XIV 



BOTA]SrT. 



The mail] depressions within this region are two, one at the base of the 

 Sierras at a level of about 3,850 feet above the sea, into which flows all of 

 drainage there is from the whole northern half of Nevada and from the 

 eastern slope of the Sierras, the other the " Great Salt Lake Basin," at an 

 altitude 400 feet greater, close upon the base of the Wahsatch and receiving 

 the waters from that range above latitude 40° and from the northeastern por- 

 tion of the Uintas. Into the first flow the Truckee, Carson, Quinn's, and 

 Humboldt Rivers. The Truckee is a clear cold stream, which issues from 

 Lake Tahoe in the Sierras and after a rapid descent breaks through the 

 Virginia Mountains and turning north soon empties into Pyramid and 

 Winnemucca Lakes. These are much the deepest of all the lakes of the 

 Basin, being hemmed in by mountains, and are moderately saline. The 

 Carson River also rises in the Sierras, farther to the south, but after leaving 

 the base of the mountains is a less rapid stream and gradually becomes 

 somewhat alkaline. Inclining more to the eastward it forms a small 

 shallow lake on the border of Carson Desert, and thence issues in a number 

 of devious channels, and is finally spent in an extensive " sink " or alkaline 

 mud plain of some twenty or thirty miles in diameter. Of a like character are 

 the " Mud Lakes," lying north of Pj^ramid Lake and fed by Quinn's River, 

 which has its source in southeastern Oregon. Beyond the limits of the sur- 

 vey to the south are Walker's and some other smaller lakes, supplied by 

 streams from the Sierras, but all strongly saline. 



Prom this western depression the general level of the country rises 

 gradually eastward very nearly to the border of Nevada, where the 

 valleys have an altitude of about 6,000 feet. Here in the northeastern part 

 of the State the Humboldt River takes its rise, by far the most important 

 river of the basin, not only as the longest but as opening a passage for 

 300 miles to the Central Pacific Railroad through the mountain ranges that 

 would otherwise have proved a serious obstruction. It is nowhere a large 

 stream, receives very few affluents, and in some parts of its course is very 

 tortuous. It at length spreads out into Humboldt Lake, shallow and sub- 

 alkaline, and from this the little remaining surplus water finds its way in a 

 manner similar to the Carson River into the same sink. 



The descent of 2,000 feet from Eastern Nevada into the Great Salt 

 Lake Basin is almost immediate, nearly the whole northwestern portion of 

 Utah being an alkaline desert, broken by fewer mountain or hill ranges and 



