814 



UNIFORMITY OF CHANGE. 



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[Ch. XIY. 



subterranean movements.— Thirdly, to pass on to the last of the 

 three topics before proposed for discussion, the reader will find 



in the account given in the Second Book of the earthquakes 

 recorded in history, that certain countries have, from time im- 

 memorial, been rudely shaken again and again ; while others 

 comprising by far the largest part of the globe, have remained 



motionless 



In the regions of convul- 



sion rocks have been rent asunder, the surface has been forced 

 up into ridges, chasms have opened, or the ground throughout 

 large spaces has been permanently lifted up above or let down 

 below its former level. In the regions of tranquillity some 

 areas have remained at rest, but others have been ascertained 

 by a comparison of measurements, made at different periods, 

 to have risen by an insensible motion, as in Sweden, or to 

 have subsided very slowly, as in Greenland. That these same 



ovements 



same 



rical or geological evidence. Thus, we find on the opposite 

 coasts of Sweden, that brackish water deposits, like those now 

 forming in the Baltic, occur on the eastern side ; and upraised 

 strata filled with purely marine shells, now j)roper to the ocean, 

 on the western coast. Both of these have been lifted up to an 

 elevation of several hundred feet above high-water mark. 

 The rise within the historical period has not amounted to 

 many yards, but the greater extent of antecedent upheaval 

 is proved by the occurrence in inland spots, several hundred 

 feet high, of deposits filled with fossil shells of species now 

 living either in the ocean or the Baltic. 



To detect proofs of slow and gradual subsidence must in 

 general be more difficult ; but the theory which accounts for 

 the form of circular coral reefs and lagoon islands, and which 

 will be explained in the concluding chapter of this work, will 

 satisfy the reader that there are spaces on the globe, several 



throughout 



which the 



thousand miles in circumference, 

 downward movement has predominated for ages, and yet the 

 land has never, in a single instance, gone down suddenly for 

 several hundred feet at once. Yet geology demonstrates that 

 the persistency of subterranean movements in one direction 

 has not been perpetual throughout all past time. There have 



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