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[MUSIC PLAYING]

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The Great Rift Valley--

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things have happened here that
happen nowhere else.

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That's the underlying
truth to this place.

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Within its walls, our
species evolved.

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Civilizations rose
and collapsed.

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And there's an even bigger
drama at play--

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the birth and death of oceans.

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It's all due to the impact
of tectonics.

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Geologist Nick Eyles is on a
quest to explore its power.

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From the cradle of humanity, to
the hottest place on earth,

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to the ruins of the oldest
civilizations, and the bedrock

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of some of the world's
modern religions, a

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journey along the river.

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There's something primeval being
up there and looking

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down into the depths
of the Earth.

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Holy cow.

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It's an absolutely fantastic
experience, not just as a

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scientist, but as
a human being.

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This is the East African Rift,
one part of the Great Rift

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Valley that stretches from
Mozambique to Turkey.

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It's a special place
for humankind.

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Embedded in these cliffs,
packed between layers of

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volcanic ash is the story
of our origin.

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The Rift system is out natural
home as it were.

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That's where humans evolved.

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We develop an association with
volcanoes, and faults,

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earthquakes, so it's a great
view of where we originated.

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The whole landscape is covered
with great thicknesses of ash,

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which is a good thing, because
those ash layers entomb the

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remains of early humans
and their ancestors.

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And they provide precise marker
horizons of time.

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Ever since Darwin suggested
that humans share common

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ancestors with African apes,
scientists have searched for

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further clues.

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The only place they found
fossils that linked directly

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to modern humans is in this
long narrow valley.

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The intriguing question
is why.

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It's geologists who think
they found the answer.

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Canadian geologist, Nick Eyles,
seeks to understand how

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human history is linked
to the geology of

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The Great Rift Valley.

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He begins his journey in Kenya
to explore the theory that the

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Rift was the catalyst
for human evolution.

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He meets German geologist,
Martin Trauth.

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Trauth has spent his career
dating sediment and

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cross-referencing them with
evolutionary changes.

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He's concluded that at each
step in our evolution

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coincided with the appearance
or disappearance of large

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lakes in the Rift basin.

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If you have major events in
human evolution occurring at

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the time when we have large
lakes everywhere, that's

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probably an evidence for that
there should be a link between

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climate, environmental changes,
and the evolution of

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early humans.

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So large lakes were the
key to human origins.

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What happened when these
lakes disappeared?

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Then they've disappeared,
probably they have to change

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dramatically the strategy to
find food in the environment.

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But these lakes, they reappear
in cycles and so that makes

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them very good for humans
to survive as they are

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generalists.

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The frequent environmental
changes drove our ancestors to

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evolve ways to better adapt to
new landscapes and diets.

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Here at Kariandusi, Trauth has
studied a particular lake

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deposit called diatomite that
dates back a million years.

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This is actually a lake sediment
that consists of

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millions and trillions of
skeletons from little plants.

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As the lake dried up,
early humans left

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traces of their lives.

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Hand axes embedded in the
walls of the gorge.

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So what uniquely defines
a Acheulian hand axe?

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The [? other ?]

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[? wide ?] tools are just very,
very simple, you know,

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round-shaped kind of hammers.

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So these ones are really
for cutting meat.

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We see the development stone
tools about two million years

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ago, and the development of
human brains, and to me,

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that's not coincidental.

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You've got to find the rock.

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You've got to know what rock
type make good tools, you've

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got to communicate
that to others.

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You need a social
organization to

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manufacture those stone tools.

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To me, that was the first
Industrial Revolution because

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it required manufacturing
on a huge scale.

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To understand why this
revolution happened, it's

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necessary to delve deep
into the tectonic

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story of the Rift Valley.

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George has come to the East
African Rift, because it's the

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largest tear affecting any
plate on the planet.

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It was a huge wound, which
is opening up.

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That wound arose because the
African plate lies above plume

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of magma that's slowly melting
the crust, causing it to

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stretch or rift.

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On the edges of warmed rock,
high shoulders rise up.

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In the middle, the floor
subsides forming a rift.

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Three million years ago,
repeated rapid swings of

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climate from wet to dry, caused
huge links to form and

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suddenly disappear.

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Combined with frequent volcanic
eruptions and

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earthquakes, our ancestors
based unbelievable odds.

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For Nick, it's part of a
greater truth that he's

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exploring that the Great
Rift Valley is unique.

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Things happen here that
happen nowhere else.

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One of the great findings of
geology over the past 40 years

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is that oceans come and
go as super continents

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form and break out.

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But how do continents split?

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And how do new oceans form?

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To find the answer, Nick
comes here, the Afar

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Depression in Ethiopia.

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The Afar Depression is one
of the most dramatic

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landscapes on Earth.

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Few people live here, and
even fewer visit.

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But to geologists like, Nick
Eyles, it's Shangri-La.

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This is a fantastic place to me,
because we driving along

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in the middle of the East
African Rift where the African

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plate is literally
being torn into.

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And Africa is over here, the
Somalian plate is on my right,

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and they're moving apart.

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The rift between the two
is slowly subsiding.

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This tectonic process has been
underway for 30 million years.

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But the Afar is so remote that
its significance has eluded

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geologists until recently.

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For Nick, it's a once in
a lifetime opportunity.

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His ultimate destination a
volcano called Erta Ale, or

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Smoking Mountain in the
local language.

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To get there, he must first
cross the Danakil Desert.

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This is a serene landscape.

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These are enormous lava flows,
which have come down from

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these margins that are from
these big volcanoes.

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Very fluid lava extending many
kilometers down slope but

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here, they've been broken
up by faults.

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It's absolutely amazing.

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It's just geology happening
before one's eyes.

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The next morning the
tarmac ends.

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Nick's transported
back in time.

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Salt is the livelihood
of many tribal people

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living in the Danakil.

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It's mined by hand, packed on
camels, and sold in markets a

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three days walk away.

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On some days a 1,000 camels
will plod by here.

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Camel trains have been taking
salt from the Danakil

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depression down there, below sea
level, all the way up to

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the highlands for centuries,
and I've just seen it.

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It's as if the modern
world never existed.

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Next stop, Nick goes even
further back in time to the

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dawn of life.

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This is the Dallol crater, a
volcano whose summit is still

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below sea level.

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The crest here is incredibly
thin, the magma

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close to the surface.

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What's unique about this place
is that this volcanic activity

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is interacting with very
thick salt deposits.

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Early life may have thrived in
environments like these four

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billion years ago.

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First to arrive are the
hot fluids migrating

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up above the magma.

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And then puncturing the salt
are these beautiful little

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industrial pots.

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The hot water's coming out,
bringing sulfur bearing

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minerals, beautiful colors.

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And there's bacteria, very
simple, blue-green bacteria in

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there that love these
hot waters.

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These simple, colorful
bacteria are

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Earth's oldest life form.

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And this may be a glimpse
into early Earth.

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This whole area is underlain
but what's referred to as a

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mantle plume, which is a huge
mass of red hot plastic rock,

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which is rising up from the
mantle impinging on the base

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of the African plate, and
pushing it apart,

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splitting it into two.

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As we go further out in the
Afar Depression, we

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go below sea level.

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And at the moment, the ocean
is only prevented from

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flooding into this area
by volcanoes.

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Eventually, they will subside
under great weight of all the

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volcanic rock and the sea
will burst in here.

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In 2005, volcanic eruptions
and earthquakes rocked the

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Afar Depression.

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Fissures opened up, and large
flows of black salt lava

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flooded the landscape,
creating crust

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of a new ocean floor.

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Nick crosses paths with a
group of scientists from

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Britain trying to explain
why that new

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ocean is forming here.

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They use seismometers to track
the numerous earthquakes that

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hit the Afar.

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Each quake corresponds to the
injection of molten rock into

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the crust slowly splitting
the continent in two.

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So how many of these do you
have across the Afar?

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In total, I think there's
somewhere around 45, but

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that's combined between
UK seismometers and US

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seismometers.

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In this particular area, the
main axis of the rift is Erta

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Ale and Tat'Ali volcanoes.

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And it steps dramatically to the
west and then further to

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the south, so there's a
well-defined rift axis.

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So you're right at
the beginning of

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this whole new ocean.

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Yeah.

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Along the areas where the rift
axis steps dramatically, there

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are aligned cones
perpendicular to

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the axis of the rift.

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So it's possible that the strain
has transferred by

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volcanic intrusion rather than
transformed faults like we see

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in mid-ocean ridges.

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With each geologic event, the
Afar Depression evolves.

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But seeing the process with eyes
instead of instruments

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requires getting to Erta Ale.

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Easier said than done.

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This is the road up to Erta Ale
where crossing the lava

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fields is just a simple track.

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This is a vehicle that's
broken down.

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It's lost a bolt out of
the steering, and we

00:15:56.230 --> 00:15:57.750
stopped to help out.

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And ironically, we just passed
the camel train taking grain

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over to Eritrea.

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And they're making much better
progress than we are.

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Nick is now 20 kilometers
from the volcano.

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His guide, Solomon Berhe,
takes him to meet some

00:16:32.580 --> 00:16:37.800
remarkable people in a village
called Ali Abdala.

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What's it like living on
a huge sea of lava?

00:16:40.840 --> 00:16:46.740
[SPEAKING FOREIGN LANGUAGE]

00:16:46.740 --> 00:16:49.880
Yeah, it's very difficult,
tough life.

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They have been here
for 10 years.

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This is the station
for their family.

00:16:54.090 --> 00:16:57.680
But they move their animals
from place to place.

00:16:57.680 --> 00:16:59.910
Do you ever consider moving
away from this area?

00:17:02.630 --> 00:17:05.930
When there is rain, Erta Ale
area, there is grass.

00:17:05.930 --> 00:17:10.170
So he takes goat, and his
common to that area.

00:17:10.170 --> 00:17:13.380
They've discovered it's
not dangerous.

00:17:13.380 --> 00:17:16.210
Now, they live-- it
doesn't slope.

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So that's why they live here.

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I'm amazed that people can
survive here living,

00:17:26.780 --> 00:17:28.790
literally, on lava.

00:17:28.790 --> 00:17:31.300
There's no soil.

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We've seen children
running around in

00:17:32.730 --> 00:17:36.250
bare feet on hot rock.

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It's absolutely amazing.

00:17:39.060 --> 00:17:42.880
This is their home, and there
have been people living here

00:17:42.880 --> 00:17:45.610
for millions of years, because
this is where some of the

00:17:45.610 --> 00:17:49.025
earliest pre-hominid fossils
have been found.

00:17:49.025 --> 00:17:53.100
So there's a continuity of
life here in an extremely

00:17:53.100 --> 00:17:55.100
arid, hostile environment.

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Finally, Erta Ale.

00:18:03.220 --> 00:18:06.080
It's not very high or
impressive, because it's a

00:18:06.080 --> 00:18:09.400
shield volcano.

00:18:09.400 --> 00:18:13.690
Shield volcanoes don't explode,
instead the lava is

00:18:13.690 --> 00:18:17.163
very fluid and flows like blood
across the landscape.

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The truck can't make
it to the crater.

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The gear goes on camels.

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Nick and Berhe go on foot.

00:18:32.880 --> 00:18:34.340
You get excited every
time you come up?

00:18:34.340 --> 00:18:35.986
Oh, yeah, I do.

00:18:35.986 --> 00:18:37.236
Except [INAUDIBLE].

00:18:50.626 --> 00:18:51.114
That's amazing.

00:18:51.114 --> 00:18:51.602
Look at it.

00:18:51.602 --> 00:18:53.870
It's really a great
sea of lava.

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Incredible.

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Enormous volumes flooding out
over into the Depression all

00:19:10.960 --> 00:19:13.700
the way through here.

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Amazing volumes.

00:19:23.020 --> 00:19:27.760
And now, Nick, I'm going to take
you to take you to the

00:19:27.760 --> 00:19:31.565
old crater where still
it has the smoke.

00:19:31.565 --> 00:19:34.500
This is all the source of all
the great lava flows, the ones

00:19:34.500 --> 00:19:35.080
that come out.

00:19:35.080 --> 00:19:36.780
Yes, they come out
from this one.

00:19:45.970 --> 00:19:49.720
It's another crater
that's set.

00:19:49.720 --> 00:19:52.400
So it's just degassing
now, right?

00:19:52.400 --> 00:19:53.845
It's sitting there
doing nothing.

00:19:53.845 --> 00:19:55.095
It is, yeah.

00:19:59.220 --> 00:20:02.670
This is the final stage when a
volcano dies, so it's bringing

00:20:02.670 --> 00:20:07.240
up sulphurs, and we get this
tremendous outgassing.

00:20:07.240 --> 00:20:10.050
These gases are actually
cooking the rock.

00:20:10.050 --> 00:20:13.050
This was hard lava just
a few years ago, but

00:20:13.050 --> 00:20:14.520
it's now really rotten.

00:20:14.520 --> 00:20:19.680
And it's been rotted by gas
coming up through it.

00:20:19.680 --> 00:20:22.690
So this is a very important
stage of volcanic activity,

00:20:22.690 --> 00:20:24.350
because it's bring up
precious minerals.

00:20:28.240 --> 00:20:33.400
Erta Ale's other crater is still
alive, and active lava

00:20:33.400 --> 00:20:36.230
lakes are extremely rare.

00:20:36.230 --> 00:20:38.730
There are only four
in the world.

00:20:38.730 --> 00:20:42.690
This is the holy grail for me,
because I've never seen fresh

00:20:42.690 --> 00:20:45.130
lava in a lake before.

00:20:45.130 --> 00:20:48.270
So this is volcano central.

00:20:48.270 --> 00:20:52.490
The 30 minute hike to the
lava lake is dangerous.

00:20:52.490 --> 00:20:56.580
Berhe wants to avoid the heat of
the day but still get there

00:20:56.580 --> 00:20:57.990
before sunset.

00:20:57.990 --> 00:20:59.820
This is pretty unstable
isn't it?

00:20:59.820 --> 00:21:03.820
Yes, it is, especially
at dark.

00:21:03.820 --> 00:21:06.070
It's very dangerous.

00:21:06.070 --> 00:21:09.742
Yeah, and now we're on one
of the main lava flows.

00:21:09.742 --> 00:21:12.380
This is interesting here, we've
got this younger, dark

00:21:12.380 --> 00:21:14.800
[? hard ?] flow sitting
on top of that lighter

00:21:14.800 --> 00:21:15.740
brown colored one.

00:21:15.740 --> 00:21:17.755
So you mean the brown
is older?

00:21:17.755 --> 00:21:20.380
Yeah, see the flat one
sitting on it?

00:21:20.380 --> 00:21:23.770
The darker the lava, the more
recent the eruption that

00:21:23.770 --> 00:21:25.020
spewed it out.

00:21:29.990 --> 00:21:32.970
This is like walking
on thin ice.

00:21:32.970 --> 00:21:37.630
It looks quite solid, but it's
actually just a very thin skin

00:21:37.630 --> 00:21:41.540
which was insulating red hot
lava streaming through as

00:21:41.540 --> 00:21:45.030
tunnels underneath and feeding
the fronts of the flows.

00:21:47.710 --> 00:21:49.850
So we've got to be very careful
moving over these in

00:21:49.850 --> 00:21:51.180
case you drop right
through into one

00:21:51.180 --> 00:21:52.430
of these open tunnels.

00:22:08.290 --> 00:22:09.930
Holy cow.

00:22:09.930 --> 00:22:12.860
Will you just look at that?

00:22:12.860 --> 00:22:14.110
That's incredible.

00:22:17.210 --> 00:22:18.460
That's amazing.

00:22:20.500 --> 00:22:24.370
It took three days to get her in
40 degree temperatures, and

00:22:24.370 --> 00:22:29.590
how many dozen bottles of water,
and it's worth it.

00:22:29.590 --> 00:22:30.840
Wow.

00:22:41.826 --> 00:22:45.690
You can see the cooled skin
and the upwelling magma

00:22:45.690 --> 00:22:46.310
between them.

00:22:46.310 --> 00:22:47.560
There's like plate tectonics.

00:22:55.320 --> 00:22:57.357
Geologists are always looking
for a small scale example to

00:22:57.357 --> 00:22:59.320
explain a bigger
global picture.

00:22:59.320 --> 00:23:02.780
Here we've got a perfect example
of plate tectonics on

00:23:02.780 --> 00:23:03.960
a small scale.

00:23:03.960 --> 00:23:10.210
And we can see dark gray rafts
which are like continents,

00:23:10.210 --> 00:23:14.680
separated by bright red rifts
where new magma's coming up

00:23:14.680 --> 00:23:16.125
forcing those continents
apart.

00:23:19.912 --> 00:23:24.870
And what's happening every now
and again is huge bubbles of

00:23:24.870 --> 00:23:27.570
sulfur dioxide coming
up in depth.

00:23:38.397 --> 00:23:42.895
That's the closest we'll come
to, actually, looking at the

00:23:42.895 --> 00:23:45.790
Earth's magma.

00:23:45.790 --> 00:23:49.420
There's something primeval being
up there and looking

00:23:49.420 --> 00:23:51.512
down into the depths
of the Earth.

00:23:51.512 --> 00:23:54.240
It's an absolutely fantastic
experience, not just as a

00:23:54.240 --> 00:23:57.274
scientist, but as
a human being.

00:24:02.184 --> 00:24:03.434
That's amazing.

00:24:16.930 --> 00:24:21.920
What Nick saw on a microscale in
the lava lake is writ large

00:24:21.920 --> 00:24:25.040
across the Danakil.

00:24:25.040 --> 00:24:27.600
I've seen a lot of rocks and
landscapes around the world,

00:24:27.600 --> 00:24:30.870
but this is the clearest example
I've ever seen of this

00:24:30.870 --> 00:24:33.610
sort of tectonic setting.

00:24:33.610 --> 00:24:37.270
We can see these long dark
cracks down here and running

00:24:37.270 --> 00:24:39.840
into the distance, through that
little volcano, there's a

00:24:39.840 --> 00:24:43.390
crater there, and then the
big guy in the distance.

00:24:43.390 --> 00:24:48.810
And this is marking the age of
the African plate on my left,

00:24:48.810 --> 00:24:51.400
and the Somalian plate
on the right.

00:24:51.400 --> 00:24:55.870
The two are moving apart as
result of magma coming up

00:24:55.870 --> 00:24:59.430
along these fissures, which is
pushing the plates apart.

00:24:59.430 --> 00:25:00.680
It's absolutely fantastic.

00:25:06.432 --> 00:25:10.590
In 10 million years, the expanse
in front of Nick will

00:25:10.590 --> 00:25:14.430
be transformed into an ocean.

00:25:14.430 --> 00:25:17.420
It's a testament to the power
of plate tectonics.

00:25:32.700 --> 00:25:35.790
Nick now leave the Afar, and
goes north through the

00:25:35.790 --> 00:25:40.840
Ethiopian highlands to explore
how the rift geology inspired

00:25:40.840 --> 00:25:42.486
some of the world's first
civilizations.

00:25:45.230 --> 00:25:48.830
This stream will widen into one
of the most fabled rivers

00:25:48.830 --> 00:25:50.330
in the world.

00:25:50.330 --> 00:25:54.670
The Nile River is a direct
product of precipitation over

00:25:54.670 --> 00:25:58.470
the Ethiopian highlands and
that's been likened to the

00:25:58.470 --> 00:25:59.720
water tank of Africa.

00:26:04.800 --> 00:26:09.480
Rainfall flows to the west, and
then north, so without the

00:26:09.480 --> 00:26:11.838
rift, there would be
no Nile River.

00:26:15.190 --> 00:26:18.720
From Ethiopia, Nick follows
the Nile into Egypt.

00:26:23.490 --> 00:26:27.300
To both the east and west is
desert, but through this

00:26:27.300 --> 00:26:31.675
valley oasis came early humans
migrating out of Africa.

00:26:35.420 --> 00:26:39.850
6,000 years ago, this valley
saw the beginning of one of

00:26:39.850 --> 00:26:42.450
the world's first
civilizations.

00:26:42.450 --> 00:26:46.400
It was a society shaped by the
river dependent on its

00:26:46.400 --> 00:26:47.650
seasonal floods.

00:26:52.070 --> 00:26:55.430
Over there, you see the
Nilometer for the measuring of

00:26:55.430 --> 00:26:58.480
the water by these sticks,
which are found in the

00:26:58.480 --> 00:27:01.290
Nilometer going down
to the water.

00:27:01.290 --> 00:27:03.950
And there are marks
in the wall.

00:27:03.950 --> 00:27:06.960
Measuring the height of the
river enabled the priests to

00:27:06.960 --> 00:27:10.940
predict potential flood levels
and to gauge what land could

00:27:10.940 --> 00:27:12.740
be cultivated.

00:27:12.740 --> 00:27:14.900
So they could predict the
floods from this.

00:27:14.900 --> 00:27:17.530
If it was high, it was going
to be a good flood.

00:27:17.530 --> 00:27:18.610
Everybody's going to make
a lot of money, so

00:27:18.610 --> 00:27:19.740
they could tax more.

00:27:19.740 --> 00:27:19.970
Yes.

00:27:19.970 --> 00:27:22.390
If it was low, then they were
going to have a hard time, and

00:27:22.390 --> 00:27:23.600
you couldn't tax them as much.

00:27:23.600 --> 00:27:24.630
Exactly.

00:27:24.630 --> 00:27:27.920
Because this is the main source
of income for the

00:27:27.920 --> 00:27:29.050
priests and the king.

00:27:29.050 --> 00:27:31.910
So it's from this simple
instrument, as crude as it

00:27:31.910 --> 00:27:35.450
seems, that they got
their power.

00:27:35.450 --> 00:27:38.925
And that power was expressed
in huge stone structures.

00:27:50.700 --> 00:27:53.900
We see these beautiful
evolution in man's

00:27:53.900 --> 00:27:57.530
relationship with the planet
in winning stone, working

00:27:57.530 --> 00:28:01.370
stone, building these
lasting monuments.

00:28:01.370 --> 00:28:03.890
So I refer to ancient Egypt
as a second industrial

00:28:03.890 --> 00:28:06.230
revolution.

00:28:06.230 --> 00:28:11.180
The power of what was called
upper Egypt rested here, the

00:28:11.180 --> 00:28:12.430
Temple of Luxor.

00:28:19.690 --> 00:28:21.940
This is my favorite statue
in the whole of Egypt.

00:28:21.940 --> 00:28:26.130
It's one massive block of black
Aswan granite depicting

00:28:26.130 --> 00:28:27.870
Ramesses II.

00:28:27.870 --> 00:28:30.020
Running throughout all
these beautiful

00:28:30.020 --> 00:28:32.490
dikes are pink granite.

00:28:32.490 --> 00:28:35.100
It's a wonderful example of
granite as sculpture.

00:28:39.450 --> 00:28:41.060
These columns are huge
aren't they?

00:28:41.060 --> 00:28:42.825
And they resemble
giant papyrus.

00:28:42.825 --> 00:28:44.075
That's right.

00:28:46.540 --> 00:28:49.350
The columns represent
papyrus reeds, the

00:28:49.350 --> 00:28:52.720
symbol of upper Egypt.

00:28:52.720 --> 00:28:54.900
Now how on Earth would
they have been built?

00:28:54.900 --> 00:29:00.380
Blocks, mud bricks, blocks, on
so on, step-by-step until

00:29:00.380 --> 00:29:03.840
arrival to the end
of the column.

00:29:03.840 --> 00:29:06.800
So they would have mauled the
blocks up, put it on top of

00:29:06.800 --> 00:29:09.630
the previous one, like a ram
made out of mud bricks.

00:29:09.630 --> 00:29:10.800
You understand.

00:29:10.800 --> 00:29:12.770
So at one time, all of this
would have been full of mud.

00:29:12.770 --> 00:29:13.580
That's right.

00:29:13.580 --> 00:29:15.070
And then they take the
mud out and start

00:29:15.070 --> 00:29:16.360
carving the columns down.

00:29:16.360 --> 00:29:17.610
That's right.

00:29:23.726 --> 00:29:26.320
You know I've been looking for
many years for depictions of

00:29:26.320 --> 00:29:29.470
the actual people that sweated
and toiled building these

00:29:29.470 --> 00:29:32.810
temples, and here
it is at last.

00:29:32.810 --> 00:29:36.450
There's the central pylon, and
you can see people climbing up

00:29:36.450 --> 00:29:40.990
ladders, teams of people with
ropes, pulling on the ropes.

00:29:40.990 --> 00:29:44.380
Here at last is a picture of
the very people that built

00:29:44.380 --> 00:29:45.630
these temples.

00:29:48.830 --> 00:29:52.520
Ancient Egypt was so firmly
rooted in the detailed

00:29:52.520 --> 00:29:56.430
knowledge of the region's
geology, that it's been called

00:29:56.430 --> 00:29:57.680
a state of stone.

00:30:02.710 --> 00:30:06.885
This sandstone quarry has been
worked for thousands of years.

00:30:10.650 --> 00:30:14.400
To be honest, as a geologist,
I find this

00:30:14.400 --> 00:30:16.140
rather dull and boring.

00:30:16.140 --> 00:30:19.860
I can't find sedimentary
structures, fossils, or color

00:30:19.860 --> 00:30:23.260
variation that tells me about
how this rock was deposited.

00:30:23.260 --> 00:30:26.050
I know it was deposited in a
very shallow seaway with an

00:30:26.050 --> 00:30:28.075
abundant supply of sand.

00:30:28.075 --> 00:30:29.420
But that's the point.

00:30:29.420 --> 00:30:32.880
What I find interesting as a
geologist is a delight to the

00:30:32.880 --> 00:30:36.750
stone masons that could easily
carve this into flats slabs

00:30:36.750 --> 00:30:38.660
for the front of temples.

00:30:38.660 --> 00:30:42.280
And what's more, it was perfect
developing the art of

00:30:42.280 --> 00:30:43.530
hieroglyphics.

00:31:06.450 --> 00:31:11.020
The most prized monuments from
ancient Egypt are obelisks,

00:31:11.020 --> 00:31:16.020
made of a specific red granite
found near the city of Aswan,

00:31:16.020 --> 00:31:18.750
everyone from the Romans
to Napoleon

00:31:18.750 --> 00:31:21.480
spirited them out of Egypt.

00:31:21.480 --> 00:31:26.354
One obelisk, however, never
made it out of the quarry.

00:31:26.354 --> 00:31:28.650
This is the unfinished
obelisk of Aswan.

00:31:28.650 --> 00:31:31.270
And they were going for a world
record when they were

00:31:31.270 --> 00:31:33.530
trying to win this one
out of the quarry.

00:31:33.530 --> 00:31:39.650
This 1,100 ton piece of red
granite is 42 meters long, a

00:31:39.650 --> 00:31:42.930
third larger than any obelisk
ever erected.

00:31:42.930 --> 00:31:46.920
Well, the Aswan granite is
naturally fractured, and like

00:31:46.920 --> 00:31:50.730
carpenters working with grain
and wood, Egyptian stone

00:31:50.730 --> 00:31:51.690
masons were very good in

00:31:51.690 --> 00:31:53.660
utilizing these giant fractures.

00:31:53.660 --> 00:31:57.040
And this beautiful smooth wall
is a fracture that runs the

00:31:57.040 --> 00:31:58.180
length of the quarry.

00:31:58.180 --> 00:32:02.840
You can still see surveyor
marks on the sidewalls .

00:32:02.840 --> 00:32:05.570
In this deep trench that runs
along the side of the obelisk,

00:32:05.570 --> 00:32:08.530
we can see how they would
have released this.

00:32:08.530 --> 00:32:10.400
They would have lit a fire
along the length of the

00:32:10.400 --> 00:32:14.080
trench, heated the rock up,
throwing water on the heated

00:32:14.080 --> 00:32:16.040
rock which would have
fractured it.

00:32:16.040 --> 00:32:17.710
And then they would have
used dolerite.

00:32:17.710 --> 00:32:21.460
This is a [? mould ?], much
harder rock than granite, and

00:32:21.460 --> 00:32:22.511
they would have used that
to escalate all

00:32:22.511 --> 00:32:23.750
the softened rock.

00:32:23.750 --> 00:32:25.990
And by all accounts,
this represents

00:32:25.990 --> 00:32:27.555
about a year's work.

00:32:27.555 --> 00:32:30.100
But, of course, it was
all for naught.

00:32:35.325 --> 00:32:38.330
Well, this is the reason why
the unfinished obelisk is

00:32:38.330 --> 00:32:40.110
still sitting in a quarry.

00:32:40.110 --> 00:32:43.200
These are cracks that appeared
just when they were starting

00:32:43.200 --> 00:32:45.225
to lever off the obelisk.

00:32:45.225 --> 00:32:47.680
But normally, they were pretty
good at winning out huge

00:32:47.680 --> 00:32:50.870
blocks between joints to affect
the whole granite

00:32:50.870 --> 00:32:51.630
system here.

00:32:51.630 --> 00:32:55.600
But because it was so long,
they'd actually stepped over

00:32:55.600 --> 00:32:58.750
some joints and they
suddenly opened up.

00:32:58.750 --> 00:33:00.525
So really, they were defeated
by plate tectonics.

00:33:05.810 --> 00:33:09.590
What's remarkable about the
ancient Egyptians is not just

00:33:09.590 --> 00:33:12.410
their expertise in
stone building.

00:33:12.410 --> 00:33:16.360
They were also the first to
develop a highly sophisticated

00:33:16.360 --> 00:33:21.350
religion based on a belief
in eternal life.

00:33:21.350 --> 00:33:24.130
It's an interesting example of
where a mew science, in this

00:33:24.130 --> 00:33:28.650
case, geology has arisen out of
a religion and the need for

00:33:28.650 --> 00:33:31.480
immortality and lasting
memorials.

00:33:31.480 --> 00:33:33.770
So it's a profound change
in the way man

00:33:33.770 --> 00:33:34.640
related to the planet.

00:33:34.640 --> 00:33:38.586
They were burrowing away in the
universe mentally in terms

00:33:38.586 --> 00:33:41.300
of their religion, but they
were burrowing away in the

00:33:41.300 --> 00:33:46.460
ground, and profoundly changed
the way back man used rocks.

00:33:46.460 --> 00:33:48.020
So they developed the
first geological

00:33:48.020 --> 00:33:49.495
maps 3,000 years ago.

00:33:49.495 --> 00:33:50.870
They're very accurate.

00:33:50.870 --> 00:33:52.040
They developed mines.

00:33:52.040 --> 00:33:55.595
They send out huge prospecting
parties, 10,000 people strong,

00:33:55.595 --> 00:33:56.950
to find minerals.

00:33:56.950 --> 00:34:00.060
And it was all out of the
need for immortality.

00:34:08.350 --> 00:34:13.310
Nick says goodbye to Egypt and
travels through a section of

00:34:13.310 --> 00:34:17.199
the Rift, where volcanic
activity along the floor of

00:34:17.199 --> 00:34:21.389
the sea has caused the valley
to spread so much that it's

00:34:21.389 --> 00:34:22.639
formed a new ocean.

00:34:28.400 --> 00:34:29.580
This is a young ocean.

00:34:29.580 --> 00:34:30.750
It will widen.

00:34:30.750 --> 00:34:34.900
It's pushing the Arabian
plate behind us away.

00:34:34.900 --> 00:34:37.880
We'll see Africa the other way,
and eventually, this will

00:34:37.880 --> 00:34:40.929
grow up into an adult
ocean, like say, the

00:34:40.929 --> 00:34:44.659
modern Atlantic Ocean.

00:34:44.659 --> 00:34:47.070
It's that intrusion of volcanic
material all the

00:34:47.070 --> 00:34:51.056
time, which is the driver
for plate tectonics.

00:34:54.060 --> 00:34:58.110
From here, Nick enters the Dead
Sea Rift, a deep-sided

00:34:58.110 --> 00:35:01.250
valley where the Arabian
plate slides past the

00:35:01.250 --> 00:35:02.800
Sinai Israel plate.

00:35:02.800 --> 00:35:07.010
It's a geological time bomb
that has already leveled

00:35:07.010 --> 00:35:10.760
ancient cities, and threatens
to do so again.

00:35:20.120 --> 00:35:22.870
This is classic Lawrence
of Arabia country.

00:35:22.870 --> 00:35:24.892
Classic typography.

00:35:24.892 --> 00:35:28.706
This is the Arabian plate, which
has been deeply bitten

00:35:28.706 --> 00:35:30.195
into by erosion.

00:35:35.780 --> 00:35:40.100
These rifted plate margins,
where one plate is moving past

00:35:40.100 --> 00:35:43.140
another one, are extremely
dangerous areas, because they

00:35:43.140 --> 00:35:45.860
produce a large number
of earthquakes.

00:35:45.860 --> 00:35:49.820
And this area has been densely
settled for thousands of years

00:35:49.820 --> 00:35:53.350
as a rich historical record
of earthquakes.

00:35:53.350 --> 00:35:56.380
So this area is a real interest
to geologists and

00:35:56.380 --> 00:35:59.730
archaeologists looking at the
relationship between large

00:35:59.730 --> 00:36:01.410
earthquakes and civilizations.

00:36:07.560 --> 00:36:11.180
Nick teams up with one of the
top scientists in the realm of

00:36:11.180 --> 00:36:16.020
earthquake study, Israeli
geologist, Shmuel Marco.

00:36:16.020 --> 00:36:19.760
Marco combines archaeology
and history with his own

00:36:19.760 --> 00:36:23.540
geological findings in order
to build a database of

00:36:23.540 --> 00:36:25.760
earthquake activity in
the Middle East.

00:36:25.760 --> 00:36:27.650
These are 2,000-year-old
inscriptions.

00:36:27.650 --> 00:36:30.080
Yeah, Nabataean inscriptions.

00:36:30.080 --> 00:36:33.200
They've come to the fabled
city of Petra.

00:36:33.200 --> 00:36:37.110
2,000 years ago, it was the
trade capital of the

00:36:37.110 --> 00:36:38.300
Nabataeans.

00:36:38.300 --> 00:36:41.470
Goods from as far away
as China and Rome

00:36:41.470 --> 00:36:43.110
pass through here.

00:36:43.110 --> 00:36:46.700
But it's the Nabataeans'
extraordinary use of rock that

00:36:46.700 --> 00:36:49.050
the scientists find
intriguing.

00:36:49.050 --> 00:36:51.350
So this grand entrance
into Petra is along

00:36:51.350 --> 00:36:52.970
a very narrow crack.

00:36:52.970 --> 00:36:56.070
It's a crack that was widened
by the erosion of water.

00:36:56.070 --> 00:37:00.730
The Siq, as it's called, was
originally a small fracture

00:37:00.730 --> 00:37:04.675
formed when the Arabic plate
split from the African plate.

00:37:04.675 --> 00:37:08.400
So that Dead Sea Rift was key
to the formation of Petra.

00:37:08.400 --> 00:37:12.250
Yes, it formed the relief
here, the topography.

00:37:12.250 --> 00:37:15.660
Without this, you'd have a flat
surface as it was before

00:37:15.660 --> 00:37:16.910
the Rift formed.

00:37:16.910 --> 00:37:21.350
So it's truly a tectonic city.

00:37:21.350 --> 00:37:23.510
The grand opening.

00:37:23.510 --> 00:37:26.020
Yeah, this is the first
impression that you get when

00:37:26.020 --> 00:37:27.344
you come to Petra.

00:37:31.200 --> 00:37:33.490
They took advantage of
a crack in the walk.

00:37:36.370 --> 00:37:40.600
Around 500 AD, Petra
was abandoned.

00:37:40.600 --> 00:37:45.020
All that is left today are the
palaces, temples, and tombs

00:37:45.020 --> 00:37:47.560
carved into the rock faces.

00:37:47.560 --> 00:37:51.720
What was built between the
valley walls is a mystery.

00:37:51.720 --> 00:37:55.060
Was it destroyed
by earthquakes?

00:37:55.060 --> 00:37:59.050
Ancient cities are often built
on the remains of earlier

00:37:59.050 --> 00:38:02.890
structures destroyed by
war, fire, or some

00:38:02.890 --> 00:38:05.100
kind of natural calamity.

00:38:05.100 --> 00:38:09.540
Fallen columns, bulging walls,
and rubble provide clear

00:38:09.540 --> 00:38:12.680
evidence of ancient
earthquakes.

00:38:12.680 --> 00:38:15.880
These are the ruins of
Petra's Grand Temple.

00:38:15.880 --> 00:38:18.640
So the trick is, how do I
possibly identify earthquake

00:38:18.640 --> 00:38:21.520
damage, and also accurately
dated it, isn't it?

00:38:21.520 --> 00:38:25.400
Yes, for example, here,
look at this.

00:38:25.400 --> 00:38:28.170
We know that the building
was constructed in

00:38:28.170 --> 00:38:31.060
the Nabataean period.

00:38:31.060 --> 00:38:34.960
They're columns are so robust
that there is no way that they

00:38:34.960 --> 00:38:38.530
followed naturally without
a horizontal push.

00:38:41.060 --> 00:38:44.570
We have been recording
earthquakes using modern

00:38:44.570 --> 00:38:48.110
seismographs only in the
past century or so.

00:38:48.110 --> 00:38:51.960
This is not enough time for
studying earthquakes, because

00:38:51.960 --> 00:38:55.910
the recurrence is much longer
than a century.

00:38:55.910 --> 00:38:58.630
So in order to study earthquakes
prior to this

00:38:58.630 --> 00:39:02.050
instrumental period, we
use fallen buildings.

00:39:04.840 --> 00:39:09.440
Cities are a treasure for
earthquake geologists.

00:39:09.440 --> 00:39:13.150
And these columns buried
the coins that were

00:39:13.150 --> 00:39:16.760
dated up to 361 AD.

00:39:16.760 --> 00:39:19.120
And coins were found
also in Aqaba.

00:39:19.120 --> 00:39:23.850
So we know that the earthquakes
affected Aqaba and

00:39:23.850 --> 00:39:25.860
Petra at the same time.

00:39:25.860 --> 00:39:32.670
And we combine this with
historical reports Northern

00:39:32.670 --> 00:39:35.740
Israel, and Northern Jordan and
Syria, and we know that it

00:39:35.740 --> 00:39:36.990
was May 19, 363.

00:39:41.600 --> 00:39:44.560
We don't know the time of the
day, but we know the date.

00:39:44.560 --> 00:39:46.810
That's very rare in geology.

00:39:46.810 --> 00:39:49.560
That's an advantage to
using history and

00:39:49.560 --> 00:39:52.710
archaeologic combined.

00:39:52.710 --> 00:39:56.520
So the widespread damage really
shows that it was a

00:39:56.520 --> 00:40:00.800
major earthquake, probably
magnitude seven or above.

00:40:00.800 --> 00:40:05.900
If it happened today, it
would be disaster.

00:40:15.180 --> 00:40:19.760
From Petra, Nick goes north
into the land of Cana, the

00:40:19.760 --> 00:40:23.270
modern day Israel.

00:40:23.270 --> 00:40:27.510
Well, I'm currently floating in
the Dead Sea at 420 meters

00:40:27.510 --> 00:40:29.470
below sea level.

00:40:29.470 --> 00:40:31.520
One of the saltiest places on
the planet, because we we're

00:40:31.520 --> 00:40:33.720
along the Dead Sea Rift.

00:40:33.720 --> 00:40:35.190
That's Israel over there.

00:40:35.190 --> 00:40:37.710
That's Jordan over there on the
other side of the Rift,

00:40:37.710 --> 00:40:40.550
both moving northwards,
but they're moving

00:40:40.550 --> 00:40:42.040
at different rates.

00:40:42.040 --> 00:40:46.340
So this area is slowly
being pulled apart.

00:40:46.340 --> 00:40:50.020
The Dead Sea has been much
higher in the past.

00:40:50.020 --> 00:40:54.160
Thick sediments, now exposed,
are a treasure trove for

00:40:54.160 --> 00:40:55.730
geologists.

00:40:55.730 --> 00:40:58.560
So these are bottom deposits
of an ancient Dead Sea, but

00:40:58.560 --> 00:41:00.620
we're not much higher than
the modern level.

00:41:00.620 --> 00:41:04.190
The lake, the Dead Sea, which
is a small lake now extended

00:41:04.190 --> 00:41:09.210
for 220 kilometers from the
Sea of Galilee all the way

00:41:09.210 --> 00:41:11.285
through the middle of
the Arabah Valley.

00:41:14.200 --> 00:41:17.070
This is the Lisan formation.

00:41:17.070 --> 00:41:20.970
It's where Shmuel Marco began
his research on earthquakes as

00:41:20.970 --> 00:41:22.710
a graduate student.

00:41:22.710 --> 00:41:25.755
And he's got evidence to
show Nick of the Dead

00:41:25.755 --> 00:41:27.130
Sea's violent past.

00:41:29.870 --> 00:41:31.950
So it's pretty unusual
to get a nice record

00:41:31.950 --> 00:41:33.246
on land isn't it?

00:41:33.246 --> 00:41:36.410
Yes, it's very unique.

00:41:36.410 --> 00:41:38.930
These are very fine
laminations.

00:41:38.930 --> 00:41:41.460
Now I presume you've measured
the thickness of each one of

00:41:41.460 --> 00:41:43.300
these all the way down?

00:41:43.300 --> 00:41:43.730
Yes.

00:41:43.730 --> 00:41:47.160
Yes, we have very, very detailed
record of every

00:41:47.160 --> 00:41:51.350
little variation in
the deposition.

00:41:51.350 --> 00:41:53.740
We see white ones
and dark ones.

00:41:53.740 --> 00:41:57.920
The alternating layers record
seasonal flows into the

00:41:57.920 --> 00:41:59.850
ancient Dead Sea.

00:41:59.850 --> 00:42:05.290
This fine lamination is well
undisturbed unless you shake.

00:42:05.290 --> 00:42:09.800
And during earthquake, this nice
layering is disrupted,

00:42:09.800 --> 00:42:14.400
and sometimes broken, and
it's deposited again.

00:42:14.400 --> 00:42:18.570
So when we look up this section,
we look for layers

00:42:18.570 --> 00:42:21.400
that are disrupted.

00:42:21.400 --> 00:42:26.180
In this rock face, which records
the last 50,000 years,

00:42:26.180 --> 00:42:30.330
Marco has found disruptions
representing 30 separate

00:42:30.330 --> 00:42:31.510
earthquakes.

00:42:31.510 --> 00:42:35.960
We show with this cycle that
earthquakes come in clusters,

00:42:35.960 --> 00:42:39.680
so we have 10,000 years of
intense activity, and then

00:42:39.680 --> 00:42:42.125
10,000 years of less
intense activity.

00:42:46.070 --> 00:42:48.430
Marco's conclusion?

00:42:48.430 --> 00:42:51.926
The 21st century will be very
seismically active.

00:42:55.790 --> 00:42:58.660
The Earth's surface is shifting
all the time.

00:42:58.660 --> 00:43:00.860
There's no one part
of the Earth's

00:43:00.860 --> 00:43:02.100
surface which is stable.

00:43:02.100 --> 00:43:06.130
Most places are moving at
several centimeters a year.

00:43:06.130 --> 00:43:08.150
There are earthquakes
globally.

00:43:08.150 --> 00:43:11.830
But the big issue is, what risks
do these pose for modern

00:43:11.830 --> 00:43:13.390
cities, modern people?

00:43:16.320 --> 00:43:22.240
The region is rich in historic
and tectonic events.

00:43:22.240 --> 00:43:28.920
Some are recorded in biblical
texts, some by the ruins of

00:43:28.920 --> 00:43:30.170
past cultures.

00:43:32.310 --> 00:43:34.570
All are recorded
in the geology.

00:43:38.100 --> 00:43:39.592
Masada.

00:43:39.592 --> 00:43:44.080
It lies right along the edge
of the Dead Sea Rift, 400

00:43:44.080 --> 00:43:47.540
meters high, surrounded
by valleys.

00:43:47.540 --> 00:43:51.940
A setting which made the fort a
near impregnable stronghold

00:43:51.940 --> 00:43:54.440
for Jewish rebels fighting
the Romans in the

00:43:54.440 --> 00:43:56.640
first century AD.

00:43:56.640 --> 00:44:01.413
So this is a Roman camp here,
here, another one over there.

00:44:01.413 --> 00:44:04.820
Up on the hill.

00:44:04.820 --> 00:44:09.640
Instead of surrendering, the
Jews committed mass suicide,

00:44:09.640 --> 00:44:13.560
but there's a geological subtext
to that history for

00:44:13.560 --> 00:44:15.200
Nick to see.

00:44:15.200 --> 00:44:19.270
The fort was originally built
by King Herod, but abandoned

00:44:19.270 --> 00:44:22.803
when the city was largely
destroyed by an earthquake.

00:44:22.803 --> 00:44:26.650
You've got three lines of
evidence regarding an ancient

00:44:26.650 --> 00:44:27.950
earthquake, don't you?

00:44:27.950 --> 00:44:30.340
Yes, we have archaeological
evidence in the

00:44:30.340 --> 00:44:32.590
form of fallen walls.

00:44:32.590 --> 00:44:37.070
All the walls here used to be
part of the storage area for

00:44:37.070 --> 00:44:38.960
King Herod.

00:44:38.960 --> 00:44:42.540
You see the course is still
aligned, but fallen.

00:44:42.540 --> 00:44:46.130
They fell in the earthquake
of 31.

00:44:46.130 --> 00:44:49.720
Traces of this same earthquake
are recorded in deformed

00:44:49.720 --> 00:44:53.610
sediments found in the Lisan
formation providing

00:44:53.610 --> 00:44:58.110
geological, archaeological, and
historical evidence of the

00:44:58.110 --> 00:45:00.290
timing of the event.

00:45:00.290 --> 00:45:04.390
It took three years for the
Romans to breach Masada.

00:45:04.390 --> 00:45:06.935
The earthquake would have
taken mere seconds.

00:45:09.480 --> 00:45:13.750
The destruction of Masada was
matched in severity by another

00:45:13.750 --> 00:45:18.280
earthquake that flattened the
ancient city of Hippos.

00:45:18.280 --> 00:45:21.360
So how do people explain
earthquakes then?

00:45:21.360 --> 00:45:25.030
It was the wrath of
God, obviously.

00:45:25.030 --> 00:45:29.480
I think each place has its own
myth and legends about

00:45:29.480 --> 00:45:30.930
earthquakes.

00:45:30.930 --> 00:45:36.590
Although only in the late 19th
century, and in the early 20th

00:45:36.590 --> 00:45:39.710
century, did people realize
that earthquakes are,

00:45:39.710 --> 00:45:45.040
actually, a rupture of the
crust of the Earth.

00:45:45.040 --> 00:45:48.220
The Dead Sea Valley illustrates
the scale of these

00:45:48.220 --> 00:45:51.030
events, each earthquake further

00:45:51.030 --> 00:45:52.306
tearing the Rift apart.

00:45:56.710 --> 00:46:00.980
It looks innocuous, but the
Jordan River flows right along

00:46:00.980 --> 00:46:05.570
the edge of the Israeli and
Arabian plate boundaries.

00:46:05.570 --> 00:46:09.170
The scene may seem peaceful, but
the river divides some of

00:46:09.170 --> 00:46:13.980
the most disputed territory on
the planet, both now and in

00:46:13.980 --> 00:46:16.830
the distant past.

00:46:16.830 --> 00:46:20.550
This ruin was once a
crusader fortress.

00:46:20.550 --> 00:46:24.170
It's history tells both
of war and geology.

00:46:24.170 --> 00:46:27.570
So this wall is excellent
evidence of an ancient rupture

00:46:27.570 --> 00:46:29.320
along the Dead Sea Rift.

00:46:29.320 --> 00:46:29.580
Certainly.

00:46:29.580 --> 00:46:33.490
The wall was built
straight here.

00:46:33.490 --> 00:46:37.670
And after an earthquake,
we find it over there.

00:46:37.670 --> 00:46:43.720
So we know exactly how much it
moved, and with a combination

00:46:43.720 --> 00:46:48.200
of history and archaeology,
we know exactly when.

00:46:48.200 --> 00:46:53.520
We know that the foundation
stone was laid in October,

00:46:53.520 --> 00:47:00.020
1178, and the earthquake
was May 20, 1202.

00:47:00.020 --> 00:47:03.310
And it's incomparable to
any other earthquake

00:47:03.310 --> 00:47:06.870
that we're aware of.

00:47:06.870 --> 00:47:11.750
The 1202 earthquake was reported
as far away as Iraq,

00:47:11.750 --> 00:47:13.735
Sicily, Turkey, and Egypt.

00:47:13.735 --> 00:47:17.130
It w was the largest earthquake
to hit the Middle

00:47:17.130 --> 00:47:21.490
East in the last 3,000 years.

00:47:21.490 --> 00:47:26.850
And the fault system lies
directly below this fortress.

00:47:26.850 --> 00:47:30.110
So you and I are standing on
completely different tectonic

00:47:30.110 --> 00:47:31.040
something aren't we?

00:47:31.040 --> 00:47:31.230
Yeah.

00:47:31.230 --> 00:47:34.280
You are on the Israel,
or Sinai, plate.

00:47:34.280 --> 00:47:35.760
And I'm on the Arabian plate.

00:47:41.590 --> 00:47:44.520
Now this hasn't moved
subsequently.

00:47:44.520 --> 00:47:46.330
Does this mean that the two
plates that you and I are

00:47:46.330 --> 00:47:48.600
standing on are locked.

00:47:48.600 --> 00:47:50.570
Oh, yes, yes.

00:47:50.570 --> 00:47:54.450
Our estimate is that about four

00:47:54.450 --> 00:47:57.830
meters of slip are missing.

00:47:57.830 --> 00:47:59.310
It's a lot.

00:47:59.310 --> 00:48:00.620
It's like an earthquake of

00:48:00.620 --> 00:48:04.690
magnitude seven point something.

00:48:04.690 --> 00:48:05.850
It's a major one.

00:48:05.850 --> 00:48:08.080
We're missing a major
earthquake here.

00:48:08.080 --> 00:48:12.210
And it will certainly strike
one of the major cities.

00:48:16.140 --> 00:48:20.370
There's a consensus among
geologists that there will be

00:48:20.370 --> 00:48:22.955
another earthquake soon.

00:48:22.955 --> 00:48:27.870
All the large cities of the
region are within the damage

00:48:27.870 --> 00:48:31.250
zone of potential future
earthquakes.

00:48:31.250 --> 00:48:33.910
And earthquakes would
not discriminate.

00:48:33.910 --> 00:48:38.220
They will hate Syrians,
Israelis, Jordanians,

00:48:38.220 --> 00:48:40.280
Palestinians, Lebanese,
all the same.

00:48:46.670 --> 00:48:51.480
The East African Rift nurtured
our emergence as a species,

00:48:51.480 --> 00:48:54.270
saw the first civilizations.

00:48:54.270 --> 00:48:58.580
Now it's a threat to the many
cities along its length.

00:48:58.580 --> 00:49:02.270
Understanding the history and
dynamics of the Rift is

00:49:02.270 --> 00:49:06.225
fundamental to understanding
our past and our future.

00:49:14.560 --> 00:49:16.790
Nick's journey ends on
the coast of the

00:49:16.790 --> 00:49:18.740
Mediterranean Sea.

00:49:18.740 --> 00:49:22.660
Unlike everything else he's
seen it, too, confront

00:49:22.660 --> 00:49:26.450
unstoppable geological forces.

00:49:26.450 --> 00:49:30.010
The African plate is being
driven north several

00:49:30.010 --> 00:49:33.830
centimeters a year up against
the backstop of Europe.

00:49:33.830 --> 00:49:37.910
So what we see now as water will
be dry land in 10 or 20

00:49:37.910 --> 00:49:39.160
million years time.

00:49:41.890 --> 00:49:44.970
One of the big revelations in
geology has been understanding

00:49:44.970 --> 00:49:47.410
that the Earth's surface
was not made the

00:49:47.410 --> 00:49:48.820
way we see it today.

00:49:48.820 --> 00:49:52.240
It's undergone these profound
changes, because oceans have a

00:49:52.240 --> 00:49:53.580
life cycle.

00:49:53.580 --> 00:49:57.390
They're born, they widen,
and they die.

00:50:02.250 --> 00:50:06.610
To people who can read the
rocks, the Great Rift Valley

00:50:06.610 --> 00:50:11.232
illuminates the power of that
tectonic cycle better than any

00:50:11.232 --> 00:50:13.702
place on Earth.

00:50:13.702 --> 00:50:43.160
[MUSIC PLAYING]