Archaeologists recently stumbled upon a set of mysterious "ghost footprints" in the salt flats of a Utah desert. These unusual ancient tracks get their eerie name not because they are from an ethereal realm, but due to their earthly composition: They become visible only after it rains and the footprints fill with moisture and become darker in color, before disappearing again after they dry out in the sun.
Researchers accidentally discovered the unusual impressions in early July as they drove to another nearby archaeological site at Hill Air Force Base in Utah's Great Salt Lake Desert. The team initially only found a handful of footprints, but a thorough sweep of the surrounding area using ground-penetrating radar (GPR) revealed at least 88 individual footprints belonging to a range of adults and children, potentially as young as 5 years old. (The GPR technique works by firing radio waves into the ground that bounce off objects that are hidden under the surface.)
The ghostly prints were left by bare human feet at least 10,000 years ago when the area was still a vast wetland. However, researchers suspect that the tracks could date back as far as 12,000 years ago during the final stretch of the last ice age during the Pleistocene epoch (2.6 million to 11,700 years ago).
