Voyage of the Continents (2012–2015): Season 2, Episode 5 - Voyage of the Continents - full transcript

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- [Narrator] Since its formation,

our planet has undergone
constant transformation.

(gentle inspirational music)

Stupendous collisions
have created continents.

Colossal forces have
raised up oceans floors

forming dramatic mountain ranges.

These movements on the Earth's surface

can be seen today in the
form of volcanic eruptions,

earthquakes, and tsunamis.

Tectonics sculpt our landscapes,

modify the climate,
displace oceans,



and can even influence the living world.

South America has the
longest mountain range

and the densest forest,

the most powerful river

and the greatest
biodiversity on the planet.

It's a world of great
beauty and infinite variety,

forged by the energy contained
within the Earth itself,

shaped and molded by
earthquakes and erosion.

This turbulent past has left
traces in rocks and cliffs.

From the heart of the Amazon jungle

to the lofty mountain peaks,

scientists attempt to
resolve the mysteries

of the South American continent,

one more tale in the never-ending story



of the voyage of the continents.

(moving dramatic music)

When it was born some
4.6 billion years ago,

our planet was gigantic ball of fire.

Then it cooled, giving
way to the first oceans,

and the first embryonic continents.

As time passed, the emerging land masses

came closer together,

forming vast islands of terrestrial crust.

Two billion years ago, one
of these continental masses,

known as the Amazonian Craton,

became the cornerstone of
the future South America.

Nelson Reis works for the
Brazilian Geology Service

and is one of the leading experts

on the history of the Amazonian Craton.

He's working in the north of Brazil

in the Tepequem region.

It is here that the last vestiges

of this original land can be found,

remaining unchanged
since they were created.

He explores the region relentlessly,

looking for rocks that
were part of the craton.

It's a delicate mission as the elements

have changed the landscape
over millions of years.

Ancestral lands lie on
the slopes of mountains

with flattened tops that
the Indians call tepui.

For Nelson Reis, these rocky peaks

provide valuable testimony
for a better understanding

of the origins of the
South American continent.

(inspiring instrumental music)

Over time, the Amazonian Craton
moved on the Earth's surface

and collided with other land masses.

(rumbling)

1.8 million years ago, it
was trapped within the vice

of a supercontinent, Columbia.

(speaking in foreign language)

- [Male Interpreter] To
reconstruct the story

of the Columbia supercontinent,

we need to do field studies.

This involves collecting
rocks for dating and studying,

what we call paleomagnetism.

The data enables us to know the
age of the rocks in question

and also where they were situated

in relation to the Earth's magnetic pole

at the moment they were formed.

- [Narrator] In recent years,
Nelson Rice and his colleagues

have collected and analyzed
hundreds of samples.

(hammer tapping)

The results reveal a
particularly complex puzzle.

(speaking in foreign language)

- [Male Interpreter] Here in South America

we can observe at least four cycles

of supercontinent formation.

The oldest led to the formation

of the supercontinent Columbia,

followed by Rodinia,

then Gondwana,

and the youngest of them in the Mesozoic,

the Pangaea.

- [Narrator] For millions of years,

through tectonic plate movements,

the future South America
was therefore at the center

of various differently-shaped
supercontinents.

Today, the history of
these successive assemblies

is still little known.

The surface of the planet
has retained little evidence

of these extremely ancient events.

But at the University
of Tucson in Arizona,

one rather adventurous geologist
has decided to investigate

in order to reconstruct the various phases

in the evolution of South America.

He is Martin Bailey Pepper,

a geologist and a motorbike fanatic.

For several years, he has been

exploring South America by bike,

collecting unusual samples.

Zircon,

a mineral present in sand grains

with a quality of being extremely stable.

(bike motor buzzes)

- What I really love about geology is that

you can pick up just,

let's say a handful of sand here,

as geologists,

using the right tools, you can get in

and just look at a single
grain like a zircon.

You can take that single grain
and you can zoom into that

and get a whole story of,

not only when this formed,

but you can go back farther.

What fluids were there before this formed.

You can also go forward and figure out

so much information about the time it took

to slowly come out of the deep mantle

as these rivers remove more and more

off the top of these mountains,

bringing this up from
hundreds of kilometers deep,

finally getting it to the surface.

There's so much information
into one of these

grains of sand,

and yet that's almost
the biggest thing we have

when we go back billions of years

to figure out what happened
to things in Rodinia,

or farther back to Columbia.

Or farther back to the
beginning of the Earth itself.

- [Narrator] Martin has already covered

some 50,000 kilometers.

From Patagonia to Ecuador.

He's collected more than 8,000 samples

from almost every river
across the continent.

- And so all I had to do was go

into these river valleys with a gold pan,

separate all the light
minerals that I didn't want,

and take just the zircon home,

and it was those zircons that I could then

take into our lab and analyze.

- [Narrator] Back in his
laboratory in Tucson,

each grain of sand is washed, filtered,

then analyzed using a laser.

This process provides the precise age

and composition of each grain of zircon.

(liquid gurgling)

Martin hopes he will
soon be able to identify

the origin of all the sediment,

and thus retrace the geological history

of Latin America over three billion years.

There are still years of work to be done,

but already the first
results are promising.

The geologist has
discovered grains of sand

from every part of the continent

that are some 900 million years old.

This would suggest that at the time,

all the fragments of land
that make up South America

were all assembled together.

- When I think of the Earth,
I like to envision it as,

almost like when you're cooking hot cocoa.

You have the heat underneath the pot,

and that causes this upwelling current,

this convection cell,

and the continents are really just these

little marshmallow bits that float around

on all that convecting magma.

On Earth,

as we know it, we see
these giant continents.

But when you go back in time,

a continent is composed of
these stabilized blocks,

and it's these blocks that will actually

separate and collide in time.

And scientists have
discovered that these blocks

separate and coalesce
into these supercontinents

about every four to 500 million years.

And these blocks can
completely disassociate

from what we understand as North America,

South America, Europe, Asia, Africa.

So when we go to the time of Rodinia,

the final assembly about
900 million years ago,

many of these continental
blocks that we would

think of associated with South America

looked completely different.

They were kind of in the
middle of this supercontinent,

but they were separated.

And so after 900 million years ago,

as all these blocks
started to be ripped apart,

we then disassociated with something

we wouldn't even recognize,

and then they started to
coalesce into something

that we could finally say, ha ha,

that looks just like South America.

- [Narrator] 900 million
years ago, the dislocation

of a supercontinent would
therefore have given rise

to the future South America.

The pieces of terrestrial
crust that compose it

began a long common existence,

and nothing would separate them.

But subsequently, the
continent would experience

other dramatic changes.

(soft piano music)

About 700 million years ago,

the landmasses of the
southern hemisphere converged,

and the future South America collided

with the future Africa.

This contact led to the appearance
of a new supercontinent,

Gondwana.

The land today can tell the
story of the birth of Gondwana,

a major episode in South American history.

We're in Rio de Janeiro,
Brazil's second biggest city.

There's a laboratory here
with a very evocative name,

the Gondwana Lab.

It was founded by Renata Schmitt.

Her objective is to
understand every detail

of every step in the
formation of Gondwana.

A century ago, it was
the first supercontinent

to be recognized as
such by the specialists.

It confirmed the
hypothesis of the existence

of plate tectonics.

- It's like a perfect puzzle

which fits together.

So this was actually
a very strong evidence

for the building of the theory
of the continental wandering.

This was in the 1920, more or less,

and it evolved in 1950, 1960,

to the theory of the tectonic plates.

It's just evolved much

faster after the '60s

because of all the knowledge
we got from the oceans.

Because we didn't have
access until the '50,

until the Cold War, in
the Cold War they started

to build up submarines,

and now they started to study
all the oceans of Earth,

and then we started to
get better information

and then we understand that the continents

actually are tectonic plates that move

along the history of Earth,

since the beginning until today.

The origin of Gondwana, the word Gondwana,

comes from the 19th century

when they found in India,
in the region in India,

Jaipur, and this region,
there was this people

who they called the Gonds.

It's like an aboriginal people.

They found there a sequence
of sedimentary rocks

of the Carboniferous period,
and within these rocks

they found the fossils of Glossopteris,

which is a kind of plant.

And the same sequence, the same flora,

they found in Antarctica,

they found in the basins of Africa,

and they found also in South
America and in Australia.

This is weird, how can a plant travel

from all this very large distance?

So this continental masses

should be together at
some part of the story,

history of Earth.

And of course, another
very strong evidence

of the Gondwana amalgamation
and the Gondwana existence

is the fit of the continental margin.

- [Narrator] For several
years Renata Schmitt

and her colleagues have been studying

the rocks of South America to learn more

about the history of the supercontinent.

(gentle piano music)

Claudio Valeriano, a geologist

at the University of Rio de Janeiro,

is particularly interested in
the famous Sugarloaf Mountain,

which stands majestically over the bay.

This granite mountain,
rising up 395 meters,

is the result of a violent collision

between tectonic plates.

- This is peculiar-shaped rock

that was eroded from a
granite, a kind of granite,

that formed when some
old continental blocks

collided about 600 million years ago.

The Sugarloaf is just an erosion form,

which was formed much later

when Africa and South America broke apart.

- [Narrator] When they collided,

the rocks of the future African

and South American continents
folded and fractured.

Magma rose to the surface
and gigantic mountain ranges

emerged from the ground.

Erosion then took over,

and the granite peaks that
dominate the Rio Bay today

are all that remain of the
monumental age-old relief.

After 300 million years of coexistence,

Africa and South America separated.

It was a brutal
dislocation, traces of which

are still visible in the
very heart of the rock.

- We have here in Rio
de Janeiro some rocks

that testify this separation

which are the dolerite dykes,

these are black rocks that fill fractures

that were created about
130 million years ago.

So these rocks, which we call dolerites,

they filled these fractures

and they can be seen

all around here and in
the Sugarloaf area also.

(gentle instrumental music)

- [Narrator] Today the
Sugarloaf and the Corcovado

are the best known vestiges
of that ancient collision.

On the latter's summit
stands the imposing statue

of Christ the Redeemer,

symbol of the city, and
indeed, of the whole country.

(sea gulls calling)

On the other side of the Atlantic,

the coasts of Africa have
also conserved traces

of Gondwana's existence.

In Namibia, the town of Keetmanshoop

is in the heart of the Karas region.

The landscape here was
formed by the encounter

between South America and Africa.

As far as the eye can see,
gigantic blocks of rock

emerge from the plain.

This breathtaking setting is where

geologist Nicole Ulrich is hard at work.

- Look at this view now
with the dune, I like this.

- [Narrator] These rocks
are strikingly similar

to those found along the Brazilian coast.

- Rocks that we see here
in this beautiful valley

give us evidence of
plate tectonic processes.

You do find similar
rocks with a similar age

on the other side of the
Atlantic Ocean in Brazil,

like for instance, the
world-known Sugarloaf

in Rio de Janeiro is
built up by similar rocks.

This proves that the two continents,

which are now separated by
thousands of kilometers of ocean,

have once been connected together,

and only later after the break up

of the Gondwana continent,
were separated again.

- [Narrator] When Gondwana broke apart,

a vast ocean gradually opened
up between the future Africa

and South America.

The Atlantic Ocean as we know it today.

But this brutal dislocation
made the Earth's crust fragile,

and in places, it was torn apart.

Magma rose from the depths

and seeped through cracks in the rock.

Today, these lava inclusions are visible

on Namibian soil and
on the Brazilian coast.

They form rather unusual
seams called dolerite dykes.

It is these rocks that
Nicole Ulrich is researching

and analyzing all along
the Namibian coast.

- Also in south Namibia,
we can find evidence

of the Gondwana separation.

What you can see here are dolerite dykes.

They occur in such great numbers

that one cannot distinguish
a single dyke anymore,

and this is why the geologists
speak of a dolerite swarm.

Dolerite is a magmatic rock
that, compared to basalt,

which flows out as a lava on the surface,

does not reach the Earth's surface,

but cools off in the Earth crust

and forms long-extending dykes.

- [Narrator] Over thousands of years,

erosion has brought the
dykes to the surface.

Today, they rise up towards the skies

like rocky icebergs in
the middle of the steppe.

They remind us that
Africa and South America

were once brutally broken apart.

After the separation, the
South American continent

began a long, solitary journey.

It drifted slowly to the west,
pushed by tectonic forces.

But as it progressed,

it encountered the gigantic
Pacific Ocean plate.

This new collision was
not without consequences.

(dramatic music)

Along the whole western
face of South America,

huge mountains rose from the Earth.

It was the birth of the Andes.

Stretching over 7,000 kilometers

from Venezuela to Chile,

the Andes form the longest
mountain range on the planet.

They mark out the precise
zone where the plates collided

some 100 million years ago.

It is in the central
part, straddling Peru,

Chile, and Bolivia, that the
range is the most imposing.

It is over 6,000 meters high

and 1,700 kilometers long.

It is also the focus of
attention for Thierry Sempere,

a geologist from the
Earth Sciences Institute

in Grenoble in France.

He is heading for Tacna, in
the extreme south of Peru,

to retrace the region's geological history

in as a detailed manner as possible.

The land here has been stripped bare

by centuries of erosion.

For Thierry, the thousands
of overlying strata

are like the pages of a history book,

an open-air geological archive.

- [Male Interpreter] So here
we have some of the strata.

As you can see it's markedly stratified,

with sediments deposited on a seabed.

The sediments are very
fine, very well stratified

on the bed of the sea, at
least 1,000 meters deep.

We're at an altitude of 2,000 meters

and so we can see that well
before the Andes existed,

we were in fact in an oceanic trench.

(hammer tapping)

- [Narrator] For a long time,
the subduction of the Andes

posed a problem for geologists.

How did such marine sediments end up

at an altitude of 2,000 meters?

And above all, in what way
could such high mountains

be formed along a continent's
border with an ocean?

- [Male Interpreter] It's
true that most mountain ranges

that have been studied in the past

result from collisions like the Alps,

the Himalayas, and others.

Here, that's not at all the case.

Throughout the region,

the strata have not
been deformed very much.

They're like I'm doing with my hands,

with a few undulations,
but there are no folds,

which would be like this.

In the Alps there are
folds and thrust faults

and ancient rock that
covers more recent rock.

And in this part of the
Andes, in the western part,

we don't see that.

- [Narrator] Most mountain
ranges on the planet

were created by the coming together

of two continental plates.

The Andes result from a
very different phenomenon.

- [Male Interpreter]
Everyone knows that the Earth

is a ball, a sphere that's
not exactly spherical,

but almost.

In its center is what we call the core,

which is composed of iron,
mostly in liquid form.

Around the core is a kind
of pulp, called the mantle,

and this mantle is covered over several

tens of kilometers by a crust.

In fact, the crust floats on the mantle

so the crust is subjected
to Archimedes' principle.

This means the thicker it
gets, the more it rises up,

and that creates mountains.

When the crust thickens,
there's a substantial part

we don't see beneath us.

A bit like an iceberg.

And there's a part that rises.

And it rises at least three kilometers.

These 3,000 meters that we gained here

are 3,000 meters that were produced

by the thickening of the
crust beneath our feet,

and that thickening,
with a rough calculation,

would be around 20 kilometers.

- [Narrator] In fact,
the South American plate

came into direct contact
with the Pacific plate.

As the latter was denser,

it slid into the depths of the mantle.

But the sediments that had
accumulated on the ocean floor

remained on the surface and were deposited

along the junction of the two plates.

This phenomenon led to the thickening

of the continental crust,
which then gradually rose.

(gentle inspiring music)

In the Andes, this
terrestrial crust is now

more than 70 kilometers thick in places,

almost twice its normal depth.

In the continent's extreme south,

in the region of Torres
del Paine in Patagonia,

the Andes landscape is very different.

Majestic peaks rise above deep valleys.

The relief is chaotic

and the rock is a brownish color.

Its intensity contrasting with the hues

of the northern Andes.

The stories of the Andes formation here

is more recent, and above
all, much more complex.

As it traveled to the west,
the South American continent

first of all encountered
the Pacific plate.

But a few tens of millions years later,

the southern tip found
itself in a tight spot,

where the Pacific and Antarctic plates

were already fact to face.

The Earth's crust was therefore compressed

and vast quantities of
magma rose to the surface.

These infiltrations considerably raised

the temperature of the surrounding rock,

giving them this very particular color.

The eternal voyage of the
plates on the Earth's surface

continues to change the face
of Latin America even today.

The continent continues
to drift slowly westward,

and its confrontation
with the Pacific Ocean

regularly causes the Earth to shake

and move along the coast.

This is notably the case
in the region of Ilo

in southern Peru.

For several years, this small coastal town

and the surrounding area
have been carefully monitored

by a team of scientists.

Anne Socquet is a geologist

with the Earth Sciences Institute

in Grenoble, and works in collaboration

with the Peruvian Geology Institute.

She is studying the movements
of the Earth's crust

thanks to a vast network of sensors

installed along the coast.

Today she is on her way to
inspect one of the GPS stations

with a colleague, Nathalie Cotte.

- [Female Interpreter] Here we are.

This is the GPS antenna.

So on this site at Playameca,

we've set up a relay next to this house,

which is under surveillance
so there's no risk

for the equipment.

- [Female Interpreter] The
fact of having a station

on the rocks is really good

to be sure that the
type of readings we get

are actually measuring the movements

of the Earth's crust itself,

and not just a superficial
landslide or something

that has nothing to do
with what's happening

with the subduction underground.

- [Narrator] The antenna
is linked to a GPS station

which picks up the ground
movement data in real time.

This is then safely guarded
in a local fisherman's home.

- [Female Interpreter] Hello, sir.

- [Female Interpreter] Hi, how are you?

- [Male Interpreter]
Hello, welcome to my home.

- [Female Interpreter] Thank you.

- [Female Interpreter]
Where's the station now?

- [Female Interpreter] Here it is.

Thank you, sir.

- [Female Interpreter] Thanks very much.

- [Female Interpreter] So
let's take a look inside.

- [Narrator] The apparatus is located

just above the subduction zone,

where the Pacific plate slides

under the South American continent.

The slightest movement, even minute,

can therefore provide the geologists

with valuable information.

- [Female Interpreter] The aim, in fact,

is to look at the deformation
generated by this subduction.

The subduction involves a fault,

which is blocked between two earthquakes,

so it can generate huge
quakes, mega quakes,

of a magnitude of eight, or even nine.

Between two quakes it's blocked

in what we call the interseismic phase.

During this phase it's
very important to measure

the deformation, and I
think here on this coast,

we should have deformation

of around two centimeters per year.

So in fact, during the interseismic phase,

the coast is moving towards
the Andes mountains,

and during the coseismic phase,

there's an elastic rebound and we'll see

a sudden displacement of around
five meters, sometimes more.

(speaking in foreign language)

So we'll collect the data.

- [Narrator] Between
earthquakes, energy builds up

in the depths of the Earth
until it is released.

But even today, predicting seismic events

is an inexact science.

Experts can't give a precise
date for the next earthquake.

But one day they are certain,

the ground will shake again
along the Peruvian coast.

At the same time, more
than a hundred kilometers

from the coast, Anne Socquet and her team

are studying another phenomenon.

The subduction of the
Pacific plate has created

countless volcanoes here.

Many of them are still active today

and pour out torrents of
lava at regular intervals.

The town of Candarave in southern Peru

lives constantly under the
threat of the volcano, Yucamane,

which rises up some 5,500 meters.

(gentle music)
(wind rustling)

- [Female Interpreter]
This volcano is actually

still active, and there's no doubt

it presents quite a considerable risk

for the town of Candarave,
which is just below it.

- [Female Interpreter]
Like all the volcanoes

here in southern Peru,

- [Female Interpreter]
there's a subduction zone

with volcanoes behind it,
except in a few places.

So it's all part of the
Pacific Ring of Fire.

Why do we call it the
Pacific Ring of Fire?

It's because the Pacific
is completely surrounded

by subductions and there are volcanoes

all around the Pacific.

But with these subductions,
what they do in fact,

is make the oceanic plates disappear.

So gradually, as they make
the oceanic plates disappear,

the Pacific will end up by closing,

and as a result,

North America and South America
will come and join Japan

and the Philippines, et cetera,

and so the Pacific will disappear.

It will be a new Pangaea.

- [Narrator] This theory
concerning the disappearance

of the Pacific in a few million years

is a controversial hypothesis

within the scientific community.

But for the moment, the
Pacific Ocean continues

to be slowly swallowed up

in the depths of the Earth's mantle.

All along the Andes, the
encounter of the plates

makes the ground quake
and the volcanoes rumble.

On the way back, Anne
Socquet and her colleagues

stop off a few kilometers from the coast.

Once again, an analysis of the ground

demonstrates that subduction
is still going on.

At this precise point,
the ocean floor dives

beneath the continental plate

and sediment has built
up over the millennia.

- [Female Interpreter] In
fact, about 40 kilometers

beneath our feet, there's
a subduction zone,

which generates earthquakes.

But it doesn't just generate earthquakes,

it also participates in
raising up the Andes.

We're very close to the coast here,

and what we can see are different layers

of different types of sediment.

And when we take a closer
look at these sediments,

we'll see that they're shells,

which were deposited by the sea.

And here we're several tens,
if not several hundreds,

of meters above sea level.

So this shows that the subduction zone

constantly generates deformation,

and this constant deformation plays a part

in raising up the coast.

Perhaps we can go and take

a closer look at these deposits?

Have you seen it?

It's really thick, it's
more than 50 centimeters.

Yes, you can see here,

there are lots of shells.

Mostly bivalves.

These deposits are quite recent

in geological terms.

Between a few tens and a
few hundred thousand years.

So the sea was here, tens,

or hundreds of thousands of years ago.

What's pretty here, in northern
Chile and southern Peru,

is that all along the coast,

we can see the uplift, like this.

There's a kind of coastal
escarpment all along the coast

in northern Chile, which
continues here in southern Peru.

This coastal escarpment can be
several hundred meters high.

And in some places, it's
even a kilometer high.

So that's quite considerable.

And it shows that there was
substantial uplift here.

Up to one kilometer in the
past three million years.

This is associated with the subduction,

and we really have
considerable interaction

between the great subduction fault,

which passes beneath our feet,

and the coastal morphology

and the beginning of
the Andes deformation.

Great, we've got a
10,000-year-old scallop.

- [Narrator] A little further north,

the geological history
of the Andes is marked

by another rather peculiar phenomenon.

In the central sector, at
an altitude of 4,000 meters,

a vast plain has formed in
the heart of the mountains.

This is the Altiplano,

the world's second highest
plateau after the one in Tibet.

We meet up again with
geologist Thierry Sempere,

who's continuing his research
into the region's history.

(gentle piano music)

He comes regularly to the
shores of Lake Titicaca,

on the border between Bolivia and Peru,

to study the origin and evolution
of this unique ecosystem.

Around a picnic, he explains
some of the background

to his young colleagues.

(water trickling)

- [Male Interpreter] Do you know the twin

or the species that's the
closest cousin to the tomato?

- [Female Interpreter] No.

- [Male Interpreter] It's the potato.

Because when the Andes rose up,

the two species diverged.

The tomato stayed lower down

and the potato adapted to the altitude.

And it also invented a new
strategy for reproducing,

which is the tuber, which
is actually a clone.

Because it's cold on
the Altiplano at night

and especially in winter.

And in case the plant might die of cold,

the tuber is always in the
ground, it can grow again.

So that's one example of
many throughout the world,

and so when you form mountain ranges,

you create whole new ecosystems.

- [Narrator] Located 3,812
meters above sea level,

Lake Titicaca is one of
the highest navigable lakes

in the world.

It's in the heart of the Altiplano,

trapped between two mountain ranges.

Thierry Sempere and his
team crisscross the region,

taking extensive rock samples,

for it's in the depths
of the Earth's crust

that can be found precious indications

to the formation of this high plateau.

- [Male Interpreter] Ah, that's not bad.

There should be quite a
lot of information inside

if we can get the grains out,

which will help to date it.

On the Altiplano, the lowest
regions are occupied by lakes,

because the Altiplano is
a sort of closed basin.

The rain that falls on the Altiplano

doesn't go to either the
Pacific or the Atlantic,

but to the lakes that are
scattered around the Altiplano.

The biggest of them is Lake Titicaca,

which is in the lowest region
in this spot of the Altiplano.

What we have to understand, too,

is that when we go down,
beneath my feet for example,

after 10 kilometers down,

maybe 10 or 12 kilometers down,

the Earth's crust is fragile
and cracks on the surface.

But after that depth it
becomes soft and plastic.

We say that it's ductile,

and so consequently, it
behaves like plasticine,

and it spreads out.

It spreads out and so as a result,

the surface of the crust we're standing on

naturally becomes flatter.

The relief becomes less
steep because we're on

a kind of mattress, a mattress
made up of 50 kilometers

of plastic crust.

- [Narrator] The central
Andes were in reality formed

in several stages.

When the Pacific plate dips

beneath the South American plate,

it raises up the continental crust,

which is gradually deformed.

An initial mountain range
rises from the ground,

the eastern Andes.

Then along the edge of
the South American plate,

subduction heats up the terrestrial crust

to the point of melting it.

This fluid and malleable terrain

enables the Altiplano to form

and rise over millions of years.

Later on, intense volcanic activity

causes the uplift of a
second mountain range,

the western Andes.

The Altiplano is therefore now locked in

on the western side.

- [Male Interpreter] We
can clearly see behind me,

these very flat plains
where people have settled.

We have the water of Titicaca,

and it's all surrounded by mountains

which are not very high.

Quite flat, we might say.

And right in the
background, you can no doubt

see the eastern Andes,
and you have to imagine

that behind those snow-capped summits,

we go very quickly down towards Amazonia,

towards the Amazon forest.

- [Narrator] The majestic
landscapes of the Altiplano

and the Andes mountains
demonstrate to what extent

tectonic forces model and
shape the land's destiny.

But in turn, these mountains
impose a considerable influence

over the surrounding regions,

and in particular, over
the Amazonian forest.

The small town of Contamana in Peru

is in the heart of the Amazon basin.

It is here that a team
of French paleontologists

have set up their base camp.

(motor purring

Every morning the scientists
respect the same ritual,

a 30-minute boat ride before setting off

into the jungle on foot.

(adventurous instrumental music)

The team leader is Pierre-Oliver Antoine,

from the Evolutionary Science Institute

in Montpellier in France.

He's been exploring western
Amazonian for a number of years,

studying the exceptional
biodiversity here.

With an area of over six
million square kilometers,

this tropical forest is the vastest

and most diverse on the planet.

(leaves rustling)

Experts say it is home
to 1.4 million species

of plants and animals,
half of all the species

so far recorded around the world.

On the ground, Pierre-Oliver
analyzes sediment strata

to see how the water course
has evolved over time.

(speaking in foreign language)

- [Male Interpreter] This is
an extremely interesting site,

which is unusual for the
large variety of environments

concerning the deposits we've noted.

Here we have a first river coming in,

which has very little energy.

It would've been very calm
with just a few ripples.

And then the energy
level goes down further

and we basically find a marshland,

a marsh with animals and plants

that are typical of a marshland.

And then quite suddenly,
the energy changes,

and there's a watercourse coming in

with quite a strong current.

So there we have a lot
of detritus laid down

with larger elements
forming a conglomerate.

This lasts for about two meters,

and above those two meters,
we actually have a torrent,

with large rocks washed
along it, like this.

So there was a very strong current.

This current required relief,

so obviously, for that
relief, we think of the Andes.

- [Narrator] The scientists
methodically examine

the ground, looking for fossils.

Tiny clues hidden in the ground

which could provide a detailed account

of the history of the Amazon basin.

(pebbles rattling)

- [Male Interpreter] Here, in
fact, we have an illustration

of what we're after.

Meaning that we come to look for fossils,

but these fossils have
a particular interest,

which is to gain a better understanding

of the Amazonian ecosystem
under the influence

of the environment, and in particular,

this environment which
is linked to the Andes

and the Andean tectonics.

- [Narrator] Experts have
known for a long time

that the history of the Amazon forest

is closely linked to that
of the Andes mountains.

- [Male Interpreter] It's a lower tooth.

- [Male Interpreter] Oh, it's spectacular.

- [Narrator] During the
growth of the mountain range,

the basin was on several occasions filled

with vast stretches of water,

the last of which appeared
about 12 million years ago.

The scientists call it the Pebas Sea.

Until recently, the scientific community

hotly debated a key question,

was it an inland saltwater sea

or a freshwater lake?

(speaking in foreign language)

- [Male Interpreter] So,
do you know what that is?

- [Male Interpreter] Yes,
of course, they're oysters.

- [Male Interpreter] Oysters,
but sea oysters, right?

- [Male Interpreter] Yes, of course.

And last year, we took
sediment samples here

and they were foraminifera,
thousands of them.

Thousands of foraminifera.

- [Male Interpreter] I've
never seen oysters here before.

- [Male Interpreter] So we're
talking about an outcrop

which is extremely unusual
in the Amazonian context,

because it's the only
outcrop that has ostrea,

or oysters, throughout Amazonia.

Obviously, they are fossilized
oysters, marine oysters,

so they resemble the oysters we eat today.

They have the particularity of having been

perforated by organisms,

which we call lithophagous organisms

which are marine creatures.

This informs us directly
that 12 million years ago,

or in the past in any
case, there was a sea here.

In fact, these oysters
represent the final obstacle

for the opponents of the Pebas Sea theory,

who consider that this was
a lake with fresh water,

quite simply because no
one had ever found oysters

in the Pebas system.

But here we are, there are.

- [Narrator] The home of what
is today the Amazon basin

was therefore covered by a vast inland sea

some 12 million years ago.

The appearance of the
Pebas Sea in the middle

of the South American continent

is the result of plate tectonics.

It is directly linked to the
uplift of the Andes mountains.

(insects singing)

- [Male Interpreter] Through the effects

of Andean tectonics,

the Andes rose up about
15 million years ago.

What we call the foreland,
the zone that precedes

the tectonised zone, the subduction zone,

under wide flexure, or folding,

and moved downwards.

And in doing so, it
allowed the sea to move in,

an ingression of the sea.

This Pebas Sea then gradually withdrew,

and the whole biodiversity of the Pebas

with hundreds of species of mollusks,

and marine rays, and notably
a whole bunch of crocodiles,

which depended on that system.

All these organisms would have disappeared

at the same time as the
system in which they lived.

On the other hand, what's certain is

that the disappearance of
that very particular system

enabled the current Amazonian
system to be established.

- [Narrator] Through its disappearance,

the Pebas Sea led to the extinction

of thousands of animal species,

but it gave way to the most
powerful river in the world.

An evolution that furthered the emergence

of an incomparable biodiversity.

(insects singing)

(speaking in foreign language)

- [Male Interpreter] The luxuriance,

the vast biodiversity of Amazonia,

in fact is ultimately very young.

It's very recent in terms
of what we know today.

But it's not so surprising
because that host of species

was born out of tectonics

from the consequences of Andean tectonics,

which over millions of
years led to the separation

of smaller basins, of the
Amazon basin and lesser basins,

and all those zones
were separated slightly.

They have slightly different vegetation

and slightly different climates.

So all that led to
distinctions among species,

what we call the phenomenon of speciation.

These sister species would then be

either in the north or the south

and would ultimately evolve independently,

and give us this whole
biodiversity that we see today.

(gentle instrumental music)

- [Narrator] Amazonia
bears irrefutable testimony

to the bonds between the
living world and geology.

Unremittingly, plate tectonics
shape and sculpt our planet.

It gives rise to seas and oceans,

to mountains and forests.

Three million years
ago, another phenomenon

radically changed the
biological equilibrium

of the South American continent,

the closure of the Isthmus of Panama,

and the junction with North America.

Isolated for some 50 million years,

North America was therefore
colonized by new species.

Once again, the land
changed shape and form,

transformed by the perpetual
voyage of the continents

across the face of the planet Earth.

(adventurous instrumental music)