Inside Planet Earth Page #5

Hey, thanks.

What I find truly remarkable

is that within this core barrel

is a massive piece of rock

from 200 feet below the surface,

and yet it contains

as many bacteria in it

as there are

people on this planet.

Now, these are living bacteria.

And they live at temperatures

approaching the boiling point

of water.

They live at pressures that are

100 times of atmosphere.

They live in a salty, briny

solution that's alkaline.

It contains gases

that are toxic to us.

And yet they still manage

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.

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