316 OKNITUOLOGY. 



Ilinnbolilt, of wliicli it is a roputetl tributary. In the upper ixtrtioii of its course of 150 

 miles it is reeiiforced to some extent liy the drainage of the Shoshone Mountains, » 

 rather higli range west of tlie Toyabes, but as it nears Ilumbohlt VaUey it iliverges 

 into siilechaunels and seldom has volume suflicient to reach the main river itself. 



The East Uuniboldt Mountains are by far the most stern and al[)ine of all these 

 ranges, the main peaks between 11,000 and 112,000 feet in height, precipitous and 

 ragged, the deeper canons evidently scooi)ed out by glaciers, gemujed with snow fed 

 lakes beneath the peaks and carrying full streams into the valleys. The southern 

 portion, however, below Fr6niont's Pass, is less rugged and of different geological 

 structure, mainly of nearly horizontal strata of limestone. The canons here, often 

 mere gorges, with close precipitous walls, are i)erfectly dry on the eastern slope, the 

 melting snows sinking almost immediately, but reappearing at the base in bold ice-cold 

 si)rings. The water from these springs and streams reunites to form Unity and Frank- 

 lin Lakes, bodies of nearly fresh water, very .shallow, and largely occuitied by a den.se 

 growth of "Tule" {Scirpus ralidm). As usual in these ranges the western slope is much 

 tlie more gentle, with a broader line of t'oot-hiils. The streams upon this side form the 

 South Fork of the Eumboldt. The 'Clover Mountains' of the Catalogue iorm the 

 northern extremity of this range, Lsolated by a depression known as Secret Valley, 

 but of equal heiglit and similar character. 



Such is a general description of the country as far east of the foot of the 

 Wah.safch in Utah. These mountains, upon a broad base of nearly hfty miles in 

 width, and with an irregular crest-line 10-12,000 feet high, have a systeui of long, 

 deep, well-watered cations, otten exceedingly rocky, and sometimes cleft like a gateway 

 to the valley level, with perpendicular mountain-walls on each side, but usually oi)ening 

 out at some part of their course into meadow-like basins or "parks.^ The prevalent 

 western winds deposit their moisture, which they have gathered in the traverse of the 

 Basin, in abundant snows in winter and at olher seasons in frequent and occasionally 

 heavy rains. The upper canons and mountain slopes are to some extent timbered, 

 much more generally so than in any of the ranges westward, and the naked peaks 

 above have a truly alpine vegetation. The Uintahs, which connect immediately with 

 the Wahsatchand extend eastward on the line of the 41st parallel for a distance of 

 one hundred and fifty miles to Green River, where they meet the outspurs of the 

 Kocky Mountains of Colorado, have more of the character of those mountains, with 

 broad open cations and extended lines of foot-hill.s, the peaks overtopping tho.se of the 

 Wahsatch, glacier scored and polished at the northern ba.se, but the declivity upon 

 the opposite side stretching southward l>eyond the limits of vision in a high plateau 

 broken only by the deeply-worn channels of numerous rapid streams, tributaries of 

 the Uintah and Green Uivei-s. 



LOCAL AVIl'AUNyE OK TIIK GUKAT BASIX. 



We have gone thus into detail with rog-.ird to the more jifominent 

 (•haracteristic features of the Great Basin for the I'eason that tlie distribu- 

 tion of the birds depends so much upon that of the vegetation; and as we 

 know that the latter is separated into several quite distinct gi-oups, whose 

 distribution depends upon altitude, humidity, proportionate amount of 



