CHAPTER XIII 

 EARTHQUAKES IN GEOLOGY 



IT is more than likely that earthquakes in the geolo- 

 gical past were very much more violent, widespread, 

 and frequent than they are now ; and they may 

 have had a more potent effect in overturning the rocks 

 of the earth. Even now their effects and the circum- 

 stances which accompany them are tremendous and terri- 

 fying. When the great earthquake comes, says Major 

 Edward Dutton in his book on Earthquakes, it comes 

 quickly and is quickly gone. Its duration is generally 

 a matter of seconds rather than of minutes, though in- 

 stances have been known in which it lasted from three 

 to four minutes. Perhaps forty-five seconds would be 

 a fair average. The first sensation is a confused mur- 

 muring sound of a strange and even weird character. 

 Almost simultaneously loose objects begin to tremble 

 and clatter. Sometimes almost in an instant, some- 

 times more gradually, but always quickly, the sound 

 becomes a roar, the clattering becomes a crashing. The 

 rapid quiver grows into a rude violent shaking of in- 

 creasing amplitude. Everything beneath seems beaten 

 with rapid blows of measureless power; loose objects 



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