GEOLOGICAL SURVEY OF THE TEREITORIES. 83 



scriptiou, but it is only through the eye that the mind can gather 

 anything like an adequate conception of them. As we approached 

 the margin of the caiion, we could hear the suppressed roar of the falls, 

 resembling distant thunder. The two falls are not more than one- 

 fourth of a mile apart. Above the Upper Falls the Yellowstone flows 

 through a grassy, meadow-like valley, with a calm, steady current, 

 giving no warning, until very near the falls, that it is about to rush over 

 a precipice 140 feet, and then, within a quarter of a mile, again to leap 

 down a distance of 350 feet. Before proceeding further with a detailed 

 description of the falls and caiion, I may attempt to present what I 

 believe to be the origin. For about a mile above the Upper Falls there 

 is a succession of rapids in the river. The walls of the channel are not 

 high, but are composed of massive basalt. Just along the Upper Falls 

 there are five huge, detached blocks of basalt in and near the center of 

 the channel. These show the force with which the water has rushed 

 down the channel at some period. Just above the Upper Falls are two 

 beautiful cascades, 20 to 30 feet high, and at the east one, the rocks so 

 wall in the channel that it is not much more than 100 feet wide, and the 

 entire volume of the water, which must form a mass 100 feet wide and 30 

 feet deep, rushes down a vertical descent of 140 feet. There seems to 

 have been a sort of a ridge or belt of very compact basalt that extended 

 across the channel, so hard as to resist successfully atmospheric power, 

 while below, the nearly vertical walls, which are composed of clay, sand, 

 and bowlders, mingled with hot-spring deposits, seem to have readily 

 yielded, and thus the river has carved out its channel. From any point 

 of view the Upper Falls are most pictijresque and striking. The entire 

 volume of waiter seems to be, as it were, hurled off of the precipice with 

 the force which it has accumulated in the rapids above, so that tlie mass 

 is detached into the most beautiful snow-white, bead-like drops, and as it 

 strikes the rocky basin below, it shoots through the water with a sort of 

 ricochet for the distance of 200 feet. The whole presents in the distance 

 the appearance of a mass of snow-white foam. On the sides of the basalt 

 walls there is a thick growth of vegetation, nourished by the spray 

 above, which extends up as far as the moisture can reach. The upper 

 j)ortion of the walls of the caiiou on the east side is composed of a coarse 

 volcanic sandstone and pudding-stone, perfectly horizontal, and below 

 are loose variegated clays and sands. There is no doubt that this 

 deposit forms a part of the bed of the ancient lake in its enlarged extent, 

 and that this deposit was made on the rugged, irregular basalt surface. 

 In the mean time, there were occasional outflows of igneous matter, and 

 the hot springs were operating in full force. The lake basiii was closed 

 at the lower end of tlie range of mountains that form the rim, and the 

 river gradually forced its way through this rim, forming the Grand 

 Canon, draining the lake basin, and the falls were the result. There is 

 all around the basin a sort of secondarj^ shore in the form of a group of 

 low, pine-covered hills, varying in height from 8,500 to 9,000 feet above 

 the sea, while the highest ranges, 10^000 to 11,000 feet, constitute the 

 primary rim. The lower hills are made up mostly of the old lake deposit, 

 and are either Pliocene or Post-Pliocene, probably both. 



But no language can do justice to the wonderful grandeur and beauty 

 of the caiion below the Lower Falls ; the very nearly vertical walls, 

 slightly sloping down to the water's edge on either side, so that from 

 the summit the river appears like a thread of silver foaming over its 

 rocky bottom ; the variegated colors of the sides, yellow, red, brown, 

 white, all intermixed and shading into each other ; the Gothic columns 

 of every form standing out from the sides of the walls with greater 



