314 OKNITUOLOGY. 



This region constitutes tlio northern portion of wliat was at first designated as 

 the "Great Basin," tiie higii ])lateati, without outU-t for its waters, separated on the 

 north by low divides from the valley of the Snake Kiver and continuing southward 

 until it niert;es into the desert of the Lower Colorado. Geologically considered, how- 

 ever, as well as botanically, the term is now properly made to include the whole similar 

 arid stretch of country northward to the plains of the Columbia, in latitude 48^. 



Tlie lotty and unbroken range of the Sierras bounds this section of the liasiu 

 on the one side by its steep eastern slope, entering Nevada at only a single point, 

 where it throws over the lH)rder a high ilinkingspur, the Washoe Mountains. On the 

 opposite side lies the broad and nearly equally elevated system of the Wahsatch, 

 broken through by the Bear, Weber, and Provo Rivers, which head among the peaks 

 of the adjoining Uintalis. The intervening siwice, 4(>(> miles l>road in latitude fJ^, hut 

 narrowed by the convergence of the opposing mountains to about L'tio miles in latitude 

 31°, is for the most part occupied by numerous short and somewhat isolated minor 

 ranges, having a general north and south trend, and at average distances of about 

 twenty miles. The bases of these ranges are usnally very narrow, even in the most 

 elevated, rarely exceeding eight or ten miles in breadth, the slopes abrupt and the lines 

 of foot-hills contracted, the mesas grading at a low and nearly uniform angle into the 

 broad uiiinterrui>ted valleys. Over the larger portion of the territory, and esi)ecially 

 in Nevada, the coml)ined areas of the valleys and the area occupied by the mountains 

 and-accompanying foothills are very nearly equal. The main depressions within this 

 region are two, one at the base of the Sierras at a level of about 3,850 (eet above the 

 sea, into which tlows 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 liasin," at an 

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

 from that range above latitude 40C'and from the northeastern portion of the Uintahs. 

 Jnto the lirst lh)w the Trnckee, Carson, Quinn's, and Humboldt liivers. The Truckeo 

 is a cleir, cold stream, which issues from Lake Tahoe in the Sierras, and after a rai)id 

 descent lireaks through the Virginia Mountains and turning north soon empties into 

 ryraniid and Winnemucca Lakes. These are much the (h'epest of all the lakes of the 

 Basin, being hemmed iu by mountains, and are moderately saline. The Carson Kiver 

 also rises in the Sierras farther to the south, but after leaving the base of the moun- 

 tains is a less ra])i(l stream and gradtnilly becomes somewhat alkaline. Inclining more 

 to the eastward it forms a small shallow lake on the border of Carson Desert, and 

 thence issues iu 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 Pyramid Lake and fed by liuinn's 

 Kiver, which has its source in southeastern Oregon. Beyond the limits of the suiTcy 

 to the south are W'alker's and some other smaller lakes, su|)[)lieil by .streams from the 

 Sierras, but all strongly saline. 



J'rom this western depression the general level of the country rises gradually to 

 the eastward very nearly to the bonier of Nevada, where the valleys have an altitude 

 of about (1,000 feet. Here in the northeastern part of the State the Ilumboldt Kiver 

 takes its rise, by far the most imitortant river of the Basin, not only as the longest but 

 as opening a i)assage for three hundred miles to the Central Pacific Kailroail through 

 the mountain ranges, that would otherwise have proved a serious obstruction. It is 

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



