170 GEOLOGICAL SURVEY OF THE TEREITORIES. 



tures, and Mr. Jackson concluded to remain several days in the valley. 

 We continued on our way, hoping to be able to cross the range and 

 descend to the West Gallatin, where we expected to join the main party 

 the next day. We reached an elevation of 9,000 feet, and found our- 

 selves surrounded by a semicircular wall, which rose 600 feet in perpen- 

 dicular height above us. At the base lay immense banks of snow. To, 

 cross was impossible, so we retraced our steps, and on reaching tbe first 

 open space above the caiiou where we had encamped three days before, 

 we crossed the ridge to Cottonwood Creek, which we followed to the 

 plain. We then proceeded along the edge of the mountains until we 

 reached the mouth of the West Gallatin Caiion, and, striking the trail 

 of the main party, we pushed up stream as rapidly as possible. The 

 rocks at the mouth of the caiion are gneisses, which dip .northwest at 

 an angle of about 75°. They are followed by immense beds of lime- 

 stone, which at first, I think, dip in a southerly direction, but soon 

 change to the northeast. The angle varies from 20° to 30°. They are 

 the direct prolongation of the layers which we observed on Middle and 

 Cottonwood Creeks, and which we also noticed on Pole and Cherry 

 Creeks when we were on our way down the Madison. The limestones 

 are again succeeded by gneisses, probably the continuation of those 

 through which the Madison cuts the Lower Cafion. Then follow lime- 

 stones "^^piug southwest. These I believe to be the continuation of 

 the layerssin the Madison Kange, which I referred to as making a turn 

 toward the east near Jackass Creek. To the east of the Gallatin Eiver it 

 is difficult to trace them, for we find ourselves immediately in a volcanic 

 region. That there is some connection between this ridge and the lay- 

 ers outcropping on Cinnabar Mountain is highly probable. Just above 

 this last ridge of limestone we found the main party encamped. On 

 the opposite side of the river there was a high bluff wall made up of 

 Cretaceous and Jurassic rocks. Our camp on the western side was 

 upon Jurassic rocks. These seem to continue to the westward in a gen- 

 tle slope from the Gallatin to the Madison Eange. The weather became 

 so snowy and unfavorable for work that I was not able to follow the 

 beds to the westward, as I desired, but the section shown in Fig. 42 

 which 1 referred to in the preceding chapter, will show what I believe 

 to be the relation of the beds exposed on the Gallatin, opposite our 

 camp, to those of the Madison Eange. To definitely settle their rela- 

 tion, however, the western side of the Madison Eange will have to be 

 worked out in more detail than it has been up to the present time. The 

 caiion of the West Gallatin is so fully treated of in other portions of 

 the report that I have thou -ht it best merely to refer to it. Leaving the 

 Gallatin Eiver we crossed the divide to the Yellowstone Eiver. On the 

 very summit I obtained specimens of silicified wood embedded in basaltic 

 rock, which is here mingled with Tertiary sandstones, which have here 

 been very much metamorphosed. The elevation of thedivide atthe point 

 we crossed it is 9,317 feet. We struck the Yellowstone just below the 

 second canon, and followed it down to Bottler's ranch. While at this 

 point 1 crossed the Yellowstone Eiver and went up Emigrant Gulch, one 

 of the regions in which gold-mining has been carried on to a somewhat 

 limited extent. The gulch cuts into the mountain-range for some dis- 

 tance in a general southeasterly direction. The rocks near the mouth of 

 the gulch are chlorite schists," which dip in a northerly direction, or 

 perhaps a little west of north, at an angle of 40° to 45°. These chlo- 

 ritic rocks extend for about two miles and a half, and are followed by 

 gneisses, which dip underneath them. These gneisses are probably a 

 continuation of those exposed in the second canon of the Yellowstone. 



