Grapevine

A river is pushing up Mount Everest's peak

Mount Everest is about 15 to 50 meters taller than it would otherwise be because of uplift caused by a nearby eroding river gorge, and continues to grow because of it, finds a new study by UCL researchers.

The study, published in Nature Geoscience, found that erosion from a river network about 75 kilometers from Mount Everest is carving away a substantial gorge. The loss of this landmass is causing the mountain to spring upwards by as much as 2 millimeters a year and has already increased its height by between 15 and 50 meters over the past 89,000 years.

At 8,849 meters high, Mount Everest, also known as Chomolungma in Tibetan or Sagarmāthā in Nepali, is the tallest mountain on Earth, and rises about 250 meters above the next tallest peak in the Himalayas. Everest is considered anomalously high for the mountain range, as the next three tallest peaks—K2, Kangchenjunga and Lhotse—all only differ by about 120 meters from each other.

A significant portion of this anomaly can be explained by an uplifting force caused by pressure from below Earth's crust after a nearby river eroded away a sizable amount of rocks and soil. It's an effect called isostatic rebound, where a section of the Earth's crust that loses mass flexes and "floats" upwards because the intense pressure of the liquid mantle below is greater than the downward force of gravity after the loss of mass.

It's a gradual process, usually only a few millimeters a year, but over geological timeframes can make a significant difference to the Earth's surface.