Practical Farming 



remains, there is a great store of carbon in the form of 

 graphite or black lead, the material from which our lead 

 pencils are made. Now, as we know of no source from 

 which this carbon could come but from the carbon dioxide 

 in the air, and the only way in which this can become 

 fixed as carbon is through the action of plants, taking the 

 carbon through their leaf-green, it is assumed that there 

 must have been a vast amount of vegetation burned up in 

 the metamorphosis of what are now the oldest rocks 

 visible on the earth. Then in later ages, as the action of 

 the heat, water, and air gave to plants some soluble food, 

 there began a growth of vegetation. 



The evidence of geology is that the only part 

 The First ^f ^j^^ American continent above the seas in 



American , ,. . , . . , 



Land ^^ earlier ages consisted of a strip across the 



continent in Canada known as the Laurentiaq. 

 fonnation , from which extended a strip down where the 

 Appalachian system of mountains was formed. All the 

 ^reat interior was occupied by a vast inland sea, extending 

 :rom what is now the Gulf of Mexico to the arctic regions. 

 There was a slow elevation of this interior, and the inland 

 sea became a series of swampy fiats to which the vegeta- 

 ;ion gradually added by its decay. The remains of this 

 vegetation show that there was a cHmate of great warmth 

 extending far northward, and intense moisture in the at- 

 mosphere. Plants that are now of a very lowly form, 

 such as our mosses and ferns, then grew to an immense, 

 tree-like stature, since plants of that character are better 

 fitted to use large quantities of carbon dioxide than the 

 plants of modem times, and the atmosphere was too full 

 of this poison to animal life to permit their existence in 



