128 



MARGARET BRADLEY FULLER 



Black Canyon on the north, Fish Creek Valley on the south, 

 and Dunraven Valley on the east between Mounts Olympus and 

 Pisgah are tributary to the Thompson within this area. They, 

 like their main, are broad, open, and U-shaped. The Thompson 

 has sunk its channel from 50 to 100 feet below the broad level of 

 the Estes Valley and locally has developed intrenched meanders. 



3. The third unit begins at the eastern end of the Estes Valley. 

 The sides are sharply constricted within granite walls, making a 



V-shaped canyon with 

 precipitous slopes in- 

 creasing in steepness 

 to the east of Love- 

 land Heights and Glen 

 Comfort. From Estes 

 Valley to the Forks at 

 Drake the river's 

 course lies through a 

 canyon whose tributa- 

 ries are narrow gulches 

 typical of youthful 

 stream erosion. 



4. The fourth unit lies between Drake and the east end of Mont 

 Rose Valley (Fig. 2). In this area the Big Thompson Valley is 

 wider than above Drake, although not as wide as in Estes, and has 

 a broad, U-shaped outline. The stream has sunk its channel over 

 100 feet into the bottom of this open valley and has made a narrow 

 canyon about 6 miles long which marks the last cycle of canyon 

 cutting. 



The North Fork enters the Thompson at Drake. This stream 

 valley is open and U-shaped in outline with gently rounded roche 

 moutonne surfaces developed on the granite in the upper part of 

 the valley bottom. As seen from Bryant's Ranch the valleys of 

 the North Fork and the Big Thompson are much alike. In fact 

 they are so similar that one seems but a continuation of the other. 

 The North Fork and the part of the Big Thompson between Drake 

 and Mont Rose are in perfect harmony, while the upper part of the 

 Big Thompson between Estes and Drake is entirely out of accord- 

 ance with the lower reaches. 



Fig. 2. — View looking upstream through Mont 

 Rose Valley (unit 4). Note the open U-shaped 

 outlines of the valley walls with the sharp ungla- 

 ciated peaks of Palisade Moimtain in the distance. 



