172 



GUIDEBOOK OF THE WESTERIC UNITED STATES. 



Golconda, another old stage station, is a warm-spring resort and a 

 supply point for numerous mining camps. In 1897 a smelter and a 



concentration miU were built at Golconda to treat 

 the copper ores from the Adelaide mine ^ about 12 

 miles to the south. The ore proved difficult to treat, 

 and the mill, in which several processes were tried, 



Golconda. 



Elevation 4,389 feet. 

 Population 430 * 

 Omaha 1,349 miles. 



is no longer used. 



It stands north of the track. The 

 Pequart imne, an early producer, is about 6 miles south of Golconda, 

 and there is a prold mine in the lone conical hill about 2 miles south of 



Ranches stretch along the river below Golconda, 



The 



the station. 



crops raised are alfaKa, native hay, and potatoes. 



The elevation of Golconda is almost exactly that of the highest 

 level attained by Lake Lahontan,^ already referred to as having 

 spread over a large part of northwestern Nevada. The history of this 

 great kike is analogous to that of Lake Bonneville, in Utah, already 

 described (pp. 97-99 and fig. 10, p. 82). 



The Overland lioute passes across the basin of Lake Lahontan at 

 what is nearly its ^^adest part. For 177 miles from a point in the 

 Humboldt River valley near Golconda to a point in Truckee Canyon 

 about 15 miles beyond Wadsworth or Fernlcy, the train passes over 

 the bed of this extinct lake, and many of the features of the landscape 



^ The Gold Ruu district, in which the 

 most important mine is the Adelaide, is 

 on the east slope of the northern part of 

 the Sonoma Ran^re — -the Ilavallah Range 

 of the Fortieth Parallel Survey reports. 

 The district was orgranized in 1866. 



The ore is a replacement of limestone 

 and contains copper, zinc, and a little 

 lead {pyrrhotite, chalcopyrite, sphalerite, 

 and *ralena with ganiet, pyroxene, etc.). 

 The general country rock is dark calca- 

 reous slate (Star Peak) of Triassic age, 



^ Tiio IsLTge lake which flooded a num- 

 ber of the valleys of northwestern Nevada 

 at a ver>- recent geologic date but has now 

 passed away was named Lake Lahontan in 

 honor of Baron La Hontan, one of the 

 early explorers of the headwaters of the 

 Missis::ippi. The 



le lake 

 uare mi 



expansion, and in its deepest part, the 

 present site of Pyramid Lake, it was at 

 least 880 feet deep— that is, its surface 

 sto<^d approximately 500 feet above the 

 present water surface of Pyramid Lake. 

 The ancient lake had no outlet exrpnt tliA 



itraight 



evaporati 



Fluctuations of the water level in these 

 ancient lakes undoubtedly record cli- 

 matic changes. It has been generally 

 concluded that the periods of lake expan- 

 sion were related to the stages cf ice 

 extension in the glacial epoch, or more 

 specifically that their waters rose to their 

 highest levels during the period when 

 the glaciers were retreating from their 

 farthest advance. 



With the decrease of water supply the 

 lake level has fallen, and in many parts 

 of the basin the water has almost or en- 

 tirely disappeared. Traces of former 

 levels remain, however, in the form of 

 elevated beaches. As the lake fell, 

 ridges emei^ed and separated it into 

 smaller units. Some of these minor 

 basins are now essentially dry, althoiigh 

 the lowest parts are periodically Hooded 

 to shallow depths during rains. When 

 these areas dry up they show almost level 

 floors with smooth mud surfaces, which 

 check or crack in the dry air. These are 

 the so-called mud lakes or playas, wliich 

 are in some basins very extensive. The 

 basins that are still fed by perennial 

 streams contain lakes. 



