474 POPULAR SCIENCE MONTHLY. 



6. The points of resemblance between the two sections exposed, 

 one by a steam shovel, the other by river action, are the horizontal 

 position of the strata and the alternations of beds of unlike character. 

 The differences are mainly that the beds making up the mountain 

 show that they are built up of alternating layers of sand (now con- 

 verted into a sandstone) and clay (now in the condition of a slate). 

 Are not these the products of a decayed continent? Is their position 

 to be explained otherwise than along the lines already stated? Our 

 only difficulty in readily accepting this conclusion is founded on a 

 hereditary belief, born in ignorance and nourished to maturity by 

 superstition, that the earth came into existence as we see it to-day, the 

 surface dissected by valleys in which the rivers find established 

 courses to the sea ; possessing a multiplicity of highland and lowland, 

 granite mountains and marble hills, as a result of some plan carried 

 into effect as a creative act. Science has revealed the impossibility 

 of this interpretation. Considered in the light of evolution, acting 

 through an immense period of time, by means of the processes 

 already enumerated, the diversity of land form is made plain to us, 

 and the ever-varying characters of rock structure and composition are 

 in the main made easy of comprehension. Viewed in the light of the 

 foregoing pages, and illustrating as they do land form and the greater 

 part of the earth's crust, the rock structures revealed on the sides of 

 the mountains and canons, as well as the broader valley itself, take 

 on a new and more intelligent interest. High and enduring as the 

 mountains may appear, resistant as their solid rocks may seem, they 

 are doomed as mountains to the same fate that their own structure 

 and composition - prove to have overtaken earlier mountains before 

 them. 



The earth has known no cessation in this cycle of decay, deposi- 

 tion, and elevation; again and again have continental masses been 

 raised from the ocean floor only to become a prey to the forces that 

 destroy them. These cycles will continue — mountain ranges will fade 

 away and new ones will be born. A more permanent relationship 

 between the lowland, the upland, and the ocean level will never be 

 attained until the forces that warp and wrinkle the earth's crust shall 

 have ceased forever. 



M. Henri Bourget. of the Toulouse (France) Observatory, has called 

 attention in Nature to a common phenomenon which he believes has not, 

 been mentioned in any scientific book. If one end of a bar of metal is 

 heated, but not enough to make the other end too hot to be held in the 

 hand, and then suddenly cooled, the temperature of the other end will rise 

 till the hand can not bear it. All workmen who have occasion to handle 

 and heat pieces of metal, he says, know this. 



