v> 



xxxiv INTRODUCTION. 



the Union Pacific Eailway Company has chosen this district' 

 as affording the best passage across the continent for the 

 central route. They have cut through the Black Hills by 



P 



means of a short tunnel at Cheyenne Pass (elevation 8,242 

 feet), with an average grade of 74 feet per mile, have laid 

 the iron ways across the level "Summit Plateau" (Laramie 

 Plains), and have crossed the continental divide by a still les 

 difficult pass than that through the Elack Hills (situated 

 about midway between South Pass and Bridger's), at an 

 elevation of 7,534 feet. 



These elevations are enormous, surpassing even tlie famous i 

 Summit Eailway which crosses Mont Cenis at an elevation 

 of 6 J 800 feet* There are few engineering difficulties, how- 

 ever, to contend against, and the construction of the railway 

 is comparatively inexpensive. 



The continental divide continues its south-easterly dii'cc- 

 tion for about fifty miles from Bridger's Pass in the western 

 main chain, then passes due south for another fifty mile|— 

 and then crosses the " Summit Plateau " from the western to 

 the eastern main chain. The portion of the plateau north 

 this transverse range (for such is the divide here) is kno 



as IS'orth Park; 



Laramie Plains by 



minor range, and is shut in along its eastern boundary by 

 eastern main chain, a spm- of which juts up into the Larami' 

 Plains, as the Medicine Bow Mountains. 



The only outlet for the drainage of JSTorth Park is throng 

 a cleft in its northern boundary. Through this the wa 

 run, forming the north fork of the "Platte Kiver. T 



stream traverses the Laramie 



tK 



ids eastward around the Black Hills, s 

 plains of Nebraska towards the Misso 



Ei\ 



