STUDIES IN THE SIERRA 



By John Mum 



NO. IV. GLACIAL DENUDATION 



GLACIAL denudation is one of the noblest and simplest 

 manifestations of sun-power. Ocean water is lifted in 

 vapor, crystallized into snow, and sown broadcast upon the 

 mountains. Thaw and frost, combined with the pressure of its 

 own weight, change it to ice, which, although in appearance 

 about as hard and inflexible as glass, immediately begins to flow 

 back toward the sea whence it came, and at a rate of motion 

 about equal to that of the hour-hand of a watch. 



Fig. X. 



This arrangement is illustrated in Fig. i, wherein a wheel, 

 constructed of water, vapor, snow, and ice, and as irregular in 

 shape as in motion, is being sun-whirled against a mountain- 

 side with a mechanical wearing action like that of an ordinary 

 grindstone. 



In north Greenland, Nova Zembla, the arctic regions of 

 Southeastern Alaska and Norway, the snow supply and general 

 climatic conditions are such that their glaciers discharge di- 



