Wind keeps mountains from growing.

• Position: Topography

Wind is a much more powerful force in the evolution of mountains than previously thought, according to a report from a research team led by the University of Arizona, Tucson, as bedrock in Central Asia that would have formed mountains instead was sandblasted into dust. "No one had ever thought that wind could be this effective." concedes Paul Kapp, associate professor in the Department 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 that wear down mountains and influence their evolution. Wind can be just as powerful, though. Kapp and his colleagues estimate it can be 10 to 100 times more effective in eroding mountains than previously reported.

The geoscientists figured out wind's rock-sculpting abilities by studying gigantic wind-formed ridges of rock called yardangs. Huge fields of yardangs that can be seen from space look like corduroy. Wind had scoured long gouges out of the bedrock, leaving the keel-shaped ridges behind. Kapp wondered where the missing material was, so he and his team went to China's Qaidam Basin to collect more information about the yardangs, the history of wind erosion, and 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:

The term "loess" refers to deposits of wind-blown silt. Parts of the American Midwest have large deposits. "Up until 3,000,000 years ago, the basin was filling up with sediments. Then, like a switch, the wind turned on and the basin sediments got sandblasted away."

Known as the "bread basket of China," the Loess Plateau is the largest accumulation of dust on Earth. Scienlists thought most of it came from the Gobi...