WARM SPRINGS. 147 



resist, so successfully as might be thought, the internal actions, which, meet- 

 ing no obstacle in the sedimentary deposits subsequently formed, must have 

 dislocated them in all ways. In fact, there is no deposit on the surface of 

 the globe, either sedimentary or crystalline, which is not found to be cracked 

 in all directions ; even on the upper surface, most rocks are broken in small 

 fragments, to a considerable depth. 



While the crust of the earth was gradually cooling, things must have 

 passed nearly as we have stated ; but, after the temperature had become 

 stationary, as it is now, it could not have been the same : the superficial 

 pellicle does not contract, because it does not grow sensibly cooler. Never- 

 theless, the interior mass is still cooling more and more, although with ex- 

 treme slowness*, and consequently diminishing in volume ; now, the fluid 

 part tending to drag with it that which covers it, and which becomes suc- 

 cessively too large, this must contract on itself, and ridge the surface by dis- 

 locations through its whole thickness. This may take place tranquilly, for 

 some time ; but, at certain moments, the effect cannot fail to take place 

 quickly, and hence the sudden catastrophes experienced on the earth's sur- 

 face. 



All observations, in accordance with geometrical considerations, show- 

 that these ridges and these dislocations are formed according to the great 

 circle of the sphere, and extend over the half of its circumference. 



2. Warm springs. The different degrees of temperature of 

 warm springs are referable to the central heat, which is communi- 

 cated through fissures of greater or less profundity. The waters 

 come to the surface with the temperature of the point whence 

 they started, and, it is known, that at the depth of ahout 3280 

 yards, they boil. Now it may be readily conceived how, during 

 earthquakes, new hot springs may appear in a country, and how 

 those that existed there maybe lost ; in the first instance, all that is 

 required is a fissure, to establish a communication between the 

 surface and a proper depth ; and, for the second, that the existing 

 communication should be interrupted. 



We may easily conceive, also, that before the earth had reached its pre- 

 sent degree of cooling, hot springs must have been infinitely more numerous 

 than they are at present. When, instead of one-thirtieth of a degree, centi- 

 grade per yard, the temperature increased one-third of a degree, that is, ten 

 times more rapidly than at present, and when water boiled at a depth of 325 

 yards, it is clear, there must have been a great many springs at a tempera- 

 ture of 212 Fahrenheit, or of boiling water, and that fumarolles, now rare, 

 were then common. Consequently, the condition of the atmosphere was then 

 very different from what it is now; thick fogs must have spread over the 

 surface of the earth, in the absence of the sun, and hence radiation towards 

 the celestial space, at present an important C;iuse of refrigeration, must then 

 have been nothing. Winter was consequently less rigorous ; and this ex- 

 plains, too, how so many plants and animals, which cannot now exist in 

 northern climates, could then live in them as between the tropics, and pre- 

 cisely as southern plants now live on northern coasts and islands which are 

 constantly shrouded in thick fogs. The whole earth, tempered by these 



* According to Fourier, a decrease of internal heat of not more than one 

 degree in thirty yards, would require 30,000 years. 



2. How is the temperature of hot springs accounted for? At what depth 

 do spring waters boil ? 



