EARTHQUAKES 



215 



Effects on drainage. The fracturing of the rock may interfere 

 with the movement of ground-water. After new cracks are de- 

 veloped or old ones opened or closed, the movement of ground- 

 water adapts itself 

 to the new condi- 

 tions. It follows 

 that a spring may 

 ciase to flow after 

 an earthquake, 

 while new ones 

 break out where 

 there had been 

 none before. The 

 character of .the 

 water of springs is 

 in some cases 

 changed, presum- 

 ably because it 

 comes from differ- 

 ent sources after the earthquake. Joints may be so widened as to 



intercept rivulets. 

 Where faults ac- 

 company earth- 

 quakes, they may 

 occasion ponds or 

 falls where they 

 cross streams. 



Effects on stand- 

 ing water. Some of 

 the most destruc- 

 tive effects of earth 

 quakes are felt 

 along shores. The 

 great sea-waves of 

 the Lisbon earth 

 quake (1775) and 

 of the earthquake 



Fi'_;. 216. Sand cones and cratcrlets observed after an 

 earthquake in Greece, in 1861. (Schmidt.) 



V\z. 217. Characteristic surface appearance of the 

 Calilnrnia fault line, south end of Tomales Bay. 

 (Photo, by Newsom.) 



on the coast of 

 Ecuador and Peru 

 in 1868, were very 



