298 GEOLOGY OF THE EUEEKA DISTRICT. 



those observed along- the Hoosac fault, miueral deposits are found identical 

 in mode of occurrence with those found on Prospect Mountain, although 

 less productive. A line of ore deposits follows Rescue Canyon on the east 

 side in the highly inclined strata of Century Ridge. Tlie Rescue mine is 

 the most important property, exploration having developed several small, 

 but rich, chambers of ore in following down the shaft between 400 and 500 

 feet below the sm-face. Otlier mines on Century Ridge are the Queen and 

 Maryland, both of which resemble the Rescue mine. 



In the Alhambra Hills a shaft has been sunk in the Fairplay mine, 85 

 feet in depth, following down a clay seam between well defined walls of 

 limestone. It carries a good deal of galena. The White Rose mine closely 

 resembles the Fairplay and lies in nearly the same geological horizon. 



Crossing to the Mahogany Hills, on the opposite or west side of the 

 Eureka Mountains, we find mining propei-ties on the southeast side of 

 Brush Peak at localities designated as the Mountain Boy and Kentuck mines. 

 They show that mineral matter was de})osited under geological conditions 

 similar to those found elsewliere. Again, at the head of Browns Canyon 

 there is a very decided break in the limestone, accompained by a sharp 

 anticlinal fold, along the axis of which occurs an outflow of rhyolite pre- 

 senting geological conditions that might readily lead one to look for ore. 

 Indications of mineral deposits were found at the surface sufficient to war- 

 rant mining exploration, and an ore channel followed for considerable 

 distance into the limestone. A stud}' of the geological position of these 

 different ore bodies makes it clear that thej^ occur throughout the Nevada 

 limestone, being foimd near the base of the epoch and again not far below 

 the suimnit. With the coming in of the White Pine shales all the charac- 

 teristic oxidized and imoxidized ores of the district cease, and they tail to 

 reappear in any of the higher geological horizons. 



No Ores in the Carboniferous.— Nowliere witlliu tllC district liave OrCS been 



recognized in any of the grand divisions of Carboniferous time. In the 

 Diamond Range northward and westward of Newark Mountain the strata 

 seem to ))e entirely free from mineral matter. It is possiljle that mining claims 

 may have been recorded along some superficial outcrop or some segregation 

 of mineral matter, but these are so obscure and unpromising and usually 



