306 SEE— THE CAUSE OF EARTHQUAKES. [October ly 



mere shaking of the earthquakes accompanying that eruption; and 

 we must, therefore, suppose that after matter had been expelled by the 

 dreadful explosions which destroyed St. Pierre and devastated Mar- 

 tinique, or in earlier eruptions, a subsidence near the roots of the 

 mountain actually took place. Again, in 1835, Captain Fitzroy and 

 Charles Darwin observed that after the violent earthquake which 

 destroyed Conception, the Chilian coast line in that region had 

 been elevated from three to five feet for several hundred miles. Not 

 only the coast but also the whole country back to the Andes was 

 raised. This could only be explained by the injection or forcing in 

 of a corresponding bulk of lava under the land ; and this lava could 

 come from nowhere except from under the bed of the great trough 

 in the adjacent sea. The ultimate effect would be to cause the trough 

 of the ocean to deepen correspondingly. And, moreover, such peri- 

 odic injections from under the sea trough would not only push along 

 the ejected stream of Tava, step by step, until the end of the column 

 reached the mountains, but the forces thus arising would supply 

 the " lateral thrusts " which are said to be much needed for the 

 explanation of the upheavals, the tipping of the strata, the inclina- 

 tions and sometimes reversed positions of the rocks, and other geo- 

 logical phenomena observed in mountains like the Andes. Hereto- 

 fore the abundant phenomena of this kind noticed in all high moun- 

 tains have not been satisfactorily explained. A correct theory must 

 account for the inclinations seen in the mountains as well as the 

 rising of the coast, and such submarine earthquakes as Darwin 

 observed to precede the uplift of the beach at Conception. The 

 present theory seems to be capable of meeting this severe test, and 

 it requires us to make no assumption except that molten lava may 

 be forced from under the bed of the trough, and pushed along its 

 course beneath the crust by the throes of successive earthquakes. 

 It is recorded that a great sea wave followed the Chilian earth- 

 quake of 1835, and such waves are very frequent along the Chilian 

 and Peruvian coasts. They almost always follow an earthquake, and 

 begin by a recession of the sea from the shore, which then returns 

 as a great wave, carrying everything before it. Some have supposed 

 the sea bottom to subside, thus withdrawing the water toward the 

 sink, till it flows in on all sides to fill up the depression, and then 



