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

(wind blowing)

(wondrous music)

- [Narrator] Since its formation,

our planet has undergone
constant transformation.

(explosion)

Stupendous collisions
have created continents.

Colossal forces have
raised up ocean 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.

For 100 million years,

Africa has existed in
the shape we know today.

But its story is far from over.

The continent is slowly
moving towards Europe,

and the collision has already begun.

To the east, the Great Rift
Valley moves mountains,

and prepares to split Africa in two.

Along the ocean shores, and
in the depths of the desert,

scientists seek clues that
may point to Africa's future.

Every relief system, every
fossil, and every earthquake

is a new enigma to resolve.



As they uncover the secrets
enclosed in the rock,

they reveal the forces
that shape Africa today

in a never-ending voyage
of the continents.

300 million years ago,

one vast super-continent united
all the planet's landmasses.

But Pangaea, as it is
called, finally broke in two.

Eurasia split off from
what would become Africa

and the other continents
of the Southern Hemisphere.

Between them, an ocean
opened up: the Tethys Sea.

The history of this marine expanse

has left traces in the heart

of one of the planet's most arid regions,

the Arabian Peninsula.

Here, the ground abounds with
a precious resource: oil.

(horn honking)

The black gold has brought
wealth to the gulf states,

and in particular to
the Sultanate of Oman.

(playful adventurous music)

The Wadi Nakhr canyon, in
the north of the country

is one of the places where
indications of how it was formed

are the most visible.

(exotic Arabian music)

Louai Machhour is a
geologist and oil prospector.

In his expert view,

Oman's situation today as an oil El Dorado

is due to the presence of
the age-old Tethys Sea.

(speaks foreign language)

- [Interpreter] We're in the heart

of the Oman mountain range.

The Tethys opened up in this
region of the Arabian plate.

At that time, this whole
area was underwater,

hence the considerable sedimentation.

- [Narrator] About 100 million years ago,

Oman was located further south,

a long way from the future Europe.

Long before the desert and the mountains,

the region was partially covered

by the waters of the Tethys Sea.

As the centuries passed,

sediments were laid down over the seabed.

The Tethys was warm and shallow,

an ideal environment
for bacteria to prosper,

transforming matter into one
particular substance: kerogen.

20 million years ago, however,

the continents drew closer,
and the Tethys Sea closed up.

The kerogen sank deeper into the ground.

Under the effects of pressure,

it transformed into hydrocarbons,

and seeped into the cracks in the rock.

(birds chirping)

(quiet adventurous music)

(water splashes)

Louai is prospecting
throughout the region.

He observes the rocks meticulously,

looking for the slightest suggestion

they could contain oil reserves.

(speaks foreign language)

- [Interpreter] A
reservoir is like a sponge

with little holes,

and all these holes are filled
with hydrocarbons or gas.

We can see that this surface

is ridden with cracks all along it,

which were certainly caused
by tectonic movements.

If these cracks remain open,

the improve the horizontal
permeability of the rock,

and aid the circulation.

- [Narrator] This area seems
to be particularly rich

in deep-set hydrocarbons.

Studying the rock even closer,

further indications confirm

that the sea once came this far inland.

(speaks foreign language)

- [Interpreter] This is a
fossil of coral, solitary.

And so we can clearly see the structure,

which is cellular and well-preserved.

So we have marine sedimentation here.

Sedimentation in a sea
that was quite shallow

and quite warm.

(hammer chipping)

- [Narrator] By observing
the rock around the cracks,

Louai confirms his initial analysis.

The next step is to
drill an exploration well

to see if oil really
exists deep underground.

The gulf countries of Iran and Iraq

are today among the world's
leading oil exporters.

Symbolizing the Emir's great wealth,

the black gold is also the
most precious of testimonies

to the whole region's geological history.

But the closure of the Tethys
Ocean 20 million years ago

left other traces too, that
are rather more surprising.

(rumbling)

In Egypt, the majestic Pyramids of Giza

stand as a millennial legacy
of ancient civilizations.

But not far away, in the Faiyum Desert

the site of Wadi El-Hitan
contains other treasures

several million years old.

(pulsing exotic music)

The roads here have given way

to trails marked out in the sand.

Improbably-shaped stone
giants rise up all around,

sculpted by erosion
over millions of years.

Francis Duranthon is a paleontologist,

and curator of the Toulouse Museum.

For many years,

he has traveled the
world looking for fossils

that can explain the evolution of species.

Wadi El-Hitan is of particular interest,

as the desert sands here conceal
some rather unusual bones.

- [Francis] Hello.

- [Digging Man] Hello.

- [Francis] You are digging?

- [Digging Man] Yes, small
(mumbles) from a whale.

- [Francis] A whale?

Can I help you digging?

- Of course.
- Yeah?

Okay. (laughs)

(brushing)

And do you have a lot of
whales here in the area?

- [Digging Man] Yeah, I can imagine

we find like 1,000 whale in the area.

- [Francis] 1,000?

- [Digging Man] Yes, 1,000.

- [Francis] Wow.

(playful mysterious music)

- [Narrator] Nicknamed
the Valley of Whales,

the Wadi El-Hitan site is a
veritable open-air museum.

The first bones were discovered
here over a century ago

by a British archaeologist.

Since then, more than a
thousand whale skeletons

have been found.

As time goes by, the wind
continues to blow away the sand,

revealing even more relics.

(speaks foreign language)

- [Interpreter] It's surprising
to find whale skeletons

like this in the middle of the desert.

Why are they here?

Well, in fact we're where
the Tethys Sea used to be,

between about 37 and 40 million years ago.

The sea was quite shallow here,

and it was probably a lagoon area

where these small whales,
Dorudons, came to reproduce.

The Dorudons were whales
about five meters long,

but they were prey to
other, much bigger whales,

called Basilosaurus, which
could measure up to 18 meters.

The small Dorudon skeletons we found,

particularly the young,
have bite marks on them,

meaning that they were the
prey of the big Basilosaurus,

so these animals came to
reproduce in this region

where the sea was about 30 meters deep.

And when they died, obviously,

they sank to the sea bed and fossilized.

Naturally, sediment subsequently
accumulated over them,

and when Africa rose up
due to the plate tectonics,

the sediment was removed and eroded.

And so the whale remains were revealed,

and uncovered by the desert wind

that they call here the khamaseen.

(quiet mysterious music)

- [Narrator] For the paleontologist,

the Egyptian desert is an open
book on the region's history.

In the middle of the sand,

whale skeletons lie
alongside shark's teeth,

fossilized mollusks, and
even the bones of crocodiles

and marine turtles.

All these remains testify

to the wealth and diversity
of the Tethys Ocean's wildlife

over 30 million years ago.

(speaks foreign language)

- [Interpreter] The Tethys
Sea was once a vast expanse

linking the Atlantic
Ocean to the Indian Ocean

and the Pacific.

Africa was completely
isolated from Eurasia,

and progressively, because
of plate tectonics,

the Arabic plate would open up and pivot

because of the opening up of the Red Sea,

and would close off this expanse of sea

to form what is today
the Mediterranean Sea,

a fragment of what the
Tethys Sea once was.

(reverent music)

- [Narrator] The existence of
this ocean, today disappeared,

is the proof of the slow rise
of the African continent,

and its collision with Europe.

Today, only the Mediterranean
Sea separates the two giants,

but the voyage of the
continents is not over.

Slowly but surely, Africa
continues to move northwards

at a rate of two centimeters per year.

The collision is underway,

and it's in the Strait of Gibraltar

that it's the most perceptible.

At Al Hoceima in Morocco,

the land quakes regularly

from the effects of tectonic forces.

On February 24, 2004,

a quake measuring 6.3 on the
Richter scale hit the city,

causing over 600 victims.

This formidable phenomenon

has occurred at regular intervals.

Philippe Vernant and Jean-Francois Ritz

geologists at the
University of Montpellier

are currently working at Al Hoceima.

(speaks foreign language)

- [Interpreter] One meter 70.

Is the radio on?

Okay, we're off.

North on the surface.

You head west and go as far as T1.

Then you take T3 and come back.

- [Narrator] The scientists
want to make precise models

of the tectonic movements
the African plate undergoes

in contact with Europe.

Armed with their GPS,
they explore the area

taking extremely precise
topographical readings.

(speaks foreign language)

- [Interpreter] The idea's
to mark out an itinerary

that will enable us to accurately measure

the topography of the
different areas we see here

and the whole profile

which forms a basic rectangle

and allows us to see
the difference in height

of the various areas.

Notably here, for
example, at the point T3,

which is an old riverbed
that has risen up.

There's the river today.

We can get a very precise measurement

of the height difference
between the old and new beds.

(quiet thoughtful music)

So we've crossed east to west,

and we have the cape point here.

You went to T3,

and here's the north-south profile

where we'll take the
samples of the pebbles.

(hammering)

Here we have an active riverbed,

but what we can see in the landscape

is that the river used to flow here.

That's the initial level.

In fact, the river sank into the ground.

It sank because the Earth's
crust rose at this point.

And where they are up there,
there are also pebbles,

which shows that there was an uplift here

of about 40 meters.

What we want to quantify
is the rate of that uplift.

To do that, we have to do two things.

We have to measure the
exact height difference

between the two riverbeds,

the current one and the old one,

and then we have to date the
pebble deposits up there.

So if we have those two
pieces of information,

we divide the height by the age,

and we get the rate of uplift.

(birds singing)

- [Narrator] Throughout the region,

the ground sinks and rises and fractures.

The collision between Africa and Europe

causes the rock to fold,
(hammering)

and numerous fault ruptures appear.

An analysis of the GPS data

will soon enable the scientists

to understand the scale of the movements.

(adventurous music)

A few days later,

Philippe Vernant and Jean-Francois
Ritz are back at work.

This time they've traded
their GPS equipment

for ropes and harnesses.

They're focusing on a rocky
cliff a few dozen meters high.

The aim is to reconstitute the
chronology of the earthquakes

that led to the appearance of this fault.

- [Interpreter] Okay Phil, pull it up!

- [Interpreter For Phil]
It's OK, I've got it.

- [Narrator] In order
to date previous quakes,

the scientists use a rather
particular technique:

dating by cosmic rays.

- [Interpreter For Phil] Okay, it's taut.

- [Narrator] The Earth is
constantly being struck

by particles from space.

When they hit the ground,

they're absorbed by the surface rocks,

whose composition is slightly altered.

(rumbling)

With each seismic event,

the ground fractures and
new rocks are exposed.

By analyzing the surfaces,

the scientists can determine

how long each strata was
exposed to the cosmic rays,

and therefore date the successive quakes.

The height of each uplift also
provides precise indications

of the magnitude of the event.

(playful adventurous music)

On the ground,

the geologists take rock samples

from along the top of the cliff.

(hammering)

(speaks foreign language)

- [Interpreter For
Phil] If we take samples

from all along this surface,

we should be able to see
that it's older up above.

So that means we're seeing a quake,

and then we can see a
different period below.

With another quake, more recent,

and so on moving to the bottom.

So we can see the history of
the different seismic events

which led to the formation
of this fault plane.

And so that tells us something

of the region's seismic destiny.

Every so many years, in fact,

there was an earthquake which led to this,

and depending on the movement,

we can get an idea of the
magnitude of the events.

- [Narrator] Characterizing
the various quakes

that shook the region
over thousands of years

will enable the scientists to
gain a better understanding

of the movements that affect
the African continent.

- [Interpreter For Phil]
Six and a half, seven here.

We can take six, six and a half, probably.

- [Narrator] This study
will ultimately contribute

to making more precise
predictions of quakes

in the Al Hoceima region,

for the land continues to
tremble here inexorably.

The movement of Africa towards Europe

is a fundamental action
that nothing can stop.

(wind blowing)

Little by little,

the Strait of Gibraltar will close up,

and in about 50 million years,

the Mediterranean Sea will
have almost disappeared.

(dramatic music)

But as Europe and Africa
face off at Gibraltar,

another plate steps into the
dance in the east: Arabia.

Arabia is gradually separating
from the Sinai region

and moving northwards.

The rate of this movement is
greater than in East Africa.

The result is that the two
plates slide against one another

and in the middle a
gigantic fault has appeared.

Known as the Dead Sea
Transform, or Dead Sea Rift,

it splits the Near East
from the Red Sea to Turkey.

Between Jordan, Israel, and Palestine,

this sliding movement of the plates

has led to the collapse of a whole region,

in the middle of which is the Dead Sea.

High up on a rocky spur,

the fortress of Masada in Israel

benefits from a unique
viewpoint over the whole region.

This is where Yann Klinger is heading.

A geologist from the Global
Physics Institute in Paris,

he has been traveling the
region for many years.

(bold adventurous music)

His objective is to
understand the movements

that have affected the Dead Sea Rift

over previous millennia.

Above the sheer cliff,

the majestic fortress
dominates a lunar landscape

framing the Dead Sea
and the Judean desert.

- [Interpreter] Here we're
on the Masada Plateau.

We're above the Dead Sea,

which is 400 meters below sea level.

So 400 meters beneath
our feet, more or less.

The plateau here is
part of the Sinai plate.

We're standing over this vast depression

filled by the Dead Sea,

which is associated with the activity

of the Dead Sea Transform.

The fault is about 1200 kilometers long,

and it enables the Arabian
plate to move northward

compared to the Sinai
plate here to the west.

(rumbling)

(mysterious music)

- [Narrator] The sliding
movement of the tectonic plates

has for a long time

produced powerful seismic
events in the region.

But their magnitude, and
above all, their frequency,

are still little-known.

To improve predictions
of future earthquakes,

Yann is attempting to
compose a complete picture

of previous events.

And so he explores the Dead Sea basin

accompanied by geologist Shmuel Marco

from the University of Tel Aviv.

(gentle piano music)

- [Yann] The fault is running here.

- [Shmuel] Each time they move,
they create an earthquake.

- [Narrator] The rocks here store records

of the alternating dry and rainy seasons,

and above all, of each
time the Earth shook.

By studying the overlying strata,

the scientists can
literally go back in time

and retrace the tectonic
history of the Dead Sea rift.

- We see two different layers here,

one dark and one white.

The white ones were
deposited in the summers,

and the dark ones are the winter deposits.

Flash floods that came into the lake

deposited fine material.

And actually each pair is one year.

- [Yann] So we can count years.

- [Shmuel] Yes, exactly.

- OK, great.

And we have a huge deformation here.

What is this thing here?

- Yes, here we have,
we see folded layers,

we see that we can
follow these up and down,

and in this quiet environment,

the only thing that can set
a layer to slump like this

is an earthquake.

- So all this layer (mumbles)

just get folded like this,

when it was flat before, right?

- [Shmuel] Yes

- [Yann] And this is a
signature of an earthquake?

- [Shmuel] Yes.

- [Yann] And you have a series
of things like this here,

that gives you a chronology
of past earthquakes

on the Dead Sea Fold here.

- Exactly.

We don't have seismographs at this time,

and we have about 50,000 years of record,

and we have about 30 strong earthquakes

that happened in this period.

- [Yann] So you make a catalogue here.

- [Shmuel] Yes, it's an
archive of earthquakes.

- [Yann] What about these tiny things,

it looks like the layers.

Are they folds here maybe, or?

(uplifting dramatic music)

- [Narrator] Nature conserves traces

of the seismic events that shape it,

but sometimes our own history
has a story to tell, too.

(wind blows)

Working in a region with such
a rich, 2,000-year old history

is a godsend for geologists.

In the north of Israel,

the ruins of the Vadum
Jacob templar castle

also tell the tale of the Dead Sea rift.

In 1178, Christian armies
built this fortress

to prevent the Muslims from
re-conquering Jerusalem.

The Christians would finally lose that war

and the Vadum Jacob was
partially razed by the enemy.

But the site was doomed anyway.

The crusaders, in fact, had
built on the fault line itself

along the course of the River Jordan.

(river running)

- [Interpreter] Here in
this castle, for example,

you can see that this wall has shifted.

This part of the wall
has moved towards me,

whereas that part has moved to the north.

This is the limit between the
Arabian plate on this side

and the Sinai plate on this side.

So we can reconstruct the
history of earthquakes here

through the archaeological remains,

and from the geological records

we can find in the area, too.

So far away from the fault line,

the movement is continual
and imperceptible to man,

of about five millimeters per year.

But here at the fault,

we can see that there's no movement.

Forces build up, and at some point

those forces exceed the
resistance of the Earth's crust

and there's a tremor.

And so, all along this fault,

there are regular seismic events

in response to the
accumulating forces here,

resisting the five
millimeters per year movements

which are continual.

(river running)

(quiet dramatic music)

- [Narrator] Thanks to historical writings

and archaeological digs,

the date of the first
earthquake to hit the castle

has been determined.

It took place on May 20, 1202,

and moved the walls by 1 meter
60 in just a few seconds.

(speaks foreign language)

- [Interpreter] So here

we're on the other side of the castle,

and of course the fault
crosses these walls, too.

As we go along the wall, there's
a gap of over two meters.

So naturally, this fault
is an integral part

of the Eastern Mediterranean geodynamics,

and when the Arabian
plate moves northward,

it needs space, it creates space

by building mountains along its front

and by pushing the
Turkish plate to the west

to continue on its way forward.

(rumbling)

These faults are the
translation of plate tectonics,

and plate tectonics are
in action on our planet,

it will never stop.

It creates topography,

it causes movements
which are locally violent

in the form of earthquakes,

and it's something

that totally goes beyond human time scales

and which will continue.

- [Narrator] Arabia today

continues to move inexorably to the north,

millimeter by millimeter.

In the future,

no doubt other earthquakes
will strike the region

and further deepen the Dead Sea rift.

A little further south,

the separation of Africa and Arabia

occurs rather differently.

Over the past 20 million years,

the two plates have been
progressively moving apart

at a rate of 15 millimeters per year.

And in the middle, a
new ocean is being born.

(waves breaking)

For the moment, it is merely a sound,

a maximum of 300 kilometers wide.

It is called the Red Sea,

prolonged in the east by the Gulf of Aden.

Off the Sultanate of Oman,

the small island of Al-Hallaniyah

is an ideal study site

for understanding the impact
of the opening of the sea.

(car drives past)

(quiet adventurous music)

The ground is often shaken
here as the plates move apart.

Felicie Korostelev and Jordane Corbeau

work at the Jussieu University in Paris.

Their research subject

is the movement affecting the
coast along the Gulf of Aden

due to tectonic forces.

(water splashing)

They're going to Al-Hallaniyah

to collect a seismograph
installed here several months ago.

(motor whining)

The island is an exceptional
site for seismic analysis.

It has very few inhabitants,

no significant buildings,

and only a single, little-used road.

(gentle piano music)

There are no vibrations caused by man

which could pollute the data recorded.

(speaks foreign language)

- [Female Interpreter] We've
set up about 20 stations

in the south of Oman,
in the Dhofar region.

This is the last station we're collecting.

All the others have
already been collected.

Once we've got it, we'll send it to France

to analyze the data.

We obtain recordings of ground movements,

of movements due to
earthquakes in particular,

and so we can therefore
study the internal structure

of the ground beneath the region.

- [Narrator] The network of seismographs

makes continual recordings

of even the slightest earthquakes.

Each quake reflects an
event of greater amplitude

that occurs a few kilometers offshore

in the depths of the Gulf of Aden.

(case clicks)

(rumbling)

At the point where Africa
and Arabia are moving apart,

a vast depression has been created,

and the sea has moved in
between the two continents.

Over the centuries,

the Earth's crust
continues to be stretched.

Magma spurts up from
deep within the mantle,

and fills the empty space

created by the separation of the plates.

This then forms what is
known as a mid-ocean ridge.

(gull squawking)

(speaks foreign language)

- [Interpreter For Jordane]
Seismological stations

have been set up along the coast of Oman

to map Oman's continental margin,

and subsequently, the opening
up of the Gulf of Aden.

The continental margin is the transition

between the continental crust

characteristic of continents,

and the oceanic crust,

which is typical of oceans.

The Gulf of Aden margin is interesting,

because it's currently being formed,

so it's in the opening phase,

moving from a continental crust

to becoming an oceanic crust.

(waves breaking)

So we're here facing
the sea floor spreading

between the Arabian plate
and the African plate.

(waves breaking)

(gentle string music)

- [Narrator] The two scientists

have gathered a massive
amount of information

during their mission.

Analyzing it all will take time,

but one day, they hope,

this study will enable a detailed modeling

of the opening up of a new ocean.

The Sultanate of Oman

is also the scene of another
scientific team's field study.

Their investigation is taking place

not far from the town of Mirbat

on the shores of the Arabian Sea.

(dramatic piano music)

Sonia Rousse and Melina
Macouin are geologists

from the research institute
for development in Toulouse.

Their mission is to determine
the date of the opening up

of the Gulf of Aden.

To do this, they're studying
rather particular rocks

known as dikes.

- [Interpreter For Sonia] I
think we're on this one, right?

- [Interpreter For Melina]
We'll have to go and see it.

- [Narrator] The dikes were
formed 700 million years ago

when the Arabian and
African plates were joined.

Within the seams of this magmatic rock

are tiny crystals containing iron.

(coring drill grinding loudly)

It is this metal that is of
interest to the scientists.

Its presence confers the dikes
with a specific magnetism.

Analyzing this can enable
even the slightest movements

on the Earth's surface to be re-traced.

- [Interpreter For Melina]
These very old dikes

can be found on the other
side, on the African plate.

We have exactly the same
dikes, the same age.

When we put them together,

we can define the rotations

of the various geological formations

and see to what extent
we can re-associate them.

(coring drill rumbling)

(coring drill grinding loudly)

- [Narrator] To find out when
the Arabian and African dikes

began to separate,

the scientists take a series
of samples along the coast.

- [Interpreter For Melina]
Concerning the past

30 million years, for the
Gulf of Aden, for example,

we're looking at sea
for magnetic anomalies,

and we can also look on land
for information we're lacking,

and which will perhaps help
to determine the period

when the gulf opened up and
the two plates separated.

- [Narrator] It will take
several months' more work

to know exactly when Arabia
began to leave Africa

and understand the movements
that the two plates underwent.

(inspiring music)

Today, the two continents are
almost completely independent.

A little further south,

a single land bridge still
links the two plates.

This region is known as the Afar Triangle.

In a few million years,

this corner of Africa,
overlapping Ethiopia, Djibouti,

and Eritrea, will in turn break off,

and move away with the Arabian plate.

(wind blowing)

The land here is fractured and fragmented.

The tearing and straining of landmasses

leads to the ground collapsing

and violent volcanic eruptions.

(playful music)

The area is 100 meters below sea level,

and exceptionally, the
formation of a mid-ocean ridge

can be studied on land here.

In the easternmost part of Ethiopia,

the Erta Ale volcano

is one of the region's mythical emblems.

All around is a torturous landscape

where sulfur deposits and lava flows

stretch as far as the eye can see.

This desert, one of the
most arid in the world,

is home to the Afar people,

semi-nomadic herdsmen,
and renowned warriors.

The volcano Erta Ale rises up
to an altitude of 613 meters.

It is one of only a few in the world

to have a permanent
lava lake at its summit.

- Okay.

(tense music)
(lava bubbling)

- [Narrator] Before his death,

the eminent volcanologist
Jean-Louis Cheminee

was fascinated by this extraordinary,

smoke-shrouded mountain,

which he visited regularly with his team.

With lava samples, gas analyses,

and rock-composition studies,

the specialists have examined
the volcano in every detail.

They have gradually
improved their understanding

of how a new ocean is formed.

But Erta Ale will continue
to fascinate scientists

for a long time to come.

The spectacle it proposes
here is unique in the world,

a symbol of the link uniting
geologists and volcanoes.

(splashing)

(dramatic music)

In Djibouti, the Ghoubbet-el-Kharab

marks the southeast points
of the Afar Triangle.

This deepwater bay
surrounded by steep cliffs

is linked to the sea by a channel
with very strong currents.

At one end is the Ardoukoba volcano,

which last erupted in 1978.

That eruption spat out

more than 12 million cubic meters of lava,

transforming the landscape
into a lunar panorama.

On the other side of the
volcano is Lake Assal.

Once filled with fresh water,

it is today increasingly salty.

As the land spreads and opens up,

the sea gradually moves in.

For several years now, Bernard Le Gall

from the University of Brest,

has been monitoring the
separation of the tectonic plates.

He's seeking to understand

exactly how the Earth's
crust is transformed

into an ocean floor.

- [Interpreter] This is an
exceptional geological site.

We're looking at Lake Assal,

which is located 150 meters

below the level of the Ghoubbet Gulf.

From here we can clearly
see the overall morphology

where the lopsided relief behind

is composed of the oldest
lava in this sector,

about three million years old,

whereas the lava covering
the base of the depression

is much more recent, only
a few thousand years old.

(quiet thoughtful music)

Here, we're on the surface

of one of the very recent lava fields.

If we consider the geochemical composition

of the lava fields in
the Assal-Ghoubbet area,

we can see that it's very comparable

to the oceanic basalt

which forms the bed of the current oceans.

- [Narrator] By studying the
chemistry of the recent rocks,

the scientists have taken a first step

in demonstrating that an oceanic crust

is in the process of replacing
the desert landscape here.

It's an exceptional geological spectacle,

which normally occurs out of sight,

deep down in the depths of the ocean.

- [Interpreter] Geophysical
studies have shown

that beneath the Assal depression,

the crust was very, very thin.

The crust is about four
to five kilometers thick,

which means that deep down,

the crust must be injected
with matter from a great depth,

and that it's probably already
reached the point of rupture.

And so this means that
here in front of us,

we're witnessing a process
of magmatic accretion,

with the creation of a new
crust of an oceanic type.

- [Narrator] Magmatic accretion

is the term do describe the
rising of magma from the mantle,

and the gradual formation
of an oceanic ridge.

(chipping)

- [Interpreter] If we apply
the current rate of separation,

which is about two centimeters per year,

into the future,

then it's probable that this
zone of accretion at Lake Assal

will be about 20 kilometers
wide in a million years' time,

and 200 kilometers wide
in 10 million years.

As the region undergoes accretion,

it will also become deeper,

and it will progressively
be flooded by seawater,

which is now at the level
of the Ghoubbet gulf.

If we compare mid-ocean ridges

with a sort of continental
fracture which spreads,

then this would be like
the top of a zipper

which is opening up.

(wind blowing)
(awe-inspiring music)

- [Narrator] It's hard
to imagine that here,

in a few tens of millions of
years, will be underwater,

several hundred meters below the surface.

(dramatic music)

But the forces which
affect the whole region

don't stop there.

To the south of the Afar Triangle,

another grand-scale
phenomenon is occurring.

A huge scar splits all
of the east of Africa,

the Great Rift Valley,

a fault line extending
over 6,000 kilometers

from Ethiopia as far as Mozambique.

Beneath the surface,

the continental plates are pulling apart

approximately one centimeter per year.

In about 100 million years,

an ocean will split Africa in two.

But for the moment,

the rift is composed
of a vast, deep valley

several kilometers wide.

In Mozambique, the Gorongosa national park

is located at the southernmost
point of the rift.

Martin Pickford is a paleontologist

at the Natural History Museum in Paris.

For an explorer seeking clues
to the history of the Earth,

the valley is of great interest.

- [Interpreter] It's magnificent, no?

We have the rift here,

and Lake Urema in the background there.

- [Narrator] The appearance of the rift

millions of years ago led to
the whole valley collapsing.

The sea swept into the
fault on several occasions,

depositing countless layers of sediment.

Within the valley,

thousands of bones were
fossilized in ideal conditions,

and have survived throughout the ages

untouched by the ravages of time.

Today, erosion has brought
a myriad of fossils

to the surface.

(blowing)

(scraping)

- [Martin] Looks like a
fragment of the pelvis.

I see (mumbles) here.

Bit of sediment stuck on it here,

but it's in terrible condition.

Very difficult to identify,

but at least it shows us that fossils,

that bones have been
fossilized in this area.

(gentle piano music)

- [Narrator] Martin Pickford
is particularly interested

in the origins of mankind.

In the year 2000, it was in
the heart of this rift valley

that he made an exceptional discovery:

the remains of Orrorin,

a hominid some six million years old.

Martin believes the formation of the rift

could have contributed to the appearance

of our distant ancestors.

Tectonic forces would have led

to a profound transformation
of the landscape,

whereas tropical forest
covered Western Africa,

savanna now dominated the
eastern part of the rift.

The first men could have
well settled in this new,

more hospitable environment.

They would have evolved very
differently from their cousins,

the great apes, more
adapted to a forest milieu.

- Actually, the eastern rift

the resulting savannah
fauna that we see today:

giraffes, hyenas, lions,

is actually a result of two movements.

One from the south, installing
some animals and plants,

and one from the north, installing
other animals and plants.

And that's really the
importance of the rift.

The rift in the tectonics
changes the climate,

changes the vegetation,

and of course, the animals
move as the situation changes,

as the conditions change.

Homo actually evolved not in
the rift itself in East Africa,

but somewhere else and then came in,

because when you find it,

you find the stone tools and so on,

almost in every locality.

And before that there's nothing.

They come in, and then they're Homo.

(footsteps crunching)

Here we have a gallery going
into the side of the cliff,

and we can see it goes
into a cave at the end,

and it opens up into a ravine at the side.

So were early humans living here,

or maybe one of them might
have fallen into the cavity

and got fossilized.

We need to go and excavate to be sure.

But when you think

there's hundreds of
kilometers of these gorges

in this region,

the chances are that at
least several of these caves

probably have early hominid remains in,

and I just have a feeling

it will yield interesting information.

It's just big enough for
a human to come inside.

(groans) There we are.

Oh here, there's a
recent infilling of sand,

but some of these will have old deposits

which have turned to stone,

and in those we can find bones and snails,

bits of wood and that sort of thing.

(playful mysterious music)

- [Narrator] The theory that
the rift played a major role

in the appearance of humans

is the subject of widespread debate.

But for Martin Pickford,

our planet would no
doubt be very different

if the Earth had not shifted

and opened up in East Africa.

- It's strange to think

that if it hadn't been for plate tectonics

and all this global activity,

climate change and so on,

humans wouldn't be here today.

In fact I wouldn't even be here

looking at the Rift Valley.

In a manner of speaking,

this would still be
the planet of the apes.

Strange, but probably true. (chuckles)

- [Narrator] In Africa,
like everywhere else,

evolution is intimately linked
to the history of the land.

Man today has conquered the whole planet,

and extended his dominion
over every natural milieu.

But will he still be here tomorrow,

to witness the transformation
of the African continent?

(dramatic inspiring music)

In a few million years,

Africa and Europe will
form a single continent.

As for the Red Sea and the Gulf of Aden,

they will become vast oceans.

And for the first time in its history,

the heart of Africa will be split in two.

The eastern part will begin a long journey

across the Indian Ocean,

drifting according to the
movement of the tectonic plates,

and possible collisons.

The all-powerful tectonic forces

have not yet drawn up
the definitive contours

of the African continent.

(sweeping dramatic music)