by Scientists think they have figured out why Mount Everest, known as Chomolungma in Tibet and Sagarmatha in Nepal, stands out so starkly from the rest of the Himalayan peaks.
New modeling suggests an overlooked ‘piracy’ that could cover as much as 50 meters of the world’s highest mountain. But not the kind that attacks ships on the high seas. The kind that catches rivers.
Obviously, Everest’s record height of 8,849 meters would be nowhere without the breaking of tectonic plates, but the uniformity of geology along the fault line should ensure that all peaks are more or less the same height.
The difference between most of the Himalayan peaks does not exceed 100 meters. With a range of no less than 250 meters above the neighbors, it is clearly hiding a secret.
Moreover, according to GPS data, Everest is still growing to this day, several millimeters per year, which is faster than the ascent expected by tectonic plates.
There must be another force at play, and scientists from the China University of Geosciences and University College London think they have found it.
Their models suggest that the world’s highest peak was elevated above its peers by geological piracy, which occurs when a river is ‘conquered’ by a neighbor. This changes sediment flow and reshapes rivers and their tributaries into new patterns.
Today, the Arun River is a major tributary that cuts a deep, narrow gorge through the core of the Himalayas, reaching an elevation gain of 7 kilometers over a length of 35 kilometers.
But when this river formed long ago, it did not require landslides or glaciers to chisel such a deep path through Chomolungma’s northern slopes. The sheer volume of flowing water gave him all the strength he needed.
Models suggest that the Arun tributary began receiving more water from its parent, the Kosi River, about 89,000 years ago, and the sudden increase in capacity could easily have caused the incision of a gorge.
The removal of large chunks of rock would have caused the Earth’s crust, which was “floating” on the mantle, to rebound, “raising the surface of the unincised portions of the surrounding area, including the mountain peaks,” writes the international team. led by Xu Han of China University of Geosciences.
Based on their models, the team estimates that between 15 and 50 meters of Chomolungma’s current height could be the result of river discharge piracy.
Compared to the Arun, other rivers flowing through the Himalayas have had a more consistent flow history, meaning that erosion at the base of the mountains is roughly the same as erosion that occurs at the peaks. This means that the total weight of the crust on the mantle remains relatively stable.
But when the River Arun started taking on more water all those millennia ago, this balanced erosion rate was disrupted. As more rock was carried along by rivers, this caused the earth’s crust to rise in certain places.
Given the crust’s elastic thickness of 10 to 30 km, researchers estimate that this phenomenon would lead to increased surface uplift of Chomolungma by up to 0.53 mm per year.
The findings suggest that the highest peak on Earth today could still be growing due to the formation of a river gorge – 89,000 years ago.
The research was published in Natural Geosciences.
