OEE PEOSPECTS IN UNEXPLORED AREAS. 519 



On Iron Hill the region west of Iron fault probably contains the con- 

 tinuation of the Iron mine bonanzas, but the depth at which it will be found 

 may be such as to render its exploitation expensive; a shaft sunk to reach 

 the contact opposite the Iron mine might have to go nearly a thousand feet. 

 As there is some uncertainty as to the actual position of the bonanzas in 

 this region, it might be more prudent to follow the contact downward from 

 some point where its depth is known, say in the neighborhood of the Devlin 

 shaft, where it is only 200 feet deep. 



On Carbonate Hill the contact should be followed westward from the 

 line of the Pendery fault. It has already been shown in Part I, Chapter V, 

 that there is a good probability that on the northwestern slopes of the hill 

 the formations dip westward, and that farther south in the Pendery ground, 

 though broken by a fault, the displacement of the latter is probably not 

 great. Were the contact followed westward from a shaft reaching the 

 limestone anywhere along the lower slopes of the hill, it would not take 

 long to determine whether it still exists under Leadville or had been re- 

 moved by erosion previous to the deposition of the Lake beds. Should the 

 latter prove to be the case it would avoid the great and, in this contingency, 

 useless expense of sinking a deep shaft under Leadville itself, which other- 

 wise will doubtless some day be undertaken. 



MINES AND PROSPECTS OUTSIDE THE LEADVILLE DISTRICT. 



The region outside the area covered by the map of Leadville and 

 vicinity was examined primarily with the object of determining its general 

 geological structure and studying the series of formations where they were 

 less metamorphosed and better exposed than in that district, in order that 

 by the experience thus gained it might be easier to unravel the complicated 

 geological problem there presented. In the few short months that could be 

 devoted to this work it was impossible to make a very complete or sys- 

 tematic study of the ore deposits opened by the various mines in this out- 

 side region, and only those that came within the line of work and were 

 accessible at time of visit were examined. The following notes, the result of 

 that examination, are offered, notwithstanding their incompleteness, mainly 

 because of the information they afford with regard to the geological dis- 



