230 DISCUSSIONS IN CLIMATOLOGY. 



stratification, which we ever observed which could be 

 regarded as bearing upon the mode of original forma- 

 tion of the ice-mass, was an occasional local thinning 

 out of some of the layers and thickening of others, — 

 just such an appearance as might be expected to result 

 from the occasional drifting of large beds of snow 

 before they have time to become consolidated." * 



The comparative absence of stones, gravel, or earth 

 on the southern icebergs shows, likewise, the flat nature 

 of the Antarctic ice-covering. "We certainly never 

 saw," says Sir Wyville, " any trace of gravel or stones, 

 or any foreign matter, necessarily derived from land, 

 on an iceberg." 



But supposing we should make the extravagant 

 assumption that in this comparatively flat and uniform 

 sheet the pressure, by some unexplained means is not 

 evenly distributed, but that, on the contrary, it is all 

 brought to bear on certain points and consumed in 

 melting the ice, and that the total quantity of ice 

 melted is the exact equivalent of the work performed 

 by gravity ; and let us further assume that the entire 

 mass of the ice is already at the melting-point, and 

 that, therefore, no work is required to raise its tem- 

 perature, then the total quantity of ice melted would 



•9 1 



be of course y^H, or tto of the entire mass. Gravity 



could perform only y^ of the amount of work 



required to melt the entire sheet. If we suppose the 



sheet to be 1400 feet thick, then y-^o of this thickness 



will be equal to 9 feet. A layer of ice about 9 feet in 

 thickness, therefore, is the total amount that gravity 



* "Antarctic Regions," p. 16. 



