1857.] ANSTED — MINERAL VEINS. 253 



with the stratified rocks in strike and dip, they not unfrequently 

 contain within their defined walls portions of schist in their normal 

 and unaltered condition, thus showing a true interstratification to 

 that extent. 4. Between the gossany outcrop of the lodes and the 

 hard solid mundicy veinstone below, is found a mass of black cupri- 

 ferous ore, as already described, entirely distinct from either, and 

 separable mechanically from both with the greatest facility. This 

 deposit reposes on the floor of mundicy veinstone, filling its hollows, 

 and apparently adapted to its irregularities of surface. 5. The width 

 of the lodes in the majority of cases, and the depth of the black ore 

 from the grass, are very distinctly affected by the present form of 

 the surface, the lode being much narrowed in the valleys, and the 

 thickness and width as well as quality of the black ore reduced, 

 while the greatest depth at which this ore has yet been seen is very 

 little indeed below the ordinary level of the valleys. 



In the three first-mentioned points of difference, and sometimes in 

 the fifth, the Ducktown veins are analogous to the auriferous quartz- 

 veins (sometimes also cupriferous) of Virginia and North Carolina, 

 and even those of California. In the first and third points they 

 agree with the Maryland veins described in the previous notice, 

 p. 242 ; but the fourth condition is altogether peculiar, and has 

 not, so far as I am aware, been hitherto recorded. Analogy would 

 point to the existence of similar black ores beneath the Maryland 

 gossans. 



These Ducktown lodes must not be considered without special 

 reference to the physical conditions of the adjacent country. They 

 are amongst the old rocks of the main Alleghany Chain, but not very 

 near any large masses of igneous rock. The general form of the 

 ground, as far as regards the ranges parallel to the main axis, is un- 

 questionably due to elevatory causes, and not to denudation ; but it 

 would be diflicult to decide, without very minute investigation, 

 whether the transverse cuts through which the natural drainage is 

 carried are partially or entirely the result of weathering and aqueous 

 action or are due to transverse elevations. No faults or heaves have 

 as yet been observed in the district, and no cross-courses are known 

 that intersect the gossan-lodes. 



No very satisfactory account has yet been given of these singular 

 deposits. Mr. Whitney and some American geologists have attri- 

 buted the existence of this band of decomposed copper-ore (which has 

 been erroneously regarded as black oxide of copper) beneath the 

 gossan and above the veinstone as an effect of the decomposition of 

 the veinstone near the surface, and have seen in the curious arrange- 

 ment of this bed near the present water-level a confirmation of their 

 views. But, independently of the fact that the present veins could 

 never by any possibility decompose into the present gossans and beds 

 of ore, there is really no water-level to which they can be referred, 

 as the floor of ore merely approximates in a general way to that of 

 the natural drainage, and is often totally opposed to that direction. 

 Whatever may have been the original condition and subsequent action, 

 it appears to me certain that the filling of the part of the vein above 



