190 THE WONDERS OF GEOLOGY. Lect. II. 



deposits, the remains of existing species of animals, and of 

 man and his works, are entombed, — in the ancient alluvial 

 sediments, those of large extinct mammalia, are chiefly 

 imbedded, and no vestiges of human remains have been 

 discovered. 



Thirdly — that the bones principally belong to extinct 

 mammalia, related to the elephant, hippopotamus, sloth, 

 horse, deer, &c. ; and to the bear, hyena, tiger, and other 

 carnivora ; and with these are associated the remains of 

 recent species. 



Fourthly — that in the period immediately antecedent to 

 the present state of the earth's surface, the dry land teemed 

 with large herbivorous animals, which roamed through the 

 primeval forests, unmolested, save by beasts of prey. Nu- 

 merous species and entire genera have since been swept 

 away from the face of the earth, — some by physical revo- 

 lutions, others by a gradual decadence, — while many have 

 been exterminated by man. 



Lastly — that the various deposits in which these fossils 

 are imbedded, whether formed in the beds of lakes, rivers, or 

 estuaries, have been elevated above the level of the waters 

 and become dry land, at a comparatively recent period, and 

 now constitute fertile countries, supporting busy commu- 

 nities of the human race. 



I have thus endeavoured to interpret one chapter in the 

 ancient physical history of our planet, and explain the 

 records of one epoch in geological chronology. We have 

 entered upon the confines of the past, and already we find 

 ourselves surrounded by an innumerable population of un- 

 known types of being, — not as dim and shadowy phantoms 

 of the imagination, but in all the reality of form and 

 structure, and bearing the impress of the mighty changes of 

 which they constitute the imperishable memorials. We 



