^ OF THE APPALACHIAN CHAIN. 505 



Indiana county, and offers a striking illustration of the existence 

 of exactly the same structural features, in the curving region of 

 the Juniata, as the other shows in the straight one of the Susque- 

 hanna. The folded or inverted axes occupy the belt of the South 

 mountain and great valley, northwest of which they are succeed- 

 ed by a broad belt of steep normal flexures, several of which lift 

 to the surface nearly the lowest formations of the system. This 

 Section also displays the manner in which the western coal region 

 is divided by the wide and gentle flexures northwest of the Alleg- 

 heny escarpment. 



Section C, (PI. XX.) Om* third Section crosses the chain in 

 a direction from the Blue ridge, at Ashby's gap, in Virginia, 

 through Winchester and Romney, to the commencement of the 

 coal rocks, on the Front ridge of the Allegheny mountain. It 

 exhibits normal flexures everywhere but in the Blue ridge and 

 great valley. In the Short hill and Blue ridge, at the southeast 

 end of the Section, the sandstones, forming the lowest group of 

 the Appalachian system, are seen in folded anticlinal flexures, 

 which equally affect the older metamorphic rocks, the whole of 

 the northwestern slope of the Blue ridge presenting an inverted 

 or southeastern dip. The general southeasterly inclination of the 

 axes-planes, or, which is the same thing, the greater steepness of 

 the northwestern, compared with the southeastern dips, is very 

 uniformly exhibited in this Section. The rocks of the Little 

 North mountain are here shown to be inverted, presenting (at c) 

 one of the phases of the prolonged fault, formerly alluded to. 



Section D, (PI. XXI.) This Section crosses the chain from a 

 point high up on the south fork of the Roanoke river, in Vir- 

 ginia, to the northwest base of the Peters's mountain, near Union. 

 Lying in the James river division of the chain, it exhibits the 

 rather confused mixture of normal and inverted flexures and 

 faults, for which that district is remarkable. On the southeast, 

 are seen the bold flexures of the strata of the lowest of the Appa- 

 lachian formations, here of extraordinary thickness, and forming 

 a lofty mountain range, while, immediately behind them, on the 

 southeast, are seen the numerous foldings of the ancient meta- 

 morphic strata. A fault (at d) at the southeast base of the 

 83 



