150 GEOLOGY OF TONOPAH MINING DISTRICT, NEVADA. 



Opposing dips of the veins probably original. The reason for the opposing 

 underground dips of these veins, which have nearly the same line of outcrop 

 and a nearly identical dip at the surface, is not clear. As before stated, the 

 Wandering Boy and the Valley View veins seem to lie in different fault blocks, 

 being separated by a probable fault which runs along the road between them; 

 and it is possible that the faulting may have been of such a differential nature 

 as to partially revolve the block containing the Wandering Boy veins and to 

 reverse the dip. Evidence obtained both in the Wandering Boy and in the 

 Fraction demonstrates that the dip of a vein may be changed and even reversed 

 by faulting, and by accompanying deformation which corresponds nearly to 

 folding, but which is probably the result of an aggregate of small faults. 



Against this interpretation is the fact that the steep south dip of the Wander- 

 ing Boy veins at their outcrop corresponds with the similar surface dips of the 

 heavy Valley View vein, which is the vein of the outcropping Valley View group 

 lying farthest east, and the one with which the Wandering Boy vein would naturally 

 be correlated. If the different dip of the veins in the two blocks is due to the 

 revolving of one block on another this difference should appear at the surface as 

 well as underground; that it does not is evidence rather in favor of the conclusion 

 that the displacement has occurred without any notable change in the attitude of 

 the veins aside from local and minor effects. In this- case it follows that the 

 veins of the Valley View system present, if the perplexing faulting were 

 eliminated, marked differences in dip, the main Wandering Boy vein dipping at 

 a moderate angle to the south, as the main Valley View vein does toward the 

 north. 



Change of dip shown by the comparison of the Valley View and the Stone Cabin. 

 In this connection the studies already made on the Valley View veins are impor- 

 tant. It has been shown that the outcropping heavy vertical veins of this system 

 on Mizpah Hill do not persist, as demonstrated by the Valley View workings, to 

 a depth of as much as 200 feet, but are represented at this depth and below by a 

 strong vein dipping about 35 to the north. In the Stone Cabin and Silver Top 

 workings, however, a vein, which is certainly the continuation of the outcrop- 

 ping heavy Valley View vein, continues down almost vertically to a demonstrated 

 depth of over 400 feet, beyond which point exploration has not been made. This 

 portion of the vein is separated from the larger portion in the Valley View 

 workings by a fault, along which the displacement of the vein seems to have 

 been normal, so that the vertical portion shown in the Stone Cabin workings 

 has been dropped down below the north-dipping portion of the Valley View. 



According to this the part of the main Valley View vein which has been 

 eroded to expose the present outcrop on Mizpah Hill must originally have extended 



