The tallest mountain on Earth named after British surveyor George Everest, rising an astonishing 5.5 miles (8.85 km) above sea level is said to be still increasing in height.
Mount Everest, along with the Himalayas, has been steadily ascending since its formation approximately 50 million years ago, when the Indian subcontinent collided with Eurasia. However, Everest’s growth rate surpasses what would be expected solely from this collision.
Merger of two river
Researchers now believe they have discovered the cause of Mount Everest’s additional growth, and said it is linked to the monumental merger of two nearby river systems.
Approximately 89,000 years ago, the Kosi river merged with the Arun river, resulting in Everest gaining an estimated 49-164 feet (15-50 meters) in height. This translates to an uplift rate of about 0.01-0.02 inches (0.2-0.5 millimeters) per year, the researchers estimated.
The geological process responsible for this phenomenon is known as isostatic rebound. It occurs when the weight of the Earth’s surface decreases, causing land masses on the crust to rise. The crust, which is the outermost layer of the Earth, floats on top of the mantle layer, which is composed of hot, semi-liquid rock.
Isostatic rebound
According to one of the leaders of the study published on Monday in the journal Nature Geoscience, a geoscientist Jin-Gen Dai of China University of Geosciences in Beijing, said, “Isostatic rebound can be likened to a floating object adjusting its position when weight is removed,” Reuters reported.
“When a heavy load, such as ice or eroded rock, is removed from the Earth’s crust, the land beneath slowly rises in response, much like a boat rising in water when cargo is unloaded,” he added.
In the case of Everest, the merger of the Kosi and Arun rivers, which was more like a hostile takeover with the Kosi subjugating the Arun as the rivers and changed course over time, leading to increased erosion which has removed significant amounts of rock and soil from the region near Everest, reducing the weight and allowing the land to rise further.
The primary canyon of the combined river network lies roughly 28 miles (45 km) to the east of Mount Everest. This finding was made by researchers who utilized numerical simulations to model the development of the river system over time.
According to their estimates, isostatic rebound is responsible for approximately 10% of the yearly uplift rate of Everest.
Not limited to the Himalayan region
Isostatic rebound is a geological phenomenon that is not limited to the Himalayan region.
Dai said, “A classic example is in Scandinavia, where the land is still rising in response to the melting of thick ice sheets that covered the region during the last Ice Age. This process continues today, affecting coastlines and landscapes, thousands of years after the ice retreated.”
The rate of uplift surpasses the ongoing surface erosion caused by natural elements such as wind, rain, and river flow. Smith said that as erosion persists, the uplift rate of Everest due to isostatic rebound may increase.
The same process also contributes to the elevation of nearby peaks, including Lhotse, the world’s fourth highest mountain, and Makalu, the fifth highest. Lhotse experiences an uplift rate comparable to Everest, while Makalu, located closer to the Arun River, has a slightly higher uplift rate.
‘Unique place in human consciousness’
“Mount Everest occupies a unique place in human consciousness,” Dai said.
He continued that “Culturally, Everest is sacred to local Sherpa and Tibetan communities. Globally, it symbolizes the ultimate challenge, embodying human endurance and our drive to surpass perceived limits.”
“Physically, it represents Earth’s highest point, giving it immense significance simply by virtue of its stature,” Dai added.
Earth is constantly changing
According to the Study co-author Adam Smith, a doctoral student in Earth sciences at University College London and co-author of the study, GPS measurements indicate that Mount Everest and the surrounding Himalayas continue to rise.
Dai further said that “This research underscores our planet’s dynamic nature. Even a seemingly immutable feature like Mount Everest is subject to ongoing geological processes, reminding us that Earth is constantly changing, often in ways imperceptible in our daily lives.”
The Earth’s outer layer is composed of massive plates that slowly shift over time through a process known as plate tectonics. The Himalayas have risen as a result of a collision between two of these plates.
Mount Everest, also known as Sagarmatha in Nepali and Chomolungma in Tibetan, is located on the border between Nepal and the Tibet Autonomous Region of China.