Stevenson.] ^4:0 [jan. 21, 



IV. Geology of the Area Drained by Clinch River. 



The whole of this area lies within Scott county. For convenience of de- 

 scription, it may be regarded as divided by the road leading from Big 

 Stone gap to the mouth of Stock creek. The easterly division .extends 

 from the crest of Powell mountain to that of Moccasin ridge, and is draiued 

 by several streams, to which reference will be made in their place ; the 

 other division extends weslwardly to the Tennessee line and southwardly 

 from tlie crest of Powell mountain to Clinch river. It is drained princi- 

 pally by Little Stock creek and the North Fork of Clinch river. 



The Western Division. 



The Medina sandstone is somewhat imperfectly exposed on the summit 

 of Powell mountain along the Jonesville and Estillville road, but appears 

 in cliffs at but a little way further east. Its junction with the shales of For- 

 mation III is well shown at the roadside, and is very sharp, there being no 

 transition bed. The Medina, for 35 feet from the base, is massive, cross- 

 bedded, and not at all conglomerate, though here and there a pebble 

 appears. Impressions of ArihropJiycus, though not abundant, are by no 

 means rare. Some imperfect exposures of Clinton rocks were seen at about 

 one-third of the way down the mountain slope and numerous fragments 

 of fossiliferous ore lie scattered in the road and on the hillside. Only one 

 bed, however, was found in place, and its ore is highly silicious. Further 

 east along this slope of the mountain, three beds have been exposed on 

 property lately belonging to the Kane estate, which are equivalent to the 

 three beds seen in the Poor Valley ridge. The upper one is very thin, and 

 its ore is silicious^but the middle and lower beds are of workable thick- 

 ness and their ore is good, though evidently somewhat leaner than that 

 from the middle bed of the Poor Valley ridge. 



These ores extend along the mountain face quite to the head of the 

 North Fork of Clinch river, whence they cross the divide and continue 

 along the southerly face of Wallen's ridge along Wildcat valley ; but no 

 measurement of the group or of its ores was made in Slemp's gap or above 

 it along the North Fork of Clinch. 



Still further down the slope or very near the foot of the mountain are 

 the Lower Helderberg and the Oriskany, beyond which come the shales of 

 the Hamilton. A small tributary to the North Fork of Clinch flows along 

 the foot of the mountain, and the road to Sneedville follows it. These 

 rocks are exposed along this stream, and the shales are reached at Robin- 

 son's mill, where they are dipping almost southward at a high angle. At 

 a little way below the mill, the stream enters a gap through a low ridge 

 produced by the Pattonsville fault, and on the other side it joins the North 

 Fork. At the entrance to the gap, one reaches the coarse sandstone, and 

 the limestone at the base of the Lower Helderberg, both of which have 

 been pushed to 5 degrees beyond perpendicular. Several exposures of 

 Lower Helderberg rocks occur within this gap, but the section is not con- 

 tinuous. 



