The tallest peak on Earth was once 50metres than its current height – but it’s been a pretty slow growth spurt.
New research has revealed that Mount Everest has grown by up to 50metres (160ft) in the last 85,000 years.
This is because a nearby river network has been cutting into the landscape around the mountain, pushing its peak further upwards.
The erosion from the river is creating a massive gorge, causing Mount Everest to grow by up to 2mm every year.
That might not seem like a lot, but researchers say this just demonstrates how much our planet’s surface changes over time.
Study co-author, PhD student Adam Smith of UCL Earth Sciences, said: ‘Mount Everest is a remarkable mountain of myth and legend and it’s 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.’
The study, published in the Nature Geoscience journal, looked at the erosion rates of the Arun, the Kosi and other rivers in the region.
They concluded that about 89,000 years ago the Arun river joined and merged with the Kosi river network, causing more water to be funnelled through the Kosi river, increasing its erosive power.
With more of the land washed away, it triggered an increased rate of uplift, pushing the mountains’ peaks higher.
Lead author Dr Xu Han of China University of Geosciences added: ‘The changing height of Mount Everest really highlights the dynamic nature of the Earth’s surface.
‘The interaction between the erosion of the Arun river and the upward pressure of the Earth’s mantle gives Mount Everest a boost, pushing it up higher than it would otherwise be.’
Mount Everest is 8,849metres (29,032ft) tall, and is about 250metres (820ft) taller than the second-tallest peak in the Himalayas mountain range in Nepal.
However Everest is seen as a bit of an outcast because the next three tallest peaks – K2, Kangchenjunga and Lhotse – all differ only by about 120metres (393ft) from each other.
Experts say this can be explained by an uplifting force caused by pressure from below Earth’s crust after the nearby river eroded away a large amount of rocks and soils.
This process causes a section of the Earth’s crust to float upwards because the intense pressure beneath the Earth is greater than the downward force of gravity.
Today, the Arun river runs to the east of Mount Everest and merges downstream with the larger Kosi river system.
Over millennia, the Arun has carved out a substantial gorge along its banks, washing away billions of tonnes of earth and sediment.
Co-author Dr Jin-Gen Dai of UCL Earth Sciences said: “‘An interesting river system exists in the Everest region. The upstream Arun river flows east at high altitude with a flat valley.
‘It then abruptly turns south as the Kosi river, dropping in elevation and becoming steeper.
‘This unique topography, indicative of an unsteady state, likely relates to Everest’s extreme height.’
Everest isn’t the only peak which benefits from the growth spurt. Lhotse and Makalu, the world’s fourth and fifth highest peaks, are also growing thanks to the river’s erosion.
Co-author Dr Matthew Fox of UCL Earth Sciences said: ‘Mount Everest and its neighbouring peaks are growing because the isostatic rebound is raising them up faster than erosion is wearing them down.
‘We can see them growing by about two millimetres a year using GPS instruments and now we have a better understanding of what’s driving it.’
Get in touch with our news team by emailing us at webnews@metro.co.uk.
For more stories like this, check our news page.
Get your need-to-know
latest news, feel-good stories, analysis and more
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
