Cn XIII.] 



THE QUANTITY OF ICE AND SNOW 



287 



appeared from Aconcagua, although it attains the height of 



23,000 feet. 



much 



at these great heights is evaporated rather than thawed.* 

 In the Himalayas, where 



some 



mountain 



attain the height of 29,000 feet, the snow-line on the southern 

 side of the chain occurs at 13,000, and on the northern at 



authorities. 18.000. < For 



some 



moist 



< deposit their snow almost wholly on the southern side, while 

 the northern is exposed to the evaporation of one of the driest 

 • j? -i-t^ ™i^i™ ' Tti lilra mnrmA-r when colder winds from 



temp 



tern 



IS 



tbiiua-x ^iv iug ^— , they will part with their moisture, so that the 

 snow will increase on the outer margin of the antarctic con- 

 tinent rather than in the interior. As it is well known that 

 great falls of snow take place chiefly when the thermometer 

 is about 32° F., and that little, if any, ever falls when the 



much lower, it would certainly be rash to 

 assume that intense cold near the pole during the aphelion, 

 when the excentricity is very large, tends to generate more 

 snow than the dry atmosphere can absorb, 

 seen by Eink to have vanished from the surface of Greenland 

 in the latter months of autumn, so that lines of erratic blocks 

 Avere disclosed to view. In like manner, B 

 observed blocks of stone on the snows of Victoria Land — facts 



Much 



Hooker 



much 



emoved from 



James 



liquefaction in high latitudes. Sir 

 that the ice of the Great Antarctic Barrier, in lat. 78° south, 

 rose only 150 feet above water, and he estimated its total 

 thickness, above and below water for about 600 miles, to be 



mo 



mere matter 



may 



Humboldt 



that the average thickness of snow on the Alps would be only 



_ _ a ""W 



much thicker m many 



leys, it would be thin on the ridges and intervening table- 



lands. 



* Darwin, Journal of the Beagle, 1845, p. 245. 



