Share This Page

Death Valley 'sailing rocks' linked to freeze-warm cycle

| Thursday, Aug. 28, 2014, 9:27 p.m.

DEATH VALLEY NATIONAL PARK, Calif. — Scientists for years have theorized about how large rocks — some weighing hundreds of pounds — zigzag across Racetrack Playa in Death Valley National Park, leaving long trails etched in the earth.

Two researchers at Scripps Institution of Oceanography at the University of California-San Diego, have photographed the “sailing rocks” being blown by light winds across the former lake bed.

Cousins Richard Norris and James Norris said the movement is made possible when ice sheets formed in the rising sun, making the hard ground muddy and slick.

On Dec. 20, 2013, the cousins catalogued 60 rocks moving across the playa's pancake-flat surface.

“Observed rock movement occurred on sunny, clear days, following nights of sub-freezing temperatures,” they wrote in a report published on Wednesday in the online scientific journal PLOS ONE.

The conclusion proves theories that have been floated since geologists began studying the moving rocks in the 1940s.

The phenomenon doesn't happen often because it rarely rains in the notoriously hot and dry desert valley.

The rocks move about 15 feet per minute, according to the report.

Richard Norris, 55, a paleobiologist at Scripps, and James, 59, a research engineer, launched their “Slithering Stones Research Initiative” in 2011, the Los Angeles Times reported.

After getting permits from the National Park Service, they installed a weather station in the area and placed 15 stones equipped with global positioning devices on the playa.

The “GPS stones,” which were engineered to record movement and velocity, were stationed at the southern end of the playa, where rocks begin their strange journeys after tumbling down a cliff.

At the end of last year, Richard and James Norris returned to inspect the instruments.

“We found the playa covered with ice,” Richard told the Times. “We also noticed fresh rock trails near shards of thin ice stacked up along the shoreline.”

The following afternoon, “we were sitting on a mountainside and admiring the view when a light wind kicked up and the ice started cracking,” he said. “Suddenly, the whole process unfolded before our eyes.”

TribLIVE commenting policy

You are solely responsible for your comments and by using TribLive.com you agree to our Terms of Service.

We moderate comments. Our goal is to provide substantive commentary for a general readership. By screening submissions, we provide a space where readers can share intelligent and informed commentary that enhances the quality of our news and information.

While most comments will be posted if they are on-topic and not abusive, moderating decisions are subjective. We will make them as carefully and consistently as we can. Because of the volume of reader comments, we cannot review individual moderation decisions with readers.

We value thoughtful comments representing a range of views that make their point quickly and politely. We make an effort to protect discussions from repeated comments either by the same reader or different readers

We follow the same standards for taste as the daily newspaper. A few things we won't tolerate: personal attacks, obscenity, vulgarity, profanity (including expletives and letters followed by dashes), commercial promotion, impersonations, incoherence, proselytizing and SHOUTING. Don't include URLs to Web sites.

We do not edit comments. They are either approved or deleted. We reserve the right to edit a comment that is quoted or excerpted in an article. In this case, we may fix spelling and punctuation.

We welcome strong opinions and criticism of our work, but we don't want comments to become bogged down with discussions of our policies and we will moderate accordingly.

We appreciate it when readers and people quoted in articles or blog posts point out errors of fact or emphasis and will investigate all assertions. But these suggestions should be sent via e-mail. To avoid distracting other readers, we won't publish comments that suggest a correction. Instead, corrections will be made in a blog post or in an article.