NATURAL SCIENCES OF PHILADELPHIA. 219 



In Pioneer Hollow, about fourteen miles west of Fort Bridger, 

 and a couple of miles from the Union Pacific Railroad, there are 

 about a dozen springs within the extent of a mile. These resemble 

 the famous Saratoga Springs of New York. The waters are cool, 

 slightly alkaline, of an agreeable taste, and highly impregnated 

 with carbonic acid. The springs range from a foot to fifteen feet 

 in diameter. Each forms a circular mound or crater from one to 

 three or four feet in height composed of a ferruginous silicious 

 sinter. The waters pour gently over the edge of the craters, 

 which have been deposited very slowly during a long period of 

 time, as the amount of silex in solution in the water is probably 

 exceedingly small. Abundance of a green filamentous alga grows 

 in the springs, apparently a species of oscillatoria. No animal 

 forms were detected in them. The rocks contiguous to Pioneer 

 hollow consist of reddish and yellow indurated clays and sand- 

 stones, in nearly horizontal strata. I detected no fossils in them, 

 but suspect from their contiguity that they are of tertiary age. 



About twenty-two miles from Fort Bridger, in the same direc- 

 tion as the former, there is an oil spring, the product of which 

 resembles the so-called lubricating oil. Judge Carter is making 

 the experiment of boring to render the spring more productive. 

 The neighboring rocks are highly inclined, and probably are of 

 cretaceous age. 



A mile or two north of Salt Lake City there is a warm spring 

 with which a sanitary establishment is connected. The water is 

 strongly saline and is impregnated with sulphuretted hydrogen. 

 Its temperature I found, with an ordinary thermometer, to be 98. 

 A mile or two further north, on the Utah Central Railroad, there 

 is a similar spring with a higher temperature, which I found to be 

 128. The water gushes forth abundantly from beneath a rock 

 and forms a clear pond, with the bottom covered with a bright- 

 green alga. This appears also to be an oscillatoria. Masses of 

 it floating near the edge of the pond were white on the upper or 

 exposed surface. This I suspected to be due to free sulphur, and 

 indeed when the alga was exposed to the flame of a spirit-lamp it 

 gave out an indistinct odor of sulphur, though the result was not 

 so marked as I had anticipated. The water is strongly saline to 

 the taste and is impregnated with sulphuretted hydrogen. No 

 animals were detected in the water not even microscopic forms. 

 The waters of these springs finally pour into Salt Lake. 



Salt Lake, as is well known, is remarkable, like the Dead Sea, 

 for the concentrated condition of its briny water, due to the accu- 

 mulation of the saline matters by the evaporation of the water 

 which has no river outlet. The many salt springs which empty 

 in the lake must have greatly contributed to the accumulation of 

 the saline constituents. The water of the lake is intensely salt to 

 the taste, and is said to contain a fifth of its weight of salt. 'This, 

 as well as some other points, I have not been able to test, from my 



