378 SEE— THE NEW THEORY OF EARTHQUAKES fNovember 15, 



sinking where the undermining due to expidsion is very active. — 

 This may be inferred from the fact that an ocean such as the 

 Pacific is surrounded everywhere by high mountains, and often 

 by table lands of great elevation. All these mountains and plateaus 

 have been raised from the sea, by injections of lava expelled from 

 beneath the bed of the ocean. The fact, however, that in many 

 places, as along the Aleutian, Kurile, Japanese, and East Indian 

 islands. South America, and elsewhere, the expulsion of lava has 

 been so rapid as to dig out trenches near the ranges of mountains 

 thus elevated, leads one to recognize that in some places the expul- 

 sion towards the land is more rapid than the creep of lava from 

 under the sea towards the shore, so that the sea bottom sinks down 

 into a trough. This expulsion of lava happens in a good many 

 places, and the phenomena are clear enough to admit of no doubt. 

 Yet it seems certain that some lava creeps under the crust towards 

 all avenues of escape, along the paths of least resistance, and en- 

 forced movements occur in submarine earthquakes. Islands are 

 thus raised in the sea, and where the undermining is rapid the 

 adjacent sea bottom sinks down. Sometimes large plateaus form 

 in the ocean, and slowly rise to the surface, so as to form a large 

 flat island, generally of an elongated type. Submarine plateaus of 

 this kind are now to be found in the north and south Atlantic, and 

 elsewhere, and there can be scarcely any doubt that the leakage of 

 the ocean finds relief by the gradual elevation of such submarine 

 masses, as well as along the shores. The effect of this process is 

 to augment the corrugation of the earth's crust in the course of 

 geological time; and eventually the highest mountains in such sub- 

 marine ridges rise above the water as islands. On October 16, 

 1907, a very powerful earthquake was felt all over the world, and 

 the seismographic records located it in the Pacific Ocean between 

 Mexico and Hawaii, about 1,000 miles south of San Francisco. 

 This earthquake seems to have been purely submarine, and even 

 more powerful than those which devastated San Francisco and 

 Valparaiso. It is by such submarine movements that the sea bottom 

 is constantly disturbed and corrugated and crumpled in a thousand 

 ways, and some of the elevations are eventually lifted above the 

 water as islands. 



