The Racetrack is a dry lakebed playa that is known for its unique geologic features and "moving rocks" phenomenon. Ten thousand years ago this area was a large lake, but climate changed over time and the water dried up and left the cracked, muddy lakebed.
On the surface, trails from rocks (some weighing hundreds of pounds) can be seen in the dried, cracked mud. The moving rocks are unique to the Racetrack and were once a mystery. A longtime theory suggested it was a combination of rain and high winds that pushed the rocks. With just enough rain the surface could become slippery and strong winds could push the rocks across the mud.
In 2013 a researcher was lucky enough to actually observe the rocks moving! Observers found that overnight temperatures periodically drop low enough to cause rain water to freeze. On a sunny day, a thin ice sheet can heat up and start to break apart into large floating pieces that the wind pushes like a sail over the muddy terrain, leaving the trails. Mystery solved? Perhaps, but either way, this unusual and interesting site is worth the long (and rough!) drive to see in person.
The playa itself is about 2 miles wide and 3 miles long. In the middle is the Grandstand, an outcropping of rock that provides great views. Most of the rocks can be seen at the southern end of the playa. As you’re exploring the area, keep an eye out for wildlife tracks in the dried mud, and be sure to bring plenty of water and sunscreen.
Note that the road to reach the playa can be rough and requires high-clearance vehicles with four-wheel drive. Also, help protect the area by staying off of the mud when it’s wet and by leaving the rocks behind.