They have been called “sailing stones,” heavy, monolithic rocks that seemingly move on their own leaving tracks behind. Explanations as to how and why the stones move have ranged from the mundane to the mystical. But, a recent discovery among a dinosaur fossil, may have solved the mystery once and for all.
A team of researchers think they’ve found the earliest example of the rocks that “move on their own,” and dates back millions of years, and it may present the most plausible explanation for the strange phenomenon.
Sailing stones, also known as “sliding rocks,” have baffled geologists because they seemingly move across the desert and leave long tracks without any kind of human or animal intervention.
The dry lake of Racetrack Playa in California’s Death Valley is famous for them. Ice, wind, and even bacteria have been some of the rational explanations offered by scientists who have studied the stones and the trails they leave behind. Some of the more “esoteric” explanations have ranged from shifts in the earth’s magnetic fields, to government experiments with vibrational or harmonic weapons, to the activities of “playful” demons or poltergeists.
Now, researchers think they’ve spotted one of these tracks on a fossil of well-preserved dinosaur footprints that’s 200 million years old, and it may finally prove a long-held theory about what causes the bizarre, seemingly inexplicable movements of the heavy stones.
Paleontologist Paul Olsen of Columbia University and his team recently presented their findings of the long smear mark that can be easily seen amongst the dinosaur footprints, which had not really been focused on before.
This is quite remarkable, being that the fossil in question, has actually been on display since 1896!
The researchers have considered how the sailing stone would have moved amongst the footprints and argued that their findings could be evidence of a brief freezing period during the Early Jurassic. This would fit in with the theory that the stones move when ice is formed if the area they’re in gets flooded.
They are then thought to sail across the ice as it melts, creating a track in the mud that hardens, and remains when the water eventually evaporates.
Microbial mats and wind-generated water waves are also potential reasons for the stones moving, but the researchers ruled these methods out for this particular ancient sailing stone. They concluded that the ice method was more likely because the details preserved in the dinosaur footprint would not have been as intricate if microbes had been involved.
If the researchers are right, then they may have found evidence of drastic climate change or a freak weather event from millions of years ago.
They have even linked it to a mass extinction event caused by volcanic activity that’s thought to have occurred 201.3 million years ago. Olsen said, “This may be evidence of the cooling caused by the volcanic winter.”
The track in the fossil does look very similar to the sailing stone tracks on the Racetrack Playa. There, though no one has ever seen them actually move in person, the trails left behind the stones, and periodic changes in their location, make it clear that they do. Though Death Valley, where the Playa is located, is known to be one of the hottest deserts on Earth, at night the temperatures do drop below freezing, and on the rare occasions that it does rain in the valley, the “ice” theory makes sense for the stones’ movements. Scientists say that in the winter of 2014, rain formed a small pond that froze overnight and thawed the next day, creating a vast sheet of ice that was reduced by midday to only a few millimeters thick. Driven by a light wind, this sheet broke up and accumulated behind the stones, slowly pushing them forward.
But what about the stones that seem to move in areas that are never flooded, or experience freezing?
There, the mystery remains.