157 



a view which is supported by the fact that near the head of Cunning- 

 ham Gulch a light blue to white limestone crops out, which, according 

 to its litbological character, must be referred to the upper Silurian or 

 lower Devonian of that region, no fossils having been found that might 

 establish its age beyond a doubt. 



The metamorphic rocks of that region, in which stations 23, 25, and 

 38 are located, show many variations. From a pure quartzite they pass 

 over into micaceous schists, into gneiss, and at some points into a coarse- 

 grained granite. Schists occur that contain the characteristic staurolite 

 twins, scarcely to be distinguished from some northeastern localities. 

 Numerous small and large A^eins of white quartz traverse these schists, 

 showing sometimes slight indications of ore. 



In speaking of the lodes of the region under consideration, it is nec- 

 essary to state that but little work had been done upon them ; that 

 there are existing no mines of any considerable depth ; and that but 

 very little time could be spent upon their inspection. These facts ex- 

 clude the possibility of deciding with any considerable degree of accu- 

 racy the character of the ore-bodies at any greater depth. It was nec- 

 essary to make almost all studies on the immediate surface; and as from 

 a series of such observations no law can be derived exhibiting the ratio 

 of development as compared to the depth, it stands to reason that non^ 

 definitively to be relied upon can be here given. The geological char- 

 acter of the veins under consideration is a verj^ interesting one, and I 

 believe that the data regarding development, with depth of the mines, 

 must necessarily afford much information on the distribution and for- 

 mation of ore-bearing veins in general. 



OCCUERENOE OF LODES. 



Two systems, chiefly of lodes, are found, the one striking approxi- 

 mately northeast to southwest, the other northwest to southeast ; and 

 the two directions may be observed to occur at the same places, produc- 

 ing a crossing of the veins. 



At all points, where none but the volcanic rocks crop out, the veins 

 run through them in a very regular course, showing but few deviations 

 from the straight line. Often quartz veins, containing but little ore, 

 were observed from our high stations some distance oft", keeping a regu- 

 lar course at times for more than a mile. As the quartz is harder than 

 the surrounding rock, it stands out prominently, while the former, imme- 

 diately adjacent, is weathered off. Decomposing pyrite imparts a brown 

 color to the projecting ledge. As a rule, the walls may be pronounced 

 well defined, although near the surface atmospheric influences would 

 have the tendency to render them less so. Frequently the veins can be 

 seen along the face of a rocky hill for several thousand feet. This was 

 the case on a mountain opposite Howardsville, where a number of veins, 

 some of them claimed, are visible for a vertical distance of more than 

 2,000 feet. From the north side of the summit five parallel veins trav- 

 erse the trachytic rock for a vertical distance of 1,200 to 1,400 feet, and 

 are in their turn cut by a large vein starting from the southern side, the 

 " Mammoth lode." Farther to the south, beyond the last named, there 

 are several smaller veins, having an almost vertical dip. Debris covers 

 the lower portion of the veins, hiding them out of sight. In Cunningham 

 Gulch the lodes, after first running through the metamorphic rock atright 

 angles to its strike, enter without apparent disturbance or dislocation the 

 horizontally stratified volcanic cap. At the shallow depths which have 

 thus far been reached, no change in the character of the ore could be 



