Nearby river contributes to the rise of Mount Everest, says new study

  • October 2, 2024
  • Posted by: OptimizeIAS Team
  • Category: DPN Topics
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Nearby river contributes to the rise of Mount Everest, says new study

Sub :Geo

Sec: Oceanography

Context:

  • Mount Everest, the world’s tallest mountain at 8,849 meters, is growing faster than expected.
  • A recent study suggests that over the past 89,000 years, it has grown 15 to 50 meters higher than anticipated.
  • The reason: A nearby river is playing a crucial role.

Details:

  • The Arun River, located 75 km from Everest, is eroding rock and soil at the mountain’s base.
  • This erosion is causing Everest to rise by up to 2 mm per year.
  • The process contributing to this growth is called “isostatic rebound.”

What is Isostatic Rebound? 

  • Isostasy (Greek isos “equal,” stasis “stand still”) is a term in geology to describe the state of mass balance (equilibrium) between the Earth’s crust and upper mantle.
  • It describes a condition in which the mantle tends to balance the mass of the crust in the absence of external forces.
  • Imagine the Earth’s crust as a floating object on a semi-liquid layer. When weight is removed from the surface (like eroded rock), the crust rises slightly, similar to a boat rising when cargo is unloaded.

The River’s Role:

  • About 89,000 years ago, the Arun River merged with the Kosi River.
  • This merger led to increased erosion, removing large amounts of rock and soil.
  • The reduced weight in the region near Everest allowed the mountain to rise more quickly.
  • Study Findings:
    • Isostatic rebound accounts for about 10% of Everest’s annual uplift rate.
    • Neighbouring peaks like Lhotse and Makalu are also affected.

However, some experts are skeptical:

  • The timing of the river merger is uncertain.
  • Dating river deposits and erosion rates is challenging.
  • Some geologists believe river erosion may have little impact on mountain uplift.

Arun river:

  • It is a transboundary river that is part of the Koshi or Sapta Koshi river system in Nepal.
  • It originates in the Tibet Autonomous Region of the People’s Republic of China where it is called the Phung Chu or Bum-chu.
  • Mouth: Confluence with Sun Koshi and Tamur River to form Sapta Koshi
  • Tributaries:
    • Left- Yeru Tsanpo, Trakar-chu
    • Right- Barun River

Source: IE

Geography Nearby river contributes to the rise of Mount Everest