Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Study of erosion and precipitation in the Himalayas presents surprising findings scholars say

11.12.2003


Scientists have found that, despite a vast difference in precipitation between the north and south sides of the Himalaya Mountains, rates of erosion are indistinguishable across these mountains.



Douglas Burbank, professor of geology and director of the Institute for Crustal Studies at the University of California, Santa Barbara, is the first author of the article, "Decoupling of erosion and precipitation in the Himalayas," to be published Thursday, December 11, in the international scientific journal Nature.

This four-year study of the interactions between climate, erosion and tectonic deformation was funded by the National Science Foundation. The Himalayas were chosen because of their unique combination of massive topography, monsoon rains, and rapid erosion.


The study relies on a network of 20 weather stations arrayed across the Himalayas. Jaakko Putkonen of the University of Washington installed and maintains the weather stations. These stations are unique in that many of them are located on mountain tops as high as 15,000 feet, whereas nearly all weather stations around the world are located in valleys.

Burbank and his team found that the difference in precipitation between the north and south is striking. The monsoon rains that originate over the Indian Ocean are drawn toward the Himalayas. As monsoon storms rise over the mountains, their moisture is wrung out of them, drenching the south side of the Himalayas with 15 feet of rainfall each summer. By contrast, to the north of the Himalayan summits, summer rainfall amounts to only about one foot. "Given this profound difference in rainfall, we expected to see large differences in rates of erosion. But this is not what we found," said Burbank.

Additionally, he explained that the tectonic plate of India is colliding with and thrusting under that of Asia at a rate of about two inches per year. About half of that collision is absorbed by the Himalayas, thrusting the mountains upward between India and Tibet. When coupled with erosion, this thrusting carries rocks to the surface from deep in the Earth’s crust.

As rocks move toward the surface, they cool, and this cooling provides the researchers with a means to measure erosion at geological time scales of millions of years. Using a mineral-dating technique called fission-track dating, co-author Ann Blythe at the University of Southern California showed that it took about a half a million years for Himalayan rocks to cool from about 280 degrees Fahrenheit to surface temperatures. Because temperatures of 280 degrees occur one to two miles deep in the crust, Blythe’s dating implies that two to four miles of rock are eroded from the Himalaya every million years.

Not only are these rates of erosion rapid, but they show no significant variation from the monsoon-drenched flank of the Himalaya to the arid conditions north of the range. This unexpected discovery led the researchers to search for the cause of this uniform erosion.

They noted that, as the climate gets drier, the mountainsides get steeper. Such steep slopes can cause landslides (and erosion) more easily with less rainfall than a gentle slope. Also, glaciers periodically advance across the northern areas and may erode very efficiently, despite the drier climate. Burbank and his team also proposed that river channels get narrower in the drier areas, thus concentrating more energy on the bedrock and eroding it just as fast as in the wetter areas.

The importance of this study, he said, lies in the fact that erosion rates are not closely linked to the dramatic changes in climate. Instead, the collision of India and Asia drives rocks steadily upward in the Himalaya and erosion sweeps them rapidly away.

In this project, Burbank is spearheading work by scholars at six other universities besides UCSB: Harvard, Dartmouth, MIT, University of Southern California, University of Washington, and the University of Wyoming. They work with the Nepalese Department of Hydrology and Meteorology.


Note: Douglas Burbank is participating in the American Geophysical Union conference in San Francisco (Dec. 9 to Dec. 11) and can be reached at The Pickwick Hotel at 415-421-7500.

Gail Gallessich | EurekAlert!
Further information:
http://www.ucsb.edu/

More articles from Earth Sciences:

nachricht Scientists discover Earth's youngest banded iron formation in western China
12.07.2018 | University of Alberta

nachricht Drones survey African wildlife
11.07.2018 | Schweizerischer Nationalfonds SNF

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

Im Focus: Chemical reactions in the light of ultrashort X-ray pulses from free-electron lasers

Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.

Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Research finds new molecular structures in boron-based nanoclusters

13.07.2018 | Materials Sciences

Algae Have Land Genes

13.07.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>