GEOLOGICAL SURVEY OF THE TERRITORIES. 31 



for existence among the crevices, and some rare shrubs and ferns were 

 all the vegetable life observed. It seems as though the Sweetwater 

 flowed through this valley for fifty miles or more with scarcely a tribu- 

 tary to add to its volume. 



These granite ridges present the finest opportunity for the study of 

 rocks. Huge fissures, which have been enlarged by atmospheric agencies 

 so that they vary in width from a few inches to several feet, seam and 

 farrow their sides. 



On the summits vast masses, of one hundred tons weight, appear just 

 ready to topple down. Many of these fragments look like gigantic 

 boulders, so rounded have they become by the process of exfoliation, and 

 such they would be called if they could be transported from the tops of 

 these mountains by water and ice to the prairies of Illinois, without any 

 further change in their form. Some of these masses are now covered 

 with thin scales or layers, which are ready to fall off, and multitudes of 

 fragments are scattered around. Before leaving Independence Eock we 

 endeavored to obtain an approximate idea of its dimensions. The cir- 

 cumference, measured with the odometer, is fifteen hundred and fifty 

 two yards, and the barometer indicated the height of the north end to 

 be one hundred and ninety-three feet, and the south end one hundred 

 and sixty-seven feet. The trend of the mass is about northeast and 

 southwest. There is a depression near the middle which cannot be 

 more.than sixty feet high. The huge fissures which pass through the 

 rock in various directions seem to form channels for water, and remino 

 one of a river and its branches. Although there is enough of red feld 

 spar to give the whole a reddish tinge, yet the white or soda feldspa. 

 occurs in great quantities. Five miles up the valley we came to an 

 other well-known locality, the Devil's Gate, a canon which the Sweet 

 water seems to have worn through the granite range. The road passes 

 through a depression in the mountain which is about thirty feet higher 

 than the bed of the stream, and I am inclined to believe that the Sweet- 

 water once flowed through it, but for some reason, not very obvious, 

 changed its channel. Perhaps the water found some fissure through 

 which it began to flow, and gradually wore its way through, as wo 

 see it at the present time, or it may have vibrated its way from point 

 to point. Now the stream flows between these lofty walls with a low, 

 gentle murmur, which cannot be regarded as the roar of a torrent. 

 Indeed, it gave forth a soothing music not common to mountain streams. 

 The current is not strong, and finds its way among the huge masses 

 which have fallen down from above without difficulty. The left wall is 

 somewhat higher than the right. The canon is about northeast and 

 southwest, as if the waters had passed through a sort of dike fissure, 

 and the northeast end shows the gate more perfectly, where the walls 

 on either side are nearly vertical, and the width of the bottom is not 

 more than one hundred feet. The southeast end is worn out to some 

 extent, and is two hundred to three hundred feet wide. By the barom- 

 eter Mr. J. W. Beaman made the right wall three hundred feet high, 

 and the opposite one to be a few feet higher. In the gate or canon is a 

 wide dike or trap, which has a trend about northeast and southwest, in 

 which the channel of the river may have started originally. At the 

 present time the waters have cut across the dike so that the southeast 

 portion still remains on the right side. These granite ranges are not 

 unfrequently banded with old trap dikes, trending about northeast and 

 southwest, and varying in width from a few feet to two or three 

 hundred feet. Some of them yield quite readily to atmospheric agencies, 

 and many conspicuous depressions are produced in the ranges, thus 



