162 W. H. Darton — Geo thermal Data from 



In James River valley the greater number of flows range in 

 temperature from 65° F. to 70° F., and the principal wells 

 vary in depth from 550 to 1500 feet. The flows are usually 

 several hundred gallons per minute, in many cases from 1000 

 to 2000 gallons and in a few instances from 3000 to 4000 gal- 

 lons per minute. 



The water-bearing horizon is the Dakota sandstone, which 

 lies upon crystalline rocks and beneath a thick mass of Upper 

 Cretaceous shales and chalk. The beds lie nearly horizontal or 

 in an irregular, very flat-bottomed synclinal.* 



As the waters from the wells selected flow in large volume 

 and have been flowing for some time, their temperature at the 

 surface is practically the same as that of the underground 

 stratum from which they rise. As the depth of the water- 

 bearing stratum is known in every case, it has been a simple 

 matter to calculate the rate of temperature-increase. In many 

 parts of the world it has been found that the rate of increase of 

 temperature averages about one degree for each 50 feet, below 

 the first 40 feet, in which the temperature is usually regarded 

 as that of the mean annual temperature of the region. In the 

 greater part of the artesian basin of the Dakotas the rate of 

 increase is found to be greatly more than this, attaining at Fort 

 Randall a rate of one degree for each 17-J- feet. At this well 

 the temperature of the water is 80° F., or possibly slightly 

 more, but the depth from which it is derived is only 576 feet, 

 which indicates the abnormally high rate of increase. At 

 Chamberlain, a rate of one degree for 21 \ feet is indicated, and 

 at Pierre one degree for 24^ feet. To the north and east these 

 amounts diminish, but over a wide area the amount of increase 

 is one degree for every 25 to 35 feet. The records of tempera- 

 tures, which I have been able to obtain, are scattered widely 

 over the artesian basin, so as to afford a very definite idea as to 

 the areal distribution of the underground temperatures, They 

 are principally derived from two observers : Prof. J. H. 

 Shepard of the U. S. Experiment Station at Brookings, South 

 Dakota,f and Col. E. S. Nettleton's report^ on " Artesian and 

 Underflow Investigation " for the Department of Agriculture. 

 The data are given in the table on page 164. 



* A description of the geology and resources of the basin may b^iound in the 

 paper entitled " Preliminary Report of Artesian Waters in a portion of the 

 Dakotas," by N. H. Darton, 17th Annual Rep. U. S. Geol. Survey, 1895-96, Part 

 H, pp. 1-92, PI. LXIX-CVII, Washington, 1896. 



\ South Dakota Agricultural College, etc. ; Bull., xli, November, 1894, 35 pp. 



\ Sen. Ex. Doc, No. 41, 52d Congress, 1st Sess., Part IY, Washington, 1893. 



