20 DESCRIPTIVE GEOLOGY. 



surface is undulating, clotted over with rounded knolls of granite, covered 

 with pines. 



Small lakes from one-half to one mile in length are characteristic of 

 the upper mountain region. There are several in the neighborhood of 

 Estes' Park, also in the region of the headwaters of the Big Thompson 

 Canon, and in the bottom of the larger eroded basins. The west side of 

 the divide is much shorter, with the trough-shaped valleys cut deeply into 

 the mountain-sides, stretching down to the interesting middle region between 

 the Colorado and Medicine Bow Ranges. These ridges are generally nar- 

 rower and sharper, with the rocks dipping steeper than on the opposite 

 side. 



This depressed middle region between the two great ranges is from 

 5 to 7 miles in width, a gently rolling country with a plateau-like character, 

 that is on the summit between Hague's Peak and Mount Richthofen in the 

 Medicine Bow Range, but to the north and south it soon passes into the 

 broad glacial valleys of the Grand River and the Cache la Poudre. 



Two principal streams, the Cache la Poudre and the Big Thompson, 

 drain nearly all this entire portion of the Colorado Range. 



The main branch of the Cache la Poudre rises on the west slope of 

 Hague's Peak, runs northward between the two great ranges already men- 

 tioned, and just south of the line of 40° 45', making a great bend flows 

 eastward; it is then joined by the South Fork, which comes down from the 

 northeast side of the same peak, and carries much of the water of the eastern 

 slope into the larger stream. A few miles farther down the river, it is joined 

 by the North Fork, which, with its numerous lesser branches, including Fish 

 and Sportsman's Creeks, drains the northern district. The resulting stream 

 leaves the range just above the town of Laporte, runs southwesterly, and 

 joins the South Platte near Greeley, 25 miles out on the plains. 



A much narrower area is drained by the Big Thompson. Two main 

 branches, the one rising on the east slope of Hague's Peak and the other in the 

 Long's Peak Group, furnish channels for all the remaining waters of the higher 

 summits. Soon after they unite, and just before leaving the mountains, the 

 stream is joined by Redstone Creek, a considerable tributary from the north, 

 which drains the foot-hills left by the South Cache la Poudre. The Big 



