16 GEOLOGICAL HLSTOKY OF LAKE LAHONTAN. 



A summary of the results of exploration in this region previous to 1857 

 was prepared by Lieut. G. K. Warren, and published in Volume XI of the 

 Reports of the Pacific Railroad Explorations, to which we must refer the 

 reader for detailed information in this connection. 



A portion of the region of interior drainage is within the boundaries of 

 California, and came within the limits of the explorations of the geological 

 survey of that State, carried on under the direction of Prof. J. D. Whitney. 

 Volume I of the reports of that survey contains a brief account of the Great 

 Basin, '^ relating principally to its southern border, wliich was compiled from 

 the notes of several travelers. 



Since the completion of railroad communication with the Pacific coast 

 in 1869, important advances have been made in our knowledge of the Great 

 Basin. The Central and Southern Pacific railroads have crossed it and sent 

 numerous branches through its desert valleys, both northward and south- 

 ward from the trunk lines ; many towns and mining camps have sprung up 

 along these highways, and almost every foot of easily irrigable land has 

 been appropriated by settlers. Herds of cattle and sheep find subsistence 

 on the mountains and in the sage-brush-covered valleys which were once 

 thought to be too barren to become of service to man. Some of the most 

 productive silver mines in the world have been developed in this inhospita- 

 ble region. Throughout the eastern border of the Great Basin, in Idaho, 

 Utah, and Arizona, the followers of the Mormon faith have found a " prom- 

 ised land," which by untiring toil and industry they have reclaimed from 

 its primitive desolation and made the home of thousands. With all this 

 advancement, however, the Great • Basin is but thinly settled, when we 

 consider its vast area ; biit, owing to its desert nature, probably contains a 

 larger population than its agriculture alone can sustain. Together with the 

 settlement of the country, exploration has gone forward until but little of 

 the great terra incognita of thii-ty years ago remains unmapped ; scarcely 

 muiu than a beginning has been made, however, in unraveling its compli- 

 cated geological history. The United States Geological Exploration of the 

 Fortieth Parallel, in charge of Clarence King, mapped tlie geology of a 

 belt 100 miles wide across its northern portion A large part of the Great 



'Page 461. 



