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Wind 'can be 10 to 100 times more effective in eroding mountains'


March 29, 2011 - Washington

A new report from a University of Arizona-led research team has revealed that wind is a much more powerful force in the evolution of mountains than previously thought.

Bedrock in Central Asia that would have formed mountains instead was sand-blasted into dust, said lead author Paul Kapp.

"No one had ever thought that wind could be this effective," said Kapp, a UA associate professor of geosciences.

"You won't read in a textbook that wind is a major process in terms of breaking down rock material."

Rivers and glaciers are the textbook examples of forces that wear down mountains and influence their evolution.

Wind can be just as powerful, Kapp said. He and his colleagues estimate wind can be 10 to 100 times more effective in eroding mountains than previously believed.

The geoscientists figured out wind's rock-sculpting abilities by studying gigantic wind-formed ridges of rock called yardangs.

Wind had scoured long gouges out of the bedrock, leaving the keel-shaped ridges behind. Kapp wondered where the missing material was.

The team's initial research was conducted using geological maps of the region and satellite images from Google Earth. Then Kapp and his team went to the Qaidam Basin to collect more information about the yardangs, the history of wind erosion and the dust. What we're proposing is that during the glacials, when it's colder and drier, there's severe wind erosion in the Qaidam basin and the dust gets blown out and deposited downwind in the Loess Plateau," Kapp said.

The term "loess" refers to deposits of wind-blown silt. Parts of the U.S. Midwest have large deposits of loess.

"Up until 3 million years ago, the basin was filling up with sediment," he said.

"Then like a switch, the wind turned on and basin sediments get sandblasted away."

The whole process is driven by global climate change, he said. "The unifying theme is wind," he added.

The study has been published in the April/May issue of GSA Today.

ANI

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