is now 

 attached to the land remains aground, whilst that which is more 

 remote being in deep water is free to sink. The accumulated weight 

 on its outer edge produces fissures or fractures at the point where it 

 takes the ground, which the frosts increase ; thus separated, the surface 

 again becomes horizontal, and continues to receive new layers from 

 snow, rain, and even fogs, being still retained to the parent mass by 

 the force of attraction. The fogs have no small influence in con- 

 tributing to the accumulation : some idea may be formed of the 

 increase from this cause, from the fact that during a few hours the ice 

 accumulated to the thickness of a quarter of an inch on our rigging 

 and spars, though neither rain nor snow fell. It may, therefore, I 

 think, be safely asserted that these icebergs are at all times on the 

 increase ; for there are few days, according to our experience in this 

 climate, in which some mode of precipitation does not prevail in these 

 high latitudes, where, according to our observations, ice seldom melts. 

 The temperature of even the summer months being rarely above the 

 freezing point, masses of a thousand feet in thickness might require 

 but few years to form. Icebergs were seen in all stages of formation, 

 from five to two hundred feet above the surface, and each exposed its 

 stratification in horizontal layers from six inches to four feet in thick- 



vol. 11. 88 



