Practical Farming 



limestone, is the oldest, though in the hills it comes to the 

 surface. He would be convinced that in the valley there 

 had been agents at work forming the later accumulation 

 on top of this older rock. 



When the earth was a molten mass, glow- 

 Agencies at jj^g ^^Yi intense heat, the waters that after- 

 Work in Sou ^ . . , . ' , , 

 Formation '^^^^ formed the great deep were a dense 



vapor, Ughted only by the glowing globe. 

 Gradually, through long ages, the surface cooled and God 

 said, "Let the waters be gathered together unto one place, 

 and let the dry land appear" ; and it was so. The cooling 

 of the surface allowed the condensation of the vapors, 

 and the waters naturally filled the depressions in the sur- 

 face. Thus seas were formed. The dry land was the 

 hard rock crust crystallized. 



Then came the action of the various agencies to which 

 we owe the formation of what we to-day call soil. This 

 condensation opened up the surface of the earth to the 

 light and action of the sun. We must understand that 

 Hght, sunlight, is one of the phenomena of motion; and 

 that one of its rays travels through space at the rate of 

 186,000 miles in a second of time, a rate utterly incon- 

 ceivable to us. The energy of the sunshine awakes in 

 nature energy of a different sort, resulting in what we call 

 heat. The rays of the sun excite motion in the molecules 

 of the soil and water, causing them to be pushed apart; 

 and by the radiation of heat set the atmosphere in motion, 

 causing wind. Much of the heat formed goes back to the 

 air through this radiation, especially during the nights. 

 In the long nights of the arctic regions more goes back 

 than in the tropics, and differences of climate are largely 



