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 lower 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 Denyer 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 
*8 The name of Grand River, in ae and Utah, has recently been changed 
to Colorado River by act of Congre 
