When you visit the White Sands National Monument in New Mexico, you will see endless waves of vibrant gypsum. It's beautiful, but a team of researchers led by Cornell University scientists were more interested in what was hidden in the sand.
The team uses ground penetrating radar, which was used to detect more rocks near Stonehenge, to study the movements of mammoths, humans and giant sloths from 12,000 years ago. Usually these songs are visible unless the conditions are perfect. Researchers call them "ghost tracks".
Scientists have published a paper, "The 3-D radar image unlocks unused behavioral and biomechanical archives of Pleistocene ghost tracks," in the journal Scientific Reports on Monday.
"We never intended to look under the footprints," says lead author Thomas Urban in a Cornell edition. "But it turns out that the sludge itself has a memory that captures the effects of animal weight and inertia in a beautiful way. This gives us a way to understand the biomechanics of extinct fauna we've never had before."
The radar revealed a captivating scene from the past, consisting of a double path of human footprints extending over 2,600 feet (800 meters). It showed the movements of what probably one person goes one way and then returns about the same way. Mammoth traces pass over human traces.
One of the mammoth tracks is special. It shows where a person steps later on the runway, leaving behind a print. This gives researchers a rare glimpse into how humans and the mega-fauna may have interacted over all those years.
This study shows how radar-penetrating radar can reveal hidden secrets from the past, even those that are as fine as footprints. "The technique could probably be applied to many other fossil footprint sites around the world, potentially including dinosaurs," says Urban.