506 OF THE PHYSICAL STRUCTUnE 



Fort Lewis mountain, shows Formation II thrown over upon 

 Viri. Some miles towards the northwest (at c) is the gi-eat 

 fault of the Little North mountain, presenting Formations 11 and 

 X, in contact, the former being uppermost. Near the northwest 

 termination of the Section (at a) is seen the fault on the 

 northwest side of the Sweet spring, or Peters's mountain axis, 

 here showing the contact of For. II with the upper part of For. 

 VIII ; the remainder of the latter, together with the other interven- 

 ing formations, being lost. In this part of the Section may be seen 

 the rapid passage of the higher rocks, from inversion to verticali- 

 ty, and thence into a very gently undulating and horizontal posi- 

 tion, towards the northw^est. 



Section E, (PI. XXI.) This Section extends from the Poplar 

 camp mountain, in Virginia, near the mouth of Reed creek, in 

 a north-northwest direction, to the commencement of the coal 

 rocks, immediately northwest of Abb's valley. Lying in the 

 Holston division, in the southwestern part of Virginia, it traverses 

 nearly all the great parallel lines of fault, for which that region is 

 so remarkable. At its southeastern extremity we notice the low- 

 est formation of the Appalachian system, bent over into an in- 

 verted position, and resting upon the next superior rock, the gi'eat 

 lower limestone, (For. II.) Steep normal, and also folded flex- 

 ures, extend across the valley to the Cove mountain, at the south- 

 east base of which we meet with a line of fault (at d), bring- 

 ing in contact Fors. II and VIII, with the usual inversion of the 

 former. Beyond this, to the northwest, near the southeast base 

 of Brushy ridge (at r), is the great dislocation referred to on 

 previous occasions, and which here brings together Fors. II 

 and X. Still further towards the northAvest, in the valley of 

 Walker's creek, on the northwest side of gyi inverted anticlinal 

 axis of For. II, a similar fault occurs (at b), with the same hiatus 

 of the intervening formations. Beyond this, or northwest of 

 the Wolf creek axis, we see (at a) an extension of the great 

 fault previously descril)ed as running along the northwest side of 

 the Sweet spring, or Peters's mountain axis. A few miles fur- 

 ther, we come upon the last, or most northwestern line belonging 

 to this division of the chain. 



