GEOLOGICAL SUEVEY OF THE TEERITOEIES. 75 



spaces, with many groves of pines. These ridges gradually slope down 

 to the Yellowstone, northeast. Far to the east and north is one jagged 

 mass of volcanic peaks, some of them snow-clad, others bald and desolate 

 to the eye. Far to the south, dimly outlined on the horizon, may be seen 

 the three Tetons and Madison Peak— monarchs of all the region. A 

 grander view could not well be conceived. The summits and sides of 

 the mountain are thickly covered with fragments of dull-brown basalt ; 

 but what seemed most strange were the rounded masses of black, very 

 compact basalt, mingled with the less compact angular fragments, 

 broken from the mountain side. How did these huge bowlders reach 

 these lofty summits? They are not numerous, and, at the present 

 time, the proofs of water having covered these mountain tops since they 

 have attained their present elevation are not clear. It is quite possible 

 they were lodged there prior to the period of its elevation. 



The three forks of Gardiner's River rise high up in the mountains, 

 among the perpetual snows. They wind their way across a broad pla- 

 teau covered mostly with a dense growth of pines, but with broad, 

 open, meadow-like spots, which' can be seen clearly from some high 

 mountain peak, and lend a charm to the landscape. After gathering a 

 sufficient supply of water, they commence wearing their channels down 

 into the volcanic rocks, which continue to grow deeper as they descend. 

 Each one has its water-fall, which would fill an artist with enthusiasm. 

 The West Fork rolls over a bed of basalt, which is divided by jointage 

 into blocks that give the walls the appearance of mason-work on a 

 gigantic scale. Below the falls the river has cut the sides of the mount- 

 ain, so that we can see a vertical section 400 feet high, with the same 

 irregular jointage. 



After exploring the Middle and West Forks we climbed up the steep 

 sides of the canon of the East Fork, passed the picturesque cascade and 

 basaltic columns, and finally reached the summit of the ridge which 

 separates the caiion from Gardiner's Eiver. The highest point of the 

 ridge is 450 feet above the bed of basalt that forms the margin of the 

 east wall of Gardiner's Eiver. Beds of sandstone are here mingled 

 with basalt in dire confusion. From this ridge the third caiion is well 

 shown. Among the ridges of sandstone and basalt, are several pretty 

 lakes from two hundred to four hundred yards in length. These little 

 lakes are really expansions of the drainage, and are usually in the 

 synclinal troughs. East of the summit of the ridge the sedimentary 

 beds assume a reversed dip from the mountains on the east side of the 

 Yellowstone. We find, therefore, the Jurassic arenaceous limestones and 

 sandstones, and the limestones of the Carboniferous, near the margins 

 of the caiion. On the summit of the ridge the basalt is quite coarse, 

 and decomposes into a kind of sandy clay. I can only give a general 

 idea of the geology of this region. The chaos is so great that it would 

 occupy one entire season to unravel the singular structure, and then 

 the results would be so meager of i)rofit or instruction that they would be 

 most unsatisfactory. The real thought involved in it is not difficult to 

 abstract. The third canon is formed partly by erosion and i)artly by 

 upheaval, and the rocks which compose its walls are granitic and 

 igneous. The basis rocks are the granitoid, while filling up the 

 irregularities of the surface are the volcanic materials of various 

 kinds. The same may be said of the lofty, rugged range of 

 mountains on the east side of the river. A group of volcanic 

 peaks of varied forms filled up the broad interval between the 

 Yellowstone and the sources of the Big Horn. They vary in height from 

 9,500 to 10,000 feet above the sea, and are grouped without the least 

 regularity. The peaks themselves do not seem to be connected together 



