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Tectonic Forces
There was once a time when you could take
a stroll from North or South America to Africa
no problem.
There was no ocean to get in the way, because
all of Earth’s continents were stuck together
in one massive supercontinent called Pangea.
But around 180 million years ago, a rift began
to form, and since then, the Americas and
Africa have been drifting apart, forming the
Atlantic Ocean in the process.
Weird, right?
Despite its rock-solid appearance, Earth’s
surface is constantly shifting and drifting.
That’s thanks to something called plate
tectonics.
Unlike other planets, Earth’s crust isn’t
simply a single shell.
It’s got big slabs of crust called tectonic
plates that float on an ocean of slowly flowing
rubbery molten rock.
These plates move because of heat from Earth’s
core.
Earth’s radioactive core generates an immense
amount of heat that keeps our planet from
completely cooling over.
Less dense molten rock travels from the core
to the surface, where it then cools and returns—a
process called convection.
Like a slowly moving conveyor belt, this rising
and sinking heat and molten rock pushes or
pulls the plates together or apart.
Through collisions, these plates can raise
great mountains or send ocean floor to the
depths of Earth’s molten interior.
When they move apart, new crust is formed,
and with it, entirely new oceans can be created.
The formation of new ocean crust occurs at
volcanic ‘mid-ocean ridges.’
The destruction of old ocean floor happens
in ‘subduction zones.’
The creation and destruction of seafloor ultimately
drives the gradual shift in the arrangement
of continents on Earth.
Scientists think that it could be possible
to walk across a single, Pangea-like continent
once again—in just a couple hundred million
years…
Presented by NASA Space Place.
For a transcript of this video
and a fun downloadable poster
visit the Space Place.
