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GUIDEBOOK OF THE WESTERN UNITED STATES. 



of the valley is composed mainly of rocks that overlie the quartzite, 

 and if a trench were cut from the top to the bottom of the slope the 

 rocks would appear as shown in figure 28. 



^ 



Figure 28. — Section across Eagle Park, showing the thin cap of quartzite on the west 

 (left) and the same bed dipping into the base of the slope on the opposite side. The 

 beds dip eastward, away from the Sawatch or Holy Cross anticline. 



Near milepost 286 the traveler has an unobstructed view to the 

 east (right) up the valley of the East Fork of Eagle River almost 

 into Fremont Pass. The width of this valley suggests that it has 

 been occupied by a great river of ice that origi- 

 nated in the high summits of the Mosquito 

 Range north of Leadville and flowed down 

 Eagle River valley to a point where the melt- 

 ing exceeded the supply of ice from above, 

 but the region has not been examined carefully 

 enough to determine this point. 



In descending the west wall of the valley 

 the traveler may look down upon the level sur- 

 face of Eagle Park, and one of the features 

 that may attract his attention is the crooked 

 course of Eagle River, which wends its way 

 down the valley in many bends or meanders. 

 These bends, as seen from a point midway be- 

 tween mileposts 286 and 287, are shown in the 

 accompanying sketch (fig. 29). Courses so 

 crooked are not limited to streams in mountain 

 regions but are characteristic of streams that 

 flow on flat surfaces with a grade insufficient 

 to enable them to straighten their channels. 

 The cause of the flat surface here was a dam 

 formed by a glacier in the valley at Pando. In the pond above this 

 dam mud accumulated, and when the ice disappeared the valley Avas 

 left with a flat mud bottom, which has since been covered with a thick 

 layer of turf. 



Figure. 29. — Meanders of 

 Eagle River in Eagle 

 Park near Deen. 



