THE LODE. 277 



been carefully examined by Mr. King's party, and the information recorded 

 by him, with additional facts from the surface, and from a few levels below 

 the bottom of the old shaft, make the section fairly satisfactory. 



Several masses of micaceous diorite crossing the new shaft are repre- 

 sented as embedded in diabase. The evidence already adduced of the rela- 

 tive age of these two rocks precludes the supposition that these bodies can 

 be intrusive, and the only tenable supposition seems to be that they are frag- 

 ments detached and moved into their present position by the diabase erup- 

 tion. That such an event is quite possible is evident, the wonder being 

 that it is not of more frequent occurrence on the Comstock. 



Fissure dipping west.— A vcry pccullar phenomenon is the occurrence of an 

 ore body in the Yellow Jacket dipping west and ending abruptly on the 

 west wall. The following is suggested as a possible solution The earlier 

 hornblende-andesite cap is in this region of considerable thickness, and its 

 under and upper surfaces seem to be nearly parallel, while the diabase 

 contact slopes at an angle of some 33°. The direction of the faulting 

 movement was at least as nearly vertical as that of this contact. To this 

 movement the tenacity of the andesite offered a resistance, but as it con- 

 tained no parting in the direction of motion it yielded in the direction of 

 least resistance, or nearly at right angles to the surface. This action gave 

 rise to the fissure dipping westward. As the faulting movement continued, 

 a second eastern fracture formed exactly as in the Virginia mines. 



cross-sectionthroughtheBeicher.— The 5e?c7ier section is made out from fewer 

 data than most of the others, in spite of the fact that the ore-bearing levels 

 were open to inspection. No galleries have been run into the east wall on 

 this plane, and there are no workings where the croppings should appear. 

 The quartz is continuous on the slope of the main fissure above its junc- 

 tion with the secondary fracture, but how far is not known. I believe, 

 however, that the fissure might be followed to the surface, though it is 

 improbable that ore in any quantity would be found. From the sketch 

 map. Fig. 1, it appears that the evidences of solfataric action run high up 

 Cro4n Point ravine, and back of the Belcher; and the decomposition seems 

 almost necessarily to indicate a structural connection between the surface 

 and the deep-seated fissures. The secondary fissure appears to represent 



