50 SILVER-LEAD DEPOSITS OF EUREKA, NEVADA. 



Relation of the Ruby Hill fault to the Jackson fault. If the SUrfaCe-Uiap, Plate I., is 



examined an extensive fault will be noticed just east of the Jackson hoist- 

 ing works. This fault extends a considerable distance to the north and 

 south, and has been called by Mr. Hague the Jackson fault. The main 

 fissure of Ruby Hill, the one containing rhyolite, joins the Jackson fault 

 somewhere south of the American shaft, but at exactly what point has not 

 yet been determined, the surface of the ground being covered by debris, 

 while the underground developments are inconsiderable. It has baen stated 

 that the limestone in which the American shaft is sunk is the Pogonip lime- 

 stone. It is therefore possible that the main fissure of Ruby Hill is identical 

 with the Jackson fault at this point, though the fault laid down by Mr. 

 Hague runs nearly due north from the American shaft. That there is 

 another fault pai-allel to the main Ruby Hill fissure is clearly shown on the 

 cross-cuts to the old Jackson shaft, and it is probable that this other fissure 

 is no other than the one which Mr. Hague has called the "Jackson fault." 

 There seems to be very little doubt that the eruptions of rhyolite which 

 occur in this neighborhood, of which Purple Mountain is a prominent 

 example, are intimately connected with all these faults. 



