Why are there continent-sized 'blobs' in the deep Earth?They're among the largest physical structures on the planet – and they're a total mystery.By Zaria Gorvett
11th May 2022
In a strange corner of our solar system live two alien blobs.
With sprawling, amorphous bodies the size of continents, these oddities are thought to spend their time lying in wait for their food to rain down upon them – then simply absorbing it.
But their natural habitat is, if anything, even more unusual than their diet. It could be described as "rocky" – all around, there are exotic minerals in unknown shades and forms. Otherwise it's fairly barren, except for a glittering sea in the far distance – one so large, it holds as much water as all of Earth's oceans put together.
Every day the "weather" is the same: a balmy 1827C (3321F), with some areas of high pressure – equivalent to around 1.3 million times the amount at the Earth's surface. In this crushing environment, atoms become warped and even the most familiar materials start to behave in eccentric ways – rock is flexible like plastic, while oxygen acts like a metal.
But this blistering wonderland is no extra-terrestrial planet – and the blobs aren't strictly wildlife. It is, in fact, the Earth itself – just very, very deep underground.
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The structures are thousands of kilometres wide and occupy 6% of the volume of the entire planet. Estimates of their heights vary, but one – found under Africa and known affectionately as "Tuzo" – is thought to be up to 800km (497 miles) high, equivalent to around 90 Everests stacked on top of each other. The second – "Jason", below the Pacific – might extend 1,800km (1,118 miles) upwards, translating to around 203 Everests. Their misshapen forms are moulded around the Earth's core like two amoebas clinging to a speck of dust.
"These features are very large, very prominent in tomography [a kind of imaging]," says Bernhard Steinberger, a geodynamics researcher at GFZ German Research Centre of Geosciences and the University of Oslo in Norway. And though these titanic shapes are almost certainly there, almost everything else about them remains uncertain – including how they formed, what they're made of, and how they might be affecting our planet.
Crucially, understanding the blobs could help to unravel some of geology's most enduring mysteries, such as how the Earth formed, the ultimate fate of the "ghost" planet Theia, and the inexplicable presence of volcanoes in certain locations around the globe. They may even shed light on the ways the Earth is likely to change over the coming millennia.
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Source:
https://www.bbc.com/future/article/20220510-why-are-there-continent-sized-blobs-in-the-deep-earth
