GEOLOGICAL SURVEY OF THE TERRITORIES. 171 



They ex-eud for a short distance, when we find igneous rocks resting 

 upon their upturned edges. These igneous rocks rise to a great height 

 on either side of the gulch, and in fact form the crest of the entire 

 range, as I noticed when on the summit of Emigrant Peak last year. 

 The stream descends very rapidly as it flows down the gulch, and there 

 are numerous cascades and waterfalls in its course. At the mouth of 

 the gulch there was formerly quite a large settlement, but at present 

 nothing remains save the stone chiinneys of Yellowstone City. As we 

 ascend the creek the gulch narrows very rapidly. There are two mining- 

 camps, one at the head of the stream, the other at the mouth of the 

 gulch. The mines are all placer-diggings, and at present there are only 

 twenty or thirty men working here. The highest yield is $\5 per day, 

 the average being about $5 per day to each man. There are four claims 

 worked at the lower camp and three at the upper, and since the dis- 

 covery, in 18G4, it is estimated that the gulch has yielded over $100,0U0. 



The chloritic rocks, which are exposed in Emigrant Gulch, extend 

 along the range as far north as the Lower Caiiou of the Yellowstone. 

 Near the latter, in one of the smaller gulches, I obtained specimens of 

 Ifacoliimitc in lamina about an inch in thickness and having a greenish 

 color. None of the specimens were flexible. Our next camp, after 

 leaving Bottler's, was just above the Lower Canon of the Yellowstone. 

 Here the limestones extend across the river, which cuts through them 

 •almost at right angles to the strike. The dip of the beds is east of north. 

 They are probably the continuation of one. branch of the anticlinal, 

 which we have referred to before in Spring Caiion. On the north side 

 of the caiion we find Jurassic layers resting immediately on thick beds 

 of quartzite, which lie between them and the Carboniierous limestones. 

 The inclination of the beds is about 25°. The Jurassic beds consist of 

 alternate layers of calcareous clay shales, which weather blue, and hard, 

 yellow limestone. They contain great quantities of fossil, among which 

 are Tngonia, Ammonites, Ostrea, and Pinna. These are succeeded by 

 Cretaceous sandstones, which . are in turn followed by Tertiary strata, 

 which are from 1,500 to 2,000 feet in thickness. Alter passing through 

 the Lower Canon, we turned to the left and proceeded up Divide Creek, 

 a small stream flowing into the Yellowstone from the western side. Its 

 valley, for the most part, is a monoclinul valley, between Cretaceous and 

 Tertiary strata. The Tertiary beds are composed of sandstones, which 

 are generally quite soft and of a gray color. The lower layers are often 

 quite hard, and of a somber brown color, seeming to have been some- 

 what changed. At several points I noticed the occurrence of dikes, to 

 which this change may be attributed. The general dip is in a northerly 

 or northeasterly direction, and the angle about 35° to 40°. 



Eeaching the head of the stream, we crossed the divide, and found 

 ourselves at the head of the creek which flows through Spring Caiion. 

 Here we turned toward the right and crossed to Bridger Creek, which 

 we followed up around the eastern side of the Bridger Range to Flat- 

 Head Pass, through which we went to the Gallatin Valley. The rocks 

 on the eastern side of the range at Flat-Head Pass are Cretaceous 

 sandstones, dipping a little north of east, angle, 30° to ~)VP, succeeded by 

 Jurassic layers, which are for the most part covered with grass, conceal- 

 ing them. The center of the range is. made np of Carboniferous lime- 

 stones, which are almost vertical. As we pass toward the westward, 

 however, they begin to dip in a westerly direction. They ai'e followed by 

 Silurian beds, which also dip in the same direction. The Silurian layers 

 are composed of slaty limestones, pebbly conglomerate limestones, 

 and compact brittle limestones, containing fragments of trUobites. 



