AMONGST THE SOUTHERN ICE. 237 



two-storied have their lower story commonly, as in the bero- 

 figured here in the text, only at one of their ends. Probably a 

 certain amount of lower platform existed all round this berg 

 when it first rose, but this was cut away on all the sides where it 

 was narrow, by being undermined by the waves. The line of 

 the main upper cliff was thus soon reached on these sides, and 

 this cliff was then itself further undermined, so that, as shown 

 in the sketch, the old wash-line was obliterated, and remained 

 only at the base of that cliff which was protected by the still 

 remaining secondary platform. 



The greater undermining of bergs at one side may, no doubt, 

 be due to their taking up, from the shape of their parts exposed 

 above water and the relation of these parts in position to the 

 form of the parts below water, a particular direction with regard 

 to the wind, and maintaining this so that one particular side is 

 usually the windward one, and therefore most battered by the 

 waves. 



It seems far more difficult to explain how it occurs that bergs 

 suddenly rise to a considerable height further out of water than 

 that at which they have floated before. Such a sudden rise 

 must necessarily be supposed in order to account for the two- 

 storied form. 



In order that, in the case of the berg figured for instance, a 

 rise should occur from the height of the old wash-line to the 

 present water-line, a mass of the berg above water must have 

 been suddenly removed, equal in volume to the whole part 

 of the berg above water lying below the level of the top of the 

 lower story. 



It seems almost incredible that such a mass should break off' 

 and fall away suddenly. A splitting of a berg in two can 

 be readily understood, but the mass in this case must come 

 entirely from the part of the berg above water. It cannot have 

 split off at an angle, for the walls of the berg in question were 

 perpendicular cliffs. The berg certainly had never toppled. 



A different explanation possible is, that nine times the 

 volume of ice above referred to, was suddenly added to the part 

 of the berg below water by its passing into cold water or a 

 change of season. It may be that the raised story represents 



