362 EEPOET UNITED STATES GEOLOGICAL SURVEY. 



axes of elevation cross each otber the disturbance is greater and thermal 

 springs ought to be abundant. This is the case at Ax in France, where 

 three axes intersect. Leuk, in Switzerland, and Mont Blanc are other 

 instances. 



The baths of Mont Dore, in France, are situated near the geographical 

 center of the hills at the point of greatest dislocation. In addition to 

 this, however, the water escapes from columnar trachyte. Professor 

 Eogers has pointed out the connection of the warm springs of Virginia 

 with the anticlinal axes and faults of the Appalachian system. The 

 thermal springs of Brazil are found in the coast ranges of mountains, 

 and their relation to the hot springs in the Andes is analogous to that 

 between the springs of the Appalachian region and those of the Pacific 

 coast region in the United States. 



In India many thermal springs owe their origin to their position in 

 high mountain regions, especially in the case of the Himalayas. As we 

 have already shown in Part II, flat, undisturbed regions such as the Mis- 

 sissippi Valley and great plains of North America, the table-lands of 

 Brazil, and the steppes of Eussia and Siberia are remarkable for the 

 absence of thermal springs. 



Second. In areas of eruptive roclcs. — The connection of warm and hot 

 springs with volcanic action is well established, and all works on geology 

 treat of them under the head of igneous or volcanic phenomena. In Part 

 II I have endeavored to show this connection, and a map of the warm 

 and hot spring localities enumerated therein would be to a great extent 

 identical with a map of the volcanic lines of the globe. The principal 

 exceptions would be in the caseof springs just noted as associated with 

 mountain corrugation. In a few regions of volcanic rocks also, such as 

 the Hebrides, there are no hot springs, and their absence can usually be 

 explained by the fact that so long a time has elapsed that the rocks have 

 lost their heat. The following facts are additional proofs of the con- 

 nection of hot springs and volcanic manifestations. 



Hot springs are formed during almost all eruptions of volcanoes,* es- 

 pecially if they are new, and the amount of volcanic activity is thought 

 to be largely dependent upon the amount of water in their liquid contents. 



Water in A^olcanoes is repeatedly noticed, and the " smoke," so called, 

 which escapes is mostly steam. After violent eruptions steam usually 

 escapes in such quantity that heavy rainfalls are caused. In Java and in 

 South America, water, vapor, and mud are poured out by the volcanoes 

 instead of lava. The water volcano of Gauteraala is a veritable geyser 

 on a grand scale. Indeed all writers ou volcanoes recognize that the 

 same causes which produce geysers are active in the production of vol- 

 canic eruptions. 



As already noted, areas of hot and warm springs need not have active 

 volcanoes in their vicinity, and two of the most noted geyser regions in 

 the world, viz, New Zealand and the Yellowstone National Park, have 

 been without any active manifestation during the historic period, and 

 in both boiling springs are numerous. In Auvergne, in France, the 

 eruptions date back to the Tertiary period, and in Nevada, which might 

 fairly divide with California the claim of being the most active hot spring 

 area of the United States outside of the National Park, the rocks are of 

 Tertiary age, the latest of its rhyolites, according to King,t having been 



* The noted eruption of Jorullo in Mexico, in 1759, caused the disappearance of two 

 rivers, which were replaced by several warm springs. During the eruption of Monte 

 Nuovo in Italy, in 1538, new hot springs broke out. Other examples will be given 

 when the effect of earthquakes is considered. 



t U. S. Geol. Expl. of 40th Parallel, Systematic Geology, Vol. I. 



