While driving to an archaeological dig site on an Air Force base in Utah, Cornell researcher Thomas Urban looked out his window and noticed a handful of tracks on the ground outside. He and his colleague, archaeologist Daron Duke, stopped the truck for a closer look, and discovered what appeared to be bare human footprints preserved in the desert salt flat.
“When I spotted them from the moving vehicle, I didn’t know they were human,” Urban, a research scientist with the Cornell Tree-Ring Laboratory, tells the New York Times’ Jeanne Timmons. “I did know they were footprints, however, because they were in an evenly spaced, alternating sequence—a track pattern.”
Urban had recently studied ancient human “ghost tracks”—or prints that appear when moisture conditions are exactly right and disappear again in the sun—in New Mexico’s White Sands National Park. With a team of researchers, he helped develop techniques for recording prints with ground-penetrating radar (GPR), per an Air Force statement.
With expertise in uncovering hidden tracks, the researchers returned the next day to see if they could conduct a GPR survey to find more than the few prints they’d seen before.
“As was the case at White Sands, the visible ghost tracks were just part of the story,” Urban says in a Cornell statement. “We detected many more invisible prints by radar.” Altogether, they discovered a total of 88 individual footprints from both adults and children.
The find was surprising; humans haven’t lived in this area for thousands of years, per the Times, and it’s a remote desert military training site. The scientists concluded that the “most logical explanation” is that the footprints were made around 12,000 years ago, during the late Pleistocene, Urban tells the newspaper.
Utah’s Great Salt Lake Desert was once filled with water similar to the nearby Great Salt Lake. Toward the end of the last ice age, the lake began to dry up, and humans briefly occupied the wetland. During this wetland period, which lasted until about 10,000 years ago, the conditions would have been ideal for the creation of the footprints.
“People appear to have been walking in shallow water, the sand rapidly infilling their print behind them – much as you might experience on a beach – but under the sand was a layer of mud that kept the print intact after infilling,” Duke, who's an archaeologist for the Far Western Anthropological Research Group, explains in a statement.
The research team is now confirming the footprints’ date and analyzing them for more clues about the people who left them and the lives they lived. Their discovery suggests that other hidden pieces of history may be waiting to be found across the western U.S.
“We have long wondered whether other sites like White Sands were out there, and whether ground-penetrating radar would be effective for imaging footprints at locations other than White Sands, since it was a very novel application of the technology,” Urban tells Cornell. “The answer to both questions is ‘yes.’”