216 



NATURE FOB ITS OWN SAKE 



The old Ap- 

 palachians. 



The older 

 plains. 



Worn-down 

 mountains. 



glacier grinds, and the avalanche tears. All 

 told, the wearing-down process is very effective. 

 Perhaps, long before the Alps were bent upward, 

 the Appalachians were towering in the air, the 

 loftiest mountains on the globe ; but countless 

 ages have given the elements the chance to wear 

 them away, until to-day the ridge lines are al- 

 most horizontal, and the once spectral peaks, 

 that may have projected like dragons' teeth, are 

 no more. The torn and splintered look of the 

 Alps and the Andes but prove their youth. 

 The time will come when they will be worn 

 away to low hills, and finally reduced to the 

 common level. The flat plains, which we never 

 think of as rock-based, are perhaps, in their 

 foundations, the spots of earth that have re- 

 mained undisturbed the longest of all. 



Many of the hill-ranges that lie about us 

 to-day are merely very ancient mountains de- 

 nuded of their mountain features by the con- 

 stant wear of the elements. But all of them are 

 not of this character. Some of the hills were 

 originally formed not by a fold but by a 

 crack or split in the crust which has allowed 

 one side to sink down and left the other side 

 exposed to view, in abrupt cleavage, as it were. 

 Such hills are not usually very high, and their 



