GEOLOGICAL SUEVEY OF THE TEEEITORIES. 57 



to the north. The west branch rises in the axis, runs parallel with the 

 middle branch, with a sharp narrow ridge between them. All the 

 branches of all the streams that flow down the Uinta Mountains from the 

 quartzite belt cut the carboniferous limestone ridge at right angles on 

 their way to the plains. At the southeast base rises one of the main 

 branches of the Uinta Eiver, runs east for about three miles, flexes south- 

 ward or a little west of south, and flows down the southern slope of the 

 range into the main Uinta. On the south side of this branch there is a 

 rather sharp ridge, with six or seven conical points rising one hundred 

 to two hundred feet higher than Gilbert's Peak, and culminating in a 

 rounded, dome-like peak, which I estimated to be 13,500 feet. All the 

 valleys of the streams that rise around this peak are more purely valleys 

 of v erosion than any I have seen in this range. The strata of Gilbert's 

 Peak and the ridges and peaks in the immediate vicinity are nearly 

 horizontal or incline southeast 4° or 5°. The principal peaks belong to 

 the southeastern side of the axis. The two sides of the anticlinal are 

 somewhat unequal. A narrow belt, comprising the highest peaks and 

 ridges, with the curves, pyramids, and cones, seems to have been lifted 

 up by forces acting nearly vertical, but the strata incline slightly to the 

 southeast side, so that the streams that flow down the north slope of the 

 range really extend their valleys a little past the anticlinal opening. At the 

 sources of Smith's, Black's, and Bear Bivers the strata incline from the 

 northwest side of this axis at a considerable angle. Here they incline 

 slightly for about five miles, when they dip 20° to 30°. I have no doubt 

 that these streams originated in this anticlinal opening, gradually cutting 

 their channels through the beds of quartzite and sandstone at right angles. 

 The quartzites as well as the sandstones are divided quite finely by 

 joints, so that they break readily into cubical masses of moderate size. 

 Besides they are very brittle, fracturing easily, as is shown by the vast 

 amount of debris. Probably water accumulating in these fissures or joints 

 would cause the debris to fall down into the anticlinal valley and be 

 swept down the channels of the streams of the northern slope. This 

 process of wearing away the horizontal quartzites from the northwest 

 side of the southeast anticlinal has continued until some of the gorges 

 extend up half a mile to a mile beyond the axis. In the beds of the 

 branches of Henry's Fork the descent is by steps from one layer of quartz- 

 ite to another down to the axis, like the horizontal layers of rock which 

 form the rapids in many of our streams. At the present time there is 

 seldom any great amount of water, in some cases none, above this axis; 

 sometimes there is a little lake, the accumulated waters of the melting- 

 snows. 



From this high elevation, with such a vast area of country within our 

 range of vision, one could glance back into the abyss of time, and trace, 

 step by step, the origin and slow erosion of these wonderful, gorge-like 

 valleys, one thousand to twelve hundred feet deep, and speculate upon 

 the beginning and growth of this beautiful mountain itself. The study 

 of the northern slope of the Uintas has been such a source of pleasure 

 and instruction, that I regretted my time would not permit me to ex- 

 amine the southern side also, but a glance over into the the Uinta Val- 

 ley showed quite plainly that the southern side is nearly or quite the 

 counterpart of the other. In all these valleys are numerous small lakes, 

 which add greatly to their picturesque beauty. At the base of Gilbert's 

 Peak, in the valley of the east branch of Henry's Fork, is one of the 

 most beautiful of these lakes, which reflects the peak and the surround- 

 ing pines in its transparent waters. Mr. Jackson succeeded in catching 

 a view of the peak and the lake, with the shadows, with his camera. 



