GEOLOGY OF THE LARAMIE 

 PLAINS 



Traveling westward along the Union Pacific Railroad, we 

 reach Cheyenne and find that we are 6,050 feet above the 

 sea. Thirty-three miles farther west, we are at Sherman, on 

 the summit of the Laramie Mountains, a little over 8,000 

 feet above sea level. Twenty-four miles farther on, we descend 

 upon the Laramie Plains and are 7,149 feet above the 

 sea. Then, for 270 miles farther, our route over the railroad 

 will pass along the valleys scalloped out of the plains and undu- 

 lating between 7,100 and 6,740 feet, until, on descending the 

 valley of Green River, we are 6,077 feet above tide. For 

 100 miles of this distance the road traverses the well-known 

 Laramie Plains. The Laramie Plains are bounded on the 

 east and north by the Laramie Hills, on the south and west 

 by the Medicine Bow Mountains and their extensions. The 

 plains may be 25 to 40 miles wide, and, beginning near the 

 line of Colorado and Wyoming, they extend northwardly 

 for 100 miles, thence northwestwardly for 50 miles. On the 

 west, the Medicine Bow Range forms a prominent barrier as 

 far north as Elk Mountain, thence it drops off into valleys con- 

 tinued beyond in the Seminole, Shirley and Indian Grove 

 Mountains to the Grand Caiion of the North Platte. These 

 mountains are all granitic; Elk Mountain is 11,000 feet alti- 

 tude. The granite of the Seminole, and similar ranges north, 

 is a coarse, red feldspathic and would undoubtedly afford an 

 excellent quarry rock. 



The plains near Laramie City are from 7,100 to 7,500 feet 

 above the sea, but northwardly they are from 6,500 to 7,000 



—25— 



