84 GEOLOGICAL SUEVEY OF THE TEEEITOEIES. 



variety and more striking colors than ever adorned a work of human 

 art. The margins of the caiion on either side are beautifully fringed 

 with pines. In some places the walls of the cai5ou are composed ot 

 massive basalt, so separated by the jointage as to look like irregular 

 mason- work going to decay. Here and there a depression in the sur- 

 face of the basalt has been subsequently filled up by the more modern 

 deposit, and the horizontal strata of sandstone can be seen. The de- 

 composition aud the colors of the rocks must have been due largely to 

 hot water from the springs, which has percolated all through, giving to 

 them the present variegated and unique appearance. 



Standing near the margin of the Lower Falls, and looking down the 

 caiion, which looks like an immense chasm or cleft in the basalt, with 

 its sides 1,200 to 1,500 feet high, and decorated with the most brilliant 

 colors that the human eye ever saw, with the rocks weathered into an 

 almost unlimited variety of forms, with here and there a pine sending 

 its roots into the clefts on the sides as if struggling with a sort of un- 

 certain success to maintain an existence — the whole presents a picture 

 that it would be difficult to surpass in nature. Mr. Thomas Moran, a 

 celebrated artist, and noted for his skill as a colorist, exclaimed with a 

 kind of regretful enthusiasm that these beautiful tints were beyond the 

 reach of human art. It is not the depth alone that gives such an im- 

 pression of grandeur to the mind, but it is also the picturesque forms 

 and coloring. Mr. Moran is now engaged in transferring this remarkable 

 IDicture to canvas, and by means of a skillful use of colors something like a 

 conception of its beauty may be conveyed. After the waters of the 

 Yellowstone roll over the upper descent, they flow with great rapidity over 

 the apparently flat rocky bottom, which spreads out to nearly double its 

 width above the falls, and continues thus until near the Lower Falls, 

 when the channel again contracts, and tbe waters seem, as it were, to 

 gather themselves into one compact mass and plunge over the descent 

 of 350 feet in detached drops of foam as white as show ; some of the 

 large globules of water shoot down like the contents of an exploded 

 rocket. It is a sight far more beautiful, though not so grand or impres- 

 sive as that of Niagara Falls. A heavy mist always arises from the 

 water at the foot of the falls, so dense that one cannot approach within 

 200 or 300 feet, and even then the clothes will be drenched in a few 

 moments. Upon the yellow, nearly vertical wall of the west side, the 

 mist mostly falls, and for 300 feet from the bottom the wall is covered 

 with a thick matting of mosses, sedges, grasses, and other vegetation of 

 the most vivid green, which have sent their small roots into the softened 

 rocks, and are nourished by the ever-ascending spray. At the base and 

 quite high up on the sides of the caiion, are great quantities of talus, and 

 through the fragments of rocks and decomposed spring deposits may 

 be seen the horizontal strata of breccia. (Fig. 24.) 



Before proceeding further, I might attempt to give what appears to 

 me to be the origin of this wonderful natural scenery. This entire basin 

 was once the bed of a great lake, of which the lofty range of mountains 

 now surrounding it formed the rim, and the present lake is only a rem- 

 nant. During the period of the greatest volcanic activity this lake was 

 in existence, though its limits, perhaps, could not now be easily defined ; 

 but it was at a later period inclosed within the rim. The basis rock is 

 a very hard, compact basalt, not easily worn away by the elements. The 

 surface is exceedingly irregular, and filling up these irregularities is a 

 greater or less thickness of volcanic breccia and the deposits of hot 

 springs. Upon all this, in some localities, continuing up to the time of 

 the drain age of this 1 ake, were deposited the modern volcanic clays, sands. 



