HOT SPRINGS AT THERMOPOLIS, WYOMING 



195 



as shown in the distance in the upper view in Fig. 2, facing a region 

 of red bed hills about a mile wide and with outer slopes descending 

 into valleys of Benton basal shales. Thermopolis is on the eastern 

 limb of the anticline, the village extending across the outcrop zones 

 of the Sundance, Morrison, and Cloverly formations, locally covered 

 by an alluvial plain which extends back a few hundred rods from 

 the river. There is no evidence of igneous rocks in the region. 



Granite ' ' ~ <~~i'S-'i '/,'^f^A''i-^-^rci-''-'}Ti; 



Fig. I. — Section through the hot springs at Thermopolis, Wyo. 

 Length of section about fourteen miles. 



Looking west. 



The springs rise from the middle beds of the Chugwater formation, 

 apparently through a number of deep cracks. The largest one 

 issues from the foot of a high bank of 80 feet of red sandstones, 

 as shown in Figs. 2 and 2a, with a volume stated to be over a thou- 

 sand gallons a second. The water is clear and hot, having a tem- 

 perature of 135°. It flows over a wide terrace built of hot-spring 

 deposits, over the edge of which it falls into the river. A part, 

 however, is diverted into conduits of various kinds which lead to 

 the various bathhouses, and to the reservoirs in which a portion 

 of the water is cooled so that it may be used for diluting the hot 

 water to the required temperature for bathing. The spring flows 

 with great force, and evidently comes from considerable depth under 

 high pressure. Numerous algse of various colors grow in the hot 

 and cooling water, as in the Yellowstone Park and other places. 

 Besides the main spring, there are on the east side of the river a 

 deep, hot pool which does not overflow and, some distance farther 

 north, a hot sulphur spring which gushes out of the travertine bank 

 a few feet above the river. On the west side are several small 

 springs, one of which is utilized for a bathhouse and swimming- 



