BETWEEN WESTON AND MIKE FAULTS. 227 



alluvial deposits of Empire gulch, and apparently passes into an anticlinal 

 fold on the west slope of Empire Hill/ On Long and Deny Ridge it is 

 defined at the Kenosha tunnel, where a body of greenish quartz-porphyry 

 on the east conies into juxtaposition with White Porphyry on the west; 

 the former body belongs below the horizon of the White lamestone, the 

 latter above that of the Blue. It descends into Iowa gulch near the point 

 where the Long and Derry grade reaches the crest of the hill, crossing the 

 gulch just west of the Now-or-Never (M-49) shaft; passes the western 

 foot of the Printer Boy Hill to California gulch between its junctions with 

 Eureka and White's gulches, and along the western slope of Breece Hill, 

 through the workings of the Mike and Star mine, from which it receives its 

 name. 



In the latter region the surface indications do not prove its existence, 

 since White Porphyry is found on both sides; but its movement is proved 

 by the relative depths of the Blue Limestone horizon under the White Por- 

 phyr}^ in the two shafts of the Park mine (0-1 and 0-4). Its movement 

 cannot be traced north of Adelaide park, and it is supjoosed to end at its 

 junction with the Breece Iron fault. 



Its movement of displacement at the south end is an upthrow to the 

 east, which is about one thousand feet on Long and Derry Ridge and 

 decreases to the northward. North of its junction with Pilot fault, in Iowa 

 gulch, as above stated, the only data are derived from the Park mine, from 

 which it is infen'ed that the movement is reversed and is an upthrow on the 

 west, gradually increasing from that point to a maximum of about thvea 

 hundred feet. 



Pilot fault. — Pilot fault might in one sense be considered the normal con- 

 tinuation of the main Mike fault, from the fact that its upthrow is the same 

 and that the amount of its displacement decreases continuously to the north 

 until its movement is entirely lost in the body of Pyritiferous Porphyry on 

 Breece Hill. Its direction diverges at first ver}- sensibh* from that of the 

 Mike fault, being a northeasterly direction across the Avestern slope of 



' On the Mosquito map (Atlas Sheet VII), hy an error of the engraver, which had been over- 

 looked, it has heen continued south of Empire gulch to a junction with Union fanlt on a line which is 

 simply the boundary between White Limestone (c) and Lower Quartzito (b). 



