258 GEOLOGICAL SURVEY OF THE TERRITORIES. 



outflow must pass wheu the .surface of the lake is from four to six feet 

 higher. The divide toward the east is only 8 feet above the lake. From 

 the west end of the more northern lalvo, about 30 feet of water How oat 

 rapidly, soon jumphig over a fall of 12 feet. Strong branches soon join 

 the stream from the north and one from the south, and double its sup- 

 ply of water. Five other falls succeed, of 0, 12, 40, 20, and 30 feet, be- 

 fore we reach the Great Falls. These show a total descent of 141 feet, 

 consisting of three larger falKs above, the third being 47 iwt high, with 

 three small ones at the bottom. The upper two are somewhat of horse- 

 shoe form, while the third and highest has a nearly straight edge. The 

 amount of water in the stream is fnlly 80 feet. The porphyritic trachyte 

 of its walls forms perpendicular cliffs, with rounded tops. A stream of 

 some size comes in about a half mile above there, on the south side, 

 with fine cascades on its upper course, while its sources lie in a basin of 

 the mountain whose form indicates that it may inclose a small lake ; the 

 left-hand branch of this stream comes from two small lakes on the di- 

 vide, as hereinafter described. 



From the lakes downward, we find laminated porphyries, succeeded 

 by trachytes and red and black porphyritic obsidian. Below the falls, 

 a high knob consists of a fine-grained, compact, white trachyte, v, hich 

 contains disseminated plates of black mica, (muscovite?) and which, with 

 but a slight change of texture, might readily be mistaken for granite. 

 From this knob we have a line view westward to the lower basin of this 

 river audits tributaries. The largest of these, Bechler's River, comes out 

 of the plateau of tlie great water-shed, about teii miles to the north- 

 M'ard, into a large basin apparently containing extensive grassy meadows, 

 and then passes among rounded timbered hills to join Falls Eiver, 

 apparently but a few miles above our lower crossing of that stream. 

 Large grassy meadows, some miles farther north, indicate another large 

 stream, probably tributary to Bechler's Eiver; but it was impossible 

 to trace its course with any certainty at that distance. Some miles 

 down Falls River our guides report another fall, about 40 feet high; so 

 that it will be seen that the stream deserves its name. The slopes near 

 the river are mainly well-rounded and fairly timbered, though, at a few 

 points, steep and even precipitous and bare. The stream presents the 

 utmost variety of water-scenery within a short distance ; from the 

 still, deep pools, which accompany a short stretch of beaver-dams, to 

 short, sharp rushes over steep rock-slopes, to successions of steps, form- 

 ing vaiious styles of rapids, and to vertical falls of various forms and 

 sizes — a perfect treasury of artistic bits. 



The elevation of this divide and the moderatecharacter of the slopes, 

 averaging about 54 feet to the mile irom Henry's Fork to the sunuuit, in- 

 dicate this to be a favorable line for railroad-access from the south to the 

 region of Yellowstone Lake, if such should be thought desirable. From 

 the maiuline up Henry's Fork to Montana, of which this would doubtless 

 be a branch, the road would follow ui) the ridge on the south side of 

 Falls River to the divide, thence keep around the foot of the northern 

 mountain to Lake Lewis, cross Lake Fork, and, passing along the eastern 

 shore of the lake, cross the flat divide, striking Yellowstone Lake about 

 the middle of its western side, and thence follow down the valley. It is 

 l)robable that a route could be located from Lewis's Lake, past the north 

 end of Shoshone Lake, to the Fire-Hole basins ; but the most easy ac- 

 cess to the Fire-Hole is by way of Henry's Lake Valley, Tyghee Pass, 

 and the Upper Madison CaQon. Between the Fire-Hole and Yellow- 

 stone Lake, the ridges are too shar^) to be passed by railroads, unless by 

 very winding routes or by long tunnels. 



