40x15 - Australia's First 4 Billion Years: Awakening

[bunniefuu]

Richard smith:
Over four billion years
in the making.

An island adrift
in southern seas.

It's australia,
the giant down under.

Step ashore and you'll find
a young nation

with all the gifts
of the modern age.

But move beyond the cities
and an ancient land awaits,

one nearly as old
as the earth itself.

Australia is a puzzle put
together in prehistoric times.

And the clues
that unlock the mystery

can be found scattered across
australia's sunburnt face.

I'm richard smith,
and this is an amazing country.

I'll show you that every rock
has a history,

every creature a tale
of survival against the odds.

Join me on an epic journey
across a mighty continent

and far back in time.

Of all continents on earth,

none preserve the great saga
of our planet

and the evolution of life
quite like this one.

Nowhere else can you so simply
jump in a car

and travel back
to the dawn of time.

In this episode,
the beginning of it all.

From a cosmic maelstrom,
a planet is born.

This is no paradise,

but somehow,
life gains a toehold,

then is nearly frozen out.

This is the tale
of the first australians,

how they survived
and flourished.

From australia's ancient stones
comes the story of our world.

"australia's first four
billion years: Awakening,"

right now on nova.

Major funding for nova is
provided by the following:

Smith:
The best way to understand
the story of australia

is to get out into it.

Feel the sun beating down
on its ancient bones.

And I do mean ancient.

To get a true appreciation
of how old australia really is,

you need to get a sense
of deep time.

Okay, so this looks like

a pretty ordinary
four-wheel drive,

but imagine just for a moment

that it's fitted
with a deep time drive.

I simply dial up the time
I want to go to,

and by the magic of time-shifted
gps, it does the rest.

Gps voice:
You have selected
"the beginning."

smith:
I've set the controls
for a million years per minute.

That's 60 million years
of history

for every hour we travel
down the road.

You want to see the real,
old australia?

It's quite a ride.

At a million years per minute,

a blink of an eye sees us

in an australia
before europeans.

A few seconds later and we pass
the first aboriginal footprints.

Within minutes, you're dodging
marsupials the size of minivans

and dragons far longer.

Gps voice:
Caution, hazardous wildlife.

Smith:
Worried about roadkill?

It gets worse.

An hour down the road,

and suddenly the land
is dominated by dinosaurs.

It will stay this way
for the next three hours

as we barrel back
deep into the past.

Gps voice:
Recalculating deep time.

Smith:
Over 250 million years
down the road of time,

about four hours at this speed,

and it's the world
before dinosaurs.

Even further and there is
no life on land at all.

I drive on.

At 500 million years,

about eight hours since we left
the present day,

all life is underwater
and distinctly weird.

But time is deep.

There's still 90%
of history to go.

While the entire history
of humanity

occupied only the first
few seconds of this journey

and complex animals
the first nine hours,

I have to travel back

over two and a half days
at this speed

to reach the first
stirrings of life.

Gps voice:
Caution: Destination
approaching.

Smith:
Finally, after over three days

traveling at 60 million years
an hour,

I've driven back four and a half
billion years.

I have run out of road.

We have arrived in the darkness
at the edge of time.

Smith:
When the first rays
of the newborn sun

shone out into space,

they illuminated a scene
of untold cosmic violence.

Swirling around the young star
was a disc of dust and debris,

every fragment locked in mortal
gravitational combat

with every other lump of rock,
metal, ice and dust in orbit.

This is the process
of gravitational cannibalism

that marked the formation
of all the planets,

and the earth grew bigger
and hotter with each conquest.

The heat came not only
from collision

but from the natural
radioactivity

building up inside.

Then, just as the outer crust
was beginning to harden,

it's thought our planet
was almost wiped out.

Another competitor,
this one the size of mars,

crossed earth's path.

[expl*si*n]

the aftermath was the formation

of our pale airless companion,
the moon,

and the red-hot
iron-rich ball of rock

we know today as home.

Understanding the fiery birth
of the earth

really helps explain how
the engine of our planet works.

The crust I am sitting on
might have cooled down,

but the planet below all of us
is still a hot ball of rock

spinning around in cold space.

And it's still trying
to cool down.

And as long as it cools,

the continents we sit on
continue to move.

This is the engine
of plate tectonics

that's driven the story
of our world since day one.

And for australia, we can pretty
much date that first day.

Nearly two thousand billion
sunrises after that first dawn,

I'm heading west
to one corner of the country

that has faithfully kept
a record

of the earliest days
of planet earth.

So we're almost there.

Just in front of us there.

Smith:
For decades,
geologist simon wilde

has been climbing the jack hills
in western australia,

date stamping the early earth.

Wilde:
This is the famous
discovery outcrop.

This is the site where the
world's oldest zircon crystals

have been recorded.

Smith:
Though ancient,

it's not the rocks themselves
that are so old here,

but the microscopic crystals
of zircon within them.

Known in the gem trade
as poor man's diamonds,

zircon crystals form when molten
rock cools in the earth's crust.

And just like diamonds,
zircons are forever.

If you ever wanted
to find a spot

to ponder your oneness
with the great age of the earth,

you couldn't do better
than this rock,

because within it
are the oldest remnants

from the early earth ever found.

Older than you and I
by a mere 4.4 billion years.

At just a whisker younger than
the age of the planet itself,

this tiny treasure,
zircon w74,

is the ultimate aussie survivor.

Recycled from rock to rock,

zircons like w74
have resisted everything

the planet has thrown at them.

And yet they've somehow managed

to keep a diary
of the earliest days

locked deep within
their crystal lattice.

Reading that diary in the lab
has been a revelation.

[explosions]

the oldest zircons, it seems,

crystallized inside molten,
continental granite

that cooled rapidly

in the presence
of abundant liquid water.

Waves were probably breaking
against the cooling shore

of the future western australia

within 150 million years
of the earth's formation.

Today's sun beats down here
on tiny fragments

of what may be our planet's
oldest continent

and much of the earth's
most ancient rock.

It's no surprise then

that australia feels like
an old, tough country.

Within a stone's throw
of the jack hills

is nearby mileura station.

Here, third-generation rancher
patrick walsh ekes out a living

from the oldest corner
of an ancient land,

a red and rocky heritage
from the dawn of time.

The geologists are up there
getting terribly excited,

bashing rocks.

Oh, yeah, they're very excited.

I always joke with them

and say that that's the new
g-spot in geology

because you get a good laugh
out of it

and it is important.

It did rewrite
the geology books.

That doesn't happen every day.

Smith:
This new picture
of the young earth

is of a landscape
you might have recognized--

rich in water, clouds
and raw geology,

but almost totally devoid
of oxygen.

If you were lucky enough
to be able

to travel back to the very
earliest days of the planet,

you would have been treated

to some of the greatest shows
on earth.

But you would have needed
a lot more

than a hard hat
and a gas mask

because this was a very
dangerous world.

We can tell
from the heavy cratering

on the moon at this time

that the early earth
must have been pounded

to within an inch of its life.

You can get a sense of what
this must have been like

by visiting wolfe creek crater
in the kimberley.

The great thing
about wolfe creek crater is

because it's so fresh,
relatively speaking,

it's a terrific place to see

what sort of impact
a big impact can make.

When the object hit over there,

it released so much energy
that it set off an expl*si*n

the equivalent
of an almighty nuclear blast.

As the material came out,
it literally flipped the rock

back onto itself
around the edges.

This sandstone is now
leaning back,

and everything that was in there
either vaporized

or was hurled out into
the surrounding countryside.

But wolfe creek crater
was formed only recently

by an object probably
only a few yards across.

Combine at least one


striking the earth every century

with a corrosive,
acidic atmosphere,

and you probably have the reason

why so little
of the early earth survives.

The craters of the moon show

that the great bombardment
slowed

about 3.8 billion years ago.

But while the moon's face
has changed little,

the archaean earth looked
nothing like the world today.

None of our familiar
continents.

No green blush of life
on land.

But dive into those ancient
australian seas

and you would have found
the first stirrings of life.

It probably looked like this:

Slime.

Some of the earliest
tantalizing signs

of what could be
fossilized bacteria

appear in western
australian rocks

around 3.5 billion years ago,

not long after the meteor
bombardment ended.

While the details
of the origin of life

remain shrouded
by the mists of time,

scientists are starting
to get a fix

on when and probably where
it happened.

And one thing is for sure:

The early earth had plenty
of the raw ingredients.

A reliable supply of water,

heat and biologically useful
chemicals

could all be found
close to volcanic vents,

like in these hydrothermal pools
in new zealand.

This blistering water
contains no free oxygen.

Instead, it's rich in poisons

like hydrogen sulfide
and arsenic.

And rich in life, too.

The orange scum
lining the rocks

is a jungle
of primitive bacteria

and archaic microorganisms,

all feeding
on the noxious goodies

oozing from the hot earth below.

Similar environments have
existed in the sunless deep sea

for billions of years.

Both habitats are home

to the most primitive
life-forms we know,

and both are closely linked

to the dynamic,
tectonic world we now live on.

Wherever it started,

life soon took hold
in the sunlit shallows.

And to see what it looked like,
we need to head to the beach.

The australian outback:
Bone dry and baking hot.

Hardly the sort of conditions
you'd associate

with the origin of life.

But it's precisely because
of this tough environment

that down at the end
of this road,

we can find a unique glimpse
into the world

at the dawn of life.

If you ever wanted
to pay a visit

to your most distant ancestors,

then shark bay in western
australia is the place to do it.

The high rates of evaporation
here in hamelin pool

make the shallow water twice
as salty as the open sea,

just the sort of tough,
preserving conditions

for slow-growing old-timers
who prefer to be left alone.

Meet your most distant living
relative: The stromatolite,

still going strong here

in the salty waters
of shark bay.

Now, these guys might look more
like rocks than your relatives,

but you shouldn't be
easily fooled.

On the outside is
a vast living community

of microscopic bacteria

that have developed the knack
of gluing mud into mounds.

And they've achieved this
with the revolutionary trick

of harnessing the power
of sunlight.

Photosynthesis
changed the world.

No longer sl*ves
to volcanic energy,

light-harvesting bacteria
began to spread

to any sunlit surface
in the sea.

And growing as stromatolites,
they could even make their own.

It's the ultimate living rock.

How the bacterial colonization
of those distant shores began

is a puzzle that scientist
david flannery is keen to solve,

and a simple living algal mat
offers a remarkable clue.

It's much easier to interpret
things in the fossil record

if you have a modern example.

Here's a piece of rock from
western australia in the pilbara

that's 2.7 billion years old,

and it has a very similar
structure

and it comes from a very
similar environment.

You can see the modern example
is made up

of these tufts and ridges
and this polygonal pattern,

and the fossil example is made
up of the exact same stuff.

Smith:
They may come in a range
of shapes and sizes,

but these high-rise bacterial
communities have barely changed

in billions of years.

To swim here is to take a dip
deep into the past.

This is a time tourist's trip

to a three-billion-year-old
beach.

We know that stromatolites

dominated the ancient
australian shorelines

because you can still
visit them,

preserved in the rocks

of western australia's
pilbara region.

The town of marble bar,

population about 350
plus a few dogs,

claims the dubious distinction

of being the hottest town
in australia.

It's probably why some joker
dubbed this torrid little spot

a few hours out of town
"north pole."

geologists can read perhaps

the oldest preserved planetary
landscape in the rocks here:

A coastline with beaches
and sandbars.

And something else.

The gentle laminations in these
rocks have been interpreted

as the first tangible evidence
of life.

Visible to the naked eye,

these may be the world's oldest
fossilized stromatolites,

dated to nearly
three and a half billion years.

Though the biological origin
of the oldest fossils

is still debated,
the pilbara's rocky ranges

are clearly awash
with once-living stromatolites

that in places must have formed
extensive coastal reefs.

As far as we can tell,
this was the australian seaside

circa three thousand
million years ago.

Stromatolites in the shallows.

Smoke on the horizon.

Fire in the sky.

[bird cawing]

these simple life-forms
made their mark on the world

in a far bigger way than
as fossils in a landscape.

They started making
the landscape themselves.

South of north pole lies
another pilbara treasure:

Karijini national park.

I'm taking a shortcut
to the distant past.

The deeper I drop
into iron-rich hancock gorge,

the further back in time
I travel.

Okay!

Down here, you can look back

at one of the earth's
great turning points.

Two and a half
billion years ago,

the atmosphere was still
without oxygen.

But beneath the waves,

stromatolites and their
photosynthetic kin

were steadily releasing
this reactive waste product

into the water.

It didn't get far.

The oceans were full
of dissolved iron

left over from the planet's
formation.

Mix oxygen with iron
and you can guess the result:

The oceans began to rust.

Year after year, for hundreds
of millions of years,

the oceans rusted.

Layer by layer of rich, red ooze

settled softly onto
the deep sea floor.

Now this is what I wanted
to show you.

See these dark bands of iron?

This is the so-called
banded iron formation.

Now each one of these layers
represents a rain of rust

that fell to the sea floor two
and a half billion years ago.

And you can see these
pale bands in between.

Now, nobody knows
if this represents

some kind of strange
seasonality,

but if you think that every one
of these layers of rust

represents a pulse of oxygen
in the oceans,

then what you are looking at
is the planet breathing--

the first breaths
of the biosphere.

Today, that first biosphere
breathes life

into the australian economy.

The massive iron ore deposits
of the pilbara

are the direct economic legacy
of the rusting of the oceans.

It's not until you stand deep
in the pit

of an iron ore mine
like mount whaleback

that you get the true sense
of the scale

of the rusting of the oceans.

The hills here are literally
made of iron.

Every year, over 33 million tons
of ore are mined

at mount whaleback alone.

And this is the business:

High-grade iron ore
exposed to sunlight

for the first time
in billions of years.

Bang it together,
it sounds like metal.

And this stuff is heavy.

All of this, australia's
great wealth of iron,

because of a waste product

pumped out by microscopic
bacterial slime

operating on an industrial scale
in those ancient seas.

The empire of the stromatolites
was without doubt

the greatest in the history
of the earth.

Forget the romans, the persians,
even the dinosaurs.

These humble bacterial mounds
dominated the planet

for over two thousand
million years

and they engineered
its greatest transformation.

Once turned on, the oxygen tap
could not be turned off.

The formation of iron

was just a phase
the earth was going through.

After 700 million years
of rusting,

the oceans pretty much
ran out of iron.

And the oxygen had nowhere
else to go but up.

Now, for the first time,

oxygen began flooding
into the atmosphere.

It was to be the greatest
pollution event in history.

Without the oxygenation of the
atmosphere, we wouldn't be here,

nor would the myriad species
we share the planet with.

There might have been
a revolution underway,

but there wasn't much
for a time tourist to see.

Or breathe, for that matter.

With oxygen concentrations

at only a twentieth
of today's levels,

your first gasp
would have been your last.

Even geologists have found

the second half
of the proterozoic a little...

Well, a little dull.

After all the earlier dramas,

things got stuck in such
a long geological rut

that they've dubbed this period
"the boring billion."

but it was quite a good time
for continental construction.

The hot planet below
had been busy,

pushing and welding together

the ancient chunks
of continental landmass

that today make up most of the
western two-thirds of australia.

By about a billion years ago,

most of the wandering
continents,

including embryonic australia,

had been crunched together
into a supercontinent

called rodinia.

Fossil evidence points
to some of the first seaweeds,

sponges and embryos
appearing at this time.

Life was moving beyond bacteria.

And just as it did so, it was
nearly stopped in its tracks.

Welcome...

To snowball earth.

Unmistakable evidence
from around the world

points to two great waves
of glaciation

that locked the planet
in the firm, icy grip

that gave the cryogenian
its name.

These were the most severe ice
ages in the planet's history.

Smith:
The flinders ranges in south
australia seem a world away

from a great global ice crisis.

Yet it was here that clues
to just such a calamity

were first found.

[birds singing]

paleontologist jim gehling
sees hard evidence

for cold climates
in these old seafloor muds.

This is tidal rhythmic
sedimentation.

In other words, every
single tide has been recorded

as a couplet of layers.

The beauty of this,
it's a complete record of tides

for as much as 60 years,

and that is unique for rocks
that are 640 million years old.

Smith:
These soft sediments
settled on the seafloor

with the precision of grooves
on an lp record,

each band turning to the beat
of an ancient tide.

The fine, undisturbed layering
of this tidal calendar

could only have formed
one way...

With the seafloor protected
by a ceiling of ice.

Gehling:
The seafloor was actually sealed
off from waves and storms

because there was
an ice cover over it.

We were almost straddling
the equator

and yet this ocean
was covered with ice.

This is what we think the oceans
of our planet

would have looked like
during one of these events.

Frozen solid from the poles
to the tropics.

Now this is the frozen
arctic ocean,

north of barrow in alaska today.

In a month or two,
most of this ice behind me

will break up and drift away.

It'll come back next year.

But just imagine if the ice
set in not for a season,

not for a century,

but for a million years
or even ten million years.

It's very hard to imagine
anything surviving

such a cold, cold world.

But survive it did.

[explosions]

it was plate tectonics
to the rescue.

Furious volcanic eruptions,
it's thought,

primed the atmosphere
with greenhouse gases.

And the great snowball was soon
followed by the great thaw.

As the ice caps melted,

seas rose and flooded back
across the land.

But the world that returned
had changed.

Life had not only survived
the ice-bound snowball years,

it was about to flourish.

The moment is caught in time
here in the flinders ranges

with a sudden shift
to warm yellow rock,

the so-called golden spike.

"now, so what?" you might say.

Well, this is a really
significant moment

in earth history

because everything down here
is "icehouse,"

the end of the great
snowball earth,

but up here the planet
has returned

to greenhouse conditions.

But much more than that,

at this precise point


we suddenly enter a world
clearly inhabited by animals.

In a secret location
in the hills not far away,

jim gehling and his team

have unearthed a whole section
of seafloor:

A tableau of life
in the ediacaran.

These are some of the oldest
multicellular animals

to be found on earth...

So significant that their
discovery near ediacara

in the flinders ranges
has given the age its name.

Gehling:
So you're looking at a snapshot

of life on the quiet bottom

just below the reach of waves
during fair weather.

Smith:
Here was a garden
of strange animals:

Frond-shaped creatures
feeding in the current...

Others resembling anchors
and throat lozenges.

Gehling:
Now, the most common one is this
little pancake-shaped thing,

dickinsonia.

Smith:
Like a puffed-up place mat,

dickinsonia could reach
about three feet across.

It seems to have slid slowly
over the seafloor,

stopping from place to place

to feast on the carpet
of bacterial slime.

One of the puzzles
has always been, though,

how did these creatures feed?

Gehling:
It probably crawled
over the mats,

decayed the mat underneath it
and absorbed the nutrients.

Smith:
So no mouth.

Gehling:
No mouth.

Smith:
What is certain is that
there were things moving about

on the seafloor
looking for food.

What's this guy here?

Oh, yeah, that's one
of my favorites.

It's spriggina,
and it's important

because we see
that there's a head end,

looks like a shield
with a bulge behind that

which might just be
a concentration

of its sensory organs.

Smith:
So a brain.

An early brain?

That's right.

So the first smart creature
on earth, perhaps.

Maybe the last.

Smith:
Spriggina was an animal
on the prowl,

a pioneer crawling
into the record books right here

on a long-lost
australian shoreline.

Gehling:
The record that we have here

is of the first animals,
the ediacara biota,

which could actually move
and feed on the seafloor,

and forever after,
the earth was going to change.

Smith:
For the great bulk
of the planet's history,

we've traveled
through a landscape

where raw geology
ruled the world

and slime ruled the waves.

And now, after nearly
four billion years on the road,

we've arrived at the end
of the beginning.

While life was starting
to soften the planet's surface,

earth's underground heat engine
had been busy driving australia,

antarctica, india, africa
and madagascar together

into the famous supercontinent
gondwana.

As the gondwanan giant
was shunted together,

shock waves rippled
across the australian mainland,

pushing up a titanic
mountain range,

the petermanns, that once
towered over central australia.

By the time the sun was glinting
off their jagged icy peaks,

it was also sparkling through

into the first seas
of the cambrian.

There you go.

Thank you very much.

A time-traveling tourist to
australia 540 million years ago

would have been able to complete

what is today
an impossible journey.

Push it well over
that side, mate.

Thanks, mate.

You would have been able
to board a ship

somewhere to the north of cairns

and sail inland almost
to the south of adelaide.

The eastern states of australia,
where they existed at all,

were still mud at the bottom
of a tropical sea.

If you'd been able to gaze down
into those warm ancient seas,

you would have seen
that they were teeming

with an abundance
and diversity of life

the like of which
the planet had never seen.

It's been dubbed
the cambrian expl*si*n,

a reflection of just how quickly

animals took over the oceans
at the time.

There'd been strange creatures
in australian seas

ever since the ediacaran,
but now, suddenly,

things that might not look out
of place on a seafood platter

were scurrying over the sand.

And one of the best places
on the planet to meet them

is kangaroo island.

Tucked away high above
the waves of emu bay

lies one of the world's
premier cambrian fossil sites.

This is awfully good fun, but I
have to keep on reminding myself

that what I'm actually
doing here is taking

a half-billion-year-old rock,

tapping it with a hammer
and coming face-to-face

with perfectly formed little
crustacean-like things

that were scurrying around
over 500 million years ago.

These are trilobites--
ancestral arthropods

that made their grand entrance
in cambrian seas.

John paterson:
The cambrian expl*si*n
was a time period

in the history of life
which is probably

one of the most significant
in earth's history.

We see animal groups
that are recognizable today

first appearing
in the fossil record.

So the arthropods, for example--

things like spiders
and crustaceans and insects,

and the mollusks, another major
group that we see today--

they have their recognizable
beginnings in the cambrian.

Smith:
There are so many trilobites
found at emu bay,

they must have been scuttling
everywhere.

The gentle days of the garden
of ediacara were over.

This was a world
of mouthparts and mobility.

Hunters and the hunted.

Armor-plated arthropods
patrolled the seas

searching for easy pickings.

They were bug-eyed

and bristling
with new technology.

Astonishingly,
some of their soft body parts

have been exquisitely preserved.

Here's looking at one of
the world's oldest eyeballs.

Here's a decent-sized beasty,
a trilobite called redlichia.

Now you can see all its segments
quite clearly

and you can see
this beautiful head shield

with these big spikes
down each side.

But if you look even more
closely up here,

you'll see its two antennae.

Just amazing.

Growing longer
than a man's hand,

redlichia was
the largest trilobite

in these gondwanan waters,

but it was still well-armored
with defensive spines.

There was good reason for this.

Top predator
in the cambrian ocean

was a giant arthropod
called anomalocaris.

Anomalocaris was an animal that
grew to over six feet in length.

So this thing would have been

fluttering around
in the surface waters

looking for probably
other arthropods.

Smith:
Clearly, the evolutionary
arms race had begun.

While the trilobites
went on to reign

for another 250 million years,

anomalocaris swam into oblivion
by the end of the cambrian.

Smith:
Back on land, and with
no botanical protection,

the high peaks of the petermann
ranges in central australia

were wearing away.

For a hundred million years
or more,

rivers had been tumbling
from their bare, snowy peaks.

These days, the petermann ranges
are little more

than a fading blue blip on
the central australian horizon,

but their legacy lives on.

As the ancient waters poured
out of the mountains,

they carried the raw materials

for two of australia's most
treasured rocky landmarks.

The rivers that roared out
of the mighty petermann ranges,

which once towered
on the horizon,

swept their heavy load
of worn-away mountain

as far as the water
would carry it.

A lot of it ended up here,

to form the magnificent bedrock
of kata tjuta.

The smooth domes of kata tjuta
are the eroded remnants

of a thick conglomerate
of rounded river cobbles

dropped by the fast-flowing
water.

A lighter load of sand was
carried further afield.

It ended up here,
about 20 miles away,

where rivers slowed
as they met the shore.

This is how uluru,
the great red rock

in australia's desert heart,
began life:

As wet sand from a recycled
mountain range

settling at the edge
of a now-vanished cambrian sea.

The lights went down
on cambrian australia

with the stage set
for the next great drama

in the story of the earth.

And the cast was already
gathering out to sea.

Despite the expl*si*n of life
going on in the sea,

if you'd taken a walk
on a cambrian beach,

you probably wouldn't have
noticed much going on at all.

Perhaps a trilobite might have
tickled your toes,

but apart from the wind and the
waves, this was a silent world.

There was still no life
up there on land.

It would not stay this way
for long.

The seas,
now bursting with life,

were set to spill their cargo
onto the bare earth.

And australia was ripe
for conquest.