THE SOIL. 



The soil is made up of decomposed rocks and decayed or 

 decaying organic matter. The proportion of organic mat- 

 ter is small not averaging in fertile soils more than five 

 per cent. All of the rest of the soil is of a mineral origin, 

 and has at some period formed a part of the rocky crust of 

 the earth. 



By the action of air, and heat, and frost, and the friction 

 of running and falling water, and the movement of rocks 

 and stones in moving water, these substances have been suf- 

 ficiently pulverized to form the foundation material of our 

 present soil. 



During uncounted ages these processes have been going 

 on, and they are still active; and, in addition to these, 

 the chemical changes which result from the exposure of pul- 

 verized mineral matter to the action of air and moisture, 

 and the successive growth and decay of plants, have oper- 

 ated, and are still operating, to ripen the soil to our uses. 



In the early ages, when perhaps the composition of the 

 atmosphere was different from what it is now (and when the 

 soil was surely very different), only plants of a low order, 

 such as are now extinct, could grow at all. These absorbed 

 certain matters from the atmosphere, and, on their decay, 

 gave them to the soil, thus helping to fit it for the growth 



