By A. H. KOSCHMANN and M. H. BERGENDAHL - USGS 1968
For many years gold was California's most valuable mineral commodity, and even today despite high mining costs and a fixed selling price, gold ranks fourth in the value of mineral commodities in the State. The total amount of gold production reported in California from 1848 through 1965 was 106,130,214 ounces: about 68,200,000 ounces placer and about 37,900,000 ounces lode and byproduct gold.
The discovery of gold in California usually is attributed to James W. Marshall, whose highly publicized placer discovery, on the American River in El Dorado County in 1848, led to the gold rush of 1849. But long before Marshall's discovery, as early as 1775, Mexicans mined small amounts of placer gold from the Colorado River and lode gold from the Cargo Muchacho Mountains (Clark, 1957, p. 223), and in the 1830's gold was discovered in Los Angeles County. These early operations were in remote, sparsely settled areas under the control of Mexico and were far from any lines of communication; thus the news did not spread.
The early placer operations, 1848-49, were small scale, the deposits were quickly depleted, and attention soon was directed to the large deposits of gold-bearing gravels of Tertiary age. In 1852 large-scale hydraulic mining began on these deposits, which for many years were the main source of the State's gold production (fig. 8). These operations were so large they caused heavy silting of navigable stream channels, partial blockage of tributary streams, and ruination of agricultural lands by debris-laden streams during spring floods. This silting even caused the Golden Gate bar in San Francisco Bay to move inshore. Beginning in 1884, court actions brought against the miners to curtail this devastation culminated in the passage by Congress of the California Debris Commission Act (or Caminetti Act) in 1893. As a result, the cost of constructing required debris dams and settling basins caused many operators to abandon large-scale hydraulic mining in favor of drift mining of the buried Tertiary channel gravels.
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