HOLMES.J THE EAST GALLATIN MOUNTAINS. 21 



although apparently not fossiliferous. They consist of shales, slates, 

 and indurated sandstones. Our animals were left at the base of the 

 western summit, which presents to the north a smooth but steep debris- 

 covered slope. We passed around the left face of this summit into 

 a low saddle, and thence up to the sharp crest of the higher eastern 

 summit. 



All the strata of the upper part of the mountain are highly metamor- 

 phosed, and the slates and quartzitic sandstones present some remarkable 

 examples of jointage. The jointage planes are well marked and very 

 persistent, but have such a variety of directions that it was impossible 

 for me to make out their exact relations to the directions of the dips 

 and strikes. One had but to strike a mass of the rock to make it fall 

 into a hundred angular blocks with faces as true and angles as sharp 

 as if they had been dressed by a joiner. The eastern summit is very 

 rugged and the sides extremely precipitous. A broken spur extends to 

 the north and overlooks the valley of Cache Creek; another extends to 

 the east and connects with Sepulchre Mountain by a low saddle, through 

 which there is a pass from the head of Cache Creek to the valley of the 

 Upper Gardiner. The height of the summit above the sea is 12,000 feet. 

 The western summit is about 50 feet lower. The dip of the strata is to 

 the north and varies from 10° to 20°. The cause of the metamorphism 

 is not very evident; the intrusion of very numerous dikes of igneous 

 rocks has at least contributed to the hardening of the strata. The 

 northern spur has been penetrated by a very complicated system of 

 dikes. Its western face is tattooed by countless dark-brown lines and 

 patches, which are probably mineral-bearing dikes of hornblendic tra- 

 chyte. The specimens of this rock collected do not differ greatly from 

 the hornblendic trachytes that occur throughout the whole series of 

 pre-Tertiary rocks. 



This i3eak, being the highest within the Park, gives a very compre- 

 hensive view of the greater part of this wonderful region. The lake 

 alone is not visible, the bulky mass of the Washburne Eange and the 

 Elephant's Back Plateau effectually hiding it. Beyond, however, can 

 be seen the Upper Yellowstone Mountains, the Eed Mountain Eange, and 

 far beyond this the Teton and Wind Eiver Mountains, with their snowy 

 uplands and serrated summits outlined against the horizon. In the 

 broad intervening space we look down upon the black forests of the 

 Geyser Eegion, which are partially relieved of their gloom by a few yel- 

 low meadows and far-distant columns of steam. Immediately beneath 

 us we have the lovely meadow country, drained by the various branches 

 of Gardiner Eiver. To the right of this and to the south we have the 

 broad mass of the Gallatin Eange, which ends in the prominent dome- 

 like summit at the soath. The broad, mass of the range, as viewed from 

 this point, seems like a lofty plateau cut by a series of transverse val- 

 leys in such a way as to sever the range into four or five east and west 

 ranges. The connecting ridge, the crest of the range, may be followed 

 along the western border of the range, although its summits are not 

 especially marked. On the west there is a pretty abrupt descent to the 

 wooded country belonging to the drainage of the Gallatin Eiver. Be- 

 yond the depressed belt rise the Madison Mountains with their many 

 picturesque summits. To the left of these is the Henry's Lake Eange, 

 of which Sawtell's Peak forms the chief summit. In the middle dis- 

 tance are the broad meadows of the third valley of the Madison, and 

 between that and Sawtell's Peak the well-known Tyghee Pass. 



In looking down on the summits of the series of ridges that form the 

 southern extension of the Gallatin Eange, one is at a loss to detect their 



