[Rockhounds] Why are there continent-sized 'blobs' in the deep Earth?

[Kreigh Tomaszewski]

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
<https://www.scientificamerican.com/article/rare-diamond-confirms-that-earths-mantle-holds-an-oceans-worth-of-water/>
.

Every day the "weather" is the same: a balmy 1827C
<https://progearthplanetsci.springeropen.com/articles/10.1186/s40645-017-0139-4>
(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 <https://www.nature.com/articles/s41467-018-08071-3>.

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.

In particular, the setting in question is the lower mantle – the layer of
rock that sits just above Earth's centre, the core. This mostly-solid mass
is another world, a place that's swirled and flecked with a kaleidoscope of
crystals, from diamonds – there are around a quadrillion tonnes
<https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018GC007534> of them
in the mantle in total – to minerals so elusive, they don't exist on the
surface.


https://www.bbc.com/future/article/20220510-why-are-there-continent-sized-blobs-in-the-deep-earth