Mount Everest Grows Taller Due to River Erosion
Mount Everest, the world’s highest peak, is growing by up to 2mm annually, according to a recent study by researchers at University College London (UCL). The study reveals that this surprising growth is partly due to the erosion caused by the Arun River, which is located 75 km (47 miles) away from Everest.
How the Arun River Contributes to Mount Everest’s Growth
The erosion of rock and soil in the Arun River basin is reducing the weight of the Earth’s crust, which in turn allows it to rise, much like a ship floating higher when it loses cargo. This phenomenon, known as isostatic rebound, helps to push Mount Everest and nearby peaks upward.
Plate Tectonics and Erosion
While plate tectonics, particularly the collision of the Indian and Eurasian plates that began 40-50 million years ago, remains the primary reason for the rise of the Himalayas, the UCL team has found that the Arun River network is also a significant contributing factor.
The River’s Erosive Power
The Arun River, as it flows through the Himalayas, carves away material from the Earth’s crust. This reduction in mass decreases the force on the mantle, causing the crust to float upward. This erosion-driven uplift is one of the factors helping to elevate Everest and other major peaks, including Lhotse and Makalu, the world’s fourth and fifth highest mountains, respectively.
Isostatic Rebound: The Science Behind It
This process of isostatic rebound means that Everest is rising faster than it is eroding, according to Dr. Matthew Fox, co-author of the study. He explained, “We can see them growing by about two millimeters a year using GPS instruments, and now we have a better understanding of what’s driving it.”
Historical Context of the Arun River’s Power
The researchers also found that the Arun River likely gained its erosive power around 89,000 years ago, when it “captured” another river or water system in Tibet. This event gave the river the ability to carve off significant amounts of rock and soil, shaping the surrounding landscape.
Everest’s Dynamic Surface
Dr. Xu Han, lead author of the study and a researcher at China University of Geosciences, highlighted the importance of this process, stating, “The changing height of Mount Everest really highlights the dynamic nature of the Earth’s surface.” The interaction between the Arun River’s erosion and the Earth’s mantle pressure is giving Everest a “boost,” making it taller than it would otherwise be.
Uncertainty and Challenges in the Study
While the study sheds light on Everest’s growth, there are still uncertainties, particularly in predicting the exact amount of uplift caused by the river’s erosion. Professor Hugh Sinclair of the University of Edinburgh, who was not involved in the study, acknowledged the plausibility of the findings but noted that predicting the long-term effects of river incision and uplift over large distances is challenging.
Conclusion: A New Insight into Everest’s Growth
Despite these uncertainties, the study offers an exciting new insight into why Mount Everest continues to grow. The idea that a nearby river could be contributing to the rise of the world’s highest peak adds a new dimension to our understanding of the dynamic forces shaping the Earth’s surface.
