WATER PROVINCES OF THE UNITED STATES 65 



North and South Dakota, Nebraska, Kansas, Oklahoma and 

 Texas is the broad belt of Cretacious and Tertiary beds forming 

 the so-called High Plains. 



These beds, which consist of a great thickness of clays, clayey 

 sands and sands with some limestones, dip gently eastward from 

 their catchment areas near the mountains on the west. Their 

 more porous beds, especially the Dakota, Arikaree and other for- 

 mations, are commonly saturated with water which is freely 

 yielded to wells. In the western portion of the High Plains the 

 great water-bearing formation, the Dakota sandstone, which 

 occurs near the base of the series, is relatively near the surface 

 and yields large supplies to wells, and, in the deeper river valleys, 

 may even give rise to flowing wells. On the higher lands between 

 the streams the water is generally raised to the surface by wind- 

 mills or by some one of the various forms of power pumps. A 

 cattle-raising industry of large proportions is made possible by the 

 waters thus obtained. 



To the east the Dakota waters are at depths beyond the 

 limits of ordinary drilling and higher formations have to be de- 

 pended upon. Besides the deep waters, the shallow underflow in 

 the gravels of dry or nearly dry stream beds are extensively uti- 

 lized throughout large portions of the High Plains Province. 



In addition to the sands and sandstones of the High Plains, 

 the limestones are also frequently important water bearers, 

 especially in Texas, where they not only afford supplies to many 

 wells, but also give rise to numerous large springs. 



The Rocky Mountain Province. In the Rocky Mountain 

 Province are included the numerous ranges that go to make up 

 the great Rocky Mountain system. Though comprising several 

 geographically distinct provinces, they may, because of the simi- 

 larity of ground water conditions, be considered as a unit. 



As in the Appalachian Mountains, the rocks are greatly dis- 

 turbed. In general, the character of the rocks and the topo- 

 graphic and geological structure is such as to prevent the existence 

 of water systems of more than local importance or extent. Fortu- 



