Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Preserved by ice: Glacial dams helped prevent erosion of Tibetan plateau

The Tsangpo River is the highest major river in the world, starting at 14,500 feet elevation and plunging to the Bay of Bengal, scouring huge amounts of rock and soil along the way. Yet in its upper reaches, the powerful Tsangpo seems to have had little effect on the elevation of the Tibetan Plateau.

New research suggests that the plateau edge might have been preserved for thousands of years by ice during glacial advances and by glacial debris deposited at the mouth of many Tsangpo tributaries during warmer times when glaciers retreated. Those debris walls, or moraines, acted as dams that prevented the rapidly traveling water in the main Tsangpo gorge from carving upstream into the plateau.

"At the edge of the plateau, the river's erosion has been defeated because the dams have flattened the river's slope and reduced its ability to cut into the surrounding terrain, making it more like a lake," said David Montgomery, a University of Washington geomorphologist.

Montgomery is co-author of a paper in the Oct. 9 issue of Nature that describes a new hypothesis of why the Tibetan Plateau has maintained its elevation when it appears it should have been worn down in the area of the Tsangpo system.

The paper's lead author is Oliver Korup of the Swiss Federal Institute for Snow and Avalanche Research in Davos, Switzerland. The work was financed in part by the European Commission and the National Science Foundation in the U.S.

The researchers focused on the three primary rivers of the Tsangpo system, the Yarlung Tsangpo and its two major tributaries, the Yigong Tsangpo and the Parlung Tsangpo. The scientists mapped geologic evidence of more than 300 natural dams, including 260 moraines, that have formed repeatedly at the mouths of tributaries in the last 10,000 years to block water flow on the three main streams.

The first evidence of the dams was found at the edge of the Tibetan Plateau, and additional evidence continued to be found upstream, Montgomery said. The dams essentially formed giant lakes along the river and prevented the water from carving into bedrock.

"The glaciers seem to have helped preserve the edge of the plateau by keeping the river from ripping into it," he said. "This isn't the explanation for why the rest of the plateau is so well preserved, but it might work for this area where the Tsangpo crosses the edge of the plateau."

There are two well-recognized mechanisms that typically are thought to be responsible for preserving a feature such as the edge of the Tibetan Plateau. But one of them, the plateau's arid climate, is not to blame because the Tsangpo is already a large river at the point that it enters the world's deepest and fastest-eroding gorge. The other conventional explanation, that tectonic faults continually push new rock to the surface and thus offset any erosion by the river, might be at work in concert with the glacial damming, the scientists believe.

In the Tsangpo gorge, also called Yarlung Tsangpo Grand Canyon, the river plunges from about 10,000 feet to about 1,000 feet in a span of 150 miles. Eventually the river becomes the Brahmaputra River, flowing through India and Bangladesh and into the Bay of Bengal.

"Up in the gorge, the river is very steep and the erosion is very high, and one would think that back through geologic time it should have sliced upstream into the Tibetan Plateau," Montgomery said.

The question is why that didn't happen. Korup and Montgomery suspect that the glacial dams on tributaries right to the edge of the plateau prevented such pronounced erosion.

"It's a transition from where the river is doing all the erosion at lower elevations to where the glaciers are doing all the erosion at high elevations, and the glaciers are limited on how deeply they erode," Montgomery said. "They shave off the top but they don't erode farther down, and the rivers can't erode back past the glaciers."

Vince Stricherz | EurekAlert!
Further information:

Further reports about: Erosion Glacial dams Tibetan plateau moraines river's erosion

More articles from Earth Sciences:

nachricht UCI and NASA document accelerated glacier melting in West Antarctica
26.10.2016 | University of California - Irvine

nachricht Ice shelf vibrations cause unusual waves in Antarctic atmosphere
25.10.2016 | American Geophysical Union

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Etching Microstructures with Lasers

Ultrafast lasers have introduced new possibilities in engraving ultrafine structures, and scientists are now also investigating how to use them to etch microstructures into thin glass. There are possible applications in analytics (lab on a chip) and especially in electronics and the consumer sector, where great interest has been shown.

This new method was born of a surprising phenomenon: irradiating glass in a particular way with an ultrafast laser has the effect of making the glass up to a...

Im Focus: Light-driven atomic rotations excite magnetic waves

Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion

Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Greater Range and Longer Lifetime

26.10.2016 | Power and Electrical Engineering

VDI presents International Bionic Award of the Schauenburg Foundation

26.10.2016 | Awards Funding

3-D-printed magnets

26.10.2016 | Power and Electrical Engineering

More VideoLinks >>>