1887.] '1 [Stevenson. 



The Saltmlle ^ault. 



This interesting fault, originating in Tennessee, enters Bland county- 

 just north from the Saltville and Sharon Springs road ; passes at only a 

 few rods north from that road at Sharon Springs ; less than one-third of a 

 mile north from the cross-roads at Seddon ; lies north from the road for 

 six miles beyond Seddon ; thence for two miles is south, but is again 

 crossed so that it is only a few rods north from the forks of the road at 

 Poplar hill, in Giles county ; it is crossed by New river in Buckeye moun- 

 tain, very near Scott's ferry ; and by the Salt Pond and Newport road in 

 a wind-gap through Buckeye mountain at half a mile north from New- 

 port. The dips of the southerly side are regularly south south-eastward, 

 and not very abrupt, rarely exceeding twenty five degrees ; those on the 

 northerly side are equally regular except near Newport, where the 

 Trenton shales are faulted against the Knox limestone and the former are 

 badly twisted. 



The Knox limestones are shown on the southerly side of the fault, and 

 notwithstanding the great variations ot horizons on the northerly side, 

 there is comparatively little change on the southerly side — even less than 

 might be expected from the influence of the Walker Creek anticlinal. 

 The variations on the northerly side possess much interest, but being due 

 to the Clinch Mountain group ot folds cannot be described until after those 

 folds have been discussed. 



The Clinch 3fountain Qroiif of Folds. 



Where tirst seen, in Scott county. Clinch and its associated Brushy 

 mountain make up a broad monoclinal, showing a section from Medina on 

 the crest of Clinch mountain to tlie highest Umbral rocks at the Saltville 

 fault. The width of Upper Silurian and Devonian is barely three miles. 

 In Smyth and Tazewell, however, a fold, the Burk's Garden anticlinal, 

 arose at the foot of Clinch mountain, widening the area of Silurian and 

 Devonian, and narrowing that of the Lower Carboniferous until at the 

 line of Wythe county only the Vespertine remains. Similarly, gentle 

 folds in Russell and Tazewell interrupt the dip at the north and the Medina 

 outcrop is carried further in that direction, so that Rich mountain, whose 

 crest is merely the continuation of Clinch mountain around a petty anti- 

 clinal, lies nearly a mile north from the previous line of Clinch. So the 

 monoclinal of Scott county is interrupted by a great fold with a broad 

 synclinal at the north as it enters Bland county. The structure becomes 

 more complicated within Bland and Giles, but gives promise of returning 

 simplicity as the group passes into Craig county beyond the limits of the 

 writei-'s examination. 



The Burk's Garden fold, which attains its greatest maximum in the cove 

 of that name, quickly flattens, so that at the easterly end of the cove, the 

 Medina outcrops of Garden mountain unite and that sandstone crosses the 

 fold in Round mountain. The decrease is so rapid that within five miles 



