106 SILVER-LEAD DEPOSITS OF EUREKA, NEVADA. 



rhyolite eruption covered a considerable period it is not improbable that 

 there have been overflows of that rock since the beginning of the ore 

 deposition at some point in the district. As the rhyolite eruption occurred 

 in the Tertiary it follows that the ore formation was not of an earlier date. 

 The solfataric action to which this region was once subjected has long 

 since spent itself, and there is nothing to indicate that the increment of heat 

 is abnormal. 



