Flying between Las Vegas and Blythe, Calif., in 1932, pilot George Palmer looked down and got a surprise — a group of enormous figures had been carved into the surface of the Colorado Desert. They had lain there for a thousand years, but they’re so large that no one had noticed them before. (The largest human figure is more than 50 meters long.)

No one knows for certain who created them; altogether there are several dozen figures, most probably representing mythic characters from Yuman cosmology. What else have we been overlooking?