.480 REPORT UNITED STATES GEOIiOGICAL SURVEY. 



The plateau on the south side of this canou consists of a long, gentle 

 slope to the northwest from the Washburn Mountains, terminating in a 

 shallow trough extending across the plateau, then a gradual rise towards 

 the north to a summit, followed by an abrupt slope northward down to 

 the river. Most of this plateau is drained by Blacktail and Geode 

 Creeks, which head in the Washburn Mountains. The long branches 

 of the former stream come down the slojje of the plateau, collect in the 

 trough above mentioned, and, re-enforced by small streams from the 

 northern slope, break through to the Yellowstone. On the west and 

 north of the depression or trough the plateau breaks down abruptly to 

 the valley of Gardiner's Eiver in a sheer cliff 2,000 feet in maximum 

 height. The summit of the plateau above this cliff is known as Mount 

 Evarts, in honor of a member of the Washburn party, who succeeded 

 in immortalizing himself by getting lost near the south shore of Yellow- 

 stone Lake. 



GARDINER'S RIVER. 



The stream, one of the principal branches of the Yellowstone in its 

 upper course, heads in three large branches, known, in the limited vo- 

 cabulary of the mountains, as the East, Middle, and West Forks. Of 

 the three the West Fork is by far the smallest. It heads in Sepulchre 

 Mountain, an outlying peak of the Gallatin Eange, flows at first south 

 down an open valley, then turning east it cuts through a mountain 

 ridge, which limits the valley of the main Gardiner's Eiver on the west, 

 making a fine fall in the caiion. 



The Middle Fork, much the largest of the three, receives most of its 

 water from the Gallatin Eange, while some good-sized branches come 

 from the timbered plateaus to the southwest and south. Its longest 

 branch heads in Electric Peak, the highest and finest mountain within 

 the limits of the Park. The stream flows thence south in the same 

 broad, open valley with the West Fork, collecting stream after stream 

 as it issues from among the mountains. Finally, turning eastward, it 

 receives the waters collected from the many springs on the plateaus, 

 cuts its way through the ridge encountered by the West Fork, and is 

 joined by it in the valley below. In the caiion this stream, like the 

 West Fork, makes a very fine fall. 



The East Fork joins the main stream about half a mile below the junc- 

 tion of the other two branches. It continues up at first in a southeast 

 course, then turns to the west, and heads in the western and northern 

 slopes of the Washburn Mountains and in the timbered plateaus lying 

 west of them. This stream also makes a fine fall at a point 2 or 3 miles 

 above its junction with the main stream. 



Below the junction of these branches, Gardiner's Eiver flows north, 

 making a very straight course to the Yellowstone, bordered on the right 

 by the cliff of Mount Evarts, on the left by a steeply-sloping vaUey, which 

 terminates in a low caiion wall on the margin of the river. 



The celebrated Mammoth Springs are situated about 4 miles above 

 the mouth of the river and 1^ miles back from it, and are elevated above 

 it nearly 1,000 feet. 



THE EAST FORK OF THE YELLOWSTONE. 



This, the largest branch of the river, in its upper section, heads entirely 

 in the Yellowstone Eange, and enters the main stream between the Grand 

 and Third Caiions. Its extreme southern branches drain the mountains 

 as far to the south as the northern shore of Yellowstone Lake, while its 



