POTASH SALTS AND OTHER SALINES IN THE GEEAT BASIN EEGION. 13 



ia steeper, varying from 150 to 110 feet to the mile. At the upper edge of the grass- 

 land the two surfaces are about 8 feet apart and a short distance beneath they inter- 

 sect in the spring belt. From this belt to Owens River the distance to ground water 

 varies from 4 to 12 feet beneath the gently sloping or level valley floor. This sudden 

 break in the slope of the ground-water surface at the spring belt is caused by the 

 change from coarse to fine material in the region of the late lake. The fine material 

 acts somewhat like a dam, raising a portion of the ground water to the surface in 

 springs and retarding the lateral movement of the remainder." 



The above quotation indicates a condition which must be common in basins char- 

 acterized by surrounding alluvial cones. The ground-water level assumes a sloping 

 surface, and, as we ascend the cone from the valley, we find this ground-water surface 

 at greater and greater depths . We would expect that in every case at the toe of the allu- 

 vial fan tKe ground-water level would be closest to the surface and deepest in the 

 vicinity of the bordering mountains. The amount of seepage water that would col- 

 lect from the contiguous watersheds, together with the rainfall, would determine 

 whether the upper surface of this ground water would be close to or at considerable 

 depth from the surface. 



DEEP SUPPLIES OP WATER AND ARTESIAN WATER. 



The bore hole put down by the United States Geological Survey in the Carson Sink 

 region encountered surface waters at a depth of 4 feet, and at depths greater than 150 

 feet a number of artesian flows were encountered. The well which was put down 

 some 985 feet flowed water. 



The Railroad Valley Saline Co. sunk a 1,200-foot bore in Railroad Valley. They 

 discovered many flows of artesian water from the 128-foot depth downward. Twenty- 

 nine separate flows are noted in the log of their well within the first thousand feet. 

 At greater depth the formations were dry. 



Artesian areas are known in Smith Valley, Nov.; the Truckee Meadows south of 

 Reno; the Carson Valley, Nev.; the Las Vegas Valley, Nev.; the Salt Lake Valley, 

 Utah; and in southern Oregon. These instances lead us to conclude that water- 

 bearing strata exist in many of the inclosed basins and at depth, and in many cases 

 that they are capable of supplying artesian water. 



SPRINGS. 



Many springs exist in the Great Basin region. A complete list of these springs 

 can not be given at this time. Russell, in his study of the Quaternary lakes of western 

 Nevada, mapped the springs occurring in this area. He shows 93 springs in an area 

 of approximately 38,000 square miles. Of these 23 are hot springs. Outside of this 

 area hot springs are encountered in many places. South of Beowawe some 6 miles 

 are a number of hot springs and geysers. Just west of Elko is a large hot spring. 

 Sixty miles north of Elko is an area in which several hot springs of considerable size 

 occur. At Rhyolite, Nov., several small hot springs are to be found. Some 12 miles 

 northwest of Goldfield is a hot spring of moderate size. In Railroad Valley a large 

 hot spring has been found. The prevalence of hot springs in the basin region may be 

 assumed to indicate the presence of deep-seated waters. Hydrothermal activity has 

 long been noted as an important feature of the basin region. In earlier geological 

 periods undoubtedly much greater activity existed than at the present. 



FISSURE AND ROCK WATER. 



That much water may be expected in fissure and brecciated zones in the mountain 

 ranges is shown by the volumes of water encountered in mining operations. Virginia 

 City is perhaps the most conspicuous example. In these mines hot springs have been 

 encountered at depths below 1,000 feet, and a water flow approximating 8,000 gallons 

 per minute represents the drainage from the rock masses of Mount Davidson within 

 the area tapped by the mines. In the Eureka district in central Nevada water was 

 encountered in the mines. In many of the other mining districts water in greater or 

 less amounts has been encountered with depth. 



EXTENT, DISTRIBUTION, AND CHARACTER OF THE ROCKS OF THE BASIN REGION. 



Volcanic rocks distinguish the basin region from other regions of the West. In 

 order to get some idea of the distribution of the different rocks in the basin region, 

 measurements were made upon the geological map of the Truckee folio, upon maps 

 Nos. 4 and 5 of the Fortieth Parallel Survey atlas, and upon Ball's map of southwestern 



