46 GEOLOGICAL SURVEY OF THE TERRITOEIES. 



and Bozeman Passes, the limestones are remarkably well shown, in some 

 instances inclining 80° with the upper edges of the strata a line of 

 rugged columns. The more yielding beds have been removed from the 

 limestones, leaving them on either side of the caiion like walls, while 

 atmospheric agencies have worn out the upturned edges into the most 

 picturesque, jagged forms. The caiion about two miles above Fort Ellis, 

 carved out by Mill Creek, forms an interesting subject of study. The 

 entire range is a true anticlinal, trending northwest and southeast, with 

 the more abrupt side northeast. This side has also been subjected to 

 much erosion, so that the more modern beds are seldom visible, the greater 

 portion now remaining, belonging to the metamorphic series, or to the 

 Carboniferous age. But on the east side, covering the hills, and crop- 

 ping out deep down in the valleys, is a vast thickness of steel-gray or 

 somber-brown sandstones* The composition and texture of these rocks 

 are quite varied. There are alternately hard and soft layers, that is, clay 

 and sandstones. The clays are quite uniform in their character, and are 

 so thick in the aggregate as to give a rounded, smooth outline to the hills, 

 and by weathering, to conceal the rocky strata beneath. East of Bridg- 

 er's Peak, and on the divide, high up in Bozeman and Bridger Passes, 

 are a large number of exi)osures, sufficient to show that there are here 

 about 1,200 to 1,500 feet of strata belonging to the Coal Series. Whether 

 this group belongs to the Upper Cretaceous or Lower Tertiary, or both, 

 I will not delay at this time to discuss, l^o animal fossils were found, but 

 a fine collection of well-preserved vegetable remains were obtained, and 

 are now in process of description by Mr. Lesquereux, The composition 

 of these rocks is mostly sand of various degrees of fineness, some argil- 

 laceous and calcareous sandstones. Most of the sandstones contain a 

 small per cent, of lime. Near the head of Spring Canon, about three 

 miles east of Fort Ellis, a coal-bed crops out near the bed of the creek, 

 from which several tons of excellent coal have been taken. The opening 

 has been made to the depth of 180 feet. There are beds of clay on either 

 side of the coal-seam, as usual. The strata are nearly vertical, dipping 

 north 80°. Great quantities of impressions of deciduous leaves are found 

 in the rocks along the borders of the streams, and on the hills." These 

 fossils seem to be confined to no particular beds, but to occur in different 

 layers of rocks, adapted to preserve them, above and below the coal and 

 extending through the series of strata. A large number of specimens 

 of plants are described by Mr. Lesquereux in a valuable report in an- 

 other portion of this volume. 



We will now return to the west side of the range, and pass up the 

 canon to the eastward. The stream which has cut its way through 

 this high ridge is a fine specimen of a mountain torrent; the water 

 is pure and full of trout. As we approach the base of the hills from the 

 level terrace on which Fort Ellis is located, the gorge appears so nar- 

 row as to be impassable; but on entering it, we find ample room for a 

 bridle-path, and we make our ascent without difficulty. As thia is the 

 canon which is regarded as most available for the passage of the Northern 

 Pacific Eailroad, it is invested with no small degree of interest. If the 

 road ascends the valley of the Yellowstone Eiver, it will cross the divide 

 just above the mouth of Shield's Eiver, and ascend the valley of a little 

 stream to the westward, which rises within a few yards of the source of 

 tlie one that flows through the caiion ; so that the greater portion of the 

 rock excavations has already been performed by nature, with these 

 two beautiful streams as her agents. This lets the road into the 

 Gallatin Yalley, where it can go up to the junction of the Three Forks; 

 thence, up the Jefferson Fork, through the finest portion of Montana, 



