. 











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Ch. VII.] 



OF MOUNTAIN-CHAINS. 



133 



diminish. 



is no 



to a foot, and then, at Stockholm, to three inches in a cen- 

 tury, while at certain points still farther south there ' 



movement. 



But in what manner, it is asked, can we account for the 



& reat lateral pressure which has been exerted not only in the 

 Andes, Alps, and other chains, but also on the strata of many 

 low and nearly level countries ? Do not the folding and frac- 

 ture of the beds, the anticlinal and synclinal ridges and 



some 



times the inverted position of the beds, imply an abruptness 

 and intensity in the disturbing force wholly different in kind 

 and energy to that which now rends the rocks during ordi- 

 nary earthquakes ? I shall treat more fully in the sequel (end 

 of Chap. XXXIII.) of the probable subterranean sources, 

 whether of upward or downward movement, and of great 

 lateral pressure ; but it may be well briefly to state in this 

 place that in our own times, as, for example, in Chili, in 

 1822, the volcanic force has overcome the resistance, and 

 permanently uplifted a country of such vast extent that the 

 weight and volume of the Andes must be insignificant in 

 comparison, even if we indulge the most moderate conjectures 

 as to the thickness of the earth's crust above the volcanic 



foci. 



To assume that any set of strata with which we are ac- 



■ 



quainted are made up of such cohesive and unyielding mate- 

 rials, as to be able to resist a power of such stupendous 



energy, if its direction, instead of being vertical, happened to 



be oblique or horizontal, would be extremely rash. But if 

 they could yield to a sideway thrust, even in a slight degree, 

 they would become squeezed and folded to any amount if 

 subjected for a sufficient number of times to the repeated ac- 

 tion of the same force. We can scarcely doubt that a mass 

 of rock several miles thick was uplifted in Chili in 1822 and 

 1835, and that a much greater volume of solid matter is up- 

 heaved wherever the rise of land is very gradual, as in Scan- 

 dinavia, the development of heat being probably, in that 

 region, at a greater distance from the surface. If continents, 

 rocked, shaken and fissured, like the western region of South 



