CHAPTER X 



PREPARATION OF THE EARTH'S SUEFAOE FOR PLANT 



LIFE 



Changes in the Earth's Surface. The surface of the 

 earth is constantly changing. In fact change is the funda- 



TC A RECENTLY COOLED LAVA SURFACE 



A surface probably somewhat like the original surface of the earth. 



mental law of life. There are forces constantly building up 

 and other forces just as steadily tearing down. Sometimes 



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