Stevenson.] 



224 



[Jan. 21, 



Powell mountain west from Slemp's gap is but a repetition of Wallen's 

 ridge as shown on the opposite side of Wallen valley. The limestones and 

 shales of Formation III are exposed on its northerly side, Medina sandstone 

 follows its crest, while the Lower Helderberg, Oriskany and a fragment of 

 the Hamilton are shown on its southerly side. These rocks are suddenly 

 cut off by the 



PaMonsville faidt, which is marked by a low ridge at, say, two-thirds of 

 a mile from the crest of Powell mountain. No evidence of its presence 

 vv^as found beyond the railroad line, and, in all probability, it originates 

 very near that line. The structure between the Wallen's valley fault and 

 the Hunter Valley fault (Clinch uplift) is shown in Fig. 4. This fault 



Fig. 4. — Cross-section through Powell mountain from the Wallen Valley fault 

 to the Hunter Valley fault in Buckner's ridge, a. Powell mountain 6, Pat- 

 tonsville ridge ; c, Buckner's ridge; /, Wallen's Vallej' fault;/', Pationsville 

 fault ; /", Hunter Valley fault or Clinch uplift. Numbers as in Fig. 1. 



brings up the Lower Helderberg rocks against the Hamilton shales ; the 

 former describe a shallow synclinal and low anticlinal, so that, before 

 reaching the North Fork of Clinch river, the Hamilton shales are again ex- 

 posed, dipping very sharply toward the south-east. The details of this 

 fault cannot be expressed on the map, owing to the narrowness of the area 

 affected by it. It is evidently parallel with the Wallen Valley fault, and it 

 is responsible for the absence of the Lower Carboniferous rocks from the 

 valley at the southerly foot of Powell mountain. This fault, according to 

 Prof. Saiibrd's map, does not exist in Tennessee. 



The Hunter Valley fault is the same with the ClincTi river uplift, whicli 

 is so fully described by Prof. Lesley in his memoir on the geology of Wise 

 and Tazewell counties.* As it lies at a considerable distance from Clinch 

 river within the area under consideration, it is best to apply to it a local 

 name. Its direction, as laid down on the map, does some violence to the 

 truth, but the writer has preferred to give the direction of the fault prop- 

 erly, even though in so doing it is thrown somewhat out of its geographical 

 relation. This fault enters Scott county near its north-western corner, 

 whence it follows an almost straight line to the gap made through it by the 

 North Fork of Clinch river, being crossed very near the head of Powder 

 Mill gap by the Bristol railroad, and by the Jonesvilie and Estillville road 

 at barely two miles from Pattonsville. It is crossed but once by the North 

 Fork of Clinch. 



This is probably the most violent of the faults observed within the region 

 examined. The rocks on both sides of the fracture are bent upward, and, 

 at more than one locality, the structure is distinctly that of a cracked anti- 

 clinal. The energy of the lift varied, for along a very considerable dis- 



* Proceedings of this Society, 1S72. 



