NATURE AND ORIGIN OF THE SOIL. II 



Conclusions: 



i-All our soils have come from the breaking down of rocky 

 material and the decay of former plants. 



2 Soils may be classed as follows: sandy, clay, loam, and vege- 

 table or humus soils. 



3 The texture of the soil depends upon the amount of sand, 

 clay, and humus mixed together forming it. 



4-The nature of the soil depends to a large extent upon the 

 nature of the rocks out of which the sand and the clay have been 

 formed. 



5-The rocks have been broken up by the action of the air, the 

 freezing of the rain water in the rocks, the grinding of ice, and the 

 down rush of rains and streams. 



6-Some soils have been carried about from one place to another 

 and spread out by the ice, snow, streams, and even to some ex- 

 tent by the wind. 



7-Some soils have been formed out of the rocks beneath them, 

 and from the decay of plants growing upon them. 



8-Some soils, such as swamp soils, have been formed almost 

 entirely from the decay of plants. 



Suggestive: 



What class of plants are most useful in improving the soil, those 

 with shallow growing roots or those having deep growing roots? 

 Have you observed any difference between the roots of clover and 

 the roots of timothy? 



