488 GEOLOGY AND MINING INDUSTRY OF LEADV1LLE. 



of vein material may be found, especially as the thickness already devel- 

 oped of about fifty feet is less than that found in many places, even where 

 the entire thickness of the horizon has been replaced by vein material. 



Little stray Horse gulch. There still remains to be described the region 



O 



bordering this valley, from which the Blue Limestone or ore horizon has 

 been removed by erosion. The data with regard to it were mainly derived 

 from dumps of abandoned prospect shafts and from testimony of miners 

 who had sunk the shafts, and are given by the outlines on the map, in addi- 

 tion to which there is not much to say. It will be understood that the 

 relative accuracy of these outlines is dependent upon the proximity of these 

 shafts, since there are absolutely no rock outcrops. 



The Little Diamond shaft, on the Dolphin claim, just south of the end 

 line of the Dunkin, found a considerable body of vein material beneath 

 the Wash, which is the base of the ore horizon, where it has a local dip to 

 the southward, as shown in Section D, the lower body of White Porphyry 

 being exposed on the crest of this fold just east of it. The two May Queen 

 shafts, near the base of the Denver City hill, find only White Porphyry. 

 The Pittsburgh shaft, as already mentioned, passes through Wash and White 

 Porphyry into White Limestone. The Little Daisy and Eudora shafts find 

 White Limestone outcropping beneath the Wash. The new Gambetta shaft 

 is in Gray Porphyry, supposed to be the cross-cutting sheet seen in New 

 Discovery ground and on Carbonate Hill. This porphyry sheet was also 

 cut at different horizons by the Eudora shaft, by the Vanderbilt on Stray 

 Horse Ridge, by the Magnolia shaft in Stray Horse gulch, and, as already 

 mentioned, by New Discovery shafts No. 5 and No. 6. The old Grambetta 

 and Monarch shafts find the White Limestone directly beneath the White 

 Porphyry, for which reason it is assumed that a portion of the Parting 

 Qiuirtzite has here been caught up by the porphyry and is somewhere in 

 it at a higher horizon. 



For the lower part of the valley direct data as to the outcrops are 

 wanting. On the ridge south of it the Ida Nyce and Ypsilanti shafts 

 have found the Blue Limestone beneath the Wash and a small amount of 

 vein material in it. As well as could be determined, the formation has 

 a slight easterly dip, as shown in Section C ; but on the south side of 



