THE COMSTOCK LODE. 67 



sively that the period of their outpouring was not a single eruption, but that 

 they were ejected through a considerable period, successive flows overpouring 

 the cooled and solidified products of the first eruption. 



The west fissure is regarded as a rupture of the crust, caused by the 

 earlier andesite disturbances, and to have been projected north and south, 

 chiefly governed in position and inclination by the strain which the heavy 

 syenite mass induced. Contemporaneously with this, or at all events with the 

 earlier andesite fractures, has occurred the series of steeply-curved fractures, 

 forming the connected ore-channel and east wall. 



Throughout Gold Hill the east and west walls approach each other, until 

 the vein in depth becomes a simple single mass of vein-material, included 

 between two walls. In this section there are no grounds for predicating 

 either a giving out or a permanent disappearance' of the vein. It differs in no 

 important particulars from others, which have continued indefinitely down- 

 ward, and whose structural lines are supposed to penetrate the solid crust of 

 the earth to immense depths. In the middle, or Virginia section, the relation 

 of the east and west fissures is such that only the most central portions 

 can continue to a great depth, since the eastern or steeper crevice terminates 

 evidently against the western wall. Explorations have proven that for several 

 hundred feet at least the vein is wanting, and there are no strong indications 

 of its ever reappearing. It is left for the central point, occupied by the Savage 

 and Hale and Norcross mines, to prove by further explorations whether the 

 quartz-body in their lowest levels is indeed the top of a deep-seated chimney, 

 or whether, like the other mines in this group, they are approaching the 

 termination of their vein. Two strong reasons point to the conclusion that 

 they have reached the deep vein. First, the series of fissures, instead of 

 shutting sharply down upon the syenite, has gradually broken and curved into 

 approximate parallelism with the west wall. Secondly, it is difficult to con- 

 ceive how such enormous masses of mineralized quartz could have entered 

 the upper fissures except from some deep-seated source, and taking this for 

 granted, there is left no other point of connection with the subterranean 

 laboratory. In the northern region explorations have not penetrated deeply 

 enough to afford the data for a well-grounded opinion, as to the probable 

 nature of the fissures in depth. But it may be said that no conditions are 



