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Mount Everest is the highest mountain on Earth – 5.5 miles (8.85 km) above sea level – and still rising.
While it and the rest of the Himalayas continue an inexorable growth that dates back to their birth some 50 million years ago when the Indian subcontinent collided with Eurasia, Everest is only rising more than expected. Scientists now think they know why, and it has to do with the monumental merging of two nearby river systems.
Researchers estimate that this change in the regional river system, with the Kosi River merging with the Arun River about 89,000 years ago, may have increased the height of Everest by about 49–164 feet (15–50 m). This translates to an uplift rate of about 0.01–0.02 inches (0.2–0.5 mm) per year.
He said that the geological process at work is called isostatic rebound. When surface weight decreases, it involves the addition of land mass to the Earth’s crust. The crust, the outermost layer of the Earth, floats on top of a mantle made primarily of hot, semi-liquid rock.
In this case, the merging of the rivers – more like a hostile takeover, the Kosi overthrew the Arun as the rivers changed course over time – resulted in rapid erosion that produced large amounts of rock and The soil was shed, which reduced the weight of the land. The area near Everest
“Asostatic rebound can be likened to a floating object when the weight is removed,” said Jin-Jin Dai, a geologist at the China University of Geosciences in Beijing, who led the study published Monday in the journal Nature Geoscience. One of the
Dye added, “When a heavy load, such as snow or crushed rock, is removed from the Earth’s crust, the ground below rises slowly in response, much like a ship unloads its cargo. If it goes, it gets up in the water.”
The main gorge of the merged river system is located about 28 miles (45 km) east of Everest.
The researchers, who used numerical models to simulate the evolution of the river system, estimated that about 10 percent of Everest’s annual growth rate is isostatic rebound.
This geological process is not unique to the Himalayas.
“A classic example is in Scandinavia, where the land is still rising in response to the melting of the thick ice sheets that covered the region during the last ice age. This process continues today, creating coastlines and Landscapes are affected, thousands of years after the ice retreated,” Dye said.
Study co-author Adam Smith, a doctoral student in Earth Sciences at University College London, said the GPS measurements show the continued rise of Everest and the rest of the Himalayas.
This development leaves behind continuous surface erosion caused by factors such as wind, rain and river flow. As this erosion continues, isostatic rebound may increase Everest’s rate of elevation, Smith said.
Neighboring peaks, including the world’s fourth-highest peak and Makalu, the fifth-highest, are also boosted by the same process. Lhotse is experiencing an ascent rate similar to Everest. Makalu, located near Arun, has a slightly higher rate of elevation.
“This research underscores the dynamic nature of our planet. Even a seemingly unchanging feature like Mount Everest is subject to ongoing geological processes, reminding us that the Earth is constantly changing, often in our daily lives. I in unimaginable ways,” Dye said.
The Earth’s rigid exterior is divided into large plates that move slowly over time in a process called plate tectonics, with the Himalayas rising after the collision between the two plates.
Everest, also known as Sagarmatha in Nepali and Chomolingma in Tibetan, is located on the border between Nepal and the Tibet Autonomous Region of China. It was named for George Everest, a 19th-century British surveyor in India.
“Mount Everest occupies a unique place in the human consciousness,” Dye said.
“Physically, it represents the highest point on Earth, which gives it great importance because of its height,” Dai added. “Culturally, Everest is sacred to local Sherpa and Tibetan communities. Globally, it symbolizes the ultimate challenge, symbolizing human endurance and our quest to transcend perceived limits.”
(Other than the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)
