16 GUIDEBOOK OF THE WESTERN UNITED STATES. 



peratures ranging from 75° to 120° F. Hotels and bathhouses make 

 the place very attractive to the traveler who can spend a few days 

 in the bracing atmosphere of this mountain resort. 



The first really noteworthy discovery of gold in Colorado is com- 

 memorated by a monument at the mouth of Chicago Gulch, a canyon 

 entering that of Clear Creek from the left of the railroad nearly 

 opposite the station at Idaho Springs, This discovery was made by 

 George A. Jackson in January, 1859. \yhen winter was over Jack- 

 son returned to the mountains and on May 7 began placer mining 

 on Jackson Bar. 



One of the most notable achievements of mining engineering in 

 this region is the Argo (formerly Newhouse) tunnel, whose large 

 waste dumps may be seen in the eastern part of Idaho Springs. This 

 tunnel extends northward for 5 miles to a point beneath the town 

 of Central City. It cuts many of the veins far below the surface, 

 draining the upper workings and facilitating deep mining. Much 

 ore is brought from the Central City district to Idaho Springs 

 through this tunnel, and mining at or below its level has shown that 

 rich gold ore persists in many of the veins at very great depths. 



In the vicinity of Idaho Springs the canyon, although wider than 

 it is in the neighborhood of Forks Creek, is still narrow and the 

 walls are studded with jagged or loose rock as they were left by the 

 cutting of the stream and the action of the weather, but from a 

 point a few miles above the town to the crest of the range the canyon 

 bottoms are broad and the slopes are generally smooth and round, 

 so that a cross section of the valley resembles in shape the letter U. 

 This form of valley (shown in fig. 4, p. 11) is due to the scouring 

 action of a glacier that originated near the summit of the range and 

 flowed down the canyon to a point where the ice melted faster than 

 it was supplied from above and where the forward movement of the 

 glacier consequently stopped. Although all this happened ages and 

 ages ago, the surface features above and below this point still present 

 a striking contrast, for the work of the glacier has not yet been 

 obliterated by weathering. The end of the glacier, which was only 

 a few miles above Idaho Springs, is also marked by a moraine — a 

 great accumulation of rounded and scratched boulders that were 

 brought down by the ice and dumped at its lower end. 



Both active and abandoned mines and many prospects may be seen 

 on almost every slope of the canyon wall above Idaho Springs. In 

 Gilpin and Clear Creek counties, as in most old mining regions, only 

 a small proportion of the mines are in operation at any one time. 

 Some of those that are not operated are " dead " — that is, their ore 

 bodies have been entirely worked out — but many are idle only tem- 

 porarily because of inefficient management or insufficient funds with 



