1906.] 



SEE— THE CAUSE OF EARTHQUAKES. 409 



If this inference should prove to be well founded, may it not be 

 possible to conclude the contest long waged between astronomy and 

 geology with credit and advantage to both of these great sciences? 

 For it seems to be proved that owing to the great pressure acting 

 throughout the earth's interior, and the solidity of the rocks which 

 cover its surface, the terrestrial spheroid, when subjected to great 

 strain, behaves and vibrates as an aeolotropic elastic solid; yet the 

 fluid medium long contended for by geologists to explain crump- 

 lings and foldings of the crust is really found to exist or develop in 

 a thin layer just beneath the outer crust, and we have explained 

 its simple and somewhat automatic mode of operation. On several 

 grounds it appears that this layer is extremely thin, certainly not 

 much thicker than the crust itself; and, moreover, it too remains 

 essentially quiescent and rigid, except when set in motion by the 

 recurring paroxysms of steam pressure seeking release, which gives 

 rise to an earthquake and the movements of molten matter essential 

 to geological processes. The original conceptions of astronomy are 

 thus apparently verified, while at the same time the long-standing 

 needs of geology are amply met. And although no effort has been 

 made in this paper to harmonize the conflicting views long prevailing 

 in the two sciences, it would seem that this unexpected result may 

 prove to be not the least interesting among several conclusions 

 respecting the constitution of the globe. 



something was pushed under it : both these movements are observed to 

 occur, and always in the same order. Along the shore, just parallel to the 

 sea coast, the crust is pushed upward to form mountains, while the adjacent 

 sea bottom is correspondingly sunk down. Can anyone doubt that we have 

 here a true cycle of events? One of these events necessitates the other, and 

 all are so connected that one can begin at either end of the chain of phe- 

 nomena and reach the other. Thus, if we begin with volcanoes we are led 

 downward through these vents to the earthquake and mountain forming 

 forces at work under the surroundijig land; and finally we come out beneath 

 the ocean where world-shaking earthquakes and seismic sea waves originate. 

 On the other hand, if we begin with seismic sea waves, we are led downward 

 through the observed subsidence of the sea bottom and pass under the crust 

 to the mountains raised along the coast, by earthquakes occurring mainly 

 under the sea, and thus finally reach the volcanoes at the top of the range, 

 erupted by the pressure of subterranean steam, and blowing out lava, pumice, 

 ashes, and vapors. All the grandest phenomena relating to the earth's sur- 

 face are thus connected in an endless chain or circuit. Could such perfect 

 order and harmony be established among all these varied phenomena without 

 the discovery of the true physical cause? (Note added December 3, 1906.) 



