In a strange corner of our solar system there are two amorphous alien masses.
They are the size of continents, and it is believed that they spend their time waiting for sustenance to fall on them, which they then simply absorb.
Its natural habitat is even more unusual than its diet.
It might be described as “rocky”: all around it are exotic minerals in unknown shades and shapes.
It is otherwise fairly barren, except for a glittering sea in the distance, so vast that it contains as much water as all the oceans on Earth put together.
Every day the “weather” is the same: a few warm 1.827°Cand its pressure in some areas is equivalent to regarding 1.3 million times that of the Earth’s surface.
In this crushing environment, atoms warp and even the most familiar materials begin to behave eccentrically: rock is flexible like plastic, while oxygen behaves like a metal.
But this scorching hot spot isn’t on an alien planet, and those masses aren’t strictly wildlife.
It is, in fact, on Earth, only deep inside it.
In that strange world
The environment in question is the lower mantle, the layer of rock that sits just above the planet’s core.
That mostly solid mantle is another world, a swirling place dotted with a kaleidoscope of crystals, from diamonds (of which there are regarding a quadrillion tons) to minerals so rare they don’t exist on Earth. planet surface.
In fact, the most abundant rocks in this layer, bridgmanite and davemaoite, are largely a mystery to scientists.
They need the ultra-high pressures unique to the interior of the planet to develop and they crumble if they are brought into our realm.
We can only see them in their natural form when they are trapped inside the diamonds that reach the surface. And even then, it’s impossible to know what they actually look like inside the Earth, as their physical properties are so different at the pressures they normally exist under.
For its part, that distant “ocean” does not contain a single drop of liquid.
It is made from water trapped within the mineral olivine, which makes up more than 50% of the upper mantle. At deeper levels, it transforms into indigo blue ringwoodite crystals.
“At those depths, the chemistry totally changes,” says Vedran Lekić, associate professor of Geology at the University of Maryland (USA).
“As far as we know, there are some minerals that become more transparent,” he says.
But it is those amorphous masses that most intrigue geologists around the world.
a complicated problem
In 1970, the Soviet Union embarked on one of the most ambitious exploration projects in human history: it attempted to drill as deep as possible into the Earth’s crust.
That solid layer of rock, sitting on top of Earth’s mostly solid mantle and eventually partially molten core, is the only part of the planet that has never been seen by human eyes.
Nobody knew what would happen if they tried to go through it.
In August 1994, the Kola superdeep well, located in the middle of an inhospitable expanse of arctic tundra in northeastern Russia, had reached amazing depthsextending some 12,260 meters underground.
At the start, the team leading the project made predictions regarding what they expected to find, specifically that the Earth would warm one degree for every 100 meters they traveled toward its center.
However, it soon became clear that this was not the case: in the mid-1980s, when they reached 10 km, the temperature was already 180°C, almost double what was expected.
But then the drill got stuck.
Under these extreme conditions, the granite was no longer drillable: it behaved more like plastic than rock.
The experiment was stopped and no one has managed to cross the threshold of the crust to this day.
“We know much less regarding the Earth’s mantle than we do regarding outer space. -which we can observe with telescopes-, because everything we know is very, very indirect”, says Bernhard Steinberger, Geodynamics researcher at the University of Oslo (Norway).
So how do you study an environment that cannot be seen or accessed, where even the chemical properties of the most common materials are distorted beyond recognition?
Turns out there is another way.
inverted coconut
Seismology involves the study of energy waves produced by sudden ground motion during massive events such as earthquakes.
Among them are the so-called “surface waves”, which are superficial, and the “internal waves”, which travel through the interior of the Earth.
To capture them, scientists use instruments on the opposite side of the world from the earthquakes they are detecting and examine everything that has made its way.
By analyzing the different wave patterns they can begin to piece together what might be happening hundreds of miles underground.
It is these characteristics that allowed the Danish geophysicist Inge Lehmann to make an important discovery in 1936.
Seven years earlier, a major earthquake in New Zealand had led to a surprising seismic result: a type of internal wave, which can travel through any material, had managed to pass through the Earth, but it had been “bent” by an obstacle in the way.
And, another type of wave, which cannot pass through liquids, had not been able to pass.
This overturned the long-standing belief that the core was completely solid and led to the modern theory that there is a solid interior enveloped in a liquid outer shell, a kind of inverted bogeyman, if you will.
A mystery hidden deep inside
Over time the method was refined, making it possible to visualize the hidden depths of the Earth in three dimensions, “using the same techniques as computed tomography” used in medicine, Lekić explains.
Almost immediately, this led to the discovery of the two amorphous masses of the Earth.
Called “Large Low Shear Velocity Provinces” (LLSVPS), they are two colossal regions, where seismic waves meet resistance and slow down.
One of them, called “Tuzo” is found below Africa; the other, “Jason”, is under the Pacific Ocean.
As with the Earth’s core, these areas are distinctly different from the rest of the mantle and are some of the largest structures on the planet.
Their structures are thousands of kilometers wide and occupy 6% of the volume of the entire planet.
Estimates of its heights vary, but Tuzo is believed to be up to 800 km high, which is equivalent to around 90 Everests stacked on top of each other.
Jason might stretch 1,800km up, which translates to around 203 Everests.
Their misshapen bodies are clinging to the core of the Earth, like two amoebas to a speck of dust.
“There is 100% certainty that these two regions are, on average, slower [en términos de la rapidez con que las ondas sísmicas se mueven a través de ellas] than the surrounding region. That is not up for debate,” says Lekić.
“The problem is that our ability to see in that region is blurry.”
Aside from how titanic their forms are, almost everything else regarding them remains uncertainincluding how they formed, what they’re made of, and how they might be affecting our planet.
Scientists know something is going on there and are trying to figure out exactly what, believing that understanding them would help 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 parts of the world.
They might even shed light on the ways the Earth is likely to change over the next few millennia.
* If you want to know regarding various theories that are being considered regarding Tuzo and Jason, Click hereand read the original note on BBC Travel (in English)
