536 GEOLOGY, 



life of lakes and seas. Thus during the Indian earthquake of 1897, 

 *' fishes were killed in myriads as by the explosion of a d^^namite car- 

 tridge . . . and for days after the earthquake, the river (Sumesari) 

 was choked with thousands of dead fish . . . and two floating car- 

 casses of Gauge tic dolphins were seen which had been killed by the 

 shock.'' ^ This wholesale destruction of life is of interest, since the 

 surfaces of layers of rock, often of great age, are sometimes covered 

 with fossils of fish or other animal forms, so numerous and so preserved 

 as to indicate that the animals were killed suddenly and in great numbers, 

 and their bodies quickly buried. It has been suggested that such rock 

 surfaces may be memorials of ancient earthquake shocks.' 



Changes of level. — Permanent changes of level sometimes accom- 

 pany an earthquake. Thus after the earthquake of 1822 ''the coast 

 of Chili for a long distance was said to have risen 3 or 4 feet.''* Similar 

 results have occurred on the same coast at other times, and on other 

 coasts at various times. Depression of the surface is perhaps even 

 more common than elevation. Thus on the coast of India all except 

 the higher parts of an area 60 square miles in extent were sunk below 

 the sea during an earthquake in 1762. Widespread depression in 

 the vicinity of the Mississippi in Missouri, Arkansas, Kentucky, and 

 Tennessee accompanied the earthquakes of 1811 and 1812. Some 

 of the depressed areas were converted into marshes, while others became 

 the sites of permanent lakes. Reelfoot Lake, mainly in Tennessee, is 

 an example. Change of level is involved wherever there is faulting, 

 and faulting is probably rather common in connection with earthquakes. 



Changes of level are not confined to the land. Where earthquake 

 disturbances affect the sea-bottom in regions of telegraph cables, the 

 cables are often broken. In such cases notable changes have some- 

 times been discovered and recorded when the cables were repaired. 

 Striking examples are furnished by the region about Greece. ■* In one 

 instance (1873) the repairing vessel found about 2000 feet of water 

 where about 1400 feet existed when the cable was laid. In another 

 instance (1878) the bottom was ''so irregular and uneven for a distance 

 of about two miles, that a detour was made and the cable lengthened 



1 Oldham, loc. cit., p. 80. 



2 Geikie. Text-book of Geology, 4tli ed., p. 375. 



3 Ibid., p. 376. 



*^Forster, Seismology, 1877. Summarized in the Am. Geol, Vol. Ill, 1889, p. 182. 



