GEOLOGICAL SURVEY OF THE TEREITOEIES. 



113 



waters of this little fountain lias worn a deep channel or furrow into 

 the vertical sides of the mountain. The Twin Buttes are two conical 

 mountains, partially separated from the main range, and on the sum- 

 mit, a few vents are sending forth their columns of steam. As far as 

 the eye can reach, can be seen the peculiar plateau mountain ranges, 

 black' with the dense forests of pine, averaging from 9,000 to 10,000 

 feet above sea-level. On the west side of the Fire-Hole, near its mar- 

 gin, are four small lakes with quiet surfaces, with water as blue as the 

 sky. One of them is about half a mile in length. The waters are 

 cold at the present time, but the basins present the appearance of having 

 been enormous hot springs at some period in the past. From our camp 

 on the main branch that enters the Fire-Hole at the upper end of 

 the lower group of springs on the borders of the rim, we made our 

 examinations down the stream, descending the east side and return- 



Fig 



ing on the opposite 

 side, and then passing 

 up the west branch, 

 noting all the springs 

 of importance, taking 

 the temperatures, and 

 securing brief descrip- 

 tions of their peculi- 

 arities. Most of them 

 do not differ materi- 

 ally from those already 

 described, so that I 

 shall notice only the 

 most important. The 

 numbers of the vents 

 can be understood by 

 reference to the chart, 

 although many of the 

 less important and 

 dead springs are omit- 

 ted. The first one we 

 shall notice is located 

 on the right branch of the river, and from the triangular shape of its basin,. 

 8 by 10 feet, we named it the ''Conch Spring." All along the margins 

 of the river hundreds of springs, which we could not note, but which 

 aid in swelling the volume of the stream, issue from beneath the siliceous 

 crust. A little below the Conch Spring, on the very margin of the 

 river, there is a fine geyser, which has built for itself a crater three feet 

 high, with a shell a foot thick. The inside of the crater is about six 

 feet in diameter, and the entire mass of water is in a constant state 

 of agitation. Sometimes it will boil u]) so violently as to throw the 

 entire mass ui^ four feet, and then die down so as to boil like a caldron. 

 Indeed, the whole process might be imitated by subjecting a caldron 

 of water to continuous and excessive heat. The water is perfectly clear, 

 and the overflow forms a stream six inches wide and two inches deep, 

 passing down the sides of the crater and thence into the river along the 

 most exquisitely decorated channel. The entire surface of the crater is 

 covered with pearl-like beads, formed by the spray of the waters. A 

 section of the crater shows it to have been built up very slowly, iu very 

 thin lamina). Another spring, with a crater like a horn, about a foot 

 in diameter at the top and six feet at the base, we called the Horn 

 Geyser. It is in a constant state of ebullition, with the same ornamenta 



8as 



RIVERSIDE GEYSER, UPPER GEYSER BASIN, 



