YouTube Transcript:
The Graveyard at the Center of the Earth
Skip watching entire videos - get the full transcript, search for keywords, and copy with one click.
Share:
Video Transcript
without plate tectonics the Earth would
look very different than it does today
our mountain ranges oceans volcanoes and
even entire continents all get their
recognizable features from the shifting
Rock plates on the Earth's mantle and
those features are pretty good evidence
that plate tectonics works but knowing
if something works doesn't always mean
we know why or how it works and when it
comes to plate tectonics continents move
in complicated ways scientists have been
trying to solve the mystery of why plate
tectonics works the way it does for over
a 100 years and they might have just
uncovered a key to cracking it the
answer may be buried in a bizarre mirror
World deep inside the Earth where
movement beneath the surface looks a lot
like it involves the remains of former
crustal rocks pieces of crusts we
thought disappeared hundreds of millions
of years ago but now live inside the planet
planet
plates when scientists first embraced
plate tectonics around the 1960s the
theory explained many observations about
the planet the idea that earth's surface
is made of Rocky plates moving over a
molten mantle explains why large
mountain ranges form in the middle of
oceans for example because Earth's
mantle is creating new plates and why
deep trenches form at the edges of the
oceans where one plate is diving beneath
another tying together these
observations geologists realized that
tectonics works as a system plates are
created at mid ocean ridges then move
away from them and finally disappear
back into the Earth at subduction zones
creating most volcanoes and many large
earthquakes in the process but even
though the theory that recognized the
constant cycle by which land forms are
created was a breakthrough it didn't
exactly explain how thisen happens what
force could move massive plates which
can weigh a madeup sounding five
quillion tons around like Driftwood
early in the days of plate tectonic
theory geologists and geophysicists
assumed plates moveed because of mantle
convection currents of hot molten
material Rising inside the earth pushed
the plates dragging them along the
surface the way Rising bubbles move foam
in a pot of boiling water logically that
idea makes sense but scientists quickly
realize that the physics of mantle
convection don't totally add up now the
mantle definitely does have currents
since 1971 scientists have known that
Rising plumes of magma travel from deep
inside the Earth to the surface creating
islands like Hawaii and Iceland but
around the same time researchers also
realized something about the Mantle's
makeup that complicates the effect those
currents could possibly have see they
they were looking at how continents
moved during ice ages when the weight of
massive ice sheets pushed them down into
the mantle and how when the ice leader
melted the same continents began popping
back up so they used data from a
satellite to measure the gradual upward
movement of the continent relative to
the ocean's surface to see just how fast
the now de glaciated continents were
popping back up and even though they
couldn't see the mantle below the
continents knowing the rate at which the
mantle pushed continents up let
scientists calculate its viscosity that
is how runny it is they found that the
Earth's mantle is much runnier than
expected later researchers estimated
that the mantle is about a billion times
runnier than the lithosphere or crust
that sits on top of it so those mantle
currents simply couldn't be enough to
move the plates the way we know they
move there must have been another Force
helping Propel this movement even more
mysteriously geophysicists modeling
Earth's mantle and continents found the
Earth should have what's called a
stagnant lid where the lithosphere sits
in place on the surface as mantle
currents move underneath in fact Earth
is the only place we know for sure where
continents move crash into each other
Rise and Fall so why does Earth have
such unique tectonics it all comes back
to the mantle which as scientists noted
back in the 1960s s shapes an important
feature of tectonic subduction that's
the process where plates slip underneath
another driving back towards the center
of the planet and while it's another
process that we can't directly see it's
one scientist inferred must be taking
place once they noted some odd features
of earthquakes with the installation of
big seismograph networks geophysicists
could suddenly tell exactly where and
how deep earthquakes happened and when
they looked at Big trimmers in places
like Alaska they saw earthquake
epicenters were far below the crust in
fact some earthquakes were happening
hundreds of kilometers down inside the
mantle that suggests that the stress of
the plate bending deep down is
triggering these earthquakes researchers
realized that these Quakes were like a
sonar scan revealing locations of where
plates were driving down into the mantle
they were seeing the edge of the
subducting plate that had disappeared
under another plate long ago Earth is
also the only planet we know where
subduction connects the surface to the
interior in a major way and scientists
soon figured out that subduction helps
explain why tectonics works the way it
does because as geologists reasoned if
plate edges sink into the mantle they'd
likely pull on the rest of the plate
dragging it along initially this was
purely logical speculation again we
can't see any of this but when
scientists plugged this new Force called
slab pull into models the calculations
worked better than mantle convection
alone but even with extra force from
slab pole added into the equation the
model still didn't quite fit Earth's
tonics plates still moved faster than
the models predicted there must be other
forces helping move the continents so
scientists kept digging in the mid 1970s
they noted that mid ocean ridges are
usually topographic highs so as new
plate material moves away from The
Ridges it travels downward as if
descending from a mountain this is due
to gravity pulling down adding a little
force in the process scientists call
Ridge push and scientists found this
does help move us closer than the two
forces of convection and slab pull alone
but according to the models the addition
of Ridge push still wasn't enough to
explain how fast our continents move
either there had to be something else at
least one more Factor scientists then
turned to another possible force acting
on continents in the 1980s something
they called slab suction slab suction
happens when the mantle flows around a
sinking plate Edge pulling it downward
more than just gravity alone like in
movies where people swimming away from a
sinking ship get sucked under water as
the boat disappears below the surface so
in the early 2000s scientists added slab
suction to their models and found this
matched observed plate movements a lot
more than before so now we have four
forces helping move continents mantle
convection Ridge push slab pull from the
weight of the plate sinking into the
Earth and slab suction pulling even
harder as those plates get sucked into
the lower mantle adding together all
these forces we get a better idea of why
Earth's tectonics Works plates are
created at mid ocean ridges and get
pushed away from those ridges by gravity
and mantle currents eventually plates
dive back into the mantle pulling the
plates along with suction then dragging
them down even harder but what makes
those pieces subduct and sink back into
the mantle this isn't something we see
happening on any other planets in our
solar system this is where the bizarre
mirror world comes in see seismic
studies done in the mid-20s show two
huge zones of something unusual at the
base of the mantle one below the Pacific
Ocean and another underneath Africa when
seismic waves hit these zones they slow
down unlike how they move through the
rest of the mantle geophysicists call
these massive 15,000 km wide features
large low velocity provinces or
lvps they can tell from the way lvps
react seismically that they're probably
denser than the surrounding mantle and
possibly made of different different
material and the strangest thing is
these lvps seem to move around much the
same way continents do on the Earth's
surface they Collide assemble and
possibly even break apart just like
continents in fact scientists recently
uncovered evidence that some of them
might actually contain the remains of
continents that used to be on the
Earth's surface conents we thought
disappeared hundreds of millions of
years ago the geophysicists running the
models to figure out what lvps might be
made of found that they could be the
remains of old surface plates that sunk
towards the core of the Earth in a giant
pile like a graveyard the idea of this
slab graveyard could explain a few
things we see at the surface like how
erupting lavas in places like Hawaii are
oddly enriched in the isotope helium 3
or how volcanoes in both the South
Pacific and off the West African Coast
erupt unusually high amounts of uranium
those are both elements we'd expect to
see on Earth's surface rather than in
plumes from the mantle but helium and
uranium makes more sense if remnants of
Earth's surface sunk deep into the
mantle are feeding plume eruptions so
those mirror slabs inside the lower
mantle are probably at least partly the
remains of old plates that got subducted
and then sank and they're invisible to
us at the surface it seems they continue
to play a role in plate tectonics like
they probably determine mantle currents
when plotting major mantle plumes that
have erupted onto Earth's surface
geologists noticed that they all seem to
burst forth from lvp zones and these
could also be the reason we have
subduction although most subduction
zones lie well away from these deep
Earth structures it might be the case
that mantle currents rise above llv PS
pushing plates off to the sides then
once the plates are pushed away from the
upwelling plume above lvps they start to
sink subducting when researchers plug in
all the data we have on the mantle and
the movements of continents that
scenario is exactly what they see and it
all comes full circle when the sinking
plates absorb back into the lvp
graveyard deep in the mantle and the
cycle continues now not all scientists
agree with this theory for example
there's debate about whether mantle
plumes rise from the center of llv PS or
from their edges scientists also argue
about whether lvps stay in one place or
migrate around the mantle another
hypothesis argues that lvps are actually
the remnants of an ancient planet that
crashed into early Earth which we talk
about in our episode when Earth ate a
planet overall lvps are pretty
mysterious even after Decades of
research into plate tectonics and a
solid understanding of how it works the
question of why it works has been harder
to pin down but it appears that from
deep in the Earth this ancient mirror
world has something to do with driving
tectonics the thing that makes our
planet unique as far as we know and
given that the mirror plates seem as
active as the surface continents the
future of tectonics could be as
surprising as this bizarre Discovery [Music]
itself eons is possible thanks to rad
viewers like you who back us on patreon
your support of our videos through
patreon is vital in keeping our
educational Mission going whether it's
the research and production of our
videos commissioning accurate paleo art
and of course paying our wonderful hosts
this all happens thanks to your support
patrons get access to special videos
from our hosts digital puzzles with our
paleo art and at the E onology level
shout outs in our episodes to show our
we're declaring Patron appreciation
month become a patron at the Paleozoic
level by March 31st and you will get the
very first eon's Trading Card created by
our team of paleo artists and writers
this art is also featured on our new
peran t-shirt which absolutely rules
many eon's viewers remember that for a
good long time our videos used to end
with a shout out to one of our patrons
Steve now you can be Steve a super
terrific extremely vital e onology for
every month we have 50 members in this
new patreon tier we'll shout out Steve
in our videos and to celebrate with the
entire eons Community this Patron
appreciation month there will be a live
stream on March 27th 2025 thank you for
all your support so we're still figuring
out the details of plate Tech tonics but
we can clearly see the effects on our
modern world if you know where to look
join Michelle Barbosa Ramirez and Blake
de pastino on a field trip to explore
the Epic Natural History Saga of La in
our episode how plate tectonics
transformed Los Angeles we got to think
this month's a tectonic e onology Addie
Annie and Eric Higgins Carl wolle Jackie
Scott Rolston Jake Hart John Davidson
ing Juan M Melanie lamb carnavale Nico
Robin and Rafael hassa become an eonite
at patreon / eons and you can get fun
perks like access to a monthly digital
paleo art puzzle and as always thank you
for joining me in the kinb bar studio
subscribe at youtube.com/ eons for more
time continental drift came out in 1912
and everybody was like y'all crazy y'all
crazy and then around the 1960s they're
like H maybe you're not as crazy as we
thought you were so it took like 50
years for scientists to be like no this
Click on any text or timestamp to jump to that moment in the video
Share:
Most transcripts ready in under 5 seconds
One-Click Copy125+ LanguagesSearch ContentJump to Timestamps
Paste YouTube URL
Enter any YouTube video link to get the full transcript
Transcript Extraction Form
Most transcripts ready in under 5 seconds
Get Our Chrome Extension
Get transcripts instantly without leaving YouTube. Install our Chrome extension for one-click access to any video's transcript directly on the watch page.
Works with YouTube, Coursera, Udemy and more educational platforms
Get Instant Transcripts: Just Edit the Domain in Your Address Bar!
YouTube
←
→
↻
https://www.youtube.com/watch?v=UF8uR6Z6KLc
YoutubeToText
←
→
↻
https://youtubetotext.net/watch?v=UF8uR6Z6KLc