252 GEOLOGY AND MINING INDUSTRY OF LEADVILLE. 



sunk to a depth of over five hundred feet in the White Porphyry, which is 

 here underlying the Agassiz deposit, but without reaching the lower Blue 

 Limestone. 1 



California gulch. On the west side of the area under consideration rock in 

 place has not been fovind south of California gulch, except in the Swamp 

 Angel and Jordan (T-14) tunnels on its south bank, which have been run 

 for some 400 feet southward on the contact. The Deadbroke (T-16) and 

 Rosebud (T-18) have also developed the contact on the north side of the 

 gulch, and the J. Harlan shaft has been sunk through Blue Limestone into 

 an underlying sheet of Gray or Mottled Porphyry. Higher up the gulch 

 the Last Rose of Summer and some adjoining shafts struck slates and sand- 

 stones belonging to the Weber Shale formation, which belong to a portion 

 of the formation included in the White Porphyry. The Prospect incline, 

 starting in at an angle of 23 in the White Porphyry, reached the contact, 

 whose angle is somewhat shallower (averaging from 12 to 20), and followed 

 it in for a distance of over five hundred feet. At 375 feet from the mouth 

 was a sharp fold, possibly accompanied by some displacement, in which the 

 contact went down almost perpendicularl} r for about one hundred and 

 twenty-five feet, and was found again in its normal position at a distance of 

 14 feet beyond in the regular course of the incline. 



The White Limestone is opened in a quarry adjoining the road on the 

 north side of California gulch, directly below the Prospect incline. This is 

 the only point where the White Limestone is found actually visible on the 

 surface in the immediate vicinity of Leadville. The O'Donovan Rossa shaft 

 is also in White Limestone, while the Irish Giant, above it, is sunk through 

 the same sheet of Mottled Porphyry shown in the J. Harlan, into the under- 

 lying half of the Blue Limestone. The shaft (T-46) is also in White 

 Limestone, while the adjoining Blind Tom shaft is in White Porphyry on 

 the west side of the fault. A second intrusive body of Gray or Mottled 

 Porphyry in the White Limestone itself is proved by some small shafts in 

 California gulch not indicated on the map, which also show the cropping of 



1 Since the close of field-work the Wolfe Tone shaft has reached vein material and limestone at a 

 depth of 625 feet, and after passing through- it struck another body of porphyry, whether belonging to 

 the underlying intrusive sheet of Gray Porphyry or White Porphyry is not known. It is probably the 

 former. 



