Racetrack Playa’s “Sailing Stones”
During heavy rains, water washes down from the surrounding mountains draining into the playa, forming a shallow, short-lived lake. Under the hot desert sun, the thin veneer of water quickly evaporates, leaving behind a surface layer of soft, slick mud.
The sailing stones are thought to be pushed along the playa’s muddy surface by strong winter winds (more than 90 mph), once it has rained enough to fill the playa with just enough water to make the clay slippery.
Slabs of rock ranging from a few hundred grams to hundreds of kilograms inscribe visible tracks as they slide along the playa surface. Stones with round bottoms (like that in the photo) tend to wander about, leaving distinctive zig-zag patterns when the mud finally dries. These linear scars can last for several years since rainfall is so scarce on the playa.