GEOLOGICAL SURVEY OF THE TEREITOEIES. 173 



and is about sixty miles long. It is well watered by the branches of 

 the Gallatin Eiver, which are extensively used in irrigation. vChe hills 

 are covered with excellent grass, and form one of the best grazing 

 grounds in the world. Quite a considerable part of the valley is already 

 under cultivation. Crossing the Gallatin, we soon arrived at Bozeman 

 City, a flourishing town, destined to be of considerable importance 

 should the Northern Pacific Eailroad run through it. Three miles be- 

 yond the town we pitched our tents at Fort Ellis. Fort Ellis is situated 

 on the eastern side of the Gallatin Yalley, on the east branch of the Gal- 

 latin. Eiver, and has a force of four companies of cavalry and one com- 

 pany of infantry, under the command of Major E. M. Baker. On the 

 11th of July we visited a small lake twelve miles southeast of the fort. 

 After a ride over a trail which led through dense timber, making our 

 progress difficult, we reached the lake, a beautifnl sheet of water en- 

 sconsed in the midst of hills which rise to a considerable height around 

 it. It is about half a mile in width, and the stream flowing from it 

 forces its way in a deep gully through quartzites. It falls about 500 

 feet in a quarter of a mile. It rushes along with furious rapiditj^, leav- 

 ing high projections of rock on either side. The lake shore is bordered 

 with limestones, which rest on the guartzites. Having refitted and ob- 

 tained an escort, we left Fort Ellis on the 15th, and, after a ride of but 

 nine miles over a very rough road, went into camp. During the day 

 we passed over fossiliferous sandstones of Tertiary ori^^in. At the head 

 of Spring Caiion, through which a small stream flows to join the Galla- 

 tin, we passed an old coal-mine. It is abandoned, and being full of 

 water prevented our entrance. The shaft, however, does not x)enetrate 

 very far. The coal is lignite, similar to that found along the Union 

 Pacific Eailroad. On top of the sandstones we again had igneous rocks, 

 (dark basalts.) For the two following days we were obliged to travel 

 very slowly, having to build our road in many places. The sandstones 

 and basalts continued until we reached the valley of the Yellowstone 

 Eiver, which we entered on the morning of the 17th. The flow of the 

 lava has spread out over the valley, forming a floor, over which our road 

 led. I obtained on our way chips of chalcedony and obsidian, which 

 were abundantly scattered over the valley. 



The valley of the Yellowstone, at the i^oint we entered it, is about 

 four miles wide, and has on its eastern margin a grand mountain range, 

 whose sharp peaks proclaim its volcanic origin. The river is easily 

 traced by the line of timber on its banks. At Botteler's Eanch we 

 formed our permanent camp, being unable to take our wagons farther, 

 and made i^reparations to i^ursue our way with pack-mules. On the 

 20th of July we left Botteler^s, stringing out in single file, with our 

 pack-train along the trail up the Yellowstone Eiver. The trail led us 

 along the left bank of the river over igneous rock, the most conspicuous 

 of which was a breccia composed of large masses of black material 

 imbedded in a red matrix. After a ride of about fifteen miles we reached 

 the lower caiion. Here the river breaks through masses of gneissic 

 rock, which rise abruptly from the water's edge, and over which our trail 

 was very steep and rocky. The canon is about three-quarters of a mile 

 in length and about 280 feet wide. At the bottom of this ravine the 

 river, of an emerald tint, rushes over the rocks, whose resistance causes 

 it to be thrown into numerous foam-caj^ped ripples. The gneissic rocks 

 are for the most i)art garnetiferous, though somewhat indistinctly so. 

 They pass in many i)laces into hornblende schists, and in others become 

 granitoid. Emerging from the canon, our way led us alternately over 

 low hills of igneous origin and expanded valleys. The soil seems to bo 



