xl INTRODUCTION. 



' The di^ainage of this moiintain belt of sixty miles coUectf 

 in a central trougli as Boar River. The river floTV'S nortlr 

 ward in this trough in the mountains for about 300 miles, 

 then bends westward around the western barriers, and flows 

 southward into Great Salt Lake. 



m 



The Central Eailway route (TJnion Pacific Eailway) 

 crosses the Wahsatch Mountains, and passes around the 

 northern end of the Great Lake ; it then follows the 

 valley of the Humboldt for 300 miles towards California. 

 In approaching Salt Lake, it is evident that the railway 

 has to cross two dividing ridges at least : 1st, the true rim ot 

 the basin, and 2nd, the false rim, or the ridge lying between 

 Bear EiA^er and the lake. This ridge really consists of the 

 lofty western range of the "Wahsatch, and would have proved 

 almost an insurmountable barrier, had not another tributary 

 of the lake cut its way thi-ough it, forming Echo and TVeber 

 Canons. 



The Colorado Basin is separated from that of the Bio 

 Grande and the Mississippi, on the east, by the continental 

 divide of the Eocky Mountains, and from the di'ainagc of the 

 Laguna do Guzman by an almost imperceptible divide, which 

 crosses the level Madi-e 'Plateau from the south-eastern 

 extremity of the Burro Mountains into the mountains pi 

 Mexico. Thence the divide runs in a westerly course, some- 

 times in Mexican, and sometimes in American territory, along 

 the boundaiy line, separating the Gila branches of the 

 Colorado from the streams of Northern Sonora. We see, then, 

 that the Colorado Basin forms a large triangle, limited, on the 

 east, by the continental di^dde of the Eocky Mountains ; on 

 the south, by the high lands about the Mexican boundary 



o 



line ; and on the north-west by the Wahsatch Mountains. 

 In the northern angle, almost reaching the 44th para 



Uel 



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