276 GEOLOGY OF THE COMSTOCK LODE. 



west wall at the bottom. By inspection of the longitudinal vertical projec- 

 tion and of the mine maps, it will also be perceived that the ore bodies lay 

 within such a space as is suggested by consideration of the probable results 

 of faulting. 



The occurrence of the rocks in the Sutro Tunnel has already been suf- 

 ficiently discussed in Chapter V. The various belts of decomposition indi- 

 cated have all been located as veins upon the surface ; but there is nothing 

 in this section to indicate any hope of ore away from the Comstock, except 

 upon the Occidental lode. 



Cross-section through the H. & N. — The Hole & Novcross section passes through 

 the edge of the largest bonanza of the Virginia group. Its thinness, com- 

 pared with the Consolidated Virginia and California bonanza, is striking, but 

 would be somewhat less so were the plane of the section nearer the axis of 

 the body. The structure of the liorse is much less regular than on the Sutro 

 section, but it is again noticeable that the western quartz diminishes in 

 width as the depth increases, while the openings at the east increase. The 

 horse is intersected by a nearly vertical quartz body. In the Chollar these 

 two eastern fissures come together. The black dike makes its appearance 

 in this section, and is found running into the Savage, but no farther north, 

 nor is it known to reach the surfiice at any point. The andesite contact is 

 laid down from inferences drawn chiefly from observations made at the 

 Savage, 700 feet farther north, the Santa Fe adit being closed. Most of the 

 lower workings of the Hale (& Norcross were also inaccessible at the time 

 of the examination, and it is not impossible that the vein is drawn somewhat 

 wider than a careful examination would justify. 



Cross-section through the Jacket. — lu tlic Imperial grouud the diorito swings to 

 the west, leaving metamorphic slates with an easterly dip as the foot wall 

 in the Gold Hill mines. 



But a small portion of the Yellow Jacket workings was accessible at the 

 time of the investigation; but a preliminary examination of the lower levels 

 had been effected before the Gold Hill mines were flooded, and an excellent 

 collection, kept by the company while sinking the new shaft, supplemented 

 by visits to the accessible tank stations, furnished all the necessary informa- 

 tion concerning the eastern portion of the section. The old workings had 



