196 N. H. BARTON 



pool. An analysis of the water from the great spring, by Professor 

 E, E. Slosson is as follows: 



ANALYSIS OF WATER FROM HOT SPRINGS AT THERMOPOLIS, WYO. 



Grains per 

 Gallon 



SiO. 4.986 



Fe203 and AI2O3 0.227 



K CI 10.249 



Na2S04 15.110 



Mg2S04 19-443 



Ca SO4 13. 156 



Ca CO3 40-454 



Na CI 26. 195 



Total 129.820 



Hot Spring deposits. — The hot-spring deposits in the vicinity of 

 Thermopolis indicate a long period of accumulation, for they occur 

 on several distinct terraces, some of which date back probably to 

 Tertiary time. The most recent deposits are being laid down on 

 a broad terrace about 30 feet above the river, which is being built 

 up very gradually. No precise estimate has been made of the rate 

 of increase, but objects placed in the water are rapidly coated with 

 the deposit, and a thickness of an eighth of an inch is accumulated 

 in a short time. There are wide areas of the deposit on both sides 

 of the river below the present springs, which were formed at no 

 distant date, while, on the buttes which rise above this terrace level, 

 there are caps of hot-spring deposits at various elevations. Some 

 of the relations of these are shown in Figs. 3 and 4. The highest 

 deposit caps a prominent butte near the cemetery, at an altitude 

 of about 700 feet above the river. A larger terrace remnant remains 

 on a butte which rises immediately west of the river to a height 

 of about 350 feet above the water. It is probable that these terraces 

 represent three distinct stages of deposition, and, although possibly 

 hot-spring action has been continuous since the formation of the 

 first or highest terrace, most of the deposits at intermediate levels 

 have been removed. As travertine is often deposited on slopes, it 

 is possible that the hot-spring waters issuing at the level of the 

 higher buttes flowed to somewhat lower levels, with a continuous 



