Image Gallery: How Ice Drives Death Valley's Sailing Stones

Natural mystery

Racetrack Playa

(Image credit: Mike Hartmann)

In Death Valley's Racetrack Playa, rocks seem to slide across the flat lakebed under their own power. Now, scientists have solved the mystery.

Geologic puzzle

rov-rocktrail-100820-02

(Image credit: NASA/GSFC/Cynthia Cheung.)

The trails are the only evidence the rocks move. Some stretch twice the length of a football field

On the playa

Racetrack Playa rock trails

(Image credit: Richard Norris)

Biologist Richard Norris stands next to a Racetrack Playa rock trail that may have formed in the late 1990s.

The testing ground

Racetrack Playa moving rock

(Image credit: Richard Norris)

A boulder brought in to Racetrack Playa to study its sailing stones. Engineer Jim Norris of Interwoof built the custom GPS unit.

Look closely

Racetrack Playa moving rock

(Image credit: Jim Norris)

The rock on the left side of the photograph is about to move, bulldozed by ice.

There, it moved!

Racetrack Playa moving rock

(Image credit: Jim Norris)

In this photograph, the small white rock has shifted from the left to the right.

Racing rocks

Racetrack Playa rock trails

(Image credit: Jim Norris)

Researchers saw rocks sail across Racetrack Playa and set fresh trails, shown here.

On thin ice

Racetrack Playa ice

(Image credit: Richard Norris)

An thin shard of ice from Racetrack Playa's pond, collected Dec. 20, 2013.

Frozen wonder

Racetrack Playa rock trails

(Image credit: Mike Hartmann)

A GPS-mounted boulder leaves a trail on Racetrack Playa

New tracks

Racetrack Playa rock trails

(Image credit: Jim Norris)

Parallel trails carved in the wet playa mud.