Inside Planet Earth Page #3

to survive.

They are known as extremophiles

because of their extreme

living conditions.

To get a closer look,

the scientists first extract

them from their rocky home.

The really exciting thing

about heat-loving bacteria

is that they're the most

primitive organisms

on the Earth.

And the fossil evidence in

the most ancient rocks on Earth

indicate that

these types of organisms

must have existed

3.7 billion years ago.

With skill and care,

the team work

inside glove boxes.

Here they can manipulate the

sample under sterile conditions.

They go to great lengths

to ensure

that the only bacteria

inside the tent

are those that have made

the journey up from the earth.

We need to pare away

the outside of the core

so that we can remove

any contamination

that may have occurred during

the process of coring.

The core is then placed in a press

and crushed to a fine powder.

Then a sample is taken

from the powder

and a culture developed

of the bacteria.

These are the earliest common

ancestors of all life--

a colony of extremophiles.

Observing how microbes survive

thousands of feet

below the surface,

some scientists have speculated

about life elsewhere.

Could there be

tiny extraterrestrials

buried in the same way

on other planets

that appear outwardly sterile?

In the sedimentary rocks

of Australia's Karijini

are all the clues that solve

another chapter

of Earth's history.

This was the first place

where life and the land

began to interact,

and the traces

are clear to this day.

The impressive thing

about the place

is how red it is.

In fact, red rocks stretch

for hundreds of miles

in every direction.

The reason they're red

is because of this red mineral,

hematite-- iron oxide, or rust.

And the way they formed

was when dissolved iron in

the ocean combined with oxygen

and precipitated out

as iron oxide,

settled down to the seafloor,

and accumulated

on the bottom of the sea.

Initially, the atmosphere

of the Earth had no oxygen.

The same applied to the oceans.

These rocks record

an intermediate period

when there was still no oxygen

in the atmosphere

but the upper layers

of the ocean contained oxygen.

There's a huge amount

of iron oxide here.

The sheer volume suggests that

the oxygen could only have had

one plausible source-- biology.

Living organisms

excreting oxygen

as a by-product

of photosynthesis.

After 2 billion years,

the oxygen had finally combined

with all the iron.

For the first time,

free oxygen was able to escape

into the atmosphere,

and the air became breathable.

Deep into the Australian outback

is more evidence of primitive

oxygen-producing organisms.

In a secret location

Buick discovered

are some of the world's

oldest and rarest fossils.

What I've done is step back

more than 3-quarters

of the way back

to the beginning

of Earth history.

And here are

wrinkly layered sediments

that occasionally dome upwards.

These are stromatolites--

sedimentary structures created

by filamentous microorganisms

trapping sand and mud

between their little filaments.

Those microorganisms

were probably photosynthetic.

The layers thicken

over the tops of these domes,

competing with each other

to get nearer the sunlight.

Now, these stromatolites are

remarkable for their great age.

3,450 million years old.

Not only are they remarkable

for that,

but we can also infer something

about the environment

in which they lived.

Just back here...

are gypsum daisies.

Little star-shaped clusters

of gypsum crystals--

calcium sulfate.

These form

when seawater evaporates

in a shallow pond

near the edge of the sea.

Living stromatolites only grow

when they're almost

permanently submerged in water,

so you only see them exposed

at very low tide.

These grew here

about 5,000 years ago,

when the sea level

was about a meter or so higher.

The living carpet of bacteria

that formed them died off

as the sea level

gradually dropped,

and the sediment

that the bacteria trapped

was turned into limestone.

These tiny bacteria

were the first organisms

to live together in colonies.

By producing oxygen,

stromatolites changed

the planet forever.

Life flourished and became

a force to shape the world.

But geological upheavals

can spell disaster.

200 million years ago,

the supercontinent Pangaea,

which stretched unbroken

from pole to pole,

began to split in 2.

It took 65 million years.

2 continents we know today

were shaped by another upheaval

that hit the remains of

the supercontinent in the south.

In the jungles of South America

are found one of the most

remarkable features

on the face of the planet.

This whole landscape

owes its existence

to this violent chapter

of Earth's history.

Iguazu Falls, Argentina--

for me, the most spectacular

waterfalls in the world,

not only because of

the spectacular scenery here--

250-foot-high waterfall

a mile wide--

but because of

the spectacular geology.

What's more,

the rocks of the falls

contain evidence pertaining

to a geological event

that took place here

135 million years ago.

The geological evidence

is here in these rocks.

This is basalt,

a hard, volcanic rock

stained red by iron oxide--

oxidation of the iron

within the rock.

In fact, we're standing here at

the base of a basaltic lava flow

more than 100 feet thick,

just one of many lava flows

in this area

which form a pile of lava

more than a mile thick.

In fact, in the waterfalls,

one can see

steps of the waterfalls

which shows the individual

lava flows in this pile.

Imagine volcanic eruptions

so enormous

as to produce lava flows

erupting from giant cracks and

fissures in the Earth's crust,

flowing out over an area

twice the size

of the state of Texas--

more than

250,000 square miles.

An enormous volcanic event.

Massive amounts

of sulfur-rich gases

spewing into the atmosphere.

Droplets of sulfuric acid

forming a veil

that cuts out the sunlight

and cools the climate.

Sulfuric acid rain

killing the vegetation.

The makings of

an environmental disaster

of enormous proportions.

This is 135 million years ago

at the end of the Jurassic

period of geological time,

a time when there were

mass extinctions

of many forms of life.

There's evidence here

in these rocks

for an even more dramatic event

in the history of the Earth.

And here is just the piece

of evidence that I need.

On the other side of the world,

across the Atlantic Ocean,

is the world's

most ancient desert.

It dominates most of

the southern African country

of Namibia.

I've traveled more than

4,000 miles,

and the rocks

are exactly the same.

They're basalts, and the age

is 135 million years.

Clearly, when these rocks

were erupted

as floods of lava traveling

hundreds of miles,

South America and Africa were

together as one supercontinent.

The Atlantic Ocean,

which now divides Africa

and South America,

owes its very existence

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