THE DECREASE OF GOLD. 509 



brought to bear for obtaining it. Volcanic forces have brought gold 

 as well as silver to the surface in the Rocky Mountains, but its exhaus- 

 tion is approaching rapidly. Montana, in 1860, produced $18,000,000, 

 while to-day its yield is $2,500,000 ; Idaho, from 18G4 to 1871, yielded 

 from $5,000,000 to $7,000,000, which in the year 1880 has decreased 

 to $1,510,546 ; Oregon and Washington yielded, in the year 1868, 

 $4,000,000 ; in 1879, not more than $1,275,000 ; Dakota has increased 

 a little, and produced $2,420,000 in 1879 ; Colorado has an average 

 yield of $3,000,000 ; California has passed through the several stages 

 of a gold-producing country ; the washing of the river-sands, after 

 1848, produced immense wealth, while at present only the Chinese 

 are engaged in it, and earn a bare living. The gold on the surface is 

 exhausted, and only the deep deposits and the veins remain to be 

 worked. 



It has been estimated that $1,200,000,000 of gold and silver have 

 been mined in the West of the United States within the last thirty 

 years ; and that, in spite of the recklessness and extravagance which 

 characterized the two decades from 1849 to 1869, a net profit of $30,- 

 000,000 per year was realized. Since 1850, the money invested and 

 the labor expended in mining in the West for precious metals are esti- 

 mated at $710,000,000. What may fairly be called the mining terri- 

 tory of the United States embraces an area of 1,190,000 square miles, 

 with a population of barely 1,500,000. 



The entire ridge of the Sierra Nevada consists of granite ; but on 

 the western slope limestone is found mixed with it. Where these two 

 rocks come together, a belt from eight to nine miles wide, and running 

 from north to south, is found,, which contains all the gold leads of the 

 district. The " Mother lode " commences at Mariposa, passes through 

 the northern boundary of the State, and is covered by the lava of the 

 large (not yet extinguished) volcanoes Pilot Peak and Lossan Peak 

 farther north. This lava also covers an old alluvial bottom with 

 overlying layers of basalt from fifty to two hundred feet thick, and 

 these form the so-called " Table Mountains." We find the same for- 

 mation south of the Sierra Nevada, near the " Big Trees," where the 

 sedimentary deposits, lying upon granite, are covered with basalt. 

 From here the auriferous sand was washed away by mountain-streams, 

 and appeared on the surface. These deep deposits, in connection with 

 the offshoots of the Mother lode, still sustain the gold production of 

 California at from fifteen to seventeen million dollars. 



In Nevada was discovered the Comstock lode, for a long time held 

 to be inexhaustible, and this is also covered with later volcanic for- 

 mation. The largest of these bonanzas is the Gold Hill mine, which 

 lies 700 feet deep, and several companies have commenced to work 

 this rich vein. The most important, the Virginia Consolidated, has 

 sunk a shaft 1,600 feet deep, and driven a tunnel of 20,000 feet in 

 length through the side of the mountain, projected by Engineer Sutro, 



