THE SOIL. 



CHAPTER XVIII . 



THE SOIL. ITS ORIGIN AND FORMATION. 



A study of the principles of geology will be found very 

 useful and instructive to the farmer, for they explain how 

 the soil which he prepares for his crops, and from which the 

 subsistence of man is procured was formed ; from what ma- 

 terials it was derived; and how it came to be available for 

 his purposes. 



The earth was once "without form and void and water 

 covered the great deep." This is the testimony of inspira- 

 tion as given in the Scriptures and it is the testimony given 

 by the rocks themselves. Everything in relation to the 

 rocks and the soil which has been derived from them, prove 

 the combined agency of great heat and of water, in their 

 construction. The solid earth is composed in greater part 

 of a few elements only ; the larger part of the 64 which are 

 known to exist, are found only in small quantities ; and 

 when we enumerate the 8 inorganic substances already men- 

 tioned as contributing the mineral elements of vegetation 

 and add to them the single one alumina which is chiefly 

 represented by clay, we have all the elements which make 

 up the vast bulk of the globe and form the soil which cov- 

 ers its surface. 



The solid rocks which form what we call the crust of the 

 earth are of two kinds, viz : those which give evidence of 

 having been erupted from a molten mass and of having been 

 cooled into a solid state, and those which give evidence of 

 having been deposited by the agency of water. It may per- 

 haps best explain our subject by giving a short history of 

 what is believed to have been the manner in which the earth 

 was brought into its present condition. 



The condensation of the gaseous materials of which the 

 earth is composed, at its original formation, produced a heat 



