Calaveras Skull

On February 25, 1866, miners claimed to have found a human skull in a mine, beneath a layer of lava, 130 feet (40 m) below the surface of the earth.

After careful study, he officially announced its discovery at a meeting of the California Academy of Sciences on July 16, 1866, declaring it evidence of the existence of Pliocene age man in North America, which would make it the oldest known record of humans on the continent.

[3] Thomas Wilson of Harvard ran a fluorine analysis on it in 1879 (the first ever usage of such on human bone), with the results indicating it was of recent origin.

[4] It was so widely believed to be a hoax that Bret Harte famously wrote a satirical poem called "To the Pliocene Skull" in 1899.

While there, he heard a story that in 1865 one of a number of Indian skulls had been dug up from a nearby burial site and planted in the mine specifically for miners to find.