188 M. R. CAMPBELL — PALEOZOIC OVERLAPS IN VIRGINIA. 



has ore been mined on its southern margin, but this area is connected 

 now to the westward with the great limestone belt at Max Meadows. 

 Before leaving the subject of these isolated bosses of lower limestone the 

 writer wishes to call attention to another such area, marked X on the 

 map. This the writer did not see personally, but from the description 

 of his assistant judges it to be of the same character as those already de- 

 scribed — a limestone boss projecting through the highest members of the 

 Devonian shale. 



The limestone area reaching from Max Meadows to Clarks summit 

 appears to have been considerably disturbed and possibly faulted, but 

 not to any great extent, but along its northern margin the rocks are 

 very regular Avest of Clarks summit. The red shales are there in con- 

 tact with the limestone throughout a very sinuous line of outcrop, and 

 owing to a slight wrinkle in the sandstone they project far into the area 

 of sandstone north of Max Meadows. South of this point of red shale 

 there is an anticline of sandstone, around the eastern end of which the 

 red shale is wanting, either through non-deposition or through subse- 

 quent erosion. Again it comes in on the southern side of the anticline 

 in contact with the limestone, but does not continue far to the westward 

 before it disappears altogether. This disappearance is possibly due to 

 faulting, as a fault of considerable magnitude occurs on this line further 

 west. 



Draper Mountain. — The structure of this mountain is very simple, be- 

 ing a regular syncline of Upper Silurian rocks, the southern limit of which 

 is faulted off. The details of structure about the western end or Ham- 

 ilton knob were not worked out, but are apparently simple. Through- 

 out most of the extent of the mountain this entire syncline is faulted on 

 its northern side, and thrust forward or northwestward until now it rests 

 upon the anticline of Devonian rocks, the Clinch sandstone being in 

 immediate contact with the Devonian shale. Around the eastern end 

 the geology was worked out more carefully. Here the fault cuts just 

 below the Clinch sandstone, and this heavy stratum lies upon the De- 

 vonian black shale, which occurs above the highest ore pits in this 

 vicinity. Below the black shale, at the extreme eastern end, there is no 

 rock visible ; the surface is a debris-covered slope on which considerable 

 iron ore has been found, together with much residual chert. The pres- 

 ence of chert on this slope makes it extremel}^ probable that the lime- 

 stone from which it is derived belongs to the Shenandoah, but the out- 

 crop is so deeply covered that it is impossible to determine its limits. 

 Here, as in many places described, this line of unconformity is marked 

 by a Une of iron-ore deposits, and, curiously enough, they always appear 

 on the southeastern margin of the limestone area. 



