Moving Rocks of Racetrack Playa

About the Moving Rocks of Racetrack

Out on Racetrack Playa, there are scattered rocks. They look oddly out of place, as though carried there by some unseen hand, but the trails left behind them tell a different story. Somehow these rocks, many quite large, have moved across the dry lake bed.

Get this image now

You can buy this image right now

You can buy this image right now

You can buy this image right now

You can buy this image right now

About Racetrack Playa

A playa is a dry lakebed. Racetrack Playa is a cream-colored playa or dry lakebed surrounded by mountains in a little valley near Death Valley, California. It is the playa that the sliding stones move across.

You can buy this image right now

Picture from kittell

You can buy this image right now

What Causes the Moving Rocks?

No one is quite certain what causes the sliding rocks of Racetrack Playa to move. There are many guesses, but most authorities on the subject agree that it has something to do with the playa surface when exposed to water, and extreme winds that go through the area occasionally.

The moving rocks need water. Since the surface of the playa is made up of fine, dry clay, when it is exposed to water each individual soil molecule is encased by water, allowing them to move against each other with very little friction. If you've ever stepped on wet clay, you may have experienced this slipperiness by falling on your butt trying to stand on the stuff. Now obviously, it takes certain amounts of water for the exact right slipperiness. Too little rain falling on the dry playa surface, and it won't get very wet. Too much rain and the water will pool up on the clay's surface. But, if just the right amount of rain falls the clay will get just the right amount of wet and perhaps be slippery enough for the rocks to slide across the surface with the right push.

The moving rocks need wind. Because of the shape of the valley where Racetrack Playa is located, it can act as a funnel and aim the winds that rush through straight at the playa. Deserts can have some extreme winds since they have little vegetation to slow it down, and the Death Valley area is no exception.

The theory is that in the right conditions, enough rain and enough wind, the slickened surface of the playa allows the rocks to slide across it when propelled by the winds.

The moving rocks may need ice. Another part of the premise is that ice may be involved. This is highly debated though. Many people think the surface area of the rocks is not enough to be propelled by the wind, unless it is distributed over a wider area than the base of the rocks themselves. They theorize that the rocks may be surrounded by ice, forming little ice rafts, and that this spreads out the weight over a wider area, allowing the wind to be able to propel them along. Ice does in fact form in the area though it is the hottest place in the continental US during the summer, but many debate whether the ice is in fact necessary.

You can buy this image right now

Visiting Racetrack Playa

Picture from Tommy Ironic

The road to Racetrack Playa is not to be undertaken lightly. It is 27 miles of washboard dirt road that can cause extreme mechanical difficulties, in a place with little cell phone service, in place where even AAA isn't in a hurry to come rescue you. A high-clearance vehicle is recommended, as well as a vehicle in good working order. It's a good idea to have at least some of the following with you:

At least one spare tire, but two is better
Fix-a-flat
Tire patch kit
Air pump
Lots of extra water
Radiator sealer
Tool kit
Extra Gas

Plenty of warm blankets
Extra food

Picture from TranceMist

You can buy this image right now

You can buy this image right now