Curious what results would pop up on Google Image for a search on “rocks” resulted in my confrontation with the sliding rocks of Racetrack Playa in Death Valley National Park. Geology.com has a great write-up of this phenomenon (also of which the image above can be attributed).
Rocks weighing several hundred pounds slide across the desert floor on their own accord with no human or animal intervention. No one knows for sure how this happens. The two most popular theories involve wind and ice.
This natural occurrence is absolutely fascinating.