PEAtE.] DISTRIBUTION GEOLOGICAL FEATUEES. 361 



Elevation, in feet, 

 above sea-level. 



Pfefifers, iu Switzerland 2,128 



Onoto, Venezuela, South America 2, 161 



Boiling Lake of Dominica, West Indies 2, 400 



Gastein, in Germany 3,520 



Xear Salt Lake City, Utah, United States 4,320 



Leuk, in Switzerland 4, 600 



Hot Springs of Lake Tahoe, California, United States 6, 500 



Lower Geyser Basin, Yellowstone Natioiial Park, United States 7,236 



Upper Geyser Basin, Yellowstone National Park, United States 7, 372 



Rustic Group, Heart Lake Basin Yellowstone National Park, United States. . 7, 475 



Gibbon Basin, Yellowstone National Park, United States 7,527 



Mud Volcanoes, Hayden Valley Yellowstone National Park, United States. 7, 723 



Hot Springs, Yellowstone Lake, Yellowstone National Park, United States. 7,738 



Hot Springs, Lewis Lake, Yellowstone National Park, United States 7,800 



Shoshone Geyser Basin, Y'ellowstone National Park, United States 7, 825 



Sulphur Springs, Middle Park, Colorado, United States 8, 000 



Dona Ana, Chili, South America 10, 000 



Yeumtong in the Himalayas, India 12,000 



Momay Spring in the Himalayas, India 16, 000 



Geyser region of Lake Tengri Nor in Thibet 16, 000 



CHAPTERII. 



GEOLOGICAL FEATURES. 



Geological position. — When thermal springs are considered in their 

 widest signification, it will be found that they are not confined to any 

 one geological formation. When, however, the definition is limited so 

 as to include only warm and hot springs, it will be noted that they are 

 found in two positions that are characteristic, viz : 1st. In regions of 

 great disturbance or dislocation, as along the base or in the midst of 

 mountain ranges; and 2d, In areas of eruptive rocks, either where vol- 

 canic action is still going on or iu regions where it has been long extinct.* 



It should be mentioned here that dislocations and fractures deter- 

 mined by the elevation of mountains maybe due primarily to the same 

 causes that are active in producing at other places the eruptions of vol- 

 canoes. This subject will be referred to again under the heading of 

 "The source of heat of thermal springs." 



A few facts in relation to the position of warm and hot springs will 

 now be briefly presented under the two heads just given. 



First. In connection with mountain corrugation. — It is a well-known 

 fact, pointed out by many writers, that warm and hot springs are apt 

 to be found along the bases of mountain ranges, and usually near the 

 line of junction of sedimentary rocks with the granitic nuclei, and the 

 high temperatures are recognized as being due to the same causes that 

 have elevated the ranges. 



The lines of junction between the sedimentary and older rocks mark 

 the points where the greatest number of fractures and fissures occur, 

 by means of which the meteoric waters have access to and from the 

 depths where they acquire their high temperatures.! Where two or three 



*It is well to remember that it is a difficult matter to determine that volcanic 

 activity is at an end even in regions that have been quiet during the historic period, 

 inasmuch as our knowledge of the cycles of volcanic action is almost nothing, and 

 cones thought to be extinct have frequently broken out in fresh eruption. 



tin Sweden and Norway, springs that have temperatures of even a few degrees 

 above the mean annual temperatures of their localities arc rarely found. This is prob- 

 ably due to tlio fact that these countries are but little fractured, and yet they have 

 been subjected to earthquake shocks. 



