PART II. THE SOIL AND ITS MANAGEMENT 



EXERCISE 11 

 THE FORMATION AND TRANSPORTATION OF SOILS 



Statement. If the soils of the world were swept into the sea and the rocks beneath were left bare, 

 the entire surface of the earth would again become covered with soil. It would require millions of 



years to form a new soil, as it has taken millions of years to form the soil 

 we now have. Some kinds of rocks would be changed into soil more quickly 

 than others. A portion of the soil would be washed or blown away from 

 where it was formed and would be deposited elsewhere, leaving at last a 

 great variation in the soil covering the earth. Then, as now, some soils 

 would be coarse and others fine ; some would be fertile and others un- 

 productive. 



Object. To learn how the soils of the neighborhood were formed and 

 how they are classified. 



Materials. Blank for recording observations. 



Directions. Make a trip to the country to study the soils of the neigh- 

 borhood and to ascertain their origin. 



i. Observe the depth of the soil and subsoil in a number of locali- 

 ties. Classify the types of soils found as sedentary or transported. De- 

 scribe the forces which have had most to do with the formation of each 

 class. Whence did the transported soils come and how were they brought 

 there ? 



2. Examine stones and pebbles taken from the bed of a stream and 

 note the smoothness of the stones as compared with the sharp corners 

 and rough surfaces of stones not subjected to the action of running water. 



3. Find a large bowlder and look for places where small pieces have 

 been slivered from its surface by the action of freezing water. 



4. Compare hillside and valley in regard to the color of the soil, and 

 the fertil- 



Fig. 14. A soil which was trans- 

 ported by the glaciers 



It is a mixture of clay, sand, gravel, 



and bowlders. (Courtesy of the 



United States Bureau of Soils) 



ity of the 

 hillside 



and valley as determined by the 

 plant growth. Observe how rapidly 

 erosion is taking place and in what 

 way it is influenced by vegetation. 

 Find a gully forming in a cultivated 

 field. Note the streams in the neigh- 

 borhood after a rain. The turbidity 

 of the streams is an indication of 

 the destructive erosion taking place. 

 What becomes of the soil washed from 

 the fields of the neighborhood ? 



Fig. 15. A good view of a soil, subsoil, and underlying rock 

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