GEOLOGICAL SUEVEY OF THE TEEEITOEIES. 191 



"vras quite aniibnndant deposit about it. It is situated on the bank of a 

 small creek, and gives off sulphureted hydrogen. 



We reached tbe junction of the two forks of the Yellowstone on the 

 25th of August, having made the circuit of Yellowstone Lake, includ- 

 ing the geysers also. Near the junction there is a large extent of 

 ground strewn with huge granitic bowlders. Farther up the East Fork 

 of the Yellowstone than we went there is said to be gold, although at 

 the present time it is unsafe to mine there, on account of the Indians.' I 

 was given several specimens of galena and pyrites, said to be from that 

 locality, from surface-diggings. We crossed the Yellowstone on the 

 first and only bridge over its water, which was built here by one of 

 the trappers in anticipation of a rush to the gold-diggings of Clarke's 

 Fork. From the junction we followed our old trail, ]3ast the White Hot 

 Springs, the Devil's Slide, and the Lower Canon, to Botteler's Eanch, 

 getting into the permanent camp on the 27th of August. On the oppo- 

 site side of the Yellowstone from our camp, there is a high volcanic 

 peak, one of a long chain. It bears the name of Emigrant Peak, and 

 rises 10,629 feet above the level of the river. Its summit is composed 

 of a very dark, compact basalt, containing a few small crystals of mica. 

 Lower down it passes into a lighter variety. In Emigrant Gulch, which 

 is at its base, there are granites and chloritic rocks. Specimens of pum- 

 ice-stone were found near the head of the gulch. There is some little 

 placer-mining for gold carried on in the gulch, though as yet not in a 

 systematic manner. 



We left Botteler's on the 29th of August, arriving at Fort Ellis the 

 following day. On the way I obtained a specimen of a rhyolitic rock, 

 having a very compact, violet-colored matrix, resembling the matrix of 

 the felstones. It was enamel-like, and contained crystals of feldspar 

 and mica. 



On the 5th of September we left Fort Ellis, starting on our home- 

 ward trip. Fording the Gallatin and Madison Eivers, we passed the 

 junction of the three forks of the Missouri, and camped near the Jeffer- 

 son Eiver. The valley is quite wide, and well cultivated. The only 

 rocks observed were limestone, which continued to the Jefferson. The 

 river cuts its way through them, forming a deep caiion, obliging us to 

 cross the hills east of the stream. Here we encountered gneissic and 

 granitic rocks, upon which rested beds of reddish quartzites. 



On the 8th we again struck the Jefferson, and followed it until we 

 reached its commencement in the union of the Big Hole and Beaver 

 Head Eivers. The mountains on both sides of the Jefferson are granitic, 

 and contain auriferous lodes. On the side opposite that on which we 

 were there were a number, two of which are named the Highland and 

 the Clipper. One has a depth of 300 feet, and has been worked steadily 

 for the last three years. At the base of the mountain there are three 

 or four quartz-mills. The formation we passed over was drift, contain- 

 iug quartz and granite bowlders. The Beaver Head coming in from 

 the left, we followed it to its sources. On the 10th we camped at 

 Beaver Head Eock. This is a huge mass of limestone, through which the 

 river has cut its way, leaving the rock on the left bank standing with an 

 almost perpendicular wail facing the stream. From a distance the re- 

 semblance'to the head of a beaver is very striking, whence its name. 

 Near here there is found a good quality of sandstone, which is employed 

 in making grindstones. It is of a light-gray color, and of a good quality 

 for that purpose. The next day we camped near Black-Tail Deer Creek, 

 the rocks we passed having been similar to those of the day before, 

 with the exception of red eivanites and felstones, of the same kind that 



