GEOLOGY OF REGION 



241 



content similar to that of a soil from a limestone forma- 

 tion, should be regarded with greater suspicion than the 

 latter soil because of the possible recontamination from 



~] 



FIG. 33. A LAYER OF ALKALI SEVERAL FEET BELOW THE 

 SURFACE. THE POSSIBILITY OF SUCH A LAYER MAKES AN 

 ANALYSIS OF THE SOIL NECESSARY BEFORE IT CAN BE 

 PROPERLY JUDGED. 



the unlimited supply of salt in the country rock. A knowl- 

 edge of the geology of a region, therefore, is a valuable 

 supplement to other information in judging alkali land. 



