No. 216.] 743 



chapter, for these will be very elementary and indispensible, and 

 very useful to those young farmers whose instruction is a little ad- 

 vanced. 



Formation of Arable soil.- — Science has proved two distinct peri- 

 ods in the formation of the globe. In the first, +hose elements destined 

 to form the solid mass of our globe, were in a state of fusion, and 

 were combined during the cooling of the masses, constituting the 

 crystaline rocks. These rocks are composed of silex, alumine, lime, 

 magnesia, potash, soda and oxide of iron, in various proportions. 



After being cooled, the rocks of igneous origin began to suffer 

 the process of disaggregation, by the influence of the water and at- 

 mospheric action. The small particles (deLris) resulting from this 

 process were deposited by the waters in horizontal beds, and after- 

 wards consolidated. This was the second period of the globe's for- 

 mation — the Diluvian Period. We find in these rocks of sedimen- 

 tary origin, the same elements, as in those of the igneous formation, 

 but the organic (debris) particles, which are found in them in great 

 abundance, indicate that living plants and beings already were exist- 

 ing at the period of their formation. The causes which disaggregat- 

 ed (crumbled) the primitive rocks, also continued to act on the sedi- 

 mentary rocks ; and the final result of their decomposition, was the 

 formation of the earths which cover them, the chemical composition 

 of which partakes necessarily of the nature of the rocks from which 

 they were derived. The earth thus formed has nourished the vegetables 

 and the animals which constantly perishing and renewing, leave in 

 the bosom of the soils, their remains. That is to say organic 

 matter. 



Vegetable earth, there is composed of inorganic (debris) particles 

 from the decomposition of rocks and of organic (debris) particles 

 from that of animals and plants. 



A few words now on the constituent principles of soil. We have 

 spoken above, of the chemical composition of the minerals which 

 compose the primitive rocks. The three first elements. Silica, Alu- 

 mine, and Lime, seldom form less than 93 per cent, of the mass of 

 soil, and therefore constitute the bases of all cultivatable soils. — 

 Magnesia, Potash, Soda and Oxide of Iron, p'ay only a secondary 

 part. We shall content ourselves with mentioning as constituents of 

 soil, also Manganese, Sulphur, Phosphorus and Chlorine. 



