Death Valley National Park attracts nearly one million visitors per year with its low elevations and sizzling temperatures. But for others, the draw is something much stranger -- large stones that seem to move across the desert on their own.

Since the 1900s, the sailing stones on Racetrack Playa have baffled scientists and visitors alike. They’ve never been recorded in motion, but the long trails behind them indicate that this is no myth.

So how could these rocks, which range from a few ounces to hundreds of pounds, drift by themselves?

In winter 2014, scientists were able to capture the movement of the stones using time-lapse photography. They observed rain form a thin pond under the rocks at night. When the pond thawed in the morning, the rocks were pushed forward by small pieces of ice and wind. This process repeated causes the rocks to move thousands of feet overtime.

According to the National Park Service, the rocks are made of dolomite and syenite, the same materials that make up the surrounding mountains. Rocks with a rough-bottomed surface leave straight tracks, while smooth-bottomed rocks curve around.

The sailing stones are one of the most fascinating mysteries of Death Valley. You'll have to visit to find out what other secrets lay within park grounds.

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