60 GEOLOGICAL SURVEY OF THE TERRITORIES. 



tliis point in the sido of the monntaiu there is a small canon, from which 

 a considerable amount of water mnst flow at certain seasons of the 

 year, and the matcTials from this canon may have assisted in building 

 up the jidge. I have no doubt, however, that the upper portion of the 

 canon has been at some period filled up with loose bowlders and drift 

 transported from above, and when the gorge broke away, most of it 

 was carried down the river, but that this portion was in some way pro- 

 tected. The entire valley between the mountains is literally paved with 

 rounded bowlders, and there is no doubt that this same coarse material 

 extends beneath to a great depth. In the caiion itself there is a still 

 more prominent ridge, and the loose rocks on every side are much larger 

 and more abundant. A fine stream comes into the river from the mount- 

 ains on the east side. This little stream has cut a narrow gorge for 

 fifteen miles, with walls on either side 2,500 to 3,000 feet high. There 

 is an abrupt bend in the river just above this ridge of bowlder-drift, 

 which may account in part for its accumulation at this particular spot. 

 The central portions of this range are mostly micaceous gneiss, some 

 parts very compact, tine-grained, steel-black in color. The variations 

 in texture and color are very great, as is usual among the metamorphic 

 rocks. From the summit of the high ridge on the east side of the river, 

 at a height of about 9,500 feet, we were able to take in a large scope of 

 country, and study out the character of these rugged mountain-peaks. 

 In this range, which is a limited one, there are a dozen peaks which will 

 reach 9,800 to 10,250 feet, while two of them are about 10,500 feet. The 

 rocks are all metamorphic or gneissic, and remarkably hard and com- 

 pact, so effectually resisting the meteoric forces that the rocks to the 

 summits of the highest peaks are as sharp and angular as if only frac- 

 tured within the present season. These unworn angles give a peculiar 

 sharp ruggedness to the view, as the eye passes across the summits of 

 the many peaks or descends into the innumerable gorges on every side. 

 To the east, toward the valley oC the Gallatin, the strata of limestone 

 may be most clearly seen where they have been cut down in the gorges, 

 jet holding a great variety of positions. Sometimes they dip down 

 suddenly in the valley and pass out of sight, then again they are ele- 

 vated bodily to the summit of a high peak, resting on the metamorphic 

 rocks. On the west side of the Madison there are three or four peaks 

 which are at least 10,000 feet high. Among these mountain-gorges we 

 see the sources of the myriad small branches which, in the aggregate, 

 form the large river. i!!?estled among the craggy cliffs are here and 

 there little ponds of clear water, derived from the melting of the snows, 

 seldom ever seen except by the birds and the game that visit them to 

 quench their thirst. The tendency of all these gorges is to work their way 

 inward toward the divide. Great masses of snow and ice accumulate 

 in them during the winter, and the water, flowing down among the frac- 

 tured masses, freeze--, and expands with a lorce that year by year tears 

 down a portion, that falls into the depths below and is swept down by 

 the torrent. The aggregate of the forces which have continued in 

 operation through a series of ages, which no man can determine now, 

 and which we agree to denominate meteoric or atmospheric, are the 

 combined action of water, air, and ice. These forces have undoubtedly 

 been far more effective in ages past than at present. In one of the 

 gorges which lead down to the river in the caiion, we discovered a 

 complete inversion of the strata, and this condition of things was 

 found afterward to prevail to a large extent in these mountain-ranges. 

 I would refer the reader to Dr. Peale's report, and also to the descrip- 



