At a staggering 8,849 meters, Mount Everest, known as Chomolungma in Tibetan and Sagarmatha in Nepali, is Earth’s tallest peak. Towering 250 meters above its nearest competitor in the Himalayas, Everest’s extraordinary height has long puzzled geologists, especially since the next tallest mountains-K2, Kangchenjunga, and Lhotse-differ in elevation by only about 120 meters. However, recent research has revealed a fascinating geological explanation for Everest’s towering stature.
Role of Isostatic Rebound
The major factor in Everest’s anomalous height is a process called “Isostatic Rebound”, which occurs when sections of the Earth’s crust ‘float’ upward in response to the loss of mass. This uplift is triggered by the erosion of rocks and soils, primarily by the Arun River, which runs east of Everest. As the river erodes the surrounding landscape, pressure from the Earth’s mantle below forces the land to rise.
This slow but steady process has added between 15 to 50 meters to Everest’s height over the past 89,000 years. According to PhD student Adam Smith (UCL Earth Sciences), “Mount Everest is still growing. Our research shows that as the nearby river system cuts deeper, the loss of material is causing the mountain to spring further upwards.”
River System in Action
The Arun River, after carving out a massive gorge, merges with the larger Kosi River network downstream. This merging, known as “Drainage Piracy”, carries more water through the Kosi system, accelerating erosion. The resulting loss of mass from the landscape allowed Everest and neighboring peaks like Lhotse and Makalu to rise higher.
Dr. Jin-Gen Dai from the China University of Geosciences highlights the unique topography of the region, “The Arun River flows east at high altitude and then abruptly turns south as the Kosi River, dropping in elevation. This topography is likely linked to Everest’s extreme height.”
Continued Growth
The isostatic rebound process affects not only Everest but also its neighboring giants, including Lhotse and Makalu, the world’s fourth and fifth tallest mountains. These peaks experience a similar rate of uplift, with Makalu’s proximity to the Arun River resulting in a slightly higher growth rate. Dr. Matthew Fox (UCL Earth Sciences) explains that, “Everest and its neighboring peaks are growing faster than erosion can wear them down. GPS instruments show they are rising by about two millimeters per year.”
Dynamic Nature of Earth’s Surface
The study reveals the ever-changing nature of Earth’s surface. The changing height of Mount Everest highlights the dynamic interaction between erosion and the upward pressure of the Earth’s mantle.
As rivers continue to carve away the landscape, Everest and its neighboring peaks will keep rising, a testament to the dynamic forces shaping the plan