80 GEOLOGICAL SURVEY OF THE TERRITORIES. 



strata on either side, forming an aggregate of abont 1,209 feet in thick- 

 ness. At the upper end of the little basin or open valley, the Carboniferous 

 limestones rise up from beneath the Jurassic and soon form high vertical 

 walls on both sides of the river. From this point to the source of the 

 river, Carboniferous limestones prevail to a greater or less extent. For 

 about fifteen miles the river has carved out a canon Avith the nearly- 

 horizontal strata of limestones rising with vertical walls on either side 

 800 t^ 1,200 feet. The inclination of the strata appears slight, not more 

 than 1° to 30. The limestones are mostly in rather thin layers, but some 

 of them form massive beds. The entire group presents the usual variety 

 of texture common to limestones of this age. The fossils are quite 

 abundant, and all, so far as could be determined, of well-known Carbon- 

 iferous types. This part of the canon is most picturesque 5 the high 

 limestone-walls on either side are weathered into towers and Gothic 

 pinnacles and in some instances wonderfully grotesque forms. It would 

 hardly be possible to find as complete a section of the strata anywhere 

 in the Northwest as is shown in this canon. 



For the entire distance of seventy miles the river has carved its chan- 

 nel out of the solid mass, most of the way hemmed in with narrow ver- 

 tical walls, but here and there expanding out a little with a narrow open 

 basin, but soon closing up again. We can here obtain something like a 

 correct estimate of the thickness of these groups of strata. I estimate 

 the Jurassic group at 1,200 feet and the Carboniferous at 2,500 to 3,000, 

 the Silurian group 800 to 1,000 feet. From time to time we see some 

 irregularities in the strata, but these seem to arise from local influences. 

 But at a point in the Gallatin Valley, about opposite Cinnabar Mount- 

 ain, the entire mass of sedimentary beds is again suddenly tilted at 

 an angle 50° to 70° about west or southwest. The entire series of beds 

 seems to be exposed here from the Silurian to the Coal group inclusive. 

 The Jurassic group of beds inclines about 50°, but a little farther up on 

 the west side of the Gallatin, and extending up toward the divide, are 

 the Cretaceous and Tertiary (coal) groups, nearly in a horizontal posi- 

 tion, capped with basaltic rocks. In this valley, from crest to crest of 

 the divide, the strata have been thrown into the most chaotic positions. 

 No system could be wrought out of the confusion. Sometimes the lower 

 limestones capped the highest hills and the youngest beds, as Cretaceous 

 and Tertiary would be found nearly horizontal in the lowest valleys 

 on the divide between the Gallatin and Yellowstone. At one point we 

 discovered a group of springs that deserves a notice here. These springs 

 gush ou^t of the side of the mountain from the limestones about 100 feet 

 above the river, and in the aggregate form quite a stream of water. 

 Great quantities of Calcareous tufa surround the springs, and the vege- 

 tation is remarkably luxuriant. Helices are scattered thickly for some 

 distance in every direction, sometimes giving the surface a snow-white 

 ai)pearance in the distance. These land-shells occur in greater or less 

 abundance among the limestones. The river is now fed almost entirely 

 by springs which issue from beneath the limestone-strata which prevail 

 everywhere. The Jurassic, Cretaceous, and Tertiary occur only in iso- 

 lated patches. As we continue on up the valley we find it sufficiently 

 open for good roads, sometimes extending out one-fourth to one-half a 

 mile in width. Grass is good, and in many places quite wide ravines 

 extend down from the divide on either side that have excellent grass. 

 For this reason this valley, or canon, as it might be called, has been in 

 times past a great resort for Indians. . Traces of the camps are seen 

 everywhere. The high walls that hem it in on either side furnished a 

 protection, not only from their enemies, but from, high winds and severe 



