Geology of ArteHan Basin in South Dakota. 385 



viously wells in the higher localities must go deeper than those 

 in the lower ones. It is found that the sandstone declines toward 

 the north and west rather more than the surface of the country 

 slopes south and west. The Dakota sandstone at Jamestown is 

 76 feet below sea level, and at Yankton 586 feet above ; this shows 

 that the artesian water runs up hill faster than the James river 

 runs down hill. The wells will be found to deepen as you go 

 north from Yankton. At Yankton they average about 628 feet; 

 Woonsocket, 750 feet ; Huron, 802 feet ; Redfield, 900 feet ; Aber- 

 deen, 908 feet; Ellendale, 1,087 ^^et; Jamestown, 1,487 feet. 



The Huron wells probably present as nearly a typical section 

 as can be afforded in the Dakotas. They are all very similar, 

 though, of course, the wells to the south do not penetrate some of 

 the formations that spread over the interior of the two states. 

 Absolute accuracy in description and depth is quite impossible. 



The first artesian well sunk at Huron gave the following 

 record : 



Feet 



Glacial drift of the usual composition of this deposit 89 



Bluish gray shale, very tough and becoming sticky when wet, 



undoubtedly of Pierre formation. 169 



Sandstone and gray shale, which may provisionally be re- 

 ferred to the Niobrara 200 



Brown shale, associated with layers of gray marly shale in 



part ; Benton in age 253 



Friable, water-bearing sandstone 80 



Hard pan penetrated only 10 



Total 802 



This is about as nearly as I can classify the strata passed 

 through at Huron. Facts are hard to get, and well borers use 

 terms very loosely. I verified this arrangement in other wells, 

 notably at the Day-Harrison well, two miles and a half southwest. 

 Aberdeen corresponds almost exactly, only the Pierre shales arc 

 heavier. 



Second, the flow in all these wells is marvelous, so great as to 

 awaken scientific incredulity so strong that the facts as first pro- 

 claimed were discredited entirely. 



The first Huron well (now there are three or four more 

 being sunk) flows 1,560 gallons per minute under a pressure 



