Some 400 million years ago, California lay at the bottom of a large sea; underwater volcanoes deposited lava and minerals (including gold) onto the sea floor.  Eventually these golden deposits in the sea floor, forced by tectonic pressure, became buried under the land mass of North America among a molten mass of magma.  The magma forced its way upward, carrying mineral deposits of gold and quartz to the surface of the Sierra-Nevada mountains. The deposits were washed down the mountainsides in a process of erosion.  Streams flowed carrying that gold into the hands of human beings...