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Moving stones
id: 10043480

Most of the sliding stones fall to the bottom of the dry lake from a 260 m high dolomite hill located at the southern end of Racetrack Playa. The mass of stones reaches several hundred kilograms. The tracks trailing behind them are several tens of meters long, 8 to 30 cm wide, and less than 2.5 cm deep. Stones move only once every two or three years, and most of the traces remain for 3-4 years. Stones with a ribbed bottom leave more direct marks, while stones lying on the flat side wander from side to side. Sometimes the stones turn over, which is reflected in the size of their footprint.
Until the beginning of the 20th century, the phenomenon was explained by supernatural forces, then during the formation of electromagnetism, an assumption arose about the effects of magnetic fields, which did not explain anything. In 1948, geologists mapped the location of the rocks and marked their tracks. A little later, the US National Park Service compiled a detailed description of the site and Life magazine published photos from Racetrack Playa, after which attempts began to explain the movement of stones. Most hypotheses agreed that the wind at the wet surface of the lake bottom at least partly explains the phenomenon. In 1955, geologist George Stanley of the University of Michigan published a paper arguing that the rocks were too heavy for the local wind to move. He and his co-author proposed a theory according to which, during the seasonal flooding of a dried-up lake, an ice crust forms on the water, which contributes to the movement of stones.

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