232 GEOLOGY AND MINING INDUSTRY OF LEADVILLE. 



through porphyry to reach it. From the Florence westward the contact 

 slopes down again towards Iowa gulch through the Sangamon (M-24) tun- 

 nel, Brian Boru, Wilson (M-38), Blacktail (M-40), G. M. Favorite (M-44), 

 and other claims and crosses the gulch. 



On the north bank of the creek southeast of the G. M. Favorite are 

 found outcrops of Parting Quartzite, consisting here of sandy beds with some 

 purplish shale, and of the top of the White Limestone, dipping 20 to the 

 westward. These facts and the outline of the Blue Limestone on the north 

 side of Printer Boy Hill and alongCalifornia gulch show that under this hill is 

 an anticlinal fold whose axis runs north and south through the west end of the 

 hill, and which, like the other folds, has a steeper slope to the west. On Long 

 and Derry Ridge its western half has been cut off by the Mike fault. The 

 White Porphyry above the Blue Limestone, on the western side of this fold, 

 is cut in the Now-or-Never (M-49) and other shafts in Iowa gulch; and 

 the Nestor (M-'28) shaft, on the crest of the ridge, has reached limestone 

 after passing through 1 70 feet of White Porphyry. 



On the north side of Printer Boy Hill, along the upper portion of Cal- 

 ifornia gulch, the presence of the Blue Limestone is proved in the Lovejoy 

 shaft (M-29) and in the workings of the Eclipse mine (M-7 and M-9). 

 The Lovejoy passes through the limestone into an underlying bed of 

 quartz-porphyry, which is also found in the Stars and Stripes tunnel and 

 which very closely resembles the Green Porphyry body found in Iowa 

 gulch under the White Limestone. The Eclipse tunnel (M-7) runs in 

 170 feet through limestone and then strikes the contact of the overlying 

 White Porphyry, which it follows. The porphyry is here unconformable 

 to the limestone, cutting across its stratification. The dip of this limestone 

 is 15 to the south. The lower tunnel (M-9), about thirty feet below this, 

 is run on the contact of Blue Limestone and Parting Quartzite; both con- 

 tacts show vein material. The small thickness of limestone included be- 

 tween Parting Quartzite and overlying White Porphyry is an additional 

 evidence that the latter is here cutting across the Blue Limestone. 



