121. 



salt masses, and by the shallowness of the salt, less than 300 feet 

 from the surface. At a depth of 1000 feet, these domes are a mile or 

 more in diameter. 



3.8 Rock salt occurs in the western states in several areas. Salt of 

 Permian age is found in the Sevier Valley in Utah. Salt, believed to 

 be of Pennsylvanian age, occurs in the Colorado River drainage in 

 eastern Utah and western Colorado. The area is sometimes called the 

 Paradox salt basing ' The extent of the salt has not been fully deter- 

 mined but it apparently is not less than 10,000 square miles. The salt 

 has intruded into a considerable number of anticlines and domes and 

 has been penetrated in some test wells to a thickness of over 3,000 feet. 



3.9 In the southwest, salt occurs in the Delaware Basin of New Mexico 

 and Texas. The margins of the area are known only approximately but 

 the total area underlain by salt may be as large as 70,000 square 

 miles.' ' The probable extent of the area is shown on Figure 6. Rock 

 salt is found in beds of Permian age belonging to the Upper Castile for- 

 mation, with an evaporite section ranging in thickness from to about 

 3500 feet. In part of the area a zone of potash salts is present which 

 has been extensively developed near Carlsbad, New Mexico. The zone 

 is about 250 feet thick and contains four workable beds of potash. The 

 lowest bed is the thickest and averages about ten feet in thickness. A 

 large area has been mined out since operations began about 25 years 

 ago. Above the McNutt potash zone is a zone of halite about 500 feet 

 thick, which has been named the Salado . The top of this zone in the 

 Carlsbad district is about 500 feet below the surface, depending upon 

 the topography. Below the potash zone is another bed of halite, about 

 900 feet thick, broken by anhydrite partings. 



Rock salt is not mined in this region except as a byproduct of the potash 

 ore, which contains 60% or more of halite. The salt extracted from the 

 potash ore is marketed to only a small extent. No space in the halite 

 beds is produced in the mining of the potash. 



4. PRODUCTION OF SALT IN THE UNITED STATES 



4. 1 The total production of salt in the United States now exceeds 20 

 million tons per year, either as dry salt or in the form of brine . '^J 

 This amount is about 35% of the world's total production. Because salt 

 is widely distributed, the United States imports very little salt; it ex- 

 ports less than 2% of the production. 



