136 



GEOLOGICAL SURVEY OF THE TERRITORIES. 



Springs on hranclt of Violet Creek. 

 Augnst 10, 187-^ ; time, 2 p. m ; elevation above sea, 7,873 feet ; boiling-point, 198°. 5 T. 



No. 



Size. 



3X4 feet 



10 feet (liiunctcr. 

 5 feet (liauieter . . 



5 X ileet 



3 feet (liamotor. . 



5X3 feet 



7 X 3 1'eot 



3 feet <liamoter.. 

 8X 1 feet 



Gas evolved. 



Carbonic acid and steam . 

 do 



.do 

 .do 

 .do 

 .do 

 .do 

 .do 

 .do 



Temperature 

 of air. 



68° F. 



68 



68 



68 



68 



68 



68 



68 



68 



Temperature 

 of spring. 



160° F. 



184 



154 



188 



180 



191 



186 



192 



194 



The tiniomit of carbonic-acid gas given off from these springs is 

 small, and, althongh there is considerable bubbling in some of the 

 springs, it is caused mostly by the escape of steam. This in some is 

 enough to canse the ground to tremble beneath. All the springs de- 

 posit iron. The first three springs given in the table are on the edge of 

 a pool of water having a diameter of 100 feet by 50 feet, in which the 

 thermometer stood at 120^ F. There is also one spring in the midst of 

 this pool which was beyond reach. The bottom of the i)ool is lined 

 with gelatinous silica, which is coated with oxide of iron. The edge of 

 the pool next the creek sloi)es to the level of the stream iu a series of 

 small basins over which the water tlows. The creek itself is divided 

 into a number of basins formed of the deposits, (mostly carbonates,) 

 and the water flows from one basin to the other, they being at different 

 levels. These basin*; are filled with a luxuriant growth of very bright 

 green confervoidea. The temperature of the water iu the creek a short 

 distance below the springs is 140° F. 



The two groups of springs given above have never before been de- 

 scribed, not being in our line of march last year. There are doubtless 

 many more groups throughout the same valley that have never been 

 studied yet, especially on the eastern side of the Yellowstone Eiver, which 

 here is not fordable, on account of quicksands. . 



The next group of si)rings to which I will refer is that at Crater Hills, 

 near the Yellowstone Kiver, about four miles below our camp. This place 

 takes its name from the occurrence here of two high buttes or hills, one 

 of which is 150 feet from top to base, and a second 140 feet. They are 

 made up in part of a trachytic tuff and hot-spring deposits, the prevail- 

 ing color of which is white, and a red, due to the weathering of the de- 

 posits, which contain iron. All of the springs are aciduhms and contain 

 sulphur as a prominent constituent. The principal sj)ring is the boiliug- 

 snlphur spring near the base of the hills. The description of this spring 

 was given in the report of last year, and I will not delay to redescribe 

 it. 1 again took its temperature, which I fonnd to be 178° F., the air 

 being 58° F., at about 10 o'clock in the morning. The temperature given 

 in last years report is' 183°. 5 F., which was probabl}' taken nearer the 

 center of the spring than I was able to take it this year, the water being 

 iu violent agitation. 



The next spring of importance is a large blue-mud spring near the large 

 sulphur si)ring, the temperature of which (104° F.) this year varies only 1° 

 from that taken last year, when it was 103° F. All the springs at this 

 locality are noticeable, not only for the sulphur they contain, but also for 

 their ahim, which I take to be an iron alum. The small stream to which 

 the springs give origin is a brancli of Alum Creek, aiid in both the main 

 creek and the brancli the wati^r is strongly astringent. A [)artial analy- 

 sis of a piece of deposit from the edge of the boiling sulphur spring, made 

 by Mr. W. B. Piatt, of the expedition, gives the following result: 



