Voyage of the Continents (2012–2015): Season 2, Episode 4 - Central America - full transcript

(peaceful instrumental music)

- [Narrator] Since its formation,

our planet has undergone
constant transformation.

Stupendous collisions
have created continents.

Colossal forces have
raised up ocean floors

forming dramatic mountain ranges.

(lively instrumental music)

These movements on the Earth's
surface can been 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.

Central America and the
Caribbean are made up

of a slim strip of land
and a multitude of islands

dispersed across turquoise waters.

These sumptuous landscapes are the fruit

of a turbulent geological history.

Caught in a vice between
North and South America,

the region has forever been
subjected to colossal forces,

and today, too, this tropical paradise

lives under the constant
threat of earthquakes

and volcanic eruptions.

From the slopes of volcanoes
to the depths of the ocean,

from remote jungles to the
heart of overcrowded cities,

scientists attempt to
understand the history



of this singular region
subject to earthly powers

and the ongoing voyage of the continents.

Straddling mountains and oceans,

Central America boasts a wide range

of exceptional landscapes.

To the east, speckled with
countless archipelagos,

the Caribbean Sea faces
the mighty Atlantic Ocean.

To the West, a thin
ribbon of land stretches

from Mexico to Northern Colombia

and the shores of the Pacific.

(gentle instrumental music)

The history of this region is unique

in planet Earth's epic journey.

Whereas most of the continents

are several billion years old,

Central America is much younger,

emerging from the depths of the sea

only 150 million years ago.

Understanding every detail and
every step in the formation

of this territory is the main objective

for Thierry Calmus, a scientist
for the Geology Institute

at the National Autonomous
University of Mexico.

His field of study is
in the north of Mexico,

not far from the town of Hermosillo,

the capital of the state of Sonora.

We're in the heart of
the western Sierra Madre,

a range of mountains
stretching over 100 kilometers

across the country.

These peaks are the vestiges
of the very first moments

of the creation of western Mexico.

About 200 million years ago,

the future North and South Americas began

to slowly drift westwards.

They hit an oceanic plate,

the ancestor of the Pacific
Ocean named the Farallon Plate.

It started to disappear
between the Earth's mantle.

(gentle instrumental music)

(speaks in foreign language)

- [Translator] This famous
Farralon Plate gradually sank

between 200 million and
20 million years ago

beneath the North and
South American plates.

This subduction caused
plutonic magma phenomena

which means the intrusion

of deep settled magmatic
rock and volcanism,

which is magmatic rock
reaching the surface.

That was the case here on
the western Sierra Madre

where we have perfectly
typical relief related

to that subduction phenomena.

- [Narrator] Thierry Calmus is
looking for the last vestiges

of the Fallaron Plate,

which is today almost totally disappeared.

He heads for the La Coridad Mine,

one of the world's biggest copper mines.

The mountain here has been
sliced apart over thousands

of square meters.

For the scientist, the exposed
rock becomes an open book

on geological history.

- [Translator] We are here
for one very simple reason.

Plates disappear and most
of the Farralon Plate

has disappeared due to subduction.

Fortunately, we have witnesses,

like today's volcanoes are witnesses

to current subduction processes.

We have witnesses to
the historic subduction

which occurred between 200
million and 20 million years ago.

And among these witnesses,
we have these copper mines

which are connected to
the magmatism associated

with the subduction of the Farralon Plate.

- [Narrator] The Copper
in the La Coridad Mine

in fact comes directly
from the ocean floor

that made up the Farralon Plate.

When the plate sank beneath
the North American Plate,

the precious mineral was
swept away by water and magma,

then rose through cracks
within the continental crust.

These copper deposits were
therefore the direct result

of that age old collision.

By taking extensive
samples, Thierry Calmus

and his team hope to get
a better understanding

of the slightest movements

that affected the region
millions of years ago.

Through its very disappearance,
the Farralon Plate

triggered the construction
of Central America.

It also gave way to another oceanic plate

situated just behind
it, the Pacific Plate.

And 150 million years ago,
a major event occurred

in the middle of this ocean.

The birth of the Caribbean Plate.

Traces of this phenomenon
can be seen today

in the heart of the Antilles archipelago

on the island of La Desirade.

(peaceful instrumental music)

Here the waves of the
Caribbean Sea roll in

along a jagged rocky coastline.

The beaches are covered
with volcanic rocks

and gigantic domes of basalt.

This torturous landscape
is an ideal study subject

for French geologists Luc
Legendre and Francois Michel.

They're looking for clues
concerning the formation

of the Caribbean Plate.

- [Translator 1] Here are
the volcanic tough rocks.

- [Translator 2] It's magnificent.

- [Translator 1] Pillow
lava, quite exceptional.

- [Translator 2] Pillow
lava's an English term.

In French we would say
(speaks in French) or cushions

and these pillow lava
are formed at the bottom

of the ocean, two, three,
or four thousand meters down

under the pressure of cold water.

We can see the base and
imagine that the lava

that emerges is hot and around
a thousand or 1200 degrees

and it forms this bubble
which cools very rapidly.

We can clearly see here a
sort of cortex around it,

a kind of envelope which
cooled more quickly.

If we look at the pillow lava below,

we can see below the
cortex an area of bubbles

and then the heart here,
which is basalt and so on,

it accumulated like that.

It's magnificent.

- [Narrator] For the experts,
these lava pillows provide

unique testimony to the
formation of the Caribbean Plate

at the bottom of the ocean.

They are the result of
intense volcanic activity

at what are called hot spots,

regions of the Earth's
surface where the temperature

below the surface is
particularly high all the time.

Vast quantities of magma
rise to the surface

from the depths, accumulate
beneath the surface,

then spread out over the seabed.

The oceanic crust thickens in
places and finally gives rise

to a new tectonic plate.

- [Translator 1] Here we
are with our bathyscaph,

150 million years ago,

looking at the seabed
with the lava arriving

and the pillow lava forming.

- [Translator 2] It would
be good if you could tell us

the age of these pillow lava.

- [Translator 1] What we've been able

to date are the radiolarites.

The radiolarites we have
here beneath our feet

contain micro fossils that
provide us with an age.

These are from the end of the Jurassic,

that would be 145 to
150 million years ago.

These micro fossils are
characteristic of that period.

We're in the presence of the
oldest rocks in the region.

(gentle instrumental music)

- [Translator 2] It's
also important to say

that at the end of the Jurassic,

145 to 150 million years ago,

the Atlantic Ocean was
just beginning to open up,

and here in a way, we're in the Pacific.

- [Translator 1] Oh yes,
and that's a puzzle.

In fact, geologists have
been wondering for decades

about these rocks and their origins.

(speaks in foreign language)

Thanks to all their studies, we now know

that here on Le Desirade,
we have testimony

to the beginning of the formation

of the Caribbean, tectonically speaking.

- [Narrator] For a long time,

the date and above all the location

of the Caribbean Plate's
formation were a mystery

for the specialists.

But these rocky formations
of the island of Le Desirade

provide the proof of its emergence

from the heart of the Pacific
Ocean thousands of kilometers

to the west of the Americas.

(peaceful instrumental music)

Subsequently, the
American plates continued

to drift slowly to the west.

The result was that the
Caribbean plate gradually slid

between the two giants.

(speaks in foreign language)

- [Translator 1] We have
here extremely rare testimony

to the formation of the Caribbean plate

150 million years ago in the Pacific.

(waves crashing)

(speaks in foreign language)

This mass of rock that
we're looking at was formed

in the Pacific and it was only gradually

that the two Americas moved to the west

and the Caribbean plate
managed to insert itself,

like with forceps, we could say,

between the two massive
blocks to the north and south.

(gentle instrumental music)

- [Narrator] Approximately
100 million years ago,

the young Caribbean Plate
reached its current position

in the tropics on the edges

of the Atlantic and Pacific plates.

To learn more about the
region's subsequent history,

Francois Michel continues
to explore the coast

of Le Desirade, seeking out more clues.

- [Translator 2] Here we
have another outcrop of rock

and we find the same basalt
we saw at the last outcrop.

These rocks are very old,
about 150 million years old,

and we find them in the form of pebbles,

these dark pebbles which
are very, very old.

And they're a complete
contrast to the lighter pebbles

which are much more recent

and a part of a whole other
story, almost contemporary

from the last few thousands
or hundreds of thousands

of years that we can find
on the terraces above us.

(peaceful instrumental music)

- [Narrator] The southern
shore of the island is lined

with a terrace of varying width,

rising about 20 meters above sea level.

As he observes the rock
strata above Mau Bay,

the geologist can almost
completely reconstitute

Le Desirade's geological past.

- [Translator] Here at Mao
Bay, we see a new outcrop

where the base is made up of
the same basalt we saw before,

the pillow lava about
150 million years old,

and above that there's a marine terrace,

which tells us a whole other story.

This is 150 million years old
and this is 120,000 years old.

As the sea gradually rises, it laid down,

as we can clearly see here,
an initial layer of rock,

mainly composed of pebbles and gravel

and an accumulation of shells.

We call that a conglomerate.

(gentle instrumental music)

And when the level of the sea rose,

we can see that something else settled

with a very different aspect

and that's quite simply a
coral reef, a barrier reef.

So here we have both the
oldest rocks in the Caribbean

and no doubt the youngest too,

in terms of geological history.

Between the two, a fantastic
amount of time passed,

a period that saw the birth
of the Caribbean Plate.

- [Narrator] Over millions
of years therefore,

the Caribbean Plate underwent
numerous dramatic changes.

The sea level rose, then fell

until the landscape we
know today appeared.

But on its eastern side,

the Caribbean experienced a very different

and much more violent phenomenon,

its encounter with the Atlantic Ocean.

The two oceanic plates collided

and the denser Atlantic Plate slid

below the Caribbean plate.

At the point of contact, the
rock fractured and split.

Magma rose up from deep down

and an arc of volcanic islands
was formed above the waves.

(gentle instrumental music)

In the heart of the Lesser Antilles,

the La Soufriere volcano
is the best known testimony

to this collision, which
is still going on today.

It's located on Guadaloupe
about 10 kilometers

from the town of Basse Terre.

On the slopes of the volcano

stands Guadaloupe's
Volcanological Observatory.

Research workers here have front row seats

to observe the activity of
the barely dormant monster.

A team of volcanologists
is today setting out

on a field trip.

Their destination is not easy to get to,

so Dominique Gilbert

from the Global Physics
Institute at Paris has

to be lowered down by
helicopter along with his team.

They've brought with them
a cutting edge apparatus,

a geological scanner which enables them

to see inside the volcano.

- [Translator] So, here we're unpacking

a cosmic ray telescope.

It's a prototype composed
of particle detectors

that we can see here, the yellow frames,

which measure the quantity
of cosmic particles

that go through the volcano.

By doing this kind of reading,

we can determine the density of the dome.

As the denser the rock, the
more it stops the particles.

So we can make x-rays of the
volcano with this telescope.

(gentle instrumental music)

- [Narrator] For hours, the
whole surface of the volcano

is subjected to the scanner's scrutiny.

A spectrum of colors emerges,
representing the density

of each type of rock.

The red zones correspond to the densest

and most solid areas.

The blue zones to the most fragile.

(speaks in foreign language)

- [Translator] The interest
of these experiments

and of these radiographs
is that they provide us

with information about
the volcano's structure.

When it was formed, it was
composed of quite new robust lava

and it had a fairly stable form.

Since its formation, the
volcano has been infiltrated

by extremely acidic fluids which come

from the hydrothermal system

and which eat away at the interior.

So, the volcano is now likely to collapse

because its lost a good deal
of its mechanical cohesion.

This could involve the
collapse of a single sector

or the whole thing,

and the radiographs
that we've done tell us

about the size and the
number of zones affected

which could collapse in
the event of an earthquake.

(gentle instrumental music)

- [Narrator] The weather is
unpredictable in the tropics

and the work on the ground
is long and fastidious.

The scientists have to move
the telescope regularly

in order to examine the
volcano from different angles.

(speaks in foreign language)

- [Translator] We now
have a good deal of data

and combine it all to try to
do what we do in medicine,

which is to create a 3D
image like with a scanner

combining the various
angles that we've examined

with the telescope.

It's been here for about three months.

It was previously in the south,

then to the east of the dome,

so we have three different viewpoints,

which should allow us to
make a 3D reconstruction

of the internal structure.

- [Narrator] The first results obtained

using the revolutionary
telescope reveal the fragility

of La Soufriere.

Eaten away from inside,
the base of the volcano

could collapse at the slightest tremor.

Such a catastrophe would have

potentially appalling consequences

for the 12,000 inhabitants of Basse Terre.

La Soufriere and many other volcanoes

at the Antilles archipelago
embody the violent encounter

between the Caribbean Plate
and the Atlantic Ocean.

4,000 kilometers away, an
identical phenomenon is underway.

On the western side, the Caribbean Plate

and the southernmost point of
the North American continent

are being shaken by
another ocean, the Pacific.

The Pacific Plate is gradually
being drawn downwards,

and once again, the contact
between the plates leads

to the emergence of new volcanoes.

The latest rose from the
land less than a century ago,

barely yesterday on a
geological timescale.

It's February 20th, 1943.

Dioniso Pulido, a Mexican
farmer, is inspecting his fields

after a long day's work.

He discovers a thick layer
of ash that is still hot.

All around, fumaroles emerge
from the bowels of the Earth.

After four days of constant rumbling,

a 60 meter high volcano appears.

It grows very quickly, throwing
out astronomical quantities

of lava and ash, which destroy
the neighboring villages.

Named Paricutin, it is
one of the rare volcanoes

on the planet to have
emerged as man looked on.

A further addition to
the long volcanic belt

that stretches all along
the West Coast of Mexico.

Not far away, the Nevado de Toluca

appeared several million years ago.

At 4,690 meters high, it's
the fourth highest peak

in the country.

(gentle instrumental music)

The volcano is today extinct

and its summit cradles
two vast craters filled

with crystal clear lakes.

This grandiose setting is
one of the hunting grounds

of geologist Jose Luis Arce

from Mexico's National
Autonomous University.

His aim is to gain a fuller understanding

of the geological history of a region home

to the greatest concentration
of volcanoes in the Americas.

(speaks in Spanish)

- [Translator] We're in
the central part of Mexico

where volcanism is due to the subduction

of part of the Pacific Plate
under the North American Plate.

This subduction produces volcanism.

In Nevado de Toluca, we can
clearly see this big crater

which is two kilometers wide
and 1.5 kilometers long.

This volcano is part of
the Pacific's ring of fire.

- [Narrator] The Ring of
Fire Jose Luis Arce refers to

is the gigantic
horseshoe-shaped volcanic arc

around the Pacific Ocean
from Indonesia to Canada

and from North America
to the south of Chile.

- [Translator] The Pacific
Ring of Fire is an area

along the edges of the plates.

It coincides with a great
number of active volcanoes

all around the Pacific.

This generally corresponds
to subduction zones

for active volcanoes and
significant seismic activity.

This is due to the interaction
between the plates.

(gentle instrumental music)

- [Narrator] But along
the West Coast of Mexico,

the subduction of the
oceanic plate does not occur

in a perfectly linear manner.

The degree of inclination of varies,

and so the volcanoes appear inland

at differing distances from the sea.

(speaks in Spanish)

- [Translator] For Mexico,
it's rather particular

as the subduction is not parallel

to the Mexican volcanic belt.

There are various angles of subduction.

In the western part of Mexico,

the subduction is quite inclined,

whereas in central Mexico, it's flatter,

and this is why the
volcanoes are further away

from the subduction zone.

(peaceful instrumental music)

- [Narrator] In the Mexico City Valley,

another volcano, Xitle, left a fatal

and indelible mark on
the country's history.

It erupted almost 1,300 years ago,

totally destroying a town of Cuicuilco,

at the time one of South
America's most prosperous cities.

Jose Luis Arce meets
Maria Sandoval Gonzales,

the archaeologist in charge of the site.

(speaks in Spanish)

Together, they explore the
archaeological remains looking

for traces of ancient lava flows.

(speaking in Spanish)

- [Translator 1] We have
lava here, volcanic rock.

The bubbles indicate that
they contained gases,

mostly CO2 and water vapor.

These gases separate from
the lava as it advances

and the bubbles deform as they're crushed.

- [Translator 2] This lava
covered the city of Cuicuilco.

It was buried in around
750 AD by the volcano Xitle

which is to the south of Mexico City.

(gentle instrumental music)

- [Translator 1] We can see
various structures here.

These are lava flows.

These structures are
like wrinkles which form

when the lava moves forward.

It advances and leaves these lines.

- [Translator 2] Because it gets colder?

- [Translator 1] Yes, it
advances and gets colder

at the same time and leaves these marks

which give us an idea of
direction of the flow.

- [Narrator] Like an American Pompeii,

the city of Cuicuilco is today
a major archaeological site,

valuable testimony recalling
that geological history

can be inexorably intertwined
with that of mankind.

In Central America, however,
volcanic eruptions are not

the only threat to the inhabitants.

Wherever plates meet, tectonic movements

regularly cause tremendous
underwater earthquakes.

These can then lead to the
formation of colossal waves

and even tsunamis.

According to the experts,
the Northern Caribbean

is particularly at risk.

Over the past 500 years,

more than 50 tsunamis have
already been recorded.

Along the eastern rim,
the Lesser Antilles region

is being closely monitored.

The Advance Lookout
Station is in Guadaloupe

at the Volcanology and
Seismology Observatory.

Its director Daniel Amorese
is today accompanying

Sebastien Deroussi on a trip
to gather the data recorded

by a whole network of sensors.

- [Translator 1] Well, the
buildings in good condition.

It hasn't moved recently.

- [Translator 2] One of the roles

of the Volcanology and Seismology
Observatory in Guadaloupe

is to take part in the tsunami watch.

The main cause is seismic activity

which we can observe at the interface

between the Caribbean and
the North American plates,

in the subduction zone about
100 kilometers from here.

Did you check the supply recently?

- [Translator 1] Yes, it's
picking up satellites.

Everything looks good.

- [Narrator] To evaluate the
risks of tsunamis in real time,

tide gauges are deployed
throughout the region.

These instruments constantly
record the slightest change

in the sea level.

- [Translator 1] If a tsunami
is triggered in the region,

then everyone around the
basin will be affected.

The instruments that we use
here, like this tide gauge,

are able to detect a wave
that's already passed,

so in a way it would already be too late.

But it will be useful for the people

in surrounding countries further away.

In return, our colleagues
around the Caribbean basin

have other instruments
which are useful for us,

so we really have to regard this system

as being of global value.

We can't simply have
a tsunami alert system

all alone in isolation.

It wouldn't work because
tsunamis cross whole oceans

and it takes time for them
to cross oceans and seas,

and it's that time that
enables us to warn people.

- [Narrator] An earthquake
in the northern part

of the Caribbean Plate
could generate waves

of more than 12 meters
and endanger the lives

of some 35 million people.

The tectonic forces in action
in the northern Caribbean

have always shaped and modeled the region.

Millions of years ago,

volcanic islands emerged from the waves,

and tomorrow they will perhaps
be swallowed up by a tsunami,

but the collision between
the Caribbean Plate

and the Atlantic Ocean also
causes slow vertical movements

in the sea bed.

This phenomenon lies behind the emergence

or the submersion of certain
fragments of the Earth's crust.

In Guadaloupe, the island of Grande Terre

is the direct result of
these constant movements.

The rock strata here bears
witness to a turbulent past.

The island has undergone a
succession of both marine

and terrestrial events
over several million years.

Jean Frederic Lebrun and Jean
Lon Latisee are geologists

at the Antilles University.

For several years now,
they have been trying

to reconstruct Grand Terre's
complex geological history.

Today they're in the town of
Sainte-Anne exploring a quarry.

- [Translator] That's what
we call white limestone.

It's dazzling.

- [Narrator] In the heart
of the limestone massif,

the scientists look for
very particular clues.

Fossilized coral would
show that the area was once

covered by the sea.

- [Translator] Look, there's
one there too, an Agaricia.

In fact, we can find all
the corals we usually see

in quite deep reefs in calm zones

which enabled the limestone mud to settle

and to construct this whole formation.

(gentle instrumental music)

So this quarry is quite exceptional

because there are two reefs,
one on top of the other.

At the bottom, there's
the agaric limestone

which is about 40 meters
thick all the same,

and then there's an eroded
surface which goes down

and which undulates
because there are channels

which have been dug out,

and it continues down there.

The eroded surface has recorded
a lowering in the sea level.

The sea went down and
erosion carved out the cliff.

- [Narrator] The sea
level therefore went down.

Subsequently, the level varied further

and the sea rose slowly,
bringing sand with it.

This sand was deposited on the coral reef

until it was completely covered.

- [Translator] So we can see
that it's getting higher.

The sea level rises and the
beaches advance and move on

and they reach as far as up there.

On the top, we can see a
second reef, an acropora reef,

which looks quite granular from here.

So that's the second reef
that's settled on the top

and that represents the stabilization

of the higher sea level.

- [Narrator] After the second flooding,

Grand Terre experienced
a final dramatic change

due to the effects of subduction.

Around 400,000 years ago,
it surfaced once more,

becoming the island we know today.

As time goes by, Jean Frederic
Labrun and his colleagues

learn ever more about the
history of the Antilles,

but the tectonic phenomenon
at play here are complex.

In their laboratory, a
map of the region reveals

a disparate tangle of faults
on the edge of the plates.

- [Translator] This is a bathymetrical

and topographical map.

It shows the regions relief

and so Guadaloupe and
Soufriere are right here,

and this is the arc of volcanic islands

with Dominica here, the Saints
Islands, and Basse Terre.

What's interesting on this
map is that we can clearly see

all the structures, all the faults.

The faults are connected to
an opening towards the north.

The front part of the
arc is drawn to the north

because of the subduction
which occurs obliquely

in this region and so
it's cut all these faults.

We can see here, for example,
the Morne-Piton Fault,

which we can clearly see on Marie-Galante.

It's like a step and it
goes from here to there.

So it's almost 60 kilometers long.

This part has gone down
and this part has risen.

(gentle instrumental music)

- [Narrator] A few kilometers
south of Grand Terre,

the island of Marie-Galante is cut in two

by a gigantic fault,

which has widened gradually
over the centuries.

Several dozen faults split the
land all around Guadaloupe.

A little further north, the
Greater Antilles archipelago

is subjected to the same tectonic stress,

and here the confrontation

of the Caribbean and North American plates

has even more spectacular consequences.

(ground rumbling)

Instead of going one under the other,

according to the subduction phenomenon,

the two plates slip against one another

and in the middle, another
gigantic fault has appeared.

(gentle instrumental music)

Haiti and its capital Port-au-Prince
are smack in the middle

of this displacement zone.

On January 12, 2010, an
earthquake of a magnitude

of seven devastated the country,

causing more than 230,000 victims.

Even today, Haiti is still
attempting to heal its wounds.

Port-au-Prince is slowly
getting back to normal,

but the scars of the catastrophe
are still only too visible.

(somber music)

This deadly earthquake sounded the alarm

among the international community.

There was an urgent need
to predict future quakes

as early as possible.

An intensive surveillance program
has therefore been set up.

Steeve Symithe from Purdue
University in the U.S.

is one of the scientists
behind the project.

For several months, he has
been traveling around Haiti

installing GPS equipment.

The apparatus enables the
slightest ground movements

to be observed month after month.

The data then provides
precise and detailed maps

of the deformation zones and
helps to determine the speed

of the plate's movement.

(speaks in foreign language)

- [Translator] We set up this apparatus

and leave it in place
for at least four days,

three or four days.

Then we remove it and
then come back every three

or four months, quite
regularly to take measures

to make sure we have a
representative series over time.

Thanks to these measurements,
we can calculate variations

in the strain in the crust

and this enables us to explain
the aftershocks we observe

after an earthquake.

And also, perhaps, to anticipate
other earthquakes to come.

(gentle instrumental music)

- [Narrator] Initial
measures show deformations

of around two centimeters per year.

The slip and friction
between the two plates

apply colossal strain to the whole region,

and it builds up as time goes by.

This energy is subsequently
released periodically

when part of the fault gives way.

It is at this point
that earthquakes occur.

To further improve their
knowledge of the movements

affecting the zone, another
team has been deployed

in the field.

Run by Bernard Mercier
de Lepinay from the CRNS

and the Sophia Antipolis in France.

It is entrusted with setting
up a series of seismographs

at strategic points in the region.

(speaks in foreign language)

- [Translator] We're here next to this

because we've set up a
seismological station

to record the seismic waves,

and this antenna is one
among 23 that we're equipping

throughout the country.

We use seismic waves,
which are waves like light,

and which enable us to create
images of the rocky milieu

and to see where the main
fractures are that cross it.

- [Narrator] The seismographs
measure the amplitude

and direction of ground
tremors in real time,

even the very slightest.

By analyzing the data,

the scientists can make detailed
models of each small fault

that splits the region at
the junction of the plates.

(speaks in foreign language)

- [Translator] Where we are
now, we're practically parallel

to the direction of the plate's movement.

Not completely parallel,
but we're on a line

we can qualify as a thrust fault,

which means one plate
wants to go under another

and that poses a problem of deformation.

You can well imagine that when
two plates are face to face

and one moves under the other,

it creates a lot of
deformation on the surface.

(gentle instrumental music)

- [Narrator] There is no doubt

that further earthquakes will occur here,

but scientists now hope to
be able to see them coming

and to warn the local population.

Meanwhile, tectonic forces continue

to shape the Haiti landscape.

The slipping plates have torn
the rock apart deep down,

transforming the ground into
a hole-filled Swiss cheese.

Underground rivers and vast
caves have formed everywhere.

In the region of Pestel,

the Bellony Caves are
among the best known.

(gentle instrumental music)

Emmanuel Solelik is the
guide in charge of the site.

He has been exploring the caves for years

and reveals their secrets to visitors.

Flooded on several occasions,
the impressively vast caves

are decorated with countless
stalagmites and stalactites.

(gentle instrumental music)

(speaks in foreign language)

- [Translator] There's friction

between the North American
plate and the Caribbean Plate.

Water came in and covered the mountain.

The empty space was created below.

Then, as it moved out,

the water created
stalagmites and stalactites,

and at the same time, these
concretions we can see

were also created by the water.

- [Narrator] Emmanuel knows the place

like the back of his hand.

As a child, he loved to
get lost in the rocky maze

despite the superstitions
that surround it.

- [Translator] When I was
little, I used to come here

when people had voodoo ceremonies.

I lived in Pestel and I
thought the Bellony Caves

were the Devil's hole.

(eerie music)

- [Narrator] Be they
underground or under the sea,

the numerous cavities in
the Caribbean Plate are one

of many local treasures.

(gentle instrumental music)

For connoisseurs, the
sumptuous Blue Hole off Belize,

for example, has become one
of the top spots for divers.

For hundreds of thousands of years,

Central America has
constantly been redrawn

by the movements of the terrestrial crust.

On its eastern facade,
volcanoes and earthquakes

are an integral part of
the Antilles history.

On the western side, a
different type of event

has profoundly transformed
the whole region.

Three million years ago,
North and South America

moved closer together to
the point of touching.

The two continents were joined together

and a new land was formed,
the isthmus of Panama.

(dramatic instrumental music)

According to the experts,

it would have been formed in
several successive stages.

It all began about 15 million years ago.

As the Pacific Plate slid
below the Caribbean plate,

a string of volcanic islands appeared.

At the same time, tectonic
movements pushed parts

of the seabed to the surface.

Other fragments of land
emerged from the waves.

Then sediment built up over the millennia

and gradually filled the empty spaces.

Finally, the isthmus closed up completely,

just three million years ago.

But at the beginning of the 20th century,

man decided to counter
the tectonic forces,

digging a gigantic canal
to link the Atlantic

and Pacific oceans as they
were previously joined.

This herculean task was one

of the most difficult
projects ever attempted,

but its impact on maritime trade

is still considerable even today.

New work has been underway
for several months.

(explosion blasting)

The aim is to widen the canal

to allow even bigger vessels to pass.

(tense instrumental music)

The work represents a great opportunity

for one team of scientists.

Andres Cardenas is a paleontologist

at the University of
los Andes in Colombia.

Along with his colleagues,
he comes here regularly

to examine the rocks
excavated by the huge diggers.

- The expansion of the
Panama Canal is giving us

a new opportunity to look at
the rocks in this location

because they are creating
artificial exposures

and then we could see the fresh
rocks and the fresh fossils.

(gentle instrumental music)

In those environments, we
have found several mammals,

some animals like the marsupials,

the opossum, the armadillos.

They are from South America originally

and they are, if you go today to Texas,

they do have that marsupials,
you have the armadillos.

In contrast, you have
here in South America,

mammals from North America
originally like the jaguars.

The mammals that we have found here are

from North American affinities.

It is telling us that there was a corridor

from the north through South America.

(gentle instrumental music)

- [Narrator] When the two
Americas came together,

the wildlife was involved
in extensive migration

across the new land bridge.

After evolving apart
for millions of years,

species from the north and
south met and interbred,

colonizing whole new territories.

This event, known as the
Great American Interchange,

had a considerable impact
on the biodiversity

of the two continents.

For Andres Cardenas, each
new fossil that is discovered

is a precious clue.

- In the coral area formations,
you can find marine fossils

like bivalves, oysters.

It is telling us that this location was,

at some point, under the sea,

and at other points, above the sea.

(gentle instrumental music)

- [Narrator] The mix of land
and marine animal fossils

provides valuable information
about the formation

of the Panama isthmus.

- That historical event
was a very drastic event

because it changes not only
the biological dispersion

of the South and North American animals,

but also it changes the
global circulation pattern

and maybe could change also
the climatic mode of the Earth.

- [Narrator] A slender
strip of land stretched

between two continents, the
Central American isthmus,

has played its part in
changing the equilibrium

of the whole planet.

(lively instrumental music)

A remarkable destiny, akin to
that of the Caribbean Plate.

Born in the depths of the oceans,

shaped by earthquakes and volcanoes,

it was formed in barely 100 million years,

a mere moment in the Earth's
geological time scale.

And it has given rise to
landscapes of exceptional beauty.

Today, the region's
history is far from over.

To the east, confrontation
with the Atlantic Ocean

will form new islands.

In a few million years, they
could perhaps join together

and even form a new land bridge
between the two Americas.

(birds singing)
(waves crashing)

(lively instrumental music)