THE HISTORY OF THE GROUND, 31 



up, transported, and sorted out again, till it is im- 

 possible to tell just how old any particular soil may be. 

 Plants and living creatures also helped to form new 

 soil. Shell-fish and countless millions of tiny creatures 

 swarmed the old seas, only to die, and leave their shells 

 and skeletons to make new stones that were afterwards 

 lifted into hills, only to be torn down again, and scat- 

 tered far and wide to form new soils. 



VII, PLANTS AND LIVING CREATURES AS 

 SOIL-MAKERS. On the rocks everywhere to-day 

 we find lichens and mosses ; dull, slow-growing plants, 

 that live low, strange lives on the bare face of rocks 

 where no other plants could grow. With your knife, 

 scrape off these close-clinging lichens and mosses, and 

 under them the rock is dusty. The plants are slowly 

 destroying the surface of the rocks, and forming a thin 

 dust in which they can find a foot-hold and live. 

 These plants perish in time ; and their dusty, powdery 

 remains slip into cracks and fissures of the rocks. 

 Seeds blown by the wind lodge in these cracks, and 

 spring up and try to live in the scanty soil. It is a 

 soil, because the mosses powdered the rocks, and 

 made a fine stony dust. Their own remains also 

 added more material, and the seeds found what they 

 wanted, food and a place to grow. The plants from 

 the seeds perished, and their remains were added to 

 the soil. In this way all plants since the world began 

 have helped to form the soil. The plants perished in 

 the changes that came over the world. No doubt 

 many times soils were formed, and trees grew for 



