Deep Artesian Wells in the Dakotas. 



163 



LEGEND 



The Fi< 



I he riOures indicate 

 number of feet to each decree 

 of increase of temperature 



; ; ; i : \ 1° «« 40-45"r ee t 



^ 



^ 



/° in 35-40reet 

 1° '" 30-35 Feet 

 t° In Z5-30 reet 



r in 20 -Z5reet 



'/f&'SZyS'-: ■:■■':■.:■ : ■■:■■■■■: 



Scale ° 5 lP 2 ° 



Map showing rates of increase of underground temperatures in deep wells in 

 Eastern South Dakota and North Dakota, by X. H. Darton. 



