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What can Australia reveal about how Earth was born and how life took hold? Join NOVA and host Dr. Richard Smith as they journey back to the very beginning of the Australian story in "Awakening." The first stop is Western Australia, around four and a half billion years ago, where we encounter an Earth shortly after its fiery birth. Hidden in the red hills of Australia are clues to the mysteries of when the Earth was born, how life first arose, and how it transformed the planet. Experts unveil how the earliest forms of life-an odd assortment of bacterial slime-flooded the atmosphere with oxygen, sparking the biological revolution that made animal life possible. It is the beginning of the great drama of life on Earth.
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00:03Over 4 billion years in the making. An island adrift in southern seas. It's Australia. The giant down under.
00:28Step ashore and you'll find a young nation. With all the gifts of the modern age.
00:36But move beyond the seas. And an ancient land awaits. One nearly as old.
00:47As the earth itself.
00:53Australia is a puzzle. Put together in prehistoric times.
01:00And the clues that unlock the mystery can be found scattered across Australia's sunburnt face.
01:13I'm Richard Smith. And this is an amazing country.
01:20I'll show you that every rock has a history. Every creature. A tale of survival against the odds.
01:29Join me on an epic journey across a mighty continent. And far back in time.
01:39Of all continents on earth. None preserved the great saga of our planet. And the evolution of life. Quite like
01:47this one.
01:48Nowhere else can you so simply jump in a car. And travel back to the dawn of time.
01:56In this episode. The beginning of it all. From a cosmic maelstrom. A planet is born.
02:07This is no paradise. But somehow. Life gains a toehold. Then is nearly frozen out.
02:16This is the tale of the first Australians. How they survived. And flourished.
02:24From Australia's ancient stones. Comes the story of our world.
02:31Australia's first four billion years. Awakening.
02:35Awakening. Right now. On NOVA.
02:55Major funding for NOVA is provided by the following.
03:01The David H. Koch Fund for Science. Supporting NOVA and promoting public understanding of science.
03:11And by the Corporation for Public Broadcasting.
03:16And by contributions to your PBS station from viewers like you. Thank you.
03:43The best way to understand the story of Australia. Is to get out into it.
03:52Feel the sun beating down on its ancient bones.
04:01And I do mean ancient.
04:05To get a true appreciation of how old Australia really is. You need to get a sense of deep time.
04:18OK. So this looks like a pretty ordinary four wheel drive.
04:21But imagine just for a moment. That it's fitted with a deep time drive.
04:26I simply dial up the time I want to go to. And by the magic of time shifted GPS. It
04:32does the rest.
04:36You have selected the beginning.
04:40I've set the controls for a million years per minute. That's 60 million years of history. For every hour we
04:48travel down the road.
04:50You want to see the real old Australia. It's quite a ride.
05:01At a million years per minute. A blink of an eye sees us in an Australia before Europeans.
05:12A few seconds later and we pass the first Aboriginal footprints.
05:19Within minutes you're dodging marsupials the size of minivans. And dragons far longer.
05:27Caution. Hazardous wildlife. Worried about road kill? It gets worse.
05:37An hour down the road and suddenly the land is dominated by dinosaurs.
05:45It will stay this way for the next three hours as we barrel back deep into the past.
05:53Recalculating deep time. Over 250 million years down the road of time. About four hours at this speed.
06:02And it's the world before dinosaurs. Even further and there is no life on land at all.
06:15I drive on. At 500 million years. About eight hours since we left the present day.
06:23All life is underwater. And distinctly weird.
06:30But time is deep. There's still 90% of history to go.
06:41While the entire history of humanity occupied only the first few seconds of this journey.
06:46And complex animals the first nine hours. I have to travel back over two and a half days at this
06:52speed.
06:53To reach the first stirrings of life.
06:59Ocean destination approaching.
07:05Finally. After over three days travelling at 60 million years an hour.
07:10I've driven back four and a half billion years.
07:16I've run out of road. We have arrived in the darkness at the edge of time.
07:36When the first rays of the newborn sun shone out into space.
07:41They illuminated a scene of untold cosmic violence.
07:48Swirling around the young star was a disk of dust and debris.
07:54Every fragment locked in mortal gravitational combat.
07:58With every other lump of rock, metal, ice and dust in orbit.
08:09This is the process of gravitational cannibalism that marked the formation of all the planets.
08:18And the Earth grew bigger and hotter with each conquest.
08:24The heat came not only from collision, but from the natural radioactivity building up inside.
08:33Then, just as the outer crust was beginning to harden, it's thought our planet was almost wiped out.
08:42Another competitor, this one the size of Mars, crossed Earth's path.
08:58The aftermath was the formation of our pale airless companion, the Moon.
09:06And the red-hot, iron-rich ball of rock we know today as home.
09:15Understanding the fiery birth of the Earth really helps explain how the engine of our planet works.
09:21The crust I'm sitting on might have cooled down.
09:23But the planet below all of us is still a hot ball of rock spinning around in cold space.
09:30And it's still trying to cool down.
09:38And as long as it cools, the continents we sit on continue to move.
09:46This is the engine of plate tectonics that's driven the story of our world since day one.
09:55And for Australia, we can pretty much date that first day.
10:14Nearly 2,000 billion sunrises after that first dawn.
10:19I'm heading west, to one corner of the country that has faithfully kept a record of the earliest days of
10:27planet Earth.
10:39So we're almost there. Just in front of us there.
10:42For decades, geologist Simon Wilde has been climbing the Jack Hills in Western Australia, date-stamping the early Earth.
10:51And this is the famous discovery outcrop.
10:53This is the site where the world's oldest zircon crystals have been recorded.
10:58Though ancient, it's not the rocks themselves that are so old here, but the microscopic crystals of zircon within them.
11:11Known in the gem trade as poor man's diamonds, zircon crystals form when molten rock cools in the Earth's crust.
11:21And just like diamonds, zircons are forever.
11:28If you ever wanted to find a spot to ponder your oneness with the great age of the Earth, you
11:34couldn't do better than this rock.
11:36Because within it are the oldest remnants from the early Earth ever found.
11:42Older than you and I, by a mere 4.4 billion years.
11:49At just a whisker younger than the age of the planet itself, this tiny treasure, zircon W74, is the ultimate
11:58Aussie survivor.
12:03Recycled from rock to rock, zircons like W74 have resisted everything the planet has thrown at them.
12:13And yet they've somehow managed to keep a diary of the earliest days locked deep within their crystal lattice.
12:26Reading that diary in the lab has been a revelation.
12:33The oldest zircons, it seems, crystallised inside molten continental granite that cooled rapidly in the presence of abundant liquid water.
12:46Waves were probably breaking against the cooling shore of the future Western Australia within 150 million years of the Earth's
12:55formation.
13:06Today's sun beats down here on tiny fragments of what may be our planet's oldest continent.
13:12And much of the Earth's most ancient rock.
13:21It's no surprise then, that Australia feels like an old, tough country.
13:32Within a stone's throw of the Jack Hills is nearby Malura Station.
13:38Here, third-generation rancher Patrick Walsh ekes out a living from the oldest corner of an ancient land, a red
13:47and rocky heritage from the dawn of time.
13:51The geologists are up there getting terribly excited, bashing on rocks and getting geeks.
13:54Yeah, they're very excited.
13:56I always joke with them and say that that's the new G-spot in geology because you get a good
14:01laugh out of it.
14:02And they, you know, it is important, you know, they did rewrite the geology books.
14:08That doesn't happen every day.
14:22This new picture of the young Earth is of a landscape you might have recognised.
14:30This new world is of a world of clouds, rich in water, clouds and raw geology, but almost totally devoid
14:37of oxygen.
14:40If you were lucky enough to be able to travel back to the very earliest days of the planet, you
14:46would have been treated to some of the greatest shows on Earth.
14:50But you would have needed a lot more than a hard hat and a gas mask, because this was a
14:55very dangerous world.
15:02We can tell from the heavy cratering on the moon at this time that the early Earth must have been
15:07pounded to within an inch of its life.
15:15You can get a sense of what this must have been like by visiting Wolf Creek Crater in the Kimberley.
15:33The great thing about Wolf Creek Crater is because it's so fresh, relatively speaking, it's a terrific place to see
15:41what sort of impact a big impact can make.
15:44When the object hit over there, it released so much energy that it set off an explosion, the equivalent of
15:50an almighty nuclear blast.
15:52As the material came out, it literally flipped the rock back onto itself around the edges.
15:59This sandstone is now leaning back and everything that was in there either vaporised or was hurled out into the
16:07surrounding countryside.
16:11But Wolf Creek Crater was formed only recently by an object probably only a few yards across.
16:19Combine at least one thirty mile wide asteroid striking the Earth every century with a corrosive acidic atmosphere.
16:27And you probably have the reason why so little of the early Earth survives.
16:39The craters of the moon show that the great bombardment slowed about 3.8 billion years ago.
16:47But while the moon's face has changed little, the Archaean Earth look nothing like the world today.
16:55None of our familiar continents.
16:57No green blush of life on land.
17:07But dive into those ancient Australian seas and you would have found the first stirrings of life.
17:17It probably looked like this.
17:20Slime.
17:23Some of the earliest tantalising signs of what could be fossilised bacteria appear in Western Australian rocks around 3.5
17:32billion years ago.
17:34Not long after the meteor bombardment ended.
17:44While the details of the origin of life remain shrouded by the mists of time, scientists are starting to get
17:51a fix on when and probably where it happened.
17:55And one thing is for sure, the early Earth had plenty of the raw ingredients.
18:04A reliable supply of water, heat and biologically useful chemicals could all be found close to volcanic vents, like in
18:13these hydrothermal pools in New Zealand.
18:22This blistering water contains no free oxygen.
18:28Instead, it's rich in poisons, like hydrogen sulphide and arsenic.
18:35And rich in life too.
18:39The orange scum lining the rocks is a jungle of primitive bacteria and archaic microorganisms.
18:48All feeding on the noxious goodies oozing from the hot earth below.
19:01Similar environments have existed in the sunless deep sea for billions of years.
19:09Both habitats are home to the most primitive life forms we know.
19:13And both are closely linked to the dynamic, tectonic world we now live on.
19:26Wherever it started, life soon took hold in the sunlit shallows.
19:32And to see what it looked like, we need to head to the beach.
19:40The Australian outback.
19:42Bone dry and baking hot.
19:44Hardly the sort of conditions you'd associate with the origin of life.
19:48But it's precisely because of this tough environment that down at the end of this road, we can find a
19:54unique glimpse into the world at the dawn of life.
20:08If you ever wanted to pay a visit to your most distant ancestors, then Shark Bay in Western Australia is
20:15the place to do it.
20:20The high rates of evaporation here in Hamelin pool make the shallow water twice as salty as the open sea.
20:29Just the sort of tough, preserving conditions for slow growing old timers who prefer to be left alone.
20:41Meet your most distant living relative, the stromatolite, still going strong here in the salty waters of Shark Bay.
20:48Now these guys might look more like rocks than your relatives, but you shouldn't be easily fooled.
20:55On the outside is a vast living community of microscopic bacteria that have developed the knack of gluing mud into
21:04mounds.
21:04And they've achieved this with the revolutionary trick of harnessing the power of sunlight.
21:18Photosynthesis changed the world.
21:21No longer slaves to volcanic energy, light harvesting bacteria began to spread to any sunlit surface in the sea.
21:32And growing as stromatolites, they could even make their own.
21:41It's the ultimate living rock.
21:47How the bacterial colonisation of those distant shores began is a puzzle that scientist David Flannery is keen to solve.
21:55And a simple living algal mat offers a remarkable clue.
22:02It's much easier to interpret things in the fossil record if you have a modern example.
22:07Here's a piece of rock from Western Australia in the Pilbara.
22:10It's 2.7 billion years old.
22:12It has very similar structures and it comes from a very similar environment.
22:16You can see the modern example is made up of these tufts and ridges and this polygonal pattern.
22:20And the fossil example is made up of the exact same stuff.
22:27They may come in a range of shapes and sizes, but these high-rise bacterial communities have barely changed in
22:35billions of years.
22:39To swim here is to take a dip deep into the past.
22:45This is a time tourist's trip to a three billion year old beach.
23:02We know that stromatolites dominated the ancient Australian shorelines because you can still visit them.
23:09Preserved in the rocks of Western Australia's Pilbara region.
23:30The town of Marble Bar, population about 350 plus a few dogs, claims the dubious distinction of being the hottest
23:39town in Australia.
23:46It's probably why some joker dubbed this torrid little spot a few hours out of town, North Pole.
23:55Geologists can read perhaps the oldest preserved planetary landscape in the rocks here.
24:00A coastline with beaches and sandbars and something else.
24:04The gentle laminations in these rocks have been interpreted as the first tangible evidence of life.
24:16Visible to the naked eye, these may be the world's oldest fossilised stromatolites.
24:22Dated to nearly three and a half billion years.
24:28Though the biological origin of the oldest fossils is still debated, the Pilbara's Rocky Ranges are clearly awash with once
24:37living stromatolites that in places must have formed extensive coastal reefs.
24:48As far as we can tell, this was the Australian seaside, circa 3000 million years ago.
25:00Stromatolites in the shallows, smoke on the horizon, fire in the sky.
25:21These simple life forms made their mark on the world in a far bigger way than as fossils in the
25:27landscape.
25:29They started making the landscape themselves.
25:37South of North Pole lies another Pilbara treasure, Karajini National Park.
25:47I'm taking a shortcut to the distant past.
25:53The deeper I drop into iron-rich Hancock Gorge, the further back in time I travel.
26:04Down here, you can look back at one of the Earth's great turning points.
26:14Two and a half billion years ago, the atmosphere was still without oxygen.
26:22But beneath the waves, stromatolites and their photosynthetic kin were steadily releasing this reactive waste product into the water.
26:34It didn't get far.
26:36The oceans were full of dissolved iron left over from the planet's formation.
26:44Mix oxygen with iron, and you can guess the result.
26:49The oceans began to rust.
26:56Year after year, for hundreds of millions of years, the oceans rusted.
27:05Layer by layer of rich red ooze settled softly onto the deep sea floor.
27:15Now this is what I wanted to show you.
27:18See these dark bands of iron?
27:20This is the so-called banded iron formation.
27:23Now each one of these layers represents a rain of rust that fell to the sea floor two and a
27:29half billion years ago.
27:31And you can see these pale bands in between.
27:34Now nobody knows if this represents some kind of strange seasonality.
27:37But if you think that every one of these layers of rust represents a pulse of oxygen in the oceans,
27:44then what you're looking at is the planet breathing.
27:48The first breath of the biosphere.
28:14Today, that first biosphere breathes life into the Australian economy.
28:24The massive iron ore deposits of the Pilbara are the direct economic legacy of the rusting of the oceans.
28:36It's not until you stand deep in the pit of an iron ore mine like Mount Waelback that you get
28:41the true sense of the scale of the rusting of the oceans.
28:52The hills here are literally made of iron.
28:57Every year over 33 million tonnes of ore are mined at Mount Waelback alone.
29:06And this is the business.
29:09High-grade iron ore exposed to sunlight for the first time in billions of years.
29:16Bang it together, it sounds like metal.
29:19And this stuff is heavy.
29:25All of this.
29:27Australia's great wealth of iron because of a waste product pumped out by microscopic bacterial slime
29:34operating on an industrial scale in those ancient seas.
29:43The empire of the stromatolites was without doubt the greatest in the history of the Earth.
29:49Forget the Romans, the Persians, even the dinosaurs.
29:53These humble bacterial mounds dominated the planet for over 2,000 million years.
29:59And they engineered its greatest transformation.
30:11Once turned on, the oxygen tap could not be turned off.
30:19The formation of iron was just a phase the Earth was going through.
30:24After 700 million years of rusting, the oceans pretty much ran out of iron.
30:34And the oxygen had nowhere else to go, but up.
30:53Now, for the first time, oxygen began flooding into the atmosphere.
30:59It was to be the greatest pollution event in history.
31:07Without the oxygenation of the atmosphere, we wouldn't be here.
31:13Nor would the myriad species we share the planet with.
31:29There might have been a revolution underway.
31:32But there wasn't much for a time tourist to see.
31:36Or breathe, for that matter.
31:39With oxygen concentrations at only a 20th of today's levels, your first gasp would have been your last.
31:50Even geologists have found the second half of the Proterozoic a little, well, a little dull.
31:57After all the earlier dramas, things got stuck in such a long geological rut,
32:03but they've dubbed this period the Boring Billion.
32:11But it was quite a good time for continental construction.
32:20The hot planet below had been busy, pushing and welding together the ancient chunks of continental land mass
32:28that today make up most of the western two-thirds of Australia.
32:44By about a billion years ago, most of the wandering continents, including embryonic Australia,
32:51had been crunched together into a supercontinent called Rodinia.
32:58Fossil evidence points to some of the first seaweeds, sponges and embryos appearing at this time.
33:07Life was moving beyond bacteria.
33:14And just as it did so, it was nearly stopped in its tracks.
33:28Welcome to Snowball Earth.
33:46Unmistakable evidence from around the world points to two great waves of glaciation
33:51that locked the planet in the firm icy grip that gave the Cryogenian its name.
33:59These were the most severe ice ages in the planet's history.
34:18The Flinders Ranges in South Australia seem a world away from a great global ice crisis.
34:27Yet it was here that clues to just such a calamity were first found.
34:40Paleontologist Jim Gayling sees hard evidence for cold climates in these old seafloor muds.
34:51This is tidal rhythmic sedimentation.
34:54In other words, every single tide has been recorded as a couplet of layers.
35:01But the beauty of this, it's a complete record of tides for as much as 60 years.
35:08And that is unique for rocks that are 640 million years old.
35:15These soft sediments settled on the seafloor with the precision of grooves on an LP record.
35:23Each band turning to the beat of an ancient tide.
35:29The fine, undisturbed layering of this tidal calendar could only have formed one wave.
35:39With the seafloor protected by a ceiling of ice.
35:45The seafloor was actually sealed off from waves and storms because there was an ice cover over it.
35:53We were almost straddling the equator and yet this ocean was covered with ice.
36:06This is what we think the oceans of our planet would have looked like during one of these events.
36:14Frozen solid from the poles to the tropics.
36:19Now this is the frozen Arctic Ocean north of Barrow in Alaska today.
36:23In a month or two most of this ice behind me will break up and drift away.
36:28It'll come back next year.
36:30But just imagine if the ice set in not for a season, not for a century, but for a million
36:38years.
36:39Or even 10 million years.
36:42It's very hard to imagine anything surviving such a cold, cold world.
36:53But survive it did.
37:02It was plate tectonics to the rescue.
37:09Furious volcanic eruptions, it's thought, primed the atmosphere with greenhouse gases.
37:17And the great snowball was soon followed by the great fall.
37:27As the ice caps melted, seas rose and flooded back across the land.
37:35But the world that returned had changed.
37:40Life had not only survived the ice-bound snowball years.
37:45It was about to flourish.
37:50The moment is caught in time here in the Flinders Ranges.
37:56With a sudden shift to warm yellow rock, the so-called golden spike.
38:05Now, so what, you might ask?
38:07Well, this is a really significant moment in Earth's history.
38:10Because everything down here is ice-house, the end of the great snowball Earth.
38:15But up here, the planets return to greenhouse conditions.
38:19But much more than that.
38:20At this precise point, 634 million years ago,
38:25we suddenly enter a world clearly inhabited by animals.
38:33In a secret location in the hills not far away,
38:36Jim Gayling and his team have unearthed a whole section of sea floor.
38:41A tableau of life in the Edie Akron.
38:58These are some of the oldest multicellular animals to be found on Earth.
39:04So significant that their discovery near Edie Akron in the Flinders Ranges
39:09has given the age its name.
39:16So you're looking at a snapshot of life on the quiet bottom,
39:22just below the reach of waves during fair weather.
39:28Here was a garden of strange animals.
39:34Frond-shaped creatures feeding in the current.
39:41Others resembling anchors and throat lozenges.
39:51Now, the most common one is this little pancake-shaped thing, Dickinsonia.
39:59Like a puffed-up placemat, Dickinsonia could reach about three feet across.
40:06It seems to have slid slowly over the sea floor,
40:09stopping from place to place to feast on the carpet of bacterial slime.
40:19One of the puzzles has always been, though,
40:22how did these creatures feed?
40:24It probably crawled over the mats, decayed the mat underneath and absorbed the nutrients.
40:32So no mouth? No mouth.
40:39What is certain is that there were things moving about on the sea floor looking for food.
40:44Let's go ahead.
40:45Oh, yeah. Now that's one of my favourites. It's Spragina.
40:49And it's important because...
40:51We see that there's a head end, looks like a shield,
40:56with a bulge behind that, which might just be concentration of its sensory organs.
41:01So a brain. An early brain.
41:03That's right. So the first smart creature on Earth, perhaps.
41:06Maybe the last.
41:11Spragina was an animal on the prowl.
41:14A pioneer crawling into the record books right here
41:18on a long lost Australian shoreline.
41:22The record that we have here is that the first animals, the Ediacrobiota,
41:27which could actually move and feed on the sea floor
41:30and forever after the Earth was going to change.
41:46For the great bulk of the planet's history,
41:49we've travelled through a landscape where raw geology ruled the world
41:54and slime ruled the waves.
42:00And now, after nearly four billion years on the road,
42:06we've arrived at the end of the beginning.
42:14While life was starting to soften the planet's surface,
42:18Earth's underground heat engine had been busy driving Australia,
42:22Antarctica, India, Africa and Madagascar together
42:25into the famous supercontinent, Gondwana.
42:30As the Gondwanan giant was shunted together,
42:35shockwaves rippled across the Australian mainland,
42:37pushing up a titanic mountain range, the Petermans,
42:42that once towered over central Australia.
42:49By the time the sun was glinting off their jagged icy peaks,
42:54it was also sparkling through into the first seas of the Cambrian.
43:11There you go. Thank you very much.
43:14A time-travelling tourist to Australia 540 million years ago
43:18would have been able to complete what is today an impossible journey.
43:23Push it right over that side.
43:25Thanks, mate.
43:25You would have been able to board a ship somewhere to the north of Cairns
43:31and sail inland almost to the south of Adelaide.
43:39The eastern states of Australia, where they existed at all,
43:43were still mud at the bottom of a tropical sea.
43:50If you'd been able to gaze down into those warm, ancient seas,
43:54you would have seen that they were teeming with an abundance
43:57and diversity of life, the like of which the planet had never seen.
44:05It's been dubbed the Cambrian Explosion,
44:08a reflection of just how quickly animals took over the oceans at the time.
44:19There'd been strange creatures in Australian seas ever since the Edeacaran.
44:24But now, suddenly, things that might not look out of place on a seafood platter
44:29were scurrying over the sand.
44:39And one of the best places on the planet to meet them
44:42is Kangaroo Island.
44:51Tucked away high above the waves of Emu Bay
44:54lies one of the world's premier Cambrian fossil sites.
45:05This is awfully good fun, but I have to keep on reminding myself
45:09that what I'm actually doing here
45:11is taking a half-billion-year-old rock,
45:16tapping it with a hammer,
45:18and coming face-to-face with perfectly formed
45:22little crustacean-like things
45:23that were scurrying around over 500 million years ago.
45:33These are trilobites,
45:36ancestral arthropods that made their grand entrance in Cambrian seas.
45:45The Cambrian Explosion was a time period in the history of life
45:49which is probably one of the most significant in Earth's history.
45:53We see animal groups that are recognisable today
45:57first appearing in the fossil record.
45:59So the arthropods, for example,
46:01things like spiders and crustaceans and insects,
46:04and the mollusks, another major group that we see today.
46:07They have their recognisable beginnings in the Cambrian.
46:15There are so many trilobites found at Emu Bay,
46:18they must have been scuttling everywhere.
46:24The gentle days of the Garden of Ediacara were over.
46:30This was a world of mouthparts and mobility.
46:35Hunters and the hunted.
46:41Armour-plated arthropods patrolled the seas,
46:44searching for easy pickings.
46:47They were bug-eyed
46:49and bristling with new technology.
46:57Astonishingly, some of their soft body parts have been exquisitely preserved.
47:05Here's looking at one of the world's oldest eyeballs.
47:14Here's a decent-sized beastie, a trilobite called Redlichia.
47:17Now you can see all its segments quite clearly,
47:19and you can see this beautiful head shield with these big spikes down each side.
47:24But if you look even more closely up here, you'll see its two antennae.
47:30Just amazing.
47:34Growing longer than a man's hand,
47:37Redlichia was the largest trilobite in these Goldwine waters.
47:43But it was still well armoured with defensive spines.
47:49There was a good reason for this.
47:57Top predator in the Cambrian Ocean was a giant arthropod called Anomalocaris.
48:06Anomalocaris was an animal that grew to over six feet in length.
48:13So this thing would have been fluttering around in the surface waters
48:16looking for probably other arthropods.
48:21Clearly, the evolutionary arms race had begun.
48:40While the trilobites went on to reign for another 250 million years,
48:46Anomalocaris swam into oblivion by the end of the Cambrian.
49:05Back on land, and with no botanical protection,
49:09the high peaks of the Peterman Ranges in Central Australia were wearing a whale.
49:17For a hundred million years or more, rivers had been tumbling from their bare, snowy peaks.
49:29These days, the Peterman Ranges are little more than a fading blue blip on the Central Australian horizon.
49:37But their legacy lives on.
49:43As the ancient waters poured out of the mountains, they carried the raw materials for two of Australia's most treasured
49:51rocky landmarks.
49:56The rivers that roared out of the mighty Peterman Ranges, which once towered on the horizon,
50:01swept their heavy load of Warnaway Mountain as far as the water would carry it.
50:06A lot of it ended up here, to form the magnificent bedrock of Katajuta.
50:19The smooth domes of Katajuta are the eroded remnants of a thick conglomerate of rounded river cobbles dropped by the
50:27fast flowing water.
50:32A lighter load of sand was carried further afield.
50:40It ended up here, about 20 miles away, where rivers slowed as they met the shore.
50:51This is how Uluru, the great red rock in Australia's desert heart, began life.
50:59As wet sand from a recycled mountain range, settling at the edge of a now vanished Cambrian Sea.
51:36The lights went down on Cambrian Australia, with the stage set for the next great drama in The Story of
51:43the Earth.
51:45And the cast was already gathering out to sea.
51:53Despite the explosion of life going on in the sea, if you'd taken a walk on a Cambrian beach,
51:58you probably wouldn't have noticed much going on at all.
52:01Perhaps a trilobite might have tickled your toes.
52:04But apart from the wind and the waves, this was a silent world.
52:08There was still no life up there, on land.
52:14It would not stay this way for long.
52:17The seas, now bursting with life, were set to spill their cargo onto the bare earth.
52:24And Australia was ripe for conquest.
52:35The adventure continues on NOVA's website, where you can watch Australia's first 4 billion years.
52:41See video extras, hear from experts, and explore interactives.
52:45Find us at pbs.org slash NOVA.
52:48Follow us on Facebook and Twitter.
52:50Next time on Australia's first 4 billion years.
52:53So this seems to be how the animal invasion of the land began.
52:57Life storms the beaches and dominates planet Earth.
53:01Ancient Australian fossils offer clues to how we got our start.
53:05My goodness, that's the world's earliest umbilical call we know of.
53:08This is something truly special, a living link to our fossil past.
53:12Life explodes on the next episode of Australia's first 4 billion years, on NOVA.
53:20Major funding for NOVA is provided by the following.
53:25The David H. Koch Fund for Science.
53:29Supporting NOVA and promoting public understanding of science.
53:34And by the Corporation for Public Broadcasting.
53:38And by contributions to your PBS station from viewers like you.
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