110 GUIDEBOOK OF THE WESTERN UNITED STATES. 



Long ago, in the Wisconsin stage of the glacial epoch, a great 

 glacier came down East Fork to a point within a mile and a quarter 

 of the Denver & Rio Grande Western Railroad. This great river of 

 ice scoured the valley clean and left it with a broad, flat bottom and 

 a gentle grade. Most of the loose material scoured from the rocky 

 sides of the valley by the moving mass was carried away by Ar- 

 kansas River, but some was dumped near the loAver limit of the ice. 

 Another glacier came down Lake Fork from the high mountains on 

 the west, and this one was so strong that it pushed out across the 

 broad, flat valley of the Arkansas, crowding the stream against the 

 bluffs on the east side. This glacier dumped a great mass of loose 

 material in semicircular form (called a terminal moraine), which 

 the traveler may see on the west (left), but he is so far below its 

 summit that he can not realize its shape. A glance at the map 

 (sheet 4) will show its semicircular shape, which conforms to the 

 curved margin of the tongue of ice that laid it down. 



About halfway between mileposts 274 and 275, a mile beyond the 

 crossing of East Fork, the railroad is crossed by a high-tension elec- 

 tric transmission line, which is carried on steel towers. This line 

 carries the power generated in a hydroelectric plant on Colorado 

 River,^^ which the traveler will see at Shoshone, 10 miles east of 

 Glenwood Springs. As the transmission line for such a plant is very 

 expensive, it follows as straight a course as possible without regard to 

 mountains or canyons. For this reason it does not follow the Denver 

 & Rio Grande Western Railroad eastward from Shoshone but turns 

 to the south and passes up Roaring Fork and Fryingpan Creek to 

 Hagermann Pass. From this point it descends Lake Fork and 

 crosses the Denver & Rio Grande Western, as noted above, and thence 

 goes to Leadville, where much of the power is utilized in the mines 

 and mills. The line then turns northeastward toward Denver and 

 crosses Fremont Pass to Tenmile Creek, which it follows to Dillon. 

 From Dillon it runs due east and crosses the Continental Divide for 

 the third time at Argentine Pass. It then descends Clear Creek, 

 serving Idaho Springs, Central City, Blackhawk, and finally Denver. 

 The traveler who visited Mount McClellan while at Denver probably 

 noted the steel towers and the wide swath cleared of timber for this 

 line along the mountain slopes. 



Near milepost 275 Arkansas Valley regains its normal width of 

 about 2 miles. The constrictions lower down are due entirely to the 

 moraines of the glaciers that flowed down from the mountain valleys 

 on the west. Another glacier from the west filled the valley above 

 milepost 278 with a great moraine, which also crowded the stream 



^* The name of Grand River, in Colorado and Utah, has recently been changed 

 to Colorado River by act of Congress. 



