SOIL FORMATION AND TRANSPORTATION 17 



LABORATORY EXERCISES 



Exercise I. — Soil formation and transportation. 



This exercise is based on observations in the field and its value 

 depends on examples available. Use Chapter II as a basis for the 

 field observations. 



If rock outcrops can be found in the neighborhood, a visit to them 

 would be worth while. Examples of wind action, heat and cold, 

 frost, and plant and animal influences in forming or transporting soil 

 should easily be found. The erosive and carrying power of streams 

 should also be studied in relation to soil formation. 



An examination of weathered rock of various kinds should be 

 made in order to illustrate the chemical phase of soil formation. 

 The rusting of iron could be used as an example of the effect of 

 gases. The iron of rocks rusts in the same way. This, together 

 with the assumption of water and a loss of soluble materials, brings 

 about the decay of the rock. Remember, however, that the 

 physical and chemical agencies work hand in hand and that these 

 agencies are as active upon the soil as upon the original rocks. An 

 examination in the spring of fall-plowed land would permit a study 

 of the effect of weathering on soil structure. 



