GENESIS OF THE SOIL AND ITS POSSIBILITIES 175 



has been termed the universal solvent, and it is not 

 difficult to see how active it must have been at the time 

 of which I speak. The sudden cooling of the surface 

 at the spot where a drop of water struck would tend 

 to crack it, the hot water would dissolve quickly any 

 of the substances soluble therein, and this continual 

 bombardment of boiling water must have had a tre- 

 mendous effect in disintegrating the original crust 

 formed over the earth's surface. As the earth contin- 

 ued to cool and diminish in size, the original surface 

 wrinkled and formed hills and valleys. The continual 

 descent of water would finally permit some of it to 

 remain in the liquid state upon the earth's surface, and 

 this coursing down the valleys continued the disinte- 

 gration, both by solution and attrition. The original 

 mineral matters were thus brought into a form of solu- 

 tion or suspension, and, seeking their natural chemical 

 affinities, began to form from the first igneous rocks, 

 the first sedimentary rocks. These are the rocks which 

 we now see in strata, underlying the greater part of the 

 earth's surface. All these stratified rocks must have 

 been laid down under the water, and thus we are con- 

 vinced that the surface of the earth during the long 

 period of" the formation of the soil must have been alter- 

 nately above and below the surface of the water collected 

 upon the globe. 



" When organic life came upon the earth's surface a 

 new disintegrating force was introduced. Organic life, 

 even in its smallest forms, such as bacteria, acts with 

 vigor in decomposing rocks. The larger forms, which 

 produce rootlets, help this disintegrating process along. 

 These toots find their way into crevices of the rocks, 

 and tend to split them open and to admit water below 

 their surface. Certain bacteria also tend to oxidize 



