76 THE MOUNTAIN. 



These waves of rocks are called by geologists " anticlinal," 

 and the troughs between are called "synclinal axes," and 

 everywhere the connection between topography and geology 

 is revealed. Where the rocks are soft and destructible we 

 are presented with valleys of denudation, or washing, and 

 where the rocks are harder and less destructible, mountains 

 are left, monuments of the war of the elements. 



Where the stata are spread out with gentle inclinations, or 

 horizontal, there are no mountain ranges, and the valleys are 

 drains or washes cut through the strata, the hills between 

 being simply piles of rocks left by the denuding forces. 



Where they are folded and wrinkled, the appearance and 

 disappearance of the same formations, at different points, 

 always show the same topography, as well as geology. 

 Thus all the mountains in the eastern portion of the range 

 are formed of two or three groups of rocks brought to the 

 surface by frequent foldings of the strata, whilst the valleys 

 between are also made of a few formations which are as con- 

 stantly cut out and washed away.* 



Thus in this apparently much diversified range of moun- 

 tains and valleys, we have a few rocks continually appearing 

 and disappearing, the out-cropping edges of the different 

 fractured foldings forming long, narrow, parallel belts, the 

 less destructible masses projecting in mountain lines, the more 

 destructible swept away out of the valleys. 



This remarkable folding or plication of the strata is the 

 most distinguishing characteristic of the geology of the Ap- 

 palachian group of rocks and mountains. Apparently a con- 

 fusion of interminable waves, arches, and troughs, of anticlinal 

 elevations and synclinal depressions, with continual bending 

 and twisting of the strata, there is still a regularity and a 

 system, an order of relative position which is never violated. 



The foldings of this portion of the skin of the world have 

 but a few general formulae in their mode of development 

 and distribution. They have a southwestern direction, with 



* See transverse section 



