Archaeologists have recently stumbled upon many "ghost footprints" in the desert of Utah, where these unusual ancient footprints have received their strange name because they become visible only after the rain and then disappear again under the influence of sunlight.
Researchers accidentally stumbled upon a handful of tracks in early July during a visit to another archaeological site in the Great Salt Lake desert in Utah, intrigued, they scanned the area using a georadar, detecting at least 88 separate traces.
Initial analysis suggests that these traces were left in the ground by adults and children at least 10,000 years ago, but they may be even older; a few years ago, a research team found the remains of a hunter camp, which was 12000 years old, a few kilometres away.
The area where these fingerprints were found was once covered by a large salty lake, and during the last ice age, the lake slowly dried up, leaving behind only dissolved salts in the water. Some 10,000 years ago, people could take the place for a short time while the transition was taking place, taking advantage of the environmental moisture.
How can we explain the appearance and disappearance of these tracks?
According to researchers, the conditions were perfect for creating this type of footprint.", explains Daron Duke, an archaeologist from the Far West Anthropological Research Group. "The sand was also a layer of dirt that could keep these tracks intact despite filling. Since then, they have been filled with salt as the marshes dry, making them indistinguishable from the surrounding landscape in a dry state.
Usually, when it rains, the water quickly absorbs into the sediment, which means that the soil quickly returns to its normal color. In this case, the mud layer helps to capture the water, eventually discovering invisible traces.
Note that this discovery has not yet been published in the peer-reviewed journal because the work is still under way. Researchers have collected several such prints. Organic residues may have been held in sediment by those who left them. If so, researchers will be able to conduct a radiocarbon date to determine their exact age.