GEOLOGY. 563 



CHAPTER V. 



TERTIARY EPOCH. 



We have just seen unrolled before our eyes a phase of 

 creation in which all animal life was under the dominion of 

 a legion of frightful reptiles. In the tertiary epoch these 

 had disappeared into the abysses of the globe, and peaceful 

 and luxuriant nature was animated for the first time with 

 varied races of inoffensive mammals, which spread over the 

 whole earth from pole to pole. Among the remains of these 

 animals, dug out of the soil and reconstructed by the skill 

 of the anatomist, some astonish us by their singular forms, 

 others by their colossal size. The creation of the present 

 time seems to have quite degenerated, when compared to 

 these giants of the animal kingdom ! Hence, looking at 

 its predominant feature, this epoch might be called the 

 epoch of the mammals. They predominate throughout. 



In the course of ages the crust of the earth, augmenting 

 in thickness as it steadily cooled down, had become compact 

 enough to intercept the central heat ; and hence the solar 

 influence, gaining the predominance, now began to mark 

 out the separate climates. 



The tertiary fauna displayed extreme richness, and among 

 the animals it offers in profusion the list of those belong- 

 ing to contemporary genera is visibly increased. We find 

 monkeys, bats, genets, marmots ; and now for the first time 

 cetaceans appeared in the seas. 



But the most remarkable of all the animals of that day 



