CHAPTER VIII. 

 THE GENESIS AND MIGRATIONS OF PLANTS. 



IF, for convenience of reference, we divide the whole history 

 of the earth, from the time when a solid crust first formed 

 on its surface and began to be ridged up into islands or moun- 

 tains in the primeval ocean, into four great periods, we shall 

 find that each can be characterized by some features in relation 

 to the world of plants. 



That Archean age, in which the oldest known beds of rocks 

 were produced rocks now greatly crumpled by the first move- 

 ments of the thin crust, and hardened and altered by heat and 

 pressure has, it is true, little to tell us. But, as elsewhere 

 stated, even it has beds of Carbon in the form of Graphite 

 veritable altered coal seams which the analogy of later forma- 

 tions would lead us to believe must have been accumulated by 

 the growth of plants. This growth is indeed the only known 

 cause capable of producing such effects. If we should ever 

 be fortunate enough to find beds of the Laurentian series in 

 an unaltered state, we may hope to know something of this old 

 flora. Nor need we be surprised if it should prove of higher 

 grade and more noble development than we should at first sight 

 anticipate. If there ever was a time when vegetation alone 

 possessed the earth, and when there were no animals to devour 

 or destroy it, we might expect to find it in its first and best 

 estate, perhaps not comparable in variety and complexity of 

 parts with the flora of the modern world, but grand in its 

 luxuriance and majesty. Of such discoveries, however, we have 

 no certain indication at present. 



