Figure 48. Rounded iceberg. 



Figure 49. Iceberg with a window . 



It is clear that the icebergs encountered cannot always be related to one of these listed forms. 



One sign, however, remains unchanged. A recently calved or recently split iceberg has 

 sharp outlines — like a broken lump of sugar. In time, due to melting and wind wastage, the sharp 

 external forms of the icebergs disappear, yielding to soft, eroded forms. Thus, the degree of 

 rounding of the iceberg's outline is a sign of its relative age. 



As we shall see further, the relation of the underwater deposit to the above-water elevation 

 of sea ice, even for floes having horizontal upper and lower surfaces and vertical side walls, fluc- 

 tuates within considerable limits, depending on the density of the ice and the density of the water in 

 which the ice is floating. 



129 



