EFFECTS OF EARTHQUAKES ON LAND. 161 



the rocky crust is that which took place during the earth- 

 quakes of 1811-12 in the valley of the Mississippi, near to 

 the mouth of the Ohio, which was convulsed to such a 

 degree, that lakes, twenty miles in extent, were formed in 

 the course of an hour. This country, which is called the 

 * sunk country,' extends some seventy to eighty miles 

 north and south, and thirty miles east and west.^ 



In the ' Gentleman's Magazine ' we read of the little 

 territory of Causa Nova, in Calabria, being sunk twenty- 

 nine feet into the earth by an earthquake, without throwing 

 down a house. The inhabitants, being warned by a noise, 

 escaped into the fields, and only five were killed.^ 



Other examples of these permanent dislocations of 

 strata are to be found in. almost every t^t-book on 

 geology. 



Geological changes 'produced, — Passing over the 

 accounts of earth movements which are more or less ficti- 

 tious, and confining our attention to the well authenticated 

 facts, we see at once the important part which earthquakes 

 have played as agents working geological changes. Even 

 in the nineteenth century long tracts of coast, as in Chili 

 and New Zealand, have been raised, whilst other areas, like 

 the Delta of the Indus, have been sunk. Sir H. Bartle 

 Frere, speaking about the disturbance which took place in 

 this latter region in 1819, remarks that all the canals 

 drawn from the Fullalee Eiver ceased to run for about 

 three days, probably indicating a general upheaval of the 

 lower part of the canal. In consequence of the earth- 

 quakes in former times it is not unlikely that water-courses 

 have ceased to flow, water has decreased in wells, and 

 districts have been depopulated.^ 



> Lyell, Princi-ples of Geology, vol. ii. pp. 107-8. 



8 Gent. Mag. 1733, vol. iii. p. 217. 



* * Earthquakes of Cutch,' Jour. Royal Geo. Sue. vol. xl. 



