Everest reaches new heights - 21st October 2024

Standing at a height of 8,849 metres, Mount Everest claims the title of the world's highest mountain. However, geologists have revealed that the rise of this stone giant has increased in recent geological time.

The Himalayas, of which Everest's the centrepiece, resulted from the Indian subcontinent and Eurasian tectonic plate colliding some 50 million years ago. Although this impact continues to push the mountain range higher today, this doesn't fully explain more recent disproportionate growth.

Investigation by a team of researchers from China and the UK identified the cause was a phenomenon called 'river capture'. 90,000 years ago, the coming together of the Kosi and Arun rivers created a river of immense power. This resulted in the erosion of large quantities of rock and soil.

Flowing just 80 kilometres from the base of Everest, the river's erosion reduced the mass of the area. It allowed the pressure within the Earth's crust to push outwards - a geological process called isostatic rebound. "Essentially, as the river carved away more rocks, the Earth's crust rebounded, rising like a boat when weight is removed," said Dai.

The team believes that this process has resulted in Everest growing an extra 15 to 50 metres in the last 89,000 years. They estimate that it forces the peak to extend skywards by an additional 0.16 to 0.53 millimetres a year.

Whilst this sounds a small rise, in geological terms it's massive, and geoscientists regard it as a growth spurt. Dr Matthew Fox from University College London and co-author of the research report also points out other contributing mechanisms. The loss of mountain glaciers now forms part of the uplift. Tectonic stress associated with earthquake cycles may also be a factor.

But whatever the causes, those wanting to scale the summit will rise a little bit further.