'56 GEOLOGICAL SURVEY OF THE TERRITOEIES. 



lower than the crests around, being over 12,000 feet above sea-level, and 

 2,000 feet above our camp at the forks. But the pass itself is an illus- 

 tration of the slow wearing away of the crest between the sources of 

 the streams. The summit of the pass is very narrow, and on the top 

 and sides are vast quantities of fragments of rocks fallen from the side- 

 walls. There is no doubt in my mind that the crest of the mountain 

 was at one time continuous, and far greater than at present, and that a 

 mass of granite rock the width of the pass, and 500 to 800 feet high, 

 has been removed by agencies not now in operation. Yet the slow pro- 

 ^cess of the breaking down of the sides still goes on summer and winter, 

 and the debris forms one of the remarkable features of this region. As 

 we descend the west side of the pass, we have before us in full view 

 one of the most spacious and regular amphitheaters we have seen, form- 

 ing the source of Morainal Creek. It is in the form of a semicircle, 

 with an irregular wall around forming the mountain-crest. On the west 

 side are two mountain-cones rising up 13,000 feet or upward ; on the 

 east side, a high rounded peak covered over with debris, while the south 

 side has been broken down so as not to be more thao 300 feet above 

 the base of the wall. Vast quantities of the debris, or talus, lie all 

 around the base of the wall, while in the center is a forest of pines. 

 "We see, therefore, that although the evidence is clear that these amphi- 

 theaters have been carved out of the massive granite, no forces are now 

 in operation to carry away the fragments of rock that are annually 

 loosened from the walls by water and ice, but they gather on the slope, 

 forming a talus of great magnitude. We shall have much to say, as we 

 pass from point to point, in regard to mountain sculpture. We believe 

 that geologists have hardly realized as yet the tremendous degradation 

 of our high mountain-ranges, which has been carried on during, or since, 

 the Tertiary period. 



We descend to the west side of the mountain to the little creek, and 

 find ourselves in the midst of the most striking examples of morainal 

 ridges yet seen in the West. These extend from a point near timber- 

 line down to the valley of Taylor's Creek, a beautiful stream that occu- 

 pies in part a valley parallel with the Arkansas on the west side of the 

 main range. I have spoken previously of the anticlinal structure of 

 this region. On the west side of the Sawatch or Mother range there is 

 an irregular parallel depression, extending northward to the Mount of 

 the Holy Cross, and southward far down the Gunnison Valley. Yet the 

 drainage is not continuous north and south like that of the Arkansas. 

 The drainage tends toward the northwest in the valleys of Eoaring 

 Fork and Frying-pan Creek, and to the southwest in the valley of Gun- 

 nison and its branches. While between the waters of the two systems 

 the divides are quite high and almost impassable, still the inclination 

 of the great mass of the rocks is toward the west in general terms, and 

 the anticlinal structure well illustrated. The interval between the 

 ridges is much more broken, and has not been worn out by one con- 

 tinuous river like the Arkansas. 



The morainal deposits are best shown on the west side of the 

 Sawatch range. Along the side of the mountains, rising 800 to 1,000 

 feet above the valley of Taylor's Creek, is a ridge entirely covered 

 with the debris falling from the summits of the range, and mo- 

 rainal matter. It is most probable that the granite rocks form 

 the nucleus, but that the ridge has been worn down by glacial action 

 and covered over with the miscellaneous deposits of morainal drift. The 

 ridge Is quite rounded in form, covered in many places with i)iues, and 

 extending up on the sides of the range nearly to timber-line. The second 



