The origin of California’s gold

Millions of years ago, underneath today’s California, molten hot magma containing a large amount of gold forced its way toward the surface through fissures in the hard quartz rock, cooling before it spewed out in a volcanic eruption. In some places earth’s tectonic plates folded up one over another along California’s coast, grinding the gold bearing quartz into gravel. The early miners who found these deposits thought they were the remains of ancient riverbeds still filled with gold. Elsewhere gold was uncovered still embedded in the quartz rock, and these underground veins, often running for many miles beneath the surface, were the real treasure of the gold rush.

All these gold bearing lodes tended to run north to south while the rivers of the gold country ran east to west, from high in the Sierra Nevada Mountains to the Sacramento and San Joaquin Rivers in the valley below. Over untold eons some of the buried gold deposits became exposed, erosion then broke apart the rock and the gold washed downhill into the rivers that cut through them. There the heavy gold settled in sandbars anywhere the flow of the water slowed. These deposits were known as placer gold, the easiest gold to mine. The vast abundance of placer deposits discovered in 1848, laying in a hundred mile wide belt of the Sierra foothills that ran from Mt. Shasta in the north to Mt. Whitney in the south, was a major impetus for the California Gold Rush.

 

Comments

  1. I find this subject fascinating. In Colorado and the Cripple Creek area, the last gold strike in the lower 48, the volcano that created this gold deposited it in the granite. When I wrote the paper on this story, I found that fascinating. They are still mining ‘battle mountain’ to this day, in a huge open pit mine. (A fascinating story in itself).

    • I think that most all gold has something to do with volcanic activity but my impression of California’s deposits centers more around the tectonic activity that happened here over millions of years as the earth folded and cracked and push up the Sierra Nevada mountains. But volcanoes are all around. Mt. Shasta sits at the north end of the major gold finds and there are at least two huge lava beds here, both with large deposits of gold under them, that came from volcanic activity. Thanks for your comments. I’d like to see that paper on Cripple Creek.

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