184 Charles Darwin. 



and others in Germany and England, have become 

 remarkably well understood. Though there is still a 

 vast area unexplored, we know enough of the ancient 

 earth and its history to enable us to view it compre- 

 hensively. If we could make a section of the crust 

 we should find the rocks arranged layer by layer. 

 At a certain depth would be what is known as the 

 Eozoic rocks, which if they have contained life do 

 not show evidences of it. Above this we find a 

 layer containing shells and low forms, and so on up, 

 layer after layer, for thirteen thousand feet in New 

 York State, or nearly two miles of solid rock, nearly 

 all the strata being characterised by peculiar forms 

 of life. If we examine these, one after another, up 

 through the crust, we notice that there appears to 

 be an elaboration of structure the higher up we 

 proceed. Thus in the Devonian, or just below it, 

 we first find back-boned animals — fishes ; then in a 

 succeeding age reptiles ; then milk-giving animals, 

 and finally man. In other words, there has been an 

 apparent evolutionary movement here, so that view- 

 ing the results we can easily imagine that one who 

 had studied the rocks as did Darwin might arrive at 

 the conclusion that he was looking at the different 

 steps in the evolution of life. 



How long was the thirteen thousand feet in New 

 York forming ? The mind fails to grasp the figures, 

 nor can we realise it without taking up instances that 

 are well defined and familiar. In one of the West- 

 em States there is an elevation, known as Amethyst 

 Mountain, a mile or more high. One side has been 

 worn away by the elements, so that it appears to 



