28 THE SOIL 



United States. Sometimes in Nebraska, western Oklahoma, 

 Kansas, and Texas there are dust storms of such violence and 

 intensity that the heavens are darkened and obscured as if 

 covered with a heavy cloud. About March 13, 1904, a dust 

 storm swept over western Kansas and northwestern Oklahoma, 

 which was so heavy and dense that day was turned into night 

 of inky blackness. The next morning everything was covered 

 with a heavy layer of dust. The damage from the storm was 

 slight, while the enrichment of the soil by the addition of 

 these accumulated dust particles was considerable. In many 

 parts of the United States we find these wind-blown soils, and 

 in many cases they are fertile and very productive. 



EXERCISES 



1. With a soil augur ascertain the depth of soil and subsoil in your 

 locality. 



2. At what depth is rock found ? 



3. Classify the soils found in your vicinity. 



4. Secure samples of the various rocks in your county and classify them. 



5. Make a mixture of rocks, pebbles, sand, and soil, and stir them up 

 well with a stick or iron poker after adding enough water to make a thin 

 paste of the soil. Allow the mixture to settle and note the results. Ex- 

 plain. A fruit jar or a candy jar will be found useful for this experiment. 

 If this cannot be had, use smaller pebbles and place the mixture in a glass 

 tumblei . 



6. Build up a soil bed of sand, gravel, and soil and cause a stream of 

 water to pass through the bed ; note the shifting and arrangement of soil 

 particles. Explain. 



QUESTIONS 



1. Define soil. 



2. Define subsoil. 



3. What is hard pan ? 



4. Discuss the origin of soil. 



5. Discuss rocks. 



6. Describe igneous rocks. 



7. Describe aqueous rocks. 



8. Discuss sedentary soils. 



9. Give the classes of transported soils. 



10. Discuss alluvial soils. 



11. Discuss drift soils. 



