MAR 



Issued February 12, 1912. 



United States Department of Agriculture, 



BUREAU OF SOILS CIRCULAR No. 61. 



MILTON WHITNEY, Chief of Bureau. 



U. S. DEPARTMENT OP AGRICULTURE, 



Washington, D. C., January 19, 1912. 



SIR: I have the honor to transmit herewith the manuscript of a report covering 

 investigations of the Otero Basin, N. Mex., for potash salts, by E. E. Free, of this 

 bureau, and to suggest that this article be published as Circular No. 61 of the 

 Bureau of Soils. 



Respectfully, MILTON WHITNEY, 



Chief of Bureau. 

 Hon. JAMES WILSON, 



Secretary of Agriculture. 



AN INVESTIGATION OF THE OTERO BASIN, N. MEX., FOR 



POTASH SALTS. 



By E. E. FREE. 



The geologic behavior of the soluble potash salts and the proba- 

 bilities as to their occurrence in undrained basins in general have 

 been discussed in Senate Document No. 190, Sixty-second Congress, 

 second session. It is necessary here to recall only that they are 

 accumulated and concentrated by the waters of the ordinary drain- 

 age, and that they will have been segregated, if at all, at that point 

 where these drainage waters suffer their final and complete evapora- 

 tion. Therefore, if potash is present on or near the surface of any 

 undrained basin, it will lie in and under the sink or play a which 

 occupies its lowest spot and forms the final resting place of its waters. 

 Obviously, the first step in searching any basin for suspected potash 

 is the examination of this central sink. But absence of potash there 

 is not fully conclusive. Erosion and deposition, orographic move- 

 ment, and climatic variations have resulted in an ever-changing 

 topography, and present conditions may bear little similarity to those 

 of the past. It is possible that beds of potash have been laid down 

 hi previous epochs only to be buried and concealed by later barren 

 deposits. It is necessary then to supplement the examination of 

 the central playa by such study of the general geologic history as 



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