262 GEOLOGICAL SUEVEY OF THE TEERITOEIES. 



of the beds are as sliowu in the section from Capitol to Sopris Peak, 

 Eig. 1, Plate XX. 



Leaving Eock Creek we proceeded down East Eiver to Cement Creek, 

 and then crossed to the Gunnison, which we followed to one of its sources, 

 and then crossed to the head of Difficult Creek, one of the branches of 

 Eoaring Fork. The divide between this creek and the Gunnison where 

 •we crossed it was 11,619 feet above sea-level. The rocks here, which are 

 all granitic and gneissic, were referred to in the preceding chapter. On 

 one of the stations (76) near the head of the creek, I found fair specimens 

 of rose quartz. The view from this station looking westward was ex- 

 tremely fine. In the foreground we had the low ridges, heavily tim- 

 bered with dark-green pines, beyond and above which the mass o'f 

 mountains about Castle Peak towered, their somber blackness relieved 

 by patches of snow. To the right and nearer us the dark colors changed 

 to a deep orange, streaked by light gray wherever there were slides of 

 rock. Still more to the right we had the red sandstones, their bright 

 color contrasted with the grassy slopes on the rounded hills. Beyond and 

 reaching high above, bathed in sunlight, stood the Capitol and Snow Mass 

 Mountains, their immense snow-fields glistening with silvery brilliancy. 

 To the right of the Capitol is a prominent point seen from all parts of the 

 Eoaring Fork Valley. It is noticeable for a bright yellowish band which 

 is distinctly outlined in its face, like the band on an escutcheon. It may 

 be a dike. We did not have time to visit the peak to determine to what 

 the appearance is due. The creek we followed to the main Eoaring Fork 

 is densely timbered, and just before reaching the main stream plunges 

 abruptly down a steep hill about 1,000 feet in height. Here we had to 

 work about six hours in order to get our train down. One thing par- 

 ticularly noticeable when we reached Eoaring Fork was the change in 

 the vegetation. On the Gunnison we had seen but little in the way of 

 vegetation besides the sage-brush, (Artemisia.) On Eoaring Fork, how- 

 ever, we found a profusion, among which we noticed the scrub-oak, 

 {Querciis alba,) a willow, {Salix,) two species of raspberry, [Euhus deli- 

 ciosus and R. strigosus,) the service- berry, [Amelanchier canadensis,) the 

 common currant, {Bibes rubrum,) and the common wild rose, {Rosa hlanda.) 

 The upper i^art of Eoaring Fork is in canon, emerging from which the 

 stream flows through a valley that gradually increases in width, and is 

 filled with drift that has been carried down by the water. Above Cas- 

 tle Creek this drift is made up principally of granitic boulders. Castle 

 Creek is the first large creek coming into Eoaring Fork from the left side. 

 It drains the east side of Castle Mountain, one branch also heading on 

 the west side of the peak. All the branches have cut deeply into the red 

 sandstones exposing the carboniferous layers below. A short distance 

 *^bove the mouth of Castle Creek Hunter's Creek comes in from the 

 east. It is here that we first meet with the stratified rocks. The Silu- 

 rian quartzites cross the main stream, and the line of outcrop extends 

 up Castle Creek. On the east side the dip seems to be north 35° west, 

 angle 25° to 30°. On the other side the beds are more highly inclined, 

 and dip in about the same direction 50°. From this point the valley 

 widens, and is covered with an extensive deposit of drift, a large portion 

 of which was probably derived from the Elk Mountains. Indeed, this 

 is shown by the great quantities of red sandstone boulders in the bed of 

 the stream. This deposit is cut into terraces by Eoaring Fork, and all 

 the branches coming in from the southwest. The terrace on the right 

 side of Castle Creek is 130 feet in height. On the opposite side it is 

 about 210 feet in height. The next creek below Castle Creek, Maroon 

 Creek, is also large, and drains the i)ortion of the Elk Mountains east 



