184 



AN AMERICAN GEOLOGICAL RAILWAY GUIDE. (VA.) 



19. From this point, for many miles towards the southwest, the railroad runs near to and almost 

 parallel with the broken synclinal, (about 25 miles long), of which the lofty Catawba and Fort 

 Lewis Mountains are the principal parts. The former, composed of southeast dipping 4 a. b., &c., 

 forms the farther or northwest rim of the synclinal, and bending abruptly around at its northeast 

 end, becomes the Tinker Mountain, which closes the basin in that direction. A shorter and gentler 

 bend at the southwest end, terminates in a fault. The corresponding rocks of the southeast, or 

 near side of the synclinal, are only partially preserved in a narrow inverted ridge at either end, the 

 remainder of this rim of the synclinal having been engulfed in the prolonged fault, which, for 

 many miles along the margin of the basin, has brought the Siluro-Cambrian rocks (4 a. c.) of the 

 valley to abut against, and over-ride the Devonian 10. to 12. and the Vespertine 13 a., of which the 

 Fort Lewis Mountain, the central mass of tbe synclinal, is mainly composed. 



20. A few miles west-by-north of this is an area of Vespertine rocks 13 a., including one or 

 more workable beds of coal, mined on Stroubler Kun and elsewhere. This area, once probably 

 continuous with the Vespertine of Fort Lewis Mountain, is almost encompassed by faults. Farther 

 to the northwest, and separated from the above by a belt of Cambrian and Siluro-Cambrian rocks 

 3 c., 4 a., &c., the Vespertine beds of the southeast slope of the Brushy Mountain, contain a similar 

 coal, mined on Tom's Creek, &c., all these seams being more or less affected by the neighboring 

 faults. The dislocation which, southeast of Brushy Mountain, brings Vespertine and Umbral in 

 apposition with Siluro-Cambrian Matinal, is part of the great fault which, with some changes of 

 direction and character, extends along the northwest edge of the great valley, from near the James 

 River to the end of the Brushy Mountain, northeast of Abingdon, a distance of about 125 miles. 



