Earth

A river is pushing up the top of Everest

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Mount Everest is about 15 to 50 meters taller than it would be otherwise, and continues to grow, due to uplift caused by erosion of nearby river gorges, UCL researchers say. found out in a new study by.

The study, published in Nature Geoscience, found that a significant canyon has been carved out by erosion from a network of rivers about 75 kilometers from Everest. This loss of landmass is causing mountains to rise by 2 millimeters per year, and their heights have already increased by 15 to 50 meters over the past 89,000 years.

At 8,849 meters above sea level, Mount Everest, also known as Chomolungma in Tibetan and Sagarmatha in Nepali, is the highest mountain on Earth, towering approximately 250 meters higher than the next highest peak in the Himalayas. Everest is considered unusually high for its mountain range, as the next three highest peaks, K2, Kanchenjunga, and Lhotse, are all only about 120 meters apart from each other.

This anomaly can be explained in large part by uplift forces caused by pressure from below the Earth’s crust, after nearby rivers have eroded significant amounts of rock and soil. This is an effect called isotropic repulsion, in which parts of the Earth’s crust that have lost mass flex and “float” upward. This is because after losing mass, the strong pressure of the liquid mantle below is greater than the downward force of gravity.

This is a gradual process, typically only a few millimeters per year, but can result in major changes to the Earth’s surface over geological time frames.

The researchers found that this process has caused Mount Everest to grow by about 15 to 50 meters over the past 89,000 years, since the nearby Arun River merged with the adjacent Kosi River network.

Co-author, Ph.D. student Adam Smith (UCL Earth Sciences) said: “Mount Everest is a remarkable mountain of myth and legend, and it continues to grow. Our research shows that the nearby river system has cut deeply into the mountain. “We found that material was being lost and the mountains were rising higher.” . ”

Today, the Arun River flows east of Mount Everest and joins the larger Kosi River system downstream. Over thousands of years, the River Arun has carved great gorges along its banks, washing away billions of tons of soil and sediment.

“An interesting water system exists in the Everest region,” said co-author Dr. Dai Jinggen of the China University of Geosciences. “The upstream Arun River flows east at high altitude with a flat valley, and then abruptly turns south. I will change it.” The Kosi River decreases in elevation and becomes steeper. This unique feature of instability is probably related to Everest’s extreme height. ”

The uplift will not be limited to Everest, but will affect nearby mountains, including Lhotse and Makalu, the fourth and fifth highest mountains in the world, respectively. Isotropic rebound pushes the height of these mountains by the same amount as Everest, but Makalu, which is closest to the Arun River, experiences a slightly higher uplift rate.

Co-author Dr Matthew Fox (UCL Geosciences) said: ‘Everest and its neighboring peaks are growing because isotropic rebound is uplifting them faster than erosion is wearing them down. “We can see them growing at a rate of about 2 millimeters per year.” By using GPS equipment, we can now better understand what is causing it. ”

By examining the erosion rates of the Arun, Koshi and other rivers in the region, researchers have determined that the Arun merged with the Koshi river network some 89,000 years ago and was linked to a confluence of rivers, known as drainage piracy. We were able to determine that there was a process called.

In doing so, more water flowed into the Kosi River, increasing its erosive power and taking more of the landscape’s soil and sediment with it. As more land was washed away, the uplift rate increased and the mountain tops became higher and higher.

Lead author Dr Xu Han, from the China University of Geosciences, who carried out the study while visiting UCL during a China Scholarship research visit, said: “Changes in the height of Mount Everest are a result of the dynamic nature of the Earth’s surface. The erosion of the Arun River and the upward pressure of the Earth’s mantle gives force to Mount Everest, pushing it higher than it should.”

Further information: Jin-Gen Dai, Recent uplift of Chomolungma enhanced by river drainage piracy, Nature Geoscience (2024). DOI: 10.1038/s41561-024-01535-w. www.nature.com/articles/s41561-024-01535-w

Provided by University College London

Citation: River Pushes Up Mount Everest Peak (September 30, 2024) Retrieved September 30, 2024 from https://phys.org/news/2024-09-river-mount-everest-peak.html

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