ORDER OF MOVEMENT OF ICEBERGS 135 



areas of the sea. They are generally found in troops, which 

 may number scores, or even hundreds, of separate masses ; 

 the result is that vast areas of the ocean have their super- 

 ficial waters so cooled down l)y the southernmost individual 

 bergs, that the greater part of the group have little chance 

 to come in contact with warm water ; it is only slowly, as the 

 advanced bergs are melted, that the more northern masses 

 are exposed to a temperature high enough to affect them in 

 any considerable measure. In much the same way the aggre- 

 gation of the icebergs hinders the air from affecting them by 

 its w^armth ; the atmosphere is chilled by the cold sea and 

 the ice with which it comes in contact, and the result is that 

 thick fogs are formed, which send off the rays of the sun and 

 convert the regions about the bergs into a natural ice-house 

 well fitted to preserve them from the effects of the more 

 southern realm into which they have journeyed. In fact, a 

 fleet of icebergs takes its native climate with it as it goes ; it 

 is enveloped by conditions of its own making, as perfectly as 

 if they were designed for the end which they attain. 



The effect of the close order, which is such a common 

 feature of the berg fleet, is so important in their history that 

 w^e must consider the way in which it is brought about. As 

 is easily seen, the cause is found in the landlocked nature 

 of the waters whence they are derived. In the winter the 

 region about the West Greenland glaciers is occupied by a 

 sheet of floe-ice strong enough to retain the icebergs against 

 their native shores. Only for a brief period in summer, in 

 all perhaps, on the average, less than four months, is the 

 water open enough to permit their escape into the wide part 

 of the Atlantic Ocean. When the summer unlocks these 

 Arctic eates, the vast assemblao^e of ice-floes and the im- 



