290 REPORT UNITED STATES GEOLOGICAL SURVEY. 



In 1873 Professor Comstock visited tlie group whicli he describes 

 tinder the head of " Thermal Springs at northeast base of E-ed Mountains, 

 on source of Heart Lake."* He says : 



We passed a number of interesting springs along the banks of the stream, but the 

 largest and most powerful members of the group were only seen at a distance. This 

 collection has never been carefully examined, and it is probable that many new facts 

 of value will yet be gathered here, if one may judge from the peculiarities of the two 

 following bowls, which received some special attention. 



He then described some springs which I have tried to identify. (See 

 Witch Creek Springs farther on.) He also says : 



Many other bowls were observed than those described, some of which were of good 

 size and quite clear, others turbid but not pasty, and a few veritable simmering sol- 

 fataras, besides a large number which were only seen in the distance while climbing 

 the peak which directly overlooks them. 



We examined the springs of the Heart Lake Basin, in 1878, under dis- 

 advantages. We arrived at Heart Lake late on the evening of Septem- 

 ber 3 in a rain storm that continued for two days, so that our work was 

 interrupted. We left early on the 7th, so that we had only one full work- 

 ing day in which the springs had to be mapped, described, and their 

 temperatures taken. It was therefore impossible to make the map com- 

 plete. The springs have not all been iflentified on the accompanying 

 sketch map, as I was obliged to work independently of my colleague, 

 Mr. Mushbach, but the principal springs are indicated. The Eustic 

 Group had previously been mapped by Mr. Gannett, but a large group 

 on one of the northern branches of Witch Creek was not visited, and 

 does not appear on the map. 



Geology. — The rocks of the Ked Mountain Eange and surrounding 

 country are volcanic, being trachytic in their nature. Mr. Holmes's re- 

 port will doubtless contain more specific information in regard to the 

 rocks of the region. 



In the valley of Witch Creek, near the lower end of the canon, I ob- 

 served a conglomerate or breccia composed of angular fragments of 

 volcanic rocks. Near the head of the creek, clay banks give rise to 

 numerous mud springs, although the general character of the springs is 

 siliceous, derived from the underlying volcanic rocks through which the 

 water first passes. Sulphur is abundant in these springs, and the sides 

 of the gulches are stained by the oxidized iron of th e deposits. Near one 

 of the springs or pools of the Upper Group, on Witch Creek, some in- 

 teresting specimens of hardened deposit were obtained, which were com- 

 posed of layers of red and white deposit, which in place had the appear- 

 ance of stratified rock. The Heart Lake Basin presents an interesting 

 field for the chemical geologist, the deposits varying quite a good deal 

 from those of the other basins of the Park in their physical features. 



WITCH CREEK SPRINGS. 



Witch Creek is the largest tributary of Heart Lake, and drains the 

 nothern slopes of Eed Mountain, which is the northern peak of the Eed 

 Mountain Eange. It is a warm creek, deriving a large part of its water 

 from the hot springs along its banks. It is about 4J miles in length, 



* Report upon the Reconnaissance of Northwestern Wyoming, &c. By Wm. A. 

 Jones, p. 239. 



