310 



GEOLOGY. 



Fig. 179. 



recognized, the advance in thought and contrivance hav- 

 ing enabled man to discover the art of preparing it, by 

 various smelting processes, for this purpose. It is curious 

 to notice how each of these ages has its peculiar style 

 of ornaments, dwellings, etc. There is no literature, and 

 therefore no history, in so rude a condition as that of the 

 Stone age, and almost none in the Bronze; but when a 

 nation or tribe is so far advanced in the arts as to work 

 iron, there is a literature, small at first, but increasing 

 with every advance in the arts of civilization. 



421. Animals. In the age just previous to the age of 

 Man brute force held sway in the animal kingdom. It 

 was fitting, therefore, that as the reign of intellect in the 

 world was ushered in, such monsters as the megatheri- 

 ums, mammoths, mastodons, etc., should drop out of ex- 

 istence, and that the animals so useful to man, and so 

 easily controlled by him, as the ox, the horse, the sheep, 

 etc., should appear upon the earth in such abundance. 

 The line of separation between this and the Terrace pe- 

 riod in regard to animals is not a fixed and definite one. 

 It is not so even in regard to the Mammalia. Some ex- 

 isting now began their existence in the Terrace period, 



