HARD PAN 



127 



seems equally certain that the part that solutions play has 

 not been given the consideration that it merits, mainly 

 because solution phenomena have not been understood 

 until comparatively recent years. 



"The study of hardpan formation necessitates a con- 

 sideration of certain physical phenomena; for instance, 

 the movement of water and various solutions in the soil. 

 This subject is receiving attention in this laboratory; but 

 while a good many observations have been made and much 

 valuable data collected, it is yet too soon to formulate a 

 complete hypothesis for this subject. The views here 

 described are put forward in the hope of furnishing an in- 

 centive to more widespread interest and work on this 

 important subject." 



Heileman (12) gives in Table XVI the composition of a 

 typical hardpan in the Kittitas Valley, Washington. 



Table XVI. Composition of Hardpan 



Breazeale (2) shows that the idea that hardpan under a 

 soil high in sodium carbonate has resulted from the sodium 

 carbonate may not be true. In fact the sodium carbonate 

 accumulation may have come from a decomposition of the 

 calcium carbonate in the hardpan and a combination with 

 sodium to form the black alkali. He succeeded in bringing 

 about this interchange in the laboratory. 



