No joke! Up to 350 kg heavy rock blocks slide in a dry lake in the west of Death Valley National Park in the United States without the help of any human beings or animals and sometimes even against the very low gradient, ie upwards. The cause of this movement remains unknown, but the tracks in the desert sands are clear and real.
This phenomenon was discovered in the 1900’s and was at this time linked to magnetic forces. Now researchers believe the movement of these stones is possible when the lake bed (very fine clay) is weaken by rain and strong winds blow. Since no one have ever seen these stones moving, it remains an unexplained phenomenon.
[…] The playa fills with water, which must be deep enough to form floating ice during cold winter nights, but shallow enough to expose the rocks. Temperatures plummet at night, and the lake freezes to form thin sheets of ice, which must be thin enough to move freely but thick enough to maintain strength. When it warms up, the ice melts and break up into large floating panels, which light winds drive across the playa, pushing rocks in front of them and leaving trails in the soft mud below the surface. (Source | Photo) […]
But the bigger mystery of this phenomenon, why never installated move detecting camera…