Mountain ranges rise dramatically faster than expected
Two new studies by a University of Rochester researcher show that mountain ranges rise to their height in as little as two million years--several times faster than geologists have always thought. Each of the findings came from two pioneering methods of measuring ancient mountain elevations, and the results are in tight agreement.
The research papers, appearing in today's issue of Science and next week's issue of Earth and Planetary Science Letters, mean scientists will have to re-evaluate tectonic processes that build high elevation plateaus, such as those in Tibet and the central Andes.
"These results really change the paradigm of understanding of how mountain belts grow," says Carmala Garzione, assistant professor of earth and environmental sciences and co-author of both papers. "We've always assumed that the folding and faulting in the upper crust produced high elevation mountains. Now we have data on ancient mountain elevation that shows something else is responsible for the mountains' uplift."
Garzione took a new approach to paleoaltimetry, the tricky science of measuring mountain height from the distant past. As mountains lift, weather erodes them, complicating the estimation of how high they might be at any given time. Until Garzione's research, geologists estimated surface uplift by examining leaf fossils to determine at what elevation the plants lived, or by dating when certain minerals began moving rapidly to the surface. Unfortunately, plant characteristics can change radically over millions of years, and changes in climate can also cause erosion, throwing a significant question mark into the equation.
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Two new studies by a University of Rochester researcher show that mountain ranges rise to their height in as little as two million years--several times faster than geologists have always thought. Each of the findings came from two pioneering methods of measuring ancient mountain elevations, and the results are in tight agreement.
The research papers, appearing in today's issue of Science and next week's issue of Earth and Planetary Science Letters, mean scientists will have to re-evaluate tectonic processes that build high elevation plateaus, such as those in Tibet and the central Andes.
"These results really change the paradigm of understanding of how mountain belts grow," says Carmala Garzione, assistant professor of earth and environmental sciences and co-author of both papers. "We've always assumed that the folding and faulting in the upper crust produced high elevation mountains. Now we have data on ancient mountain elevation that shows something else is responsible for the mountains' uplift."
Garzione took a new approach to paleoaltimetry, the tricky science of measuring mountain height from the distant past. As mountains lift, weather erodes them, complicating the estimation of how high they might be at any given time. Until Garzione's research, geologists estimated surface uplift by examining leaf fossils to determine at what elevation the plants lived, or by dating when certain minerals began moving rapidly to the surface. Unfortunately, plant characteristics can change radically over millions of years, and changes in climate can also cause erosion, throwing a significant question mark into the equation.
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