The moving rocks of Racetrack Playa

In the arid desert of Death Valley, there's a flat patch of land where the rocks mysteriously move along the sun-baked ground — with no evidence as to how, or why.

Some of these "sailing stones" weigh hundreds of pounds, and the only evidence that they've moved is a rock-sized trail in the dirt — no footprints to suggest they were pushed by man or beast. The prevailing wisdom says that the wind is to blame, in combination with a frozen layer of water that envelops the rocks.

(Via geology.com)