28 TALKS ABOUT THE SOIL. 



home for plants and grasses. The sun, we learned, is 

 the great rain-mover; and thus it is indirectly the 

 great soil- mover. 



Added to the moving water we have the wind, that 

 may blow loose dust and sand long distances. Ice 

 in streams may push loose gravel before it along a 

 river-bottom, or even carry it floating on the water. 

 These agencies water, ice, and wind have been 

 sufficient to transport whole mountain ranges from one 

 place to another. All that was required was time, and 

 in the history of the ground a million years may be as 

 one day in our lives. 



There is also one other circumstance to be observed 

 in the slow formation of the soil that now nearly every- 

 where covers the rocky shell of the world. The sur- 

 face rock itself, even where there are no hills, slowly 

 breaks up into fine bits, scraps and dust; and, the 

 surface being level, this broken material left after the 

 weathering of the ground-rock may remain where it is, 

 and thus slowly form a covering of soil over the rock 

 itself. This process is going on all the time, and 

 slowly deepens the soil all over the world. This fact 

 we must enter in our note-books also, because it is 

 of the utmost importance to every man, woman, or 

 child who sows a field of wheat, or plants a flower- 

 seed. 



While we have observed the effects of weathering 

 upon the rocks, and noticed how running water tends 

 to move and sort the loose material broken off from 

 the rocks, we must not forget that there have been in 



