386 GEOLOGY AND MINING INDUSTRY OF LEADVILLE. 



gulch, the Blue Limestone outcropping near the Robert Emmet tunnel and 

 opposite the Globe shaft, in which the Lower Quartzite is cut. 1 



Dome fault. The Dome fault is in one sense the proper continuation of 

 the Iron fault, since it forms the great break on Dome Hill, as Iron fault 

 does on Iron Hill, and, like the latter, passes at its extremity into an anti- 

 clinal fold. Considered in this way, the Iron, California, and Dome faults 

 would form a single fracture, somewhat irregular in direction, but having a 

 general north-and,-south trend, while the southern continuation of the Iron 

 fault, as at present indicated, and the Emmet fault, would be simply 

 branches, relieving the strain at the sudden bend of the fault in California 

 gulch. To the east of this line of fracture are the principal outcrops of Blue 

 Limestone and the main ore developments in this region, while to the west 

 this horizon is more or less deeply buried beneath a covering of porphyry. 

 The Dome fault proper has a general nort'i-and-south direction. Its plane 

 has been proved by underground workings only in the Vining tunnel, but 

 the line as given on the map is tolerably closely determined by the develop- 

 ments of adjoining shafts and inclines, those on the west finding White 

 Porphyry, underlaid by Gray Porphyry, on a level with Blue Limestone on 

 the east, in the Rock and Dome workings. 



Emmet fault. This small fault, running in a southwest direction from 

 the California fault, has a movement of displacement the reverse of the 

 majority of the faults in this region that is, the upthrow is to the west in- 

 stead of to the east. Its plane has actually been proved by a drift running west- 

 ward from a winze sunk in the Robert Emmet tunnel. It is further proved 

 by the discrepancy in the position of the Blue Limestone and the overlying 

 porphyries on either side of it, as shown in Section G, Atlas Sheet XXV. 

 That it actually continues to its junction with the Iron fault to the south, 

 as indicated on the Leadville map, is merely a matter of conjecture. 



Dome Mm. By reference to Atlas Sheet XXV, Sections E and F, it will 

 be seen that the northern portion of the ridge of Dome Hill, adjoining Cal- 



1 Since the close of field-work, developments iu tho Garden City mine have definitely located the posi- 

 tion of the western end of this fault. The lower shaft on this claim was sunk perpendicularly 100 feet 

 through limestone aiid vein material, and then passed into the Lower Quartzite, crossing the fault 

 diagonally. At 120 feet a drift to the southwest cut the fault at 5 feet from the shaft, showing that 

 its dip is to the south. At 75 feet from the *haft the same drift cut the plane of the Iron fault and passed 

 into i lie White Porphyry on the west side of this fault. 



