Stevenson.] ^^ [Jan. 21, 



the Coal Measures, without doubt, covered Powell Mountain at one time, 

 and it is equally probable that both the Quinnimont series and the Coal 

 Measures existed at one time on Brushy mountain. It is altogether proba- 

 ble that on some of the high knobs of Brushy mountain, the Quinnimont 

 beds have been spared by erosion. In such case, the extent of the Clinch 

 river uplift would be not far from 10,500 feet and that of the Holston up- 

 lift very nearly 11,000 feet. 



Poor Valley ridge is crossed by the South Fork of Powell river, by 

 Powell river itself and by the North Fork : Wallen's creek crosses the 

 Wallen Valley fault ; the Clinch River uplift is crossed by the North Fork 

 of Clinch, by Stock creek, by both branches of Cove creek and by several 

 forks of Stony creek ; Copper creek fault is crossed by Clinch river, and 

 Copper creek in its windings crosses it several times ; the Holston fault is 

 crossed by a stream entering the river near the mouth of Moccasin creek 

 and by Abraham's creek ; while the Walker Mountain fault is crossed by 

 the stream along which the railroad passes through the mountain. 



II. General Description of the Groups. 



The section exposed within the region examined extends from the Coal 

 Measures to the base of the Knox group as recognized by Prof. Safford in 

 Tennessee. Lower rocks are reached in the Great Valley of Virginia, 

 which is drained by the South Fork of Holston river, but the reconnais- 

 sance stopped at Walker mountain on the northerly side of the Valley. 

 Some of the groups show peculiarities not observed by Profs. Lesley and 

 Fontaine in the area further east or by Prof. Safiord in Tennessee. 



The Upper Carboniferous. 



The Upper Carboniferous is represented by the Coal Measures and the 

 Quinnimont group or Serai (Pottsville) Conglomerate. 



TTie Goal Measures. 



The Coal Measures are found north from Stone mountain, and extend 

 beyond Black mountain into Kentucky. Their thickness, as determined 

 partly by estimate but mostly by barometric measurement, is not far from 

 2000 feet along Roaring Fork of Powell river and its tributary, Calahan's 

 creek ; but the highest part of Black mountain was not reached, since, ac- 

 cording to Mr. Moore's barometric determination, the summit of that 

 mountain at the head of Looney branch is 2200 feet above the Poor branch 

 of Cumberland river ; so that the thickness of Coal Measures is not less 

 than 2500 feet, or somewhat less than that observed in the south-western 

 part of Pennsylvania. There was no opportunity during the recent recon- 

 naissance to complete the detailed section of these measures, and the 

 highest 500 feet of the section given in the former memoir still remains un- 

 examined in detail. 



This area is not more than ten miles wide, for, according to the report 

 on Mr. Moore's reconnaissance, already referred to, the Coal Measures are 



