22 Recent Antarctic Exploration 



grain immersed in it increases, and the freezing-point of the 

 medium falls. When ice is removed from the grain by 

 melting, the medium is diluted and its freezing-point rises. 

 The effect produced molecularly by variation of dilution is 

 similar to that produced mechanically by increase and diminu- 

 tion of pressure. The maximum size of the grain at any 

 point in a glacier is roughly a function of its distance from 

 the source, and is a measure of the amount of metamorphism 

 which the ice has experienced (Antarctic Manual, pp. 93, 94). 

 If the Barrier ice-sheet is a self-contained neve' or firn, situated 

 at, and to a great extent below, the level of the sea and we 

 think that Captain Scott's observations clearly point to its 

 being so it can have no motion in its mass under gravity, 

 and cannot therefore develop the adult grain of the glacier. 

 Its granular structure must remain rudimentary like that of the 

 Alpine neve. Being already at the lowest possible level, glaciers 

 cannot flow from it ; and its surplus material is dispersed as 

 icebergs, which are thus generated directly by the neve. 



It is remarkable that, in spite of the very low temperature 

 continuously experienced by the expedition, in certain parts, 

 as on the Ferrar glacier, there was at the beginning of January, 

 locally at least, extensive melting of the ice. The Ferrar 

 glacier appeared to be stationary. There must, however, 

 have been at some time considerable motion of ice from the 

 inner highland to the level of the sea, or to that of the 

 Barrier sheet, in order to furnish the abundance of moraine 

 matter which is found on Ross Island, covers White Island 

 nearly to the summit, and is distributed all over the lower 

 ice-flats in the vicinity of the " Discovery's " winter-quarters. 

 When a glacier is moving, it develops of itself the heat 

 which initiates and promotes the metamorphosis of the 

 ice. No information as to the size of the grain of these 

 glaciers is given ; and indeed it is not easy to obtain it in 

 latitudes where the power of the sun, even at midday, is in- 

 sufficient to disarticulate completely the grains of a mass 

 of ice. The ice of the inland plateau seems to be an accumu- 

 lation of snow more or less consolidated ; the annual incre- 

 ment, if any, is probably small. The continuous and violent 



