OF THE APPALACHIAN CHAIN. 509 



flexures on the southeast, and that, therefore, if the axes or fold- 

 ings were produced solely by lateral pressure, the whole force 

 must have been propagated from the lines, where the wedging in 

 of the igneous matter occurred in this southeastern region, to the 

 remotest of the axes, through all the intervening folds. But, con- 

 sistently with mechanical analogies, such a transmitted force, in- 

 stead of producing the gentle gradation of flexure, which we 

 behold, would have expended itself in merely compressing or 

 crushing the contiguous tracts across a narrow belt, a little wid- 

 ened by a succession of these tangential actions. The narrow dis- 

 turbed belt would abound in irregular contortions, and beyond it 

 we should suddenly come to the strata in their original horizon- 

 tal ity. 



That such would really be the effect of the supposed horizon- 

 tal action, is clearly proved by the singularly undisturbed condi- 

 tion, already stated, of the strata immediately, and for some dis- 

 tance, northwest of all our great lines of dislocation. Along these 

 lines, the uniform inversion, and the crushed and contorted state 

 of the higher rocks, immediately northwest of the fracture, indi- 

 cate plainly an enormous lateral thrust in that direction from the 

 fault. Yet, even where the greatest energy of this force is mani- 

 fested, the inversion or other disturbance extends only for a few 

 hundred yards northwest of the fissure, while a little beyond, the 

 horizontal posture of the rocks has been even less changed than in 

 parts of the same region, where no fault exists. 



Even granting, that such a force, transmitted to a great distance 

 across the chain, were capable of bending the strata of the re- 

 moter tracts into gentler undulations, the flexures on their north- 

 western sides ought to be relatively still steeper than they are, 

 for in that quarter the curves are almost symmetrical. On the 

 other hand, this near approach to a symmetry of curvature in the 

 remoter axes, is an obvious consequence of the greatly reduced 

 force and size of the nearly exhausted waves. 



The widening of the interval between the axes, as we go to the 

 northwest, is another general fact, which, while it finds a ready 

 explanation in the hypothesis of a violent undulation of the strata, 

 would seem to be wholly at variance with the operation of a 



