BETWEEN BALL MOUNTAIN AND WESTON FAULTS. 



to the Colorado Prince fault. A more detailed description of the structure 

 in the immediate vicinity of these mines will be found in Part II, Chapter V. 



In the east fork of Lincoln gulch, according to Mr. Jacob, the Boulder 

 incline is sunk on the line of the Colorado fault at an angle of 45 to the 

 north, with granite in the roof and White Porphyry in the foot-wall; while 

 the Cumberland shaft, a short distance east, is sunk 150 feet in White Por- 

 phyry. The evidence of the former would prove, therefore, that the Colo- 

 rado Prince fault at this point is a reversed fault, viz, that the upthrow is 

 on the hanging-wall side, instead of, as is usually the case, on the foot- wall; 

 and the fact that the latter was sunk to so great a depth in White Por- 

 phyry without reaching granite Avould be explained by the nearly vertical 

 position of the sheet. This explanation, which considers the White Por- 

 phyry as an interbedded sheet, is supported by the apparent continuity of 

 White Porphyry north of the Colorado Prince fault, around the outcrop of 

 Archean. It seems possible, however, that these shafts may be sunk in the 

 actual channel through which the porphyry came up across the Archean. 

 The Fitchburg incline, on the south side of Lincoln gulch, opposite the 

 Boulder, was run down on the contact of Lower Quartzite and White 

 Limestone, which here dip 20 to the southwest. 



South Evans anticline. The granite body which forms the crest of South 

 Evans anticline, extending from the north fork of Lincoln gulch to the 

 mouth of South Evans, is shown wherever prospecting has stripped the 

 rock of the overlying soil; also, by the Caledonia (G-59) and Slim Jim 

 (G-46) shafts and by the Silver Tooth bore-hole (G-45) This bore-hole 

 was sunk 314 feet, cutting in its passage downwards 49 feet of White Por- 

 phyry, probably a small dike within the granite. The granite in the Cale- 

 donia is red and coarse grained ; that from the bore-hole, compact and fine 

 grained. The White Cloud shaft (K-15) on the. west side of the fold in 

 Lincoln gulch was sunk in the Lower Quartzite, which also outcrops near 

 the road, showing a western dip. A shaft (K-14) on the north side of 

 Evans gulch has found quartz-porphyry directly under the Wash. The 

 Hoosier Girl (G-44), on the east, is in Lower Quartzite, which must be 

 a portion separated from the main body by the lower sheet of White Por- 

 phyry. This lower sheet of White Porphyry forms the western point of 



MON XII 15 



