Deep Artesian Wells in the Dakotas. 



167 



edge of the vertical gradients of temperature-increase in the 

 individual wells, it would not be safe to attempt to calculate 

 the temperature to a uniform depth beneath the surface, so I 



Contour map of "Bed Rock " surface in a portion of the Dakota Artesian Basin, 

 by N. H. Darton. 



have employed the " feet per degree " product for the " iso- 

 geotherms." 



The most notable features in figure 1 are, the strip of high 

 temperature along the Missouri River valley beginning near 



