MOVEMENTS AND DEFORMATIONS 349 



of springs is sometimes changed, presumably because it comes from 

 different sources after the earthquake. Joints may be so widened 

 as to intercept rivulets. Where faults accompany earthquakes, 

 they may occasion ponds or falls where they cross streams. 1 



Effects on standing water. Some of the most destructive effects 

 of earthquakes are felt along shores. The great sea-waves of the 

 Lisbon earthquake (1755) and of the earthquake on the coast of 



Fig. 284. Characteristic surface appearance of the fault line, south end of 

 Tomales Bay. (Photo, by Newsom.) 



Ecuador and Peru in 1868, were most destructive. Such waves 

 have been known to advance on the land as walls of water 60 feet 

 in height. They are most destructive on low coasts where the 

 water may sweep over great areas of land. The great loss of life 

 during an earthquake is often caused by such waves. Lakes are 

 also affected by earthquakes, but their waves are much feebler 

 than those of the sea, and are not often very destructive. 



Earthquake shocks are sometimes remarkably destructive to 

 the life of lakes and seas. Thus during the Indian earthquake of 



1 Oldham, Report on the Indian Earthquake of June 12, 1897, p. 138. 

 Mem. Geol. Surv. of India. Cited by Geikie, loc. cit., p. 374. 



