122 THE CULTURE OF FARM CROPS. 



waves : and as the ice melted under the heat of the pressure 

 and friction, great floods emerged from under the glaciers- 

 and carried the broken down rock, sand, and mud, with them, 

 and spread them in the valleys ; forming broad shallow lakes 

 which eventually dried up and left wide areas of soil. 



Thus were formed the broad plains and prairies; the 

 gently swelling vales and the broad valleys ; and the hills 

 and mountains were left to give birth to the rivers which 

 cut their ways through the soil, on their passage to the 

 source from which the all powerful beams of the sun first 

 drew them. 



Then came the first plant ; a humble moss or lichen, cov- 

 ering the soil in the first ages of vegetation, and gradually 

 gathering from the atmosphere the carbon, nitrogen, oxy- 

 gen, and hydrogen; and the various inorganic elements which 

 have been described; furnished by their death and decay 

 the sources from which future ages of life might spring. 

 And by the gradual accumulation of stores of carbon and 

 nitrogen in the soil, a better and richer vegetation was 

 evolved, until the time came when the sweetly odorous 

 flowers; the verdant meadows; the glorious forests; the 

 teeming fruits and the nutritious grains covering the prolific 

 soil; made a fit home for man; and the earth was given to 

 him for his eternal heritage and dominion. 



Thus was the soil formed and man became a tiller of the 

 ground. 



