182 GEOLOGY. 



FOURTH EPOCH. 



Universal deluge ; appearance of aerolites ; trains of erratic 

 masses; beds of rolled flints ; change in the astronomical posi- 

 tion of the planet; extinction of many races of large animals; 

 new races smaller; volcanic phenomena very powerful; erec- 

 tion of the highest mountains; appearance of Man upon the 

 globe; local inundations; sinking of valleys at various stages ; 

 diminution of intensity in volcanic phenomena; actual period. 



EARTHS OF THE FOURTH EPOCH. 



DILUVIAL EARTH. 



This earth is composed exclusively of sand and rotted flints 

 mingled without regular stratification. Diluvial deposits are 

 most usually accompanied with erratic masses. This appel- 

 lation is given to enormous fragments of rock more or less 

 rounded at their angles ; some are known which weigh as 

 much as three hundred thousand kilogrammes. These va- 

 rious materials are generally in a movable condition; some- 

 times, however, we see sands and flints cemented by a marlous 

 or ferruginous clay introduced by infiltrations which still 

 continue at some points. This earth includes no remains of 

 those singular animals which abound in the tertiary soil. 

 Pachydermata, however, still prevail [the Mammoth, Masto- 

 don, Rhinoceros, Hippopotamus, Tapir]. These Pachyder- 

 mata are attended with numerous remains of Horses, large 

 Ruminantia [Stags, Oxen] ; remains are also found of Hyenas, 

 Bears, Tigers, &c. In caverns, called bony gaps, in the midst 

 of a red cement, we also find remains of two gigantic Edentata, 

 the Megatherium and Megalonyx. 



FOSSIL ELEPHANT. RUSSIAN MAMMOTH. 



From fifteen to eighteen feet high ; covered with a thick 

 reddish wool, and with long, stiff and black hairs, forming a 

 crest along the back ; enormous tusks implanted in alveoli 

 longer than those of our Elephants; in other respects it re- 

 sembles the Indian Elephant. It has left thousands of car- 

 cases from Spain to the extremity of Siberia, and some are 

 found in every part of North America. Its tusks are so well 



