2 AGRICULTURE FOR BEGINNERS 



Learned men believe that at first the surface of. the 

 earth was solid rock. How were these rocks changed 

 into workable soil ? Occasionally a curious boy picks up 

 a rotten stone, squeezes it, and finds his hands filled with 

 dirt, or soil. Now, just as the boy crumbled with his 

 fingers this single stone, the great forces of nature with 

 boundless patience crumbled, or, as it is called, disinte- 

 grated, the early rock mass. These simple but giant- 

 strong agents that beat the rocks into powder with a club- 

 like force a million fold more powerful than the club force 

 of Hercules were chiefly: (i) heat and cold; (2) water, frost, 

 and ice ; (3) a very low form of vegetable life ; and (4) tiny 

 animals, if such minute bodies can be called animals. In 

 some cases these forces acted singly; in others, all acted 

 together to rend and crumble the unbroken stretch of rock. 

 Let us glance at some of the methods used by these skilled 

 world makers. 



Heat and cold are working partners. You remember that 

 most hot bodies shrink, or contract, on cooling. These early 

 rocks were hot. As the outside shell of rock cooled from 

 exposure to air and moisture, it contracted. This shrink- 

 age of the rigid rim, of course, broke many of the rocks, 

 and here and there left cracks, or fissures. In these fis- 

 sures water collected, froze, and, as freezing water expands 

 with irresistible power, the expansion still further broke 

 the rocks to pieces. The smaller pieces again, in the 

 same way, were acted upon by frost and ice, and again 

 crumbled. This process has continued more or less until 

 this day. 



Running water was another giant soil former. If you 

 would understand its action, observe some usually sparkling 



