Active mountain ranges like the Olympic Mountains, Taiwan Central Range or the Southern Alps are still growing, but they are not getting any taller. River cutting and erosion keep the heights and widths of uplifted mountain ranges in a steady state according to an international team of geoscientists.
"These mountains grew to 2.5 to 3 miles high over the past few million years and then they stopped increasing," says Dr. Rudy L. Slingerland, professor of geology and head of Penn States geosciences department. "We assumed that various erosional forces were compensating for the constant uplift of the mountains, but few observations have been available to validate this assumption."
Mountain ranges form near the border of two tectonic plates. When one plate slides beneath the other, or subducts, a veneer of rocks on the subducted plate is scraped off and piles up to form the mountains. Even though tectonic plates subduct for tens of millions of years, mountain ranges usually stay between 2.5 and 3 miles high and about 75 to 150 miles wide. This is because the slopes become steeper as the mountains grow in elevation and more material erodes away via landslides, river cutting and other forms of erosion. The higher and steeper the mountains, the greater the slope and the more material is transported away to the oceans.
Andrea Elyse Messer | EurekAlert!
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