318 GEOLOGICAL EXCURSION TO THE ROCKY MOUNTAINS. 

 ARTESIAN WELLS OF EASTERN DAKOTA. 



By Geo. n. Eldmdgb. 



A most remarkable series of artesian wells is developed in two belts 

 of country coinciding in a general way with the meridional valleys of 

 the Red River, which fche road crosses at .Fargo and Moorhead, and of the 

 .James River, which is passedat Jamestown, about 100 miles farther west. 

 The geological horizons from which the wells derive their waters are: 

 (1) The Pleistocene drift of the Red River valley. (2) The middle and 

 upper portions of the Cretaceous. (3) The Dakota sandstone which 

 forms the base of the Cretaceous system on the Great Plains. (I) The 

 Cambrian sandstones. 



The last of these affords but a single well, which is in the bed River 

 valley, 100 miles (161 km.) north of the railroad. It has a total depth 

 Of 915 feet (270 in.), of which the last 12 feet are in granite. It obtains 

 fresh water at 503 feet (151 m.) and salt water at 003 feet (271 in.) 



The Pleistocene wells are confined to the Red River valley, and obtain 

 their water from seams of sand and gravel in the glacial till at depths 

 of 85 to 270 feet (20 to 82 m.) These wells are developed in a belt 375 

 miles long. Fresh water is obtained from the southern portion of the 

 belt, brackish and alkaline waters from that to the north of Blanchfbrd, 

 in North Dakota. The source of these waters is not distant, and the 

 supply depends on the rainfall and the configuration of the immediate 

 region. 



The Middle and Upper Cretaceous wells are limited in number, and, 

 with one exception, are also located in the Red River valley. They 

 are from 250 to 305 feet (70 to L20 m.) deep, and their water flow is 

 COpions but brackish. 



The Dakota sandstones supply the most important series of wells, 

 which occupy a belt, along or adjacent to the James River valley, 

 extending from Yankton, on the Missouri River, to Devil's Lake, north of 

 Jamestown, a distance of 100 miles (04 1 km.) The standstones are 200 

 to 400 feet (ISO m.) thick, and lie at depths of from 000 feet (00 to 120 

 m.) in the southern to L,500 feet (450 m.) in the northern portion of 

 the belt. The wells are from 4* to inehes (11.4 to 15 em.) in diameter 

 and the flow of water in some of the wells is 8,000 gallons (30,0001.) 

 per minute, at a pressure of 25 to 28 pounds per square inch. Their 

 waters are utilized for running the machinery of mills, for city tire sys- 

 tems, and for irrigating, to a limited extent. 



The geological strueture of the basin, so for as known, is that of a 

 gently dipping series of Cretaeeous roeks, resting unconformably upon 

 the Cambrian and Arch can of northwestern Minnesota, and rising 

 slowly towards the base of the Rocky Mountains, where the first out- 

 orops of Dakota sandstones are 250 to too miles (400 to 650 km) away 

 and at elevations of 3,000 to 5,000 feet (900 to 1.200 m.) above sea level. 



