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 Climate change weakens Walker circulation
20.10.2017 | MARUM - Zentrum für Marine Umweltwissenschaften an der Universität Bremen

nachricht Shallow soils promote savannas in South America
20.10.2017 | Senckenberg Forschungsinstitut und Naturmuseen

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

Climate Engineering Conference 2017 Opens in Berlin

10.10.2017 | Event News

 
Latest News

NRL clarifies valley polarization for electronic and optoelectronic technologies

20.10.2017 | Interdisciplinary Research

Metallic nanoparticles will help to determine the percentage of volatile compounds

20.10.2017 | Materials Sciences

Shallow soils promote savannas in South America

20.10.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>