10 THE PLAINS. 



separated from each other by ravines 300 or 400 

 feet deep, and from 200 to 400 yards wide. I once 

 described this formation to Professor Agassiz. Without 

 seeing, he could not accurately account for it ; but his 

 hypothesis was, that Nature by her slow processes 

 had built up immense beds of secondary rocks about 

 the foot of the great wedge-shaped mass of the Medi- 

 cine Bow Eange. A convulsion uplifted the mountain, 

 forcing it through the portions of secondary resting on 

 its shoulders, turning over a great mass as the plough 

 turns the earth from the furrow. Subsequently there 

 came another upheaval, Hfting the mountain higher, and 

 turning another parallel mass from its sides. He con- 

 sidered that the number of parallel hills showed the 

 number of lifts that the mountain had received before 

 arriving at its present elevation. 



Twenty miles south of Eawlin's Springs is another 

 curious freak of nature, the parallel ridges being over- 

 turned, not by the upheaval of a wedge-shaped mountain, 

 but by the successive lifts given to a huge plain (part of 

 first plain). A succession of parallel ranges of barren 

 rocky hills is finally greatly overtopped by what appears, 

 looking at its face, to be a fine mountain range, it being 

 8,000 or 9,000 feet high, and on this face looking 

 north can all the year round be found patches of snow. 

 Eeaching its summit with difficulty, one is surprised to 

 find stretching far to the south and west an apparently 

 boundless plain, with a gentle declination from the 

 northern face. Proceeding a mile or two south, this 

 plain begins to be broken with the shallow depressions 

 deepening gradually into ravines, the beds of beautiful 

 streams (full of fine trout), the heads of the Muddy, a 

 tributary of Green Eiver. 



In the ravine formed by the grand northern face of 

 this magnificent plain and the parallel range on the north, 

 runs the old overland stage road ; and the ravine itself is 

 Bridger's Pass, celebrated in the olden time for its natural 



