PEALE.] SPRINGS OF YELLOWSTONE EIVEK. 85 



is a collection of vents and small warm springs or oozes. Only one is 

 well defined. It is about 2 feet in diameter and 18 inches in depth, 

 having a black muddy basin. The water, which is acid in its reaction, 

 has a temperature of 127° F., and gives off sulphuretted hydrogen and 

 carburetted hydrogen. Sulphur and alnm are the principal deposits. 

 The atmosphere is so impregnated with the gases that the springs are 

 readily found. One has simply to be guided by his nose. There is a 

 black deposit, which is probably partly carbonaceous, surrounding the 

 springs. On the east side of the Yellowstone, opposite the mouth of 

 Tower Creek, the high bluff is brilliantly colored with sulphur which 

 has been deposited from hot springs. On the edge of the river the old 

 deposits are abundant, consisting mainly of sulphur, selenite, and alum. 

 There are no active springs ; the ruins mark only the seat of former 

 activity. The only active springs here now are on the west side of the 

 river. 



SPRINGS ON EAST FORK OF YELLOWSTONE. 



On the East Fork of the Yellowstone, a few miles abovethe mouth of 

 Soda Butte Creek, there are two small spring areas in which most of 

 the springs are dead or dying, and do not therefore deserve special 

 mention beyond this reference. Mr. P. W. ISTorris, in his report for 1880 

 (page 7), mentions the discovery, on one of the forks at the head of the 

 East Fork, of a spring area resembling that of Soda Butte. It lies 

 just outside of the limits of the Park. On Soda Butte Creek, 2^- miles 

 above its mouth, stands the cone or butte from which the creek is 

 named. Although named Soda Butte, it is composed mainly of cal- 

 careous material in which there is probably only a trace of soda, if it 

 exists at all. It is a conical mound about 20 feet high, 25 feet in 

 diameter at its base. It is situated on a sort of platform, of the same 

 deposit, which is 75 feet long and is 15 feet above the surrounding level. 

 It contains no water, nor is there any hot spriug near it at present. A 

 cold spring close by gives an acid reaction, tastes strongly of alum, and 

 gives off" suli^huretted hydrogen. The cone was doubtless once a gey- 

 ser or spoutiug spring, and is interesting from the fact that it is now 

 a ruin and teaches something of the formation of springs. Dr. Hayden, 

 writing of this cone, says : 



This old ruin is a fine example of the tendency of the cone to close np its summit in 

 its dying stages. The top of the cone is somcTvhat broken, but it is 18 feet in diame- 

 ter at this Time, and near the center there is a hole or chimney 2 inches in diameter, 

 plainly a steam vent. This marks the closing history of this spring. The inner por- 

 tions of this small chimney are lined with white enamel, thickly coated with sulphur, 

 which gives it a sulphur-yellow hue. The base upon which the cone rests varies in 

 thickness. On the east side huge masses have been broken off, exposing a vertical 

 wall 20 feet high, built up of thin horizontal lamiufe of limestone. On the west side 

 the wall is not quite as high, perhaps 8 or 10 feet. It would seem, therefore, that it 

 was at first an overflowing spring, depositing thin horizontal layers until it built up 

 a broad base 10 to 20 feet in height; then it gradually became a spouting spring, 

 building up with overlapping layers like the thatch on a house, until it closed itself 

 at the top and ceased.* 



The tufa which composes the mass of the deposit is similar to that of 

 the Mammoth Hot Springs of Gardiner's Eiver. We have not far to 

 look to find the source of the lime. In the geological map Mr. Holmes 

 colors a strip of Carboniferous limestones on the north side of the valley 

 a short distance below the Butte. On the Carboniferous rest late vol- 

 canic Tertiary rocks. As Dr. Ilayden says, there is no doubt that the 

 limestones pass underneath the valley of the East Fork, and from the 

 passage of the water through these the lime which predominates was 



* Report U. S. Geol. Survey for 1871, 1872, p. 138. 



