Mount Everest – Why is it still rising?
Discover the surprising role of river erosion in Mount Everest’s rise. Recent research unveils how the nearby Arun River’s erosion may be adding to Everest’s height, as scientists explain the fascinating process of isostatic rebound and the impact of “river piracy.”
Mount Everest, the grandest of all peaks, towers at a staggering 8,848.86 metres above sea level. But how did this mighty mountain manage to overshadow all others? Recent research has unveiled some rather startling revelations about its height and the role a nearby Himalayan river plays in its ascent.
According to scientists, Mount Everest’s increasing altitude is tied to river erosion, specifically from the Arun River, which flows a mere 75 kilometres from the mountain’s base. Geologists assert that this river has contributed to a height increase of anywhere between 15 to 50 metres. It’s a bit like the mountain’s got a cheeky little helper working behind the scenes.
A recent study published by University College London (UCL) specifically highlights this phenomenon of river erosion. The river in question, Arun, has been identified as a key player in Everest’s lofty ambitions. But don’t get too comfortable; it’s not just Mount Everest that’s stretching skyward. All the peaks in the surrounding Himalayan region are following suit.
Co-author of the research, Adam Smith, illustrated this process with a rather colourful analogy. Imagine a cargo ship unloading its wares. Once the load is lifted, the vessel floats higher in the water. The same principle applies to Everest: as erosion takes its toll, the mountain finds itself a tad lighter, allowing it to rise even higher.
Smith noted that the Everest region is elevating by at least two millimetres each year due to the Arun River’s erosion. This means the mountain’s official height now stands at 8,848.86 metres (or 29,031.69 feet, for those of you who prefer the imperial system). It’s as if Everest decided to give itself a new pair of shoes and strut a little taller.
But how did Everest come to be in the first place? Its formation is a tale of two tectonic plates—the Indian and the Eurasian plates—colliding over a span of 40 to 50 million years. These geological forces have shaped the iconic peak we know today.
UCL’s research paper meticulously details how the river’s erosion has altered the geography of the Himalayan region. The Arun River has effectively adjusted the underlying crust, causing the land to rise further skyward. If you thought Everest was a drama queen before, just wait until you see its siblings! Other nearby peaks like Lhotse and Makalu are also gaining height, thanks to the process of isostatic rebound, which has been reducing their erosion and giving them a boost.
Once upon a time, the Arun River was burdened with an immense load of sediment. However, about 89,000 years ago, it lost a territorial battle to another river, the Koshi, which flows down from Tibet, leading to an uptick in erosion rates. Geologists have whimsically dubbed this phenomenon “river piracy.”
In essence, scientists explain that the Earth’s outer crust is essentially floating on the semi-liquid layer known as the mantle. Following the merger of the Arun and Koshi rivers, the erosion led to a significant decrease in the weight above the mantle, allowing the land to rise even more. It’s a case of “less is more,” it seems!
A paper titled “Recent Rise of Chomolungma Enhanced by River Drainage Piracy,” published in Nature Geoscience, also corroborates these findings. But not everyone is entirely convinced. Some geologists, like Professor Hugh Sinclair from Edinburgh University, argue that while the theory makes sense, there are gaps. The rivers’ distance from Everest’s base raises questions about how much interaction truly influences the mountain’s height.
Similarly, Mike Searle from Oxford University has pointed out the challenges of pinpointing the timing and direction of river erosion. The crux of the argument, he suggests, lies in geography itself; he’s sceptical that river erosion plays a major role in the mountain’s uplift.
Despite these reservations, UCL researchers have confidently dismissed the sceptics. They’ve employed numerical models to trace river evolution accurately, claiming that isostatic rebound accounts for about 10% of Everest’s annual rise.
In conclusion, it seems that Everest’s relentless ambition to reach for the heavens may have a little help from the rivers below. While some scientists might squabble over the finer details, the notion that a humble river could boost the world’s tallest mountain is as delightful as it is astonishing. So, next time you gaze at Everest, remember: it’s not just a mountain; it’s a monument to geological mischief and a testament to the tenacity of nature!
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