NUMMULITES AND MOUNTAINS. 195 



CHAPTEE XIX. 



NUMMXJLITES AND MOUNTAINS. 



Both tlie proverb " as old as the hills," and the 

 phrase the " everlasting hills," are l:nit the expression of 

 the natural tendency of the human mind to regard all 

 hills and mountains as the most lasting and ancient 

 objects with which we are familiar. As, however, is so 

 often the case, science steps in and tells us that, although 

 the proverb and the phrase are true enough as regards 

 human experience, jet that when we go bact and study 

 the origin of things, as revealed by geology, we find that 

 many hills and mountains — and more especially the 

 highest of them — are actually among the very newest 

 features in the phvsiognomy of the earth, and that the 

 expression ' ' as old as the plains " would, in many instances, 

 be a far truer simile than the one current. 



If, indeed, we reflect for a moment, we shall l)e con- 

 vinced that the highest mountains of the globe — always 

 excejjting volcanoes, which have the power of renewing 

 their height — must necessarily, as a general rule, be 

 younger than nianv of those of lower height, or even than 

 the plains from which they rise. Thus rain, snow, frost, 

 and rivers are perpetually tending to wear down and wash 

 away all the higher points of the earth's surface, and to 

 carry the debris to the valleys below. Consequently, we 

 are led to conclude that, primil facie, the higher a moun- 

 tain range is, the less time it has been subject to this 

 washing-away process, and, therefore, the yoiuiger it is as 

 regards relative age. It might, indeed, be objected to this 

 that the mountains that are now the highest have always 

 been the highest ; and that at the beginning of all things 

 their original height as much exceeded their present 

 height as the latter does that of the smaller ranges. In 

 this view, however, their original heights W(nild have had 

 to be so stupendous as to be almost inconceivable, and 



o 2 



