NARRATOR: Earth, a unique
planet, restless and dynamic. Continents shift and clash,
volcanoes erupt, glaciers grow and recede, titanic forces that
are constantly at work, leaving a trail of geological
mysteries behind. This investigation ventures
deep into remote Russia in search of a vast sea of
stone called the Siberian Traps. Experts will dig deep
into Earth's ancient past to discover how this
rocky wilderness formed, and unearth evidence
in surprising places to prove how deadly volcanic
eruptions in Siberia wiped out nearly every
living thing on Earth. The most dramatic
episode yet in the story of "How The Earth Was Made." [music playing] The investigation into
the cataclysmic event that radically changed planet Earth
begins in the deep frozen land of Siberia. 50% bigger than the
entire United States, this land is locked in
ice for most of the year. Temperatures plummet to minus
90 degrees Fahrenheit and below. But in summer, the
ice melts and reveals one of the largest and
most mysterious geological formations on Earth,
the Siberian Traps. Nearly 5% of Earth's landmass
is covered by this ancient sea of rock. Deep canyons expose layers
hundreds of feet thick. These giant stepped
formations are called traps from the Swedish
word for stairs. They were discovered under
unusual circumstances. Polish geologist
Aleksander Czekanowski was exiled to Siberia in
1863 for political crimes against Russia. While banished, he
surveyed the landscape and stumbled upon this
unique, unexplained expanse of layered rock. Today, the journey
to fully understand how this strange stone formation
was made begins in a swamp. I'm not sitting in
this swamp just for fun. This swamp's actually very
characteristic of what Siberia was probably like before
the Siberian Traps formed. This vegetation, this
shallow, stagnant water is very different
to the environment we see in Siberia today. NARRATOR: The clue that enabled
scientists to figure out that Siberia was once a swamp
came from a particular kind of rock found beneath the traps,
coal, trillions of tons of it. This rock here is coal. It's very important in Siberia. It forms when plant matter,
trees, and thick vegetation dies and falls into a
swamp, and over millions of years of geological
time, they're compressed into a
hard rock substance, like what I'm holding
in my hand today. NARRATOR: The age of
the coal was determined by dating the plant fossils
trapped inside the rock. The process revealed that the
coal was formed more than 300 million years ago. It continued to collect and
be compressed over the next 50 million years. So the environment was
fairly stable swamps, thick vegetation, then suddenly,
250 million years ago, it all stops, and you have the Siberian
Traps lying on top of the coal. So something very dramatic must
have happened at that time. So we really need to
study this phenomenon to investigate the geology
and see what we can find out. NARRATOR: But investigating the
geology of the Siberian Traps is no easy task
because they're located in one of the most remote
and least explored areas of the planet. It's an arduous journey
for Howard and his team, a 1,000-mile trek through
Siberia over land and water, camping out in
mosquito-infested forests. Taken us nearly seven days
to get to this remote corner of Siberia, but this afternoon,
we finally found the rocks that we were hoping to study. NARRATOR: These towering
pinnacles of rock mark the edge of the Siberian Traps. Even from a distance,
without leaving their boat, the geologists can identify
this distinctive formation. The rocks you
can see behind me are all basalts forming
wonderful towers. We stopped and studied
these in several locations, and what we've seen is only
a tiny part of the basalt covers such a large
part of Siberia. NARRATOR: This evidence
unlocks the mystery of how the traps were made. Basalt is what geologists
call igneous rock, and that only comes from one
source, a volcanic eruption. The Siberian Traps must once
have been of vast, red hot lava field. CLIVE OPPENHEIMER: I think the
Siberian Traps would have been 1,000 times more
intense than anything I've seen during
my own fieldwork. And if I could go
in a time machine and watch it all happen,
it would be really just fantastic to see
the scale of it. The length of the lava
flows and the height of the fire fountains would have
been really something to see. NARRATOR: There are
several types of lava rock. This basaltic lava is a
free-flowing liquid when it first erupts from the ground. Just looking at
how fluid this-- this rock appears gives us some
of the clues what it might have been like in Siberia if
we could have gone there. There would've been
really gooey, goopy, runny lava flowing across
the land surface for 1,000 miles in all directions. NARRATOR: This semi-liquid
lava gives these rocky planes their name, flood basalts. They still erupt today
in Kilauea in Hawaii, currently the world's
most active volcano. After 25 years of
constant eruption, the basalt lava
field has engulfed more than 4 square miles
of Hawaii's big island. But the Siberian Traps are
bigger, 500,000 times bigger. Each distinct step is laid down
by an individual lava flow. Layer pours out upon layer until
the traps are more than a mile deep in black hard
top over an area nearly the size of
the continental US. So imagine the
entire United States covered in a lumpy, uneven
parking lot, like asphalt everywhere as far
as the eye can see, and that is what the Siberian
Traps looks liked when it first formed. NARRATOR: Geologists have
discovered how the traps were made. The next step is calculating
how long this vast Siberian super eruption lasted. Fortunately, volcanic rocks
contain little minerals that formed when the rock
crystallized when the rock cooled and solidified,
and some of these minerals are radioactive and
they decay over time. And so they're like
little time clocks. They start when the rock cools,
and then when we measure them, the clock stops, and we know how
much time has passed since that rock formed. NARRATOR: Dating the oldest lava
here reveals that the Siberian Traps first ripped the landscape
apart 250 million years ago. And by also dating
the youngest lava, scientists can figure out
exactly how long the eruptions lasted. The results are surprising. They show that lava carried
on pouring out and building up into ever deeper layers for
an almost unimaginable one million years, forging the
largest lava flow on land. The next step in the
journey is to figure out why this vast eruption
happened here in Siberia. Most volcanoes exist at
plate boundaries, thin spots on Earth's crust where the
floating plates that support the continents jostle
together as they drift across the face of the Earth. Yet, the Siberian Traps
are right in the heart of a huge continent,
so experts have to come up with an explanation. This is a mantle plume. It may not look like it, and
you have to imagine that this is going on over about 1,500
miles rather than a bottle, but it's quite a good simulation
of how mantle plumes work. They're heated from below. This candle is the Earth's
core supplying heat, and this is the
bottom of the mantle, and the heat is heating
up some of the mantle, and it rises up as these blobs
up towards the Siberian Traps, which are up at the top here. NARRATOR: Mantle plumes are one
of geology's great mysteries. No one knows why they
switch on or off, but their shape is a crucial
clue as to why plume eruptions are so fierce and so massive. That mushroom
head, in reality, can be 1,500 miles across. And so the volcanic eruptions
can cover huge areas, hundreds of thousands of square miles. And also, the--
the actual head is is a very short-lived
phenomenon. That probably erupts in
hundreds of thousands of years, at most, a million years. NARRATOR: Evidence
has been uncovered to reveal how and when
the Siberian Traps formed. 250 million years ago,
a vast magma bubble burst, cracking and
slashing open Earth's crust. And for life on Earth, a
new devastating era began. Two types of rock are proof
of very different landscapes in ancient Siberia. Coal reveals that before
the traps existed, this area was a swamp. Basalt lava is evidence
this era ended with a bang, a super volcanic eruption. But now, geologists have
evidence that the Siberian supervolcano was about to become
Earth's greatest ever killer. The deadliest million
years in Earth's history were about to begin. 300 million years ago,
Siberia was a swamp. But deep underground, a plume
of hot mantle rock was rising. 250 million years ago, the
bulging crust burst open, and boiling lava erupted
onto the surface. The most cataclysmic
and destructive million years in Earth's
existence was about to begin. With every eruption, basalt
lava surged across Siberia in rivers and waves. Terrifying forest fires raged. Animals were burnt alive. A new deadly Earth
story was underway, one which would have
catastrophic consequences for all life on Earth. To figure out what chaos
this mega eruption caused for the planet, geologists
are taking a closer look at Siberia's ancient lava rocks. This rock is very typical of
what you see in flood basalt provinces. And we have many what
we call vesicles. They're small holes in the
rock, and those suggest the gases left this rock. They escaped from this rock
when this rock started cooling at the surface of the Earth. NARRATOR: The search
for what kind of gas Siberia was producing
begins nearly 8,000 miles away at Mammoth
Mountain in California. This is an ancient
dormant volcano. For years, it was
thought to be harmless, but then in 1989, a ranger
had a terrifying experience. CHRISTOPHER FARRAR:
It was wintertime, and the ranger was just
checking on the area, and He wanted to take
a break from the wind, so he crawled in
through a hatch that's in the roof of this cabin, and
he became very dizzy inside and didn't feel well. And he had the common sense
to think that maybe there was some bad air in the
cabin, and he crawled back up the ladder and
got out safely, but it always kind of
remained a mystery initially. NARRATOR: Then, just a few
months later, the trees here began to die. Clearly, something
strange was happening. CHRISTOPHER FARRAR: So it
required an explanation of what could combine with
making a person feel dizzy and disoriented,
and would also kill trees at the same time. NARRATOR: Farrar's research
revealed that a poisonous gas was to blame, one that
was seeping upwards out of the ground. Analysis proved that the gas
was carbon dioxide, a byproduct of volcanic activity. It's released when magma
rises from deep underground. So just like this
bottle of soda water, the magma beneath us contains
dissolved carbon dioxide. And when it reaches the
surface of the Earth, the pressure is
released, just like this, when you open the water,
the pressure is released, and carbon dioxide is coming out
of this bottle of soda water, and that's the same gas that's
coming out here at Mammoth. NARRATOR: Today, lava deep
beneath Mammoth Mountain pumps out 1,000 tons of
carbon dioxide every day. This suggests to scientists
that trillions of tons of gas could have been released
into the atmosphere by one of the Earth's
largest eruptions in Siberia 250
million years ago. And evidence comes from
an unlikely source. Well, this is a ginkgo
tree, and ginkgo trees are very special, because the
ginkgo family has been around for a very long time,
270 million years, and it's remained fairly
unchanged over the course of of Earth's history. NARRATOR: Because the ginkgo
changes so little over time, it is the ideal specimen
for comparing the present with the past. The leaf surface is peppered
with microscopic pores called stomata. Plants use these
stomata like tiny mouths to breathe in carbon dioxide. The number of stomata
on the leaves of a ginkgo indicate how much carbon
dioxide is available to them in the atmosphere. When there's a lot of carbon
dioxide in the atmosphere, they only need to have a few. When we look at fossils
of ginkgo leaves that formed 250
million years ago, we noticed that they have very,
very few stomata to take up carbon dioxide, and
this means that there was a lot of carbon dioxide
available in the atmosphere. NARRATOR: Investigators
have studied ancient leaves from locations
all over the world and calculated that there was
three times more carbon dioxide in Earth's atmosphere 250
million years ago than there is today. This was a deadly and
global gas disaster. And the only culprit
capable of producing such substantial quantities
of carbon dioxide is volcanic activity on
a truly massive scale. STEPHANIE INGLE: When you
have an eruption the size of something like
the Siberian Traps, you imagine something almost
apocalyptic in nature, ash blocking out the sun. But then you have a
kind of double whammy, where you also have the
release of volcanic gases from the eruptions, and
these gases trap in the heat, so it gets hotter and hotter. NARRATOR: Lava from
the traps turns Siberia into a lifeless disaster zone. But carbon dioxide can mingle
and mix in the atmosphere, trapping heat inside like
a parked car on a hot day. 7,000 miles away from Siberia
is South Africa's Karoo Basin. Here, evidence in
rocks gives geologists a tip off that carbon dioxide
from the eruption provoked a climate disaster that
wasn't confined to Siberia. An old river channel slices
through the landscape, exposing the layers. These rocks have been dated
to just before and just after the Siberian
Traps began to erupt. These are mud stones. They form on lake beds
from squashed mud, so they're evidence
that, just as in Siberia, the land was once swamp-like
and covered in water. But they're also
evidence of change. These rocks beneath my feet,
which are green in color, are the older rocks here. And then these rocks, which
have got a more red color, are the younger rocks. And the red color
indicates that there's an environmental change,
that the climate was possibly drying out and becoming warmer. NARRATOR: The mud
is rich in iron. When it is shaded by
plants or covered by water, it stays green. When it's exposed to the
sun, it turns rusty red. So the red stones are evidence
that plants and water, which shaded the mud, had disappeared. 250 million years ago, as
Siberia spewed volcanic gases into the air, South Africa
was drying out, warming up, and turning to desert. The Karoo Basin is also
where the first evidence was discovered that
it was not just the plants that were dying. Well, this animal
was found in 1934. My aunt, who was then a
little girl at school, she came home from school one
day and she said to her father, daddy, what is a fossil? And my grandfather's
response was, let's go off into the
hills for a picnic and see if we can find one. So they went off to the hills,
and amongst other bones, they found this. NARRATOR: In their own
backyard, the Rubidge family had unearthed the
remains of an animal completely unknown to science. This creature is a gorgonopsid. It was a carnivorous
lizard 10 feet long, which roamed South
Africa during an era called the Permian, hundreds
of millions of years before even dinosaurs evolved. But dating these fossils reveals
that as Siberia began to erupt, these animals were dying. Gorgonopsids are
the dominant predators of the Permian period. We find them in all
these different layers in the Permian rocks. Gorgons lived in this area about
260 to about 251 million years ago. Then, suddenly, when
you get higher up at this sort of level
in the Permian sequence, they disappear. NARRATOR: And the
gorgonopsids were not alone. There are virtually no
animal fossils here younger than 250 million years. 7,000 miles from the
Siberian supervolcano, something caused the land
to dry up, plants to die, and nearly every land
animal to go extinct. And one critical cause
of this Global Disaster is carbon dioxide
from the lava rocks. Yet, this deadly million
year long chain reaction triggered by Siberian eruptions
is only just starting. The investigation
has uncovered how volcanic activity in Siberia
created a global catastrophe. Fossil leaves of the
ginkgo tree reveal evidence that the atmosphere was full
of volcanic carbon dioxide. Gorgonopsid skulls show
animals were dying out at the same time. But worse was to come. The catastrophic
Siberian eruptions were about to unleash a
new murderous nightmare. 300 million years ago, Siberia
was a waterlogged, swampy bog. 50 million years later, Earth's
biggest ever volcanic eruption on land was smothering
Siberia in layer after layer of solid, silvery
basalt lava hundreds of feet thick. An atmosphere saturated
with volcanic carbon dioxide had raised global temperatures
by around 10 degrees Fahrenheit. Life on land was dying. Now, the hunt is on
to uncover evidence of how Siberia's
supervolcano precipitated a marine catastrophe in
all of Earth's oceans. But scientists aren't looking
for answers in the sea. They're climbing 10,000
feet above sea level up into the Dolomite Mountains. Here, in the mountains
of northern Italy, these rocks give evidence of
one of the greatest crises in the history of the planet. NARRATOR: Crack open
the layered rocks, and fascinating
secrets are revealed. Mysterious and long
extinct sea creatures called trilobites are
preserved in their millions. Their existence here proves
these peaks were once a seabed. The trilobites were trapped in
sediment settling on the ocean floor. Over millions of years,
geological upheavals have thrust them 2
miles up in the air. The rock layers here
are a perfect record of life in the ancient oceans. What we can see is-- just below the
level of my hand, is lots of nice fossils, a
big diversity of things we can find in here. And then these younger rocks,
just above just a little bit higher, basically, there's
few fossils in here, and much lower diversity. NARRATOR: In between the two
different layers of life, Wignall hacks into a black band. In here, there are not
just fewer fossils. Here, there are none at all. This is what geologists
call the extinction zone. It has been dated as
250 million years old. Worrying evidence that having
killed off most of the life on land, the Siberian
super volcanic disaster was spreading to the seas. This black clay contains
microscopic glittering clues, crystals of a mineral
called iron pyrite. Its shiny appearance has earned
this rock the nickname fool's gold. It's worth just a few cents, but
it holds priceless information about ocean waters where the
rock formed 250 million years ago. This mineral, this
iron pyrite will only form in the absence of oxygen,
and so, therefore, it's a nice, very direct line of
evidence for what's going on at this time. NARRATOR: The presence
of fool's gold is evidence that the
water in which it formed had no oxygen at all. And scientists believe
the warming effect of volcanic carbon dioxide
from the Siberian eruptions was directly to blame
for this lack of oxygen. The ocean circulation
is driven by the fact that we have a good
temperature gradient. It's cold at the poles, and
it's warm at the equator, and so the water circulate
between the poles and the equator like
a conveyor belt. But if you make everywhere warm,
the conveyor belt turns off, and the water just sits there
and stagnates and no longer has the ability to sort
of resupply oxygen. NARRATOR: The ocean had become
as still and warm as bath water, and warm water
absorbs less oxygen. PAUL WIGNALL: It's possible to
recreate these nasty conditions in a fish tank, in fact. All you need do
with a fish tank is to put it in the window
on a bright, sunny day. The sun will warm the
water up, and the water will start to lose
its oxygen, and it'll basically-- it'll stagnate. If you leave it for too
long, your fish will die, and you'll have a sort
of mini recreation of one of the greatest extinction
events of all time. NARRATOR: As volcanic
eruptions tore Siberia apart, life was fighting for survival
in the oxygen-depleted seas. But the Siberian eruptions were
about to flood and even more deadly poison into the oceans. To find out what happened
next, researchers hunted for a modern day location
that could recreate life in the Siberian
damaged Permian ocean. Unexpectedly, they found it in
central New York state, Green Lakes State Park. This unusual little lake is
extremely salty and nearly 200 feet deep, making
it a model in miniature of the ancient seas. We get asked, why
do you go to a lake to study the Permian ocean? Turns out, this lake is a
lot like the ocean, actually. It's fairly salty, and its
circulation system, the process that brings oxygen down
deep into this lake is shut down, just like we think
happened to the Permian ocean. NARRATOR: The top layer of the
lake is healthy and thriving, but deep down, the bottom
layer is stagnant and still. By lowering a water
sampler 150 feet down, Kump's diving deep
into the past to a time when the Siberian
traps were erupting. LEE KUMP: Well, we
have a couple of clues from this water that's telling
us about what's going on down there at the bottom of the
lake, one of which is its color. And this water is
pink, because it's loaded with tens of millions
of purple bacterial cells in each ounce of water. And the other is the smell. So if I open up the lid
here and take a whiff, it's a very potent
smell of rotten eggs, and that's a very characteristic
smell of hydrogen sulfide. NARRATOR: Oxygen is
toxic to purple bacteria, so stagnant water is a
perfect breeding ground. These single-celled survivalists
flourish where other sea life suffocates. But they have a nasty side. They produce a noxious and
pungent poison gas called hydrogen sulfide. The tiniest amounts
can be fatal. The same bacteria
live in sewers, so workers there must
carry gas detectors. Hydrogen sulfide deprives
your body of oxygen. It's also a strong neurotoxin,
so it has that detrimental effect as well. And the really insidious
thing about hydrogen sulfide is that it paralyzes
our olfactory nerve. In other words, we
can't smell it anymore. And that's what's so terrible,
because right after you stop being able to smell it, if
the level keeps building up, it can become
instantly poisonous. NARRATOR: Kump's
trying to figure out of the same lethal microbes
plagued the seas stripped of oxygen by the
Siberian eruptions. He's searching for proof in
rocks from 250 million years ago. But bacteria don't
leave fossils, so instead, he's pursuing
the chemical traces they leave behind. So the clues we're
looking for are compounds called biomarkers. These are chemical fossils. They're fragments
of the organism that have been preserved over
long periods of geologic time in these rocks. And from these fragments,
from these chemical fossils, we can try to identify what
organisms might have been involved in this
mass extinction. NARRATOR: Like a fragment
of bone or shell, a chemical fossil is a
fingerprint identifying the microorganism which made
it, and Kump's struck lucky. This is it. This is the clue we've
been looking for. This is the chemical fossil,
the biomarker that tells us that these organisms
were existing at the time of the greatest
mass extinction of all time. NARRATOR: As Siberia
erupted, the purple bacteria were in paradise, vigorously
poisoning the water with hydrogen sulfide. The sea became a
suffocating, toxic cesspool. The trilobites and virtually
every other species of sea life died out and never returned. The evidence is
building up as to how massive volcanic
eruptions in Siberia wiped out nearly all
marine life on Earth. Fool's gold shows the
sea lost its oxygen. Biomarkers show it was also
poisoned with lethal hydrogen sulfide. The Earth was choking. Life could no longer depend on
its two most vital resources, air and water. But a new threat loomed as
Siberia's underground coal reserves added
fuel to the flames. 250 million years ago, a sudden,
violent volcanic eruption began in Siberia. The traps erupted over
the next million years, forging basalt lava layers
thousands of feet thick. Buried underneath the basalts
were 5 trillion tons of coal. As Siberia erupted, a powerful
few was about to catch fire. For geologists, coal is a
crucial clue in figuring out how a huge volcano wiped out
nearly all life on Earth. Coal is the remains
of dead plant material, and when coal burns,
the volatile materials are released, and these
include gases such as methane. NARRATOR: And lava from
the volcanic eruption was the ultimate
source of ignition. It was like pouring
gasoline on a barbecue. Now, Saltzman is
hunting for evidence of how this colossal coal
fire damaged the planet. His search begins in a
barren blacktop wasteland. But this is not Siberia. This is a town in Pennsylvania. I'm MATTHEW SALTZMAN: Standing here
in what looks like a war zone. It's hard to believe
this was the main road into a thriving community
of several thousand people. These cracks and these
gases all around me are a clue not only to what
extinguished this town, but also provide
one of the key clues into the mystery of the greatest
mass extinction of all time. NARRATOR: In 1962, the
mining town of Centralia was a community of 4,000
people, but an accidental fire ignited a coal seam and caused
an uncontrollable underground blaze. Dangerous methane gas began
to seep from the ground. Today, the residents
have abandoned the town. The fire still rages
underneath Centralia, and methane is still
released into the air. The situation raises the
question of whether the burning of Siberia's far greater coal
reserves set alight by lava 250 million years ago also
released catastrophic levels of methane gas into the air. The volcanoes in Siberia would
have erupted through the coals to get to the surface. On their way, they would
have cooked these coals. And this burning of coal
would have released methane, amongst other gases,
and this methane would have had an extreme
effect on the global climate. NARRATOR: As Siberia
continued to erupt, temperatures all over the planet
rose by a further 10 degrees. It's a climatic change too
dramatic to be caused by carbon dioxide alone. There must be an
additional culprit. Methane is top of the list,
because it's over 20 times more effective in trapping heat
in the atmosphere than carbon dioxide. Today, scientists are
analyzing rocks for proof that methane from the Siberian
coal fire was the culprit. They've discovered a telltale
chemical clue, light carbon. It's a fingerprint
of methane gas, and it has been recorded
in every extinction zone all over the globe, from
Antarctica to Italy. Proof of the eruption's
global reach. The levels of light
carbon geologists have discovered are
so incredibly high, it equates to the sudden release
of a trillion tons of gas. [music playing] Temperatures surged as the
methane from Siberia spread across the globe, leaving every
part of the planet devastated by climate chaos
and mass extinction. MATTHEW SALTZMAN: This would
have been a very nasty place to live. There would have been
less oxygen in the oceans. There would have been much
warmer and drier conditions on land. There would have been problems
with the depletion of the ozone layer as a result of this
methane-rich atmosphere. And so it just would have been
a very, very inhospitable place to be. NARRATOR: But burning coal
isn't the only possible source of the methane gas that
warmed the world a quarter of a billion years ago. At the Brookhaven Energy Lab,
scientists are making ice. But this is ice that
burns, methane ice. In nature, it's buried
beneath sea beds and locked into permafrost. Its discovery got
geologists very excited, because there's more energy
locked inside methane ice than all Earth's other
fossil fuels put together. It could be the
fuel of the future. But it could also be
the key to the past. After hundreds of thousands
of years of eruption, burning coal and
melting ice together released enough methane to raise
temperatures by some 20 degrees Fahrenheit. Life on Earth was heading
for total wipeout. Finally, a million years after
the Earth's deadliest eruption began, the most catastrophic
event in the planet's history is at an end. But life on Earth
paid a high price. Over 95% of species have
been driven to extinction. The investigation reveals the
reach of the volcanic eruption and how planet Earth
continue to change. Light carbon found
in rocks is evidence of a methane-rich atmosphere. Burning coal in
Siberia is thought to be the source of this gas. The Earth is a different place
from just a million years ago, from the air, to the
land, to the sea. The few species
that have survived are pioneers in a
brave new world. They are about to change
the course of history. 250 million years ago, a
volcano erupted into life, paving Siberia with basalt lava
layers a mile and a half thick. At the end of the worst million
years in Earth's existence, as life teetered on the
brink of total wipeout, the eruptions finally stopped. Now, geologists want to find
out whether the volcano died, or whether it simply
changed location. The place where a mantle
plume hits the surface is called a hotspot. The plume's shape is a clue
to the hotspot's activity over time. The head is a huge lava bubble,
which feeds short-lived, but massive eruptions. When the lava plume
head is all used up, the mega eruptions stop, but
the narrow tail can live on, like a chimney spouting
small eruptions for hundreds of millions of years, while
Earth's tectonic plates are shifting above it. Here is our mantle plume. And it could be Siberia,
it could be Hawaii. And here is the plate. And the hotspot,
obviously, is stationary, but we're going to see
that the plate is actually moving above it. So the plate is continuously
moving, hotspot staying put. And you've got to imagine
lots and lots of lavas are erupting out
at the same time. So I think what we've
achieved is actually a rather good representation
of a hotspot track. At this end, the old end, that's
where the plume head first hit the top of the mantle. Over time, it's left a track
that would, in reality, have been lots of other volcanoes,
just like the one we find in the Hawaiian islands today. NARRATOR: The Hawaiian
chain was forged by a plume as the Pacific plate passed
above it at a speed of 30 miles every million years. But scientists searching
for a plume track in Siberia are left scratching their
heads, because there's no evidence of a trail. The investigation has discovered
Siberia's hotspot caused a million years of worldwide
chaos and destruction, but after that, the
hotspot trail goes cold. The Siberian Traps
would have left a line of volcanic landforms
that related to that movement, but over such a
long period of time, the geological processes have
hidden the evidence, buried it. And parts of it may have been
subducted back into the Earth's mantle. NARRATOR: What
happened to the hotspot after it forged the Siberian
Traps is a mystery that may never be solved. The dynamic Earth has wiped
away all trace of the evidence. One thing is certain,
Siberia didn't succeed in destroying all life on Earth,
but it was a very close call. PAUL WIGNALL: This is the
worst extinction of all time, and a partial measure
of that is just how long it took the planet
to recover from this. We estimate eight to
10 million years later, there was still only
the very beginnings of recovery, the increasing
diversity of life on Earth. NARRATOR: Coal, which opened the
investigation into the Siberian Traps, testifies to the
volcano's devastating effects. No new coal formed for
another 25 million years, not just in Siberia, but
around the entire world. It's conclusive proof that
although tree life survived the mass extinction, it
could not and did not thrive for tens of millions of years. And the same is true for
South Africa's land animals. On his family's
land, Rubidge has discovered yet another fossil
crucial to the investigation. If burrow holes fill
up with sand or mud, they can themselves
become fossils. Anything trapped inside
is fossilized too. BRUCE RUBIDGE: This is the
plug of an ancient burrow, but the exciting part about
this particular specimen is that it's got a little animal
actually curled up, preserved in the burrow. This animal died here in this
burrow about 250 million years ago, and that is
what he looks like. There, you can see is the head. And you see there's his
little tail over there. NARRATOR: Amazingly,
this tiny creature plays an enormous role in the
last 250 million years of life on this planet. This fossil represents the
future of life on Earth. This burrow has huge
significance for our presence here today, because
this little animal is one of the distant
ancestors of mammals. This is our ancestor. And the reason why he's
preserved in a burrow after the extinction event
is because this burrow maybe protected him from what was
causing other animals to go extinct. So maybe it's thanks
to a hole like that that you and I are here today. NARRATOR: The eruption
of the Siberian Traps triggered a brutal
race for survival. Over 95% of the
competition was eliminated. Only the well-adapted and the
lucky made the finish line. It was Earth's
worst million years, but from the perspective
of life on Earth today, it was the best thing
that ever happened. This was the greatest crisis
that life has ever suffered, but if it wasn't for
this, then evolution would have taken a different course,
and humans wouldn't be here today. NARRATOR: The million year
eruption of the Siberian Traps drastically altered
the entire Earth. From the atmosphere, to the
ocean depths, the planet changed at a rate so rapid,
evolution could not keep pace. In this new geologic world,
life was hopelessly outdated. The few animals that
survived shaped the future, passing adaptations onto their
descendants, dinosaurs, birds, mammals, and humans. The tree of life had undergone
some drastic pruning, but it allowed our branch to
flourish, and humans to evolve. Yet today, 250 million
years after Siberia erupted, life is still fragile, still at
the mercy of the ever-changing, volatile, and
unpredictable Earth.
