The stones of Death Valley move on their own. A few of the sailing stones are as heavy as 80 pounds. Some stones have moved as far as 659 feet in a single winter, leaving long trails behind them. Some do not move at all for up to 4 years.
No one knows why the sailing stones move. Racetrack Playa, the home of the sailing stones, seems to be a dry lake bed like any other. The dried mud left behind after the lake dried is thought to be at least 1,000 feet thick. The stones leave long, shallow trails on top of that dried mud. Many of those trails are less than an inch deep.
Stones which are rough on the bottom leave straight, striated tracks. Those with smooth bottoms leave tracks that are smooth and not so straight. Some stones turn over and start sailing on a different side.
Most of the sliding stones consist of the same dark dolomite as the cliffs to the south of Racetrack Playa. However, when they sail, they do not slide down any slope. The dried lake bed is almost completely flat. There is no slope.
Their paths don't always remain straight. Sometimes a stone will veer without warning. While most tracks are parallel, sometimes one stone will veer away at an angle while the other continues on its straight way. Sometimes the sailing stones of Death Valley will even backtrack. No one knows why.
Many people have studied the sailing stones over the years. Many studies have named or labeled the stones and carefully marked their locations as they moved. In 1948, their positions were marked with stakes. Current studies mark them with GPS tracking. In 1972, Bob Sharp and Dwight Carey even tried to block one of the sailing stones by building a 3-inch corral around it. The corral never even slowed the stone down.
Yet even today, no one has ever seen a sailing stone move. All that can be seen is the trail stretching out behind some of the stones.
Many people have tried to guess what makes the sailing stones of Death Valley move. So far, the best guess has been initiated by John Reid and a team of 6 research students. They found that at least some of the stones of the Racetrack Playa sail on ice floes that could be as much as half a mile wide, in whichever direction the wind comes from that winter
The motive forces behind the other sailing stones of Racetrack Playa continue to be a complete mystery. Death Valley holds many secrets yet to be uncovered.