356 



KEPOKT UNITED STATES GEOLOGICAL SURVEY. 



Section I— GENERAL FEATURES. 

 CHAPTER I. 



Definition of Thermal Springs— Source of Water — Outflow — Life in Hot 



Springs— Distribution. 



In the first place we have to inquire what thermal springs are and. 

 whence they derive their supply of water ; next to consider their out- 

 flow, the life which they contain, and their distribution over the globe. 



DEFINITION OF THERMAL SPRINGS. 



Thermal springs strictly considered are those whose mean annual 

 temperature exceeds the mean annual temperature of the locality in 

 which they are found. This, of course, includes more than the springs 

 that are usually called warm or hot, for if the temperature exceeds, no 

 matter in how small a degree, the mean temperature of the place in which 

 it rises, it is truly a thermal spring. There will, of course, be a variation 

 according to geographical position. Thus a spring which is warm in Sibe- 

 ria, where the ground is frozen to the depth of 630 feet, would be a cold 

 spring in the West Indies, or in the Eastern Archipelago. In the cata- 

 logues of Part II the lowest temperature given, with one exception, is 6(P 

 F. Very few springs below 75° F. are, however, included, most of them 

 ranging from the latter temperature to the boiling jioint, and it is to springs 

 of this range in temperature that we here refer. The one exception 

 noted above is in Alaska, a spring of 33<^ F. being included in the table. 

 When this temperature was taken the air was 13° colder than the spring. 

 According to Walton waters of 70° to 85° may be termed temperate j 

 from 85° to 92° F., tepid ; from 92° to 98° F., warm; and all above 98° F., 

 hot. 



The following sjjrings are given by Adolph Erman,* but were not in- 

 cluded in the table of Siberian springs : 



Location. 



Tempera- 

 ture of 

 the air. 



Tempera- 

 ture of 

 springs. 



Springs at Slatonst, Siberia 



Springs at Aleshki, Siberia 



Springs at Tomsk, Siberia , 



Springs at mouth of Uda, Siberia . . 

 Springs near Ust Kiakhta, Siberia . 



Springs near Irkutsk, Siberia 



In the mines of Achiusk, Siberia. . . 



°r. 



+18.5 

 -10.6 

 - 2.8 



-19.7 



1'. . 



+42 



+32. 11 



+33. 12 



+35.4 



+35.2 



+38.7 



+36.5 



The springs in this list never freeze. They were not included in the 

 table on page 344, as I do not know what their mean annual temperatures 

 are, nor the mean annual temperatures of their localities. They are, 

 however, probably true thermal springs. 



SOURCE OF WATER IN SPRINGS. 



The source of water found in springs was long a puzzling question to 

 philosophers. Aristotle taught that there were large cavities in the 

 interior of the earth filled with air, and that this air condensed to water 

 on the cold roofs, and made its way to the surface through fissures. 



* lu Travels in Siberia, by Adolpli Erman. London, 1848. 



