Mount Everest has been making headlines lately because it’s still growing! Scientists have finally figured out why this iconic mountain continues to rise.
The Himalayan mountain range has been lifting for around 50 million years, ever since the Indian subcontinent collided with Eurasia.
Researchers wanted to understand why Everest keeps growing. They suspect it has to do with the merging of two rivers that flow near the mountain.
According to Channel News Asia (CNA) on Wednesday (Oct 2, 2024), Everest’s height increased by about 15 to 50 meters due to changes in the regional river system. It’s believed that the Kosi and Arun rivers merged around 89,000 years ago, which means the uplift rate is about 0.2 to 0.5 mm per year.
This geological process, known as isostatic rebound, involves the landmass rising as weight on the Earth’s crust decreases. The Earth’s crust, the outer layer of our planet, essentially floats on the hot, semi-liquid mantle beneath.
In this case, the rivers merging acted like a forced takeover, with the Kosi River overpowering the Arun and changing direction over time. This sped up erosion, removing a lot of rocks and soil, which lightened the weight on the land near Everest.
The main canyon from this river system is about 45 km east of Everest.
This process isn’t just happening in the Himalayas.
Adam Smith, a co-author of the study and a doctoral student at University College London, noted that GPS measurements reveal that Everest and the entire Himalayan range are still rising.
This uplift is outpacing the ongoing surface erosion caused by factors like wind, rain, and rivers. As erosion continues, the uplift of Everest due to isostatic rebound could actually increase, according to Smith.
Neighboring peaks like Lhotse (the world’s fourth tallest mountain) and Makalu (the fifth tallest) are also rising due to the same process. Lhotse’s uplift rate is similar to Everest’s, while Makalu, which is closer to the Arun River, has a slightly higher uplift rate.
The Earth’s rigid outer layer is divided into massive tectonic plates that gradually shift over time, causing the Himalayas to rise as a result of the collision between these plates.
Everest, also known as Sagarmatha in Nepal and Chomolungma in Tibet, sits on the border between Nepal and the Tibet Autonomous Region of China. It was named after George Everest, a 19th-century British surveyor in India.