428 SIR CHARLES LYELL 



Uniformity of change considered, thirdly, in reference to 

 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, Vol. II., 

 of the earthquakes recorded in history, that certain coun- 

 tries have from time immemorial, been rudely shaken again 

 and again; while others, comprising by far the largest part 

 of the globe, have remained to all appearance motionless. In 

 the regions of convulsion 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 measure- 

 ments made at different periods, to have risen by an insensi- 

 ble motion, as in Sweden, or to have subsided very slowly, 

 as in Greenland. That these same movements, whether 

 ascending or descending, have continued for ages in the 

 same direction has been established by historical or geolog- 

 ical 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 proper 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. 



It must in general be more difficult to detect proofs of 

 slow and gradual subsidence than of elevation, 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 thousand miles in circumference, 

 throughout which the downward movement has predomina- 

 ted 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 



