338 SEE— THE CAUSE OF EARTHQUAKES. [October 19, 



The terrific violence of the earthquakes which are still felt in northern 

 India gives us an idea of the amazing power of the subterranean 

 forces by which this great uplift was produced. In elevating the 

 highest mountains of the world, it is not remarkable that they also 

 raised the highest plateau. 



In his work on the '' Face of the Earth," Vol. I, p. 452, Professor 

 Suess remarks with surprise that the tangential movement shown 

 by the mountains has opposite direction on the two sides of the 

 Bramaputra ; this confirms the present theory in the most conclusive 

 manner. 



§ 25. On the elevation of plateaus. 



It will be seen that in this paper we abandon contraction as 

 the principal modifying cause and consider only the light matter 

 proved to be injected under mountains and narrow plateaus by the 

 power of steam, which gives all these masses a substratum of honey- 

 combed material identical with the lighter lava and denser pumice. 

 That this material now lies under these regions of greatest elevation 

 seems certain, and in place of the contraction theory, we may sub- 

 stitute that of steam expansion and solidification, upon which moun- 

 tain building depends. This is, of course, effected in accordance 

 with Henry's law of gaseous absorption, and the still more general 

 law that matter adapts itself to the pressure to which it is subjected. 



It will be seen that all the mathematical reasoning is the same 

 whether we suppose greater contraction under the oceans, or an 

 actual heaving up of the land areas by the injection of light vol- 

 canic material more or less full of bubbles, which decreases the 

 average specific gravity of the land and mountains. 



Pendulum observations made at many points on land and sea also 

 give the same indication as respects the earth's arrangement of 

 density ; and if the present view be sound the interpretation of these 

 observations will now become more obvious. 



If we apply the foregoing theory to a narrow plateau, like that 

 of Mexico, which is a uniform tableland, with mountains on both 

 sides, it will become evident that the mountains were formed when 

 they were near the sea ; and that when the shore line had remained 

 fixed there for a long time it again receded, after the elevation of 

 the mountains and the tableland, both of which probably were 



