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Wind and Deserts
Wind and Deserts-Articles
Roger Weller, geology instructor
by Ben Maheu
Mystery Of Death Valley's Moving Rocks
Formation of Death Valley
Death Valley, CA, was formed by slow changes over time. Rocks dated back to the
Precambrian Era are still visible today. During the Paleozoic Era Death Valley
was covered by the sea. The sea left behind fossil sediment and many different
types of marine life.
The landscape of Death Valley today was formed during the Cenozoic Era. Faults in the earth’s crust created an uplifting action to create the mountain ranges and the lowered valley. Even today Death Valley is still being shaped by eroding mountains, and tremendous rain fall.
For decades moving rocks on the floor of Death Valley have stumped many scientists and visitors. People claimed that the boulders of black dolomite have been moving across the floor because of the trails they left behind.
Until a few years ago there has been no real evidence of moving rocks. People came up with ideas such as: slippery algae, magnetic fields created from earth and gale force winds strong enough to push these boulders across the Valley’s floor.
One strong theory was that the Valley floor would become covered in a thin sheet of ice. This ice would then pick up the boulders and the wind coming off the surrounding mountains would push the boulders along the ice as if the boulder were ice skating. Unfortunately the ice couldn’t pick up the boulders because of their weight. The only things that were sliding across this thin sheet of ice were small pebbles and the scientist.
Solving the mystery with science
In order for scientists to figure out what was really forcing these boulders to
be move, they had to use weather stations, GPS tracking, and a time lapse of
Scientist knew water and wind had to be a factor in moving these boulders. They
knew the ice would have to act as a lubricant reducing the friction, making it
easier for the wind to move the rocks.
For rocks to move every condition must be right. The weather has to
be cold enough to freeze the water on the ground. There has to be rain fall to
create the puddles and thin lake. And the wind has to be strong enough to help
push the rocks along.
All Coming Together
On December 2013 a group of scientist went to Death Valley to do
more studies. What they didn’t know was that they would leave Death Valley with
the answer as to why the rocks where mysteriously moving across the Valley
The night before the team of scientists arrived to Death Valley, there was a small rain storm. Fortunately for the team the weather that night dropped low enough to freeze three to four inches of water on the ground. Death Valley was actually creating a natural ice rink.
When the sun came up in the morning, the warming temperatures started to crack the ice and the rocks became free. The wind off the mountain and the cracking ice were factors in pushing rocks across the ground. “Hundreds of rocks were in motion, Norris said. ‘The ice was just crackling and popping and making all these noises across the playa.’”
The speed the rocks moved was probably close to the speed of cars in LA rush hour. These rocks move a few inches per second. If spectators were too far away from the crawling rocks, they would have never noticed these rocks moving.
Before coming to a halt some rocks could move up to 200 feet across the floor. The team of scientist recorded this event to take place over the span of 16 minutes. This was how the Valley floor was scarred with all the trails created by the rocks moving.
Today’s Technology at Work
After receiving the correct permits from the National Park Service, a team trying to figure out the science behind the moving rock phenomenon, installed a weather station. They placed 15 rocks at the southern end of the Valley where most rocks begin their journey.
These 15 rocks were no ordinary rocks. These rocks were equipped with GPS tracking devices. These devices traced the movement and the velocity (speed) at which these rocks moved.
After a year passed, the rocks did indeed move. They used the information from
the weather station, along with the information from the GPS tracking devices
placed on the rocks, to figure out the speed, distance, and confirming how the
rocks really moved.
Mystery still to be had
Even though the team of scientist figured out how the rocks of black dolomite sailed across the Valley floor. They still have no explanation of how the massive boulders are moving. There are many theories that try to explain the phenomenon but none have been proven.
Extra information can be found here
http://www.basicplanet.com/death-valley-national-park/ (national park)
http://www.ohranger.com/death-valley/geology (formation of Death Valley)
http://news.discovery.com/earth/weather-extreme-events/mystery-of-death-valleys-moving-rocks-solved-1408271.htm (moving rocks)
http://nypost.com/2014/08/29/scientists-solve-the-mystery-of-death-valleys-moving-rocks/ (using technology)