PHYSICAL HISTORY OF NEW HAMPSHIRE. 519 



approach each other, we can see that the Atlantic schists between would 

 be crowded by lateral forces so as to produce mountains, if the pressure 

 be sufficiently great. It would not be easy in this case to say that the 

 force came from the south-east or from the north-west, but practically 

 from both quarters. If the Profile-Sunapee porphyritic range were 

 moved north-westerly, it might not be more influential in folding up the 

 Green Mountains than the Adirondacks, since their power of resist- 

 ance is practically an energy pushing in the opposite direction. It has 

 been common among geologists to argue that the pressure inducing 

 elevation in North America has come mainly from the south-east, or 

 from the ocean towards the interior; but in the present case there is 

 certainly reason to believe that the force has come as much from one as 

 from the other quarter. 2. Accepting the doctrine of the earth's refrig- 

 eration from the condition of igneous fluidity, it is easy to understand 

 why parallel ridges should be made to approximate to each other, and 

 consequently in their motion crumple up the thick rock masses lying 

 between them. In cooling, a crust forms over an igneous interior. This 

 crust eventually becomes so large that it cannot fit the nucleus within it, 

 and hence there must be a bending of the stiff envelope to bring the two 

 parts together. The crust cannot possibly fit the interior save by sinking 

 down almost everywhere, and rising along a few lines, so as to make 

 ridges on the surface. The process of shrinkage and ridging by the 

 close of the Atlantic period may be supposed to have been carried on so 

 far that the three parallel lines of land just spoken of correspond to three 

 elevated lines on the surface of the earth's crust. The process of cool- 

 ing had been going on for an immense period ; the interior is ready to 

 fall away from the stiff envelope ; the sinking of several hundred thou- 

 sand square miles of surface takes place. Consequently the older ridges 

 are forced nearer together, and as they move towards each other the 

 intervening horizontal Atlantic rocks are mercilessly crumpled up, folded, 

 and broken. As the force exerted is irresistible, the two prominent Mt. 

 Washington and Green Mountain ranges are crowded up so as to become 

 conspicuous elevations.* 



* It is sufficient for our present purpose to refer the origin of the Atlantic mountains to a lateral pres- 

 sure produced in connection with the shrinkage of the earth's crust. There are « multitude of considera- 

 tions which ought to be presented in order to elucidate the subject properly. I propose to devote an entire 

 chapter to the statement of a proper theory of the elevation of mountains, with abundant historical references, 



