498 GEOLOGY AND MIXING INDUSTRY OF LEADVILLE. 



This basin has been described somewhat in detail to show how much 

 fruitless labor has been expended in a region whose surroundings would 

 lead one to suppose that it contains fine bodies of ore. Although so many 

 shafts have been sunk to depths of 200 to 500 feet, the contact has been 

 seldom reached, and even then but little explored. The main difficulty has 

 been the great amount of water met in depth, which could not be controlled 

 by the pumping apparatus in ordinary use. That such a basin should hold 

 a large amount of water, especially when its outcrops are crossed by two 

 such stream beds as those of Big Evans and Stray Horse gulches, is most 

 natural, and it will probably be impracticable for any one mine to work in 

 it alone. Work must be carried on by combination either of actual prop- 

 erties or else of working expenses, and powerful pumping apparatus must 

 be established to drain the whole basin from its deepest point. 



YANKEE HILL ANTICLINE. 



On the western slope of Yankee Hill the J. B. Grant shaft found about 

 eight feet of vein material between White Porphyry and White Limestone, 

 which is only significant as showing that replacement action has gone on 

 to a certain extent beneath the lower sheet of White Porphyry. 



On the eastern side of Yankee Hill a large body of iron vein material 

 has been found, extending from the Clara Dell and Little Champion north- 

 ward through the Bevis and Boulder Nest mines, and thence eastward to 

 the Andy Johnson, which reached it after passing through 200 feet of Gray 

 and White Porphyries. This body consists of iron oxides and chert and 

 is undoubtedly much more extensive than has been represented on the 

 map; it contains some ore, but the data obtained with regard to it were 

 too meager to do more than prove the same probability of the existence 

 of valuable ore bodies in the synclinal basin to the eastward that exists in 

 regard to Stray Horse Park. The Superior (K-61) and Mountain Boy 

 (K-60) shafts struck a considerable body of limonite and chert on the 

 southwestern edge of this basin, dipping at an angle of about 30 to the 

 northeast. This body, which is some fifty feet thick, is supposed to be 

 the replacement of a split-off portion of the Blue Limestone. This supposi- 

 tion accounts for the apparent want in the thickness of this horizon to the 

 west on a line drawn through the Leavenworth shaft, as shown on the map 



