What Are Sailing Stones?

Imagine this: You’re walking through Death Valley, the hottest place on Earth. You come across tracks in the sand. But these tracks are not ordinary. Instead of footprints or paw prints, you’re following a single, long line. What could create a track like this? A snake? A person on a unicycle? You continue walking, and eventually, you reach the end of the line. And there it is, the object that caused this track. It’s… a rock?

You’ve discovered a sailing stone! These stones have only been found in Racetrack Playa, which used to be a lake. That changed due to significant climate change that occurred over 10,000 years ago. This resulted in the complete evaporation of the entire lake, leaving behind a layer of light brown mud that is over 1,000 feet thick.

Currently, Racetrack Playa receives only about one to two inches of rainfall each year. This dry and extremely hot environment is one of the most inhospitable places on Earth. Footprints left on the playa can persist for many years before they are erased by enough moisture and wind.

The erosion of the surrounding mountains causes rocks of various sizes to tumble onto the surface of Racetrack Playa. For many years, visitors to Racetrack Playa have observed that these rocks appear to have moved on their own. Clear tracks left behind the rocks showed that some of them had moved up to 1,500 feet. Since there were no footprints nearby, these rocks – the sailing stones – were somehow moving by themselves.

But how is that possible? Rocks don’t have legs. Have you ever seen a rock move by itself? Certainly not! The sailing stones of Racetrack Playa puzzled scientists. There were certainly plenty of theories. From extraterrestrial beings to some sort of strange magnetic effect, none of these theories could ever be substantiated with physical evidence.

Scientists who studied the rocks noticed that not all of them moved. The ones that did move only did so every two or three years. Adding to the complexity was the fact that the stones never moved simultaneously or in the same direction. What is happening at Racetrack Playa?

Recently, scientists used time-lapse photography, motion-activated GPS receivers, and a great deal of patience to unravel the mystery. They discovered that the movement of the stones is caused by a unique combination of water, ice, and wind.

When the playa fills with water after rainfall or snowmelt from nearby mountains, thin layers of floating ice can form during cold winter nights. As the temperatures rise throughout the day, the sheets of ice begin to melt and break into large, jagged pieces of ice that resemble shattered windows.

These sheets of ice can be easily pushed across the slippery, wet mud by even gentle breezes. As they glide across the playa, they push the rocks in front of them. The rocks leave trails in the mud as they move. When the ice melts and the playa dries up, all that remains visible are the rocks and the evidence of how far they have traveled.

The mystery may have been solved, but the sailing stones continue to captivate many people. Would you like to visit Racetrack Playa to search for sailing stones one day? Perhaps you’ll witness one in motion!

Give It a Try

Are you prepared to explore Death Valley National Park? Make sure to participate in the following activities accompanied by a friend or family member:

  • Interested in witnessing the movement of the sailing stones at Racetrack Playa? Go online and watch this time-lapse video capturing the stones in motion. What are your thoughts? Would you have ever imagined that water, ice, and wind could result in such a phenomenon? Share this video with a friend or family member and explain how the stones are able to move.
  • Curious about the geology of deserts? Learn more from OneGeology! What new information did you discover about deserts? Summarize your findings for a friend or family member.
  • Would you like to virtually visit Death Valley? Immerse yourself in the experience with these pictures. Which sight in Death Valley would you be most excited to see? Write a paragraph explaining your choice.

Sources of Wonder

  • http://www.livescience.com/45876-sailing-stones.html (accessed on Sept. 06, 2020)
  • https://www.nps.gov/deva/planyourvisit/the-racetrack.htm (accessed on Sept. 06, 2020)
  • http://www.nationalparks.org/connect/blog/sailing-stones-death-valley (accessed on Sept. 06, 2020)

FAQ

1. What are sailing stones?

Sailing stones, also known as sliding rocks or moving rocks, are a natural phenomenon that occurs in certain desert areas. These rocks seem to move across the desert floor, leaving long tracks behind them, without any apparent human or animal intervention.

2. How do sailing stones move?

The exact mechanism behind the movement of sailing stones is still not completely understood, but there are a few theories. One popular theory suggests that a combination of wind, ice, and a slippery surface allows the rocks to move. During cold winter nights, water on the desert floor freezes, creating a thin layer of ice. When the wind blows, it pushes the ice and rocks, causing them to slide or sail across the desert.

3. Where can sailing stones be found?

Sailing stones can be found in a few specific locations around the world, most notably in Death Valley National Park in California, USA, and the Racetrack Playa within the park. Other locations include the Little Bonnie Claire Playa in Nevada, USA, and the Llano de Ucanca in Tenerife, Spain.

4. Are there any famous sailing stones?

One of the most famous sailing stones is the “Racetrack Playa Grandstand” stone in Death Valley National Park. This particular rock has left a distinct track behind it, attracting the attention of many visitors. It is estimated that this rock weighs around 700 pounds and has moved several times throughout the years. The movement of this rock, along with others in the area, continues to intrigue scientists and visitors alike.

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