https://www.vice.com/en_us/article/k7bbyw/air-force-discovers-strange-disappearing-ghost-footprints-in-utah-desert

Archaeologists working for the Air Force have uncovered evidence of early human life in the alkali flats on the Utah Test and Training Range (UTTR) in the form of “ghost” footprints that disappear and reappear.

The scientists have uncovered 88 preserved human footprints they believe date back 12,000 years, according to a Cornell University news release. They’re working to confirm the find now and, if the find is genuine, it would be the second discovery of Ice Age era human footprints in the U.S.