Australia Rise of the Continents


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Australia

Iain Stewart explores how the Earth's continents have transformed evolution. He shows how Australia's journey has affected everything from Aboriginal history to mining.


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THUNDER CRACKS

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In the darkest hours of a winter night...

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..in a forested corner of southeastern Australia...

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..I'm on a mission to find an extraordinary creature.

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It's a bizarre animal, and one that few people have seen in the flesh.

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And it can help us unravel the mysterious history of Australia,

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perhaps the most surprising of all the continents.

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Australia is famous for its odd and unusual animals,

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but the one that I'm hoping to see tonight

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has got to be the strangest on the planet.

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This is a...is an ancient survivor,

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the rarest of beasts that goes back 160 million years to a lost world.

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A lost world, not only full of strange creatures...

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..but also a world where the shape and character of our continents

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was utterly different.

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This is the way to see rocks!

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I want to reach back in time using the clues that are hidden all around us...

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You don't get much clearer evidence than that.

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..in living creatures...

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There's one. Can you see that, just over there?

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..in landscapes...

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..and written into the rocks.

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The tiniest detail can reveal the history of a vast continent.

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I'm going to piece together these clues

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to uncover key moments in Australia's history...

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..and find out how Australia's journey

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has created the conditions that allowed people to settle this harsh land

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and shaped the lives of those who followed,

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but also how that journey continues to affect the destiny of people

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far beyond the shores of this island continent.

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I've come to the Yarra Valley in the state of Victoria

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to search for the creature that takes us back

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to the beginning of Australia's geological story.

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It is a legendary creature.

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I mean, it's described as venomous, egg-laying, duck-billed,

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beaver-tailed, otter-footed, mole-furred.

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Plus, it's odd, it lactates, but it's got no nipples.

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I mean, the lactating business means it is a mammal,

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but the egg-laying, that's much more like a reptile.

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It's a... It's an odd fusion of animal.

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I'm here with Josh Griffiths, a biologist who does regular surveys...

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So, have you caught them here before?

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Yeah, I've caught some just upstream here before.

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..to check on the welfare of these unusual animals.

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Just need to stretch this out and tie it up to the bank so it's nice and secure.

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This creature, which links back to Australia's past,

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lives today only in the wetter forested parts of the continent

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but it's hard to track down,

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because it leaves almost no detectable trace.

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So, we could be in for a very long night.

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Do you think they can see us? Do you think they're laughing?

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Finally, after seven hours, I get my first glimpse of an animal that few people

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have ever seen in the wild - a platypus.

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Oh, my gosh. That's incredible.

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This is what we've been waiting for. It's a male, is it?

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Yeah, it's a male. It's an adult one.

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Can I see his face? Can I see that classic, classic face?

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Three in the morning it is. You kept us up till three in the bloomin' morning.

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But isn't that worth the wait? Ah, no, absolutely.

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Can I stroke...? Yeah.

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He's perfectly happy, is he? Lovely.

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I mean, the fur is very mammalian.

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The fur's definitely mammal,

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and the way that they regulate their temperature.

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Right. Their eyes are quite reptilian,

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and the way their legs are splayed out to the side is like a lizard.

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This strange mix exists in the platypus

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because it's a link back to a world 160 million years ago.

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A time when our mammal ancestors were just beginning to evolve from early reptiles.

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Millions of years ago, we all would have shared a common ancestor,

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and it would have been very reptilian,

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and it would have looked a lot more like a platypus

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than it would look like you or me.

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I have to say, it's hard to imagine that we've got a common ancestor.

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It just looks so different from us.

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It certainly does now, but millions of years ago

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we all would have looked much the same.

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While the platypus survives in the backwaters of Australia,

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the common ancestor is long gone.

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All that's left are tiny fossil fragments

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that reveal creatures from that long lost world.

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The animal that gave rise to the platypus and to all of the mammals we see today

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might well have looked something like this.

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Crucially, their remains have been found across the globe.

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These creatures were living all over the place.

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And that suggests something highly intriguing.

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Just as all life has a common ancestor,

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so too does the land that we're standing on.

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To imagine that time, you've got to try to undo the shape and position

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of each continent that's been imprinted in your brain

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by every atlas and world map you've ever seen.

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If you turn back the clock through geological time...

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..you see Australia was once part of a huge landmass...

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..in which most of today's continents were joined...

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..and over which the platypus' ancestors roamed.

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It's hard to imagine what this ancient world looked like,

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and how our modern continents were arranged within it.

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But there are clues if you know where to look.

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And the first one comes from the substance that has helped to make modern Australia

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one of the wealthiest nations on the planet.

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This black layer that I've been following here is coal.

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This is a natural layer that's been exposed by the waves.

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Just a few miles away, though,

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there's vast diggers pulling this stuff out of the ground.

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Around one million tonnes of coal are exhumed from this land each and every day.

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But it has another value that goes beyond the financial.

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What I'm looking for is a fossil that's in here.

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There's a nice one, see that, just here.

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That's a little fragment. That's a nice one too.

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These fossils contain evidence of Australia's past

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and that of the whole southern hemisphere.

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But their importance was brought home

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only when almost identical fossils were found on a famous expedition

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to another continent entirely.

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On the 1st of November 1911, Robert Falcon Scott and his team

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set out across Antarctica

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on their ill-fated attempt to be the first to the South Pole.

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Their final days, in March 1912, are now legendary.

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Suffering frostbite, snow-blindness and malnutrition,

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they were only 11 miles from a supply base

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when a fierce blizzard hit and trapped them for ten days.

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Their last.

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Almost eight months later, when their frozen bodies were found,

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something extraordinary was laid out beside them.

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16 kilograms of fossils.

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Clearly Scott thought they were valuable. And he was right.

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They would help define the boundaries of the landmass in which Australia sat

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and the nature of the landscape that covered it.

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What I'm really looking for in these rocks is that exact same fossil that Scott found

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in Antarctica.

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For all those that think rocks are boring, look at this.

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Look, it's just beautiful.

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It just feels as though it was created yesterday.

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From these fossils

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I can find the type of vegetation that once covered Australia.

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Glossopteris, lost forests, fossils found in Antarctica.

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Just packed full of plant debris.

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These are leaves of a tree called glossopteris

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which formed 255 million years ago,

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and that means that 255 million years ago, this part of Australia was lush forest.

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It was these glossopteris forests that transformed over time

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into Australia's enormous coal reserves.

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And that's why the fossils are found inside them.

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But more importantly, because the exact same fossil was found in Antarctica,

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it means that Antarctica was also lush forest.

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But that's not all.

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Glossopteris fossils from elsewhere also reveal the extent of the landmass.

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In fact, glossopteris is found right across the southern hemisphere.

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It's found in southern Africa, it's found in South America.

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Thing is, the spores of these glossopteris

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just couldn't be transported across vast oceans.

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In other words, all those land masses must have been together.

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Glossopteris has helped reveal the arrangement of all the continents

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in the southern hemisphere at the time.

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Not only was Australia linked to Antarctica...

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..but also to Africa, India and South America.

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This vast landmass was called Gondwana,

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a supercontinent which was the southern half of the even larger landmass

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of Pangaea.

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The primeval land of Gondwana was on an almost mythic scale.

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It was carpeted with glossopteris trees.

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A forest more than four times the size of the Amazon Basin,

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stretching further than any eye could see.

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A tiny fraction of Gondwana's forest still remains today

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in a cool pocket of New South Wales

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in eastern Australia.

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It's quite an eerie sensation, really,

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to just be amongst these giant ferns and things.

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You know, you spend all this time studying rocks and fossils in the laboratory,

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trying to piece together the Gondwana forest, and here it is!

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Here it is, just all laid out for us.

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I've been dumped into the heart of Gondwana.

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This tiny remnant stands for a great phase in this continent's history.

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Australia was green and lush for over 300 million years.

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Enduring through the reign of the dinosaurs

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as well as the rise of the mammals.

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Gondwana was so huge that it was destined to break up.

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And it was that break-up that created the character of Australia.

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The mighty supercontinent of Gondwana and its fairytale forests

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would soon be lost for ever.

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A great change was about to come across this land,

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an event that would transform Australia into the continent we know today.

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To piece together what happened,

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you need to travel deep into this continent's red heart.

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The interior of Australia today couldn't be more different.

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A vast, empty expanse.

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Thousands of kilometres of burning, barren earth.

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But as you fly deeper into the interior, there's an odd sight.

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Strange white pock-marks across the surface,

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hundreds of thousands of them.

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Each pock is an entrance to a hidden world beneath the scorched surface.

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And down there is where I'll find evidence of what happened

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when Gondwana broke up.

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This is the unusual country town of Coober Pedy.

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Unusual because the 3,000 people who live here

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mostly live underground.

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Houses, restaurants, hotels, churches.

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There's even a subterranean bookshop.

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The people here have dug out these caves to escape the desert heat.

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You know, at first, the idea of people living underground,

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modern-day troglodytes,

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just seems bizarre, really, and there's definitely odd things here,

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but actually, it mainly makes sense.

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It's not claustrophobic, it's cool and it's airy.

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And for a geologist like me, to be surrounded by rocks,

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just ideal.

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The reason the townsfolk go to such lengths

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is because this rock contains a treasure,

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one of the most precious jewels on the planet.

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For them it provides a livelihood.

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For me, it's a crucial clue to how this land changed

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when Gondwana broke up.

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And I'm on my way to see what everyone's digging for

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with straight-talking miner Kevin Swain.

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So this is it? Yep, this is it. No doubt.

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So, lift this over. Yep.

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Step through it.

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Yep, lift it a bit. Down.

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It's quite smooth. I like this. Sit square.

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Liking it less now.

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There's no-one to answer you. Stop talking to yourself.

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HE LAUGHS

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This is Kevin's patch for mining, one of thousands around Coober Pedy.

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A 22-metre shaft that takes me into a warren of tunnels.

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Oh, ho! Stop!

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Kevin spends every day down here, alone, digging for one thing.

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It's like a knife through butter. Very soft.

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Where's the valuable rock here, then?

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Well, right up there by the light, you can see it.

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There's, er... That kind of opaque, kind of...?

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Yeah. That's good quality stuff, that, there, yeah. Yeah. Yeah.

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It's opal.

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A precious gemstone that, at best quality, has more value than diamond.

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That's a good enough reason for miners to work here

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in these solitary subterranean conditions.

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This is no place for big mining companies

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because of the very small seams in which opal occurs.

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And how often do you strike lucky, hit a rich seam?

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Rarely.

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Does that mean five years, ten years, one year?

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No, it's unpredictable.

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If you work steadily at it... Yeah.

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..you get...you'll cover your expenses

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and every now and then, you have a surprise comes along.

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So, every time you come to work, are you hoping for that big find?

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Yeah. You wouldn't come to work if you didn't. Yeah.

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Pick's always sharp, bucket's always empty.

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Opals are extraordinary.

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The highly specific conditions in which they form

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have occurred only rarely in the history of our planet,

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and then, mainly here in the Australian outback.

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But they've also occurred somewhere strangely similar to here -

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the planet Mars.

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These distant places share a similar chemistry in their red rocky deserts.

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In Australia, opals only occur

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because of what happened during the demise of Gondwana.

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Ah, now, there's a bit.

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And I can figure out those ancient events by examining these gemstones.

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Silica.

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Sulphuric acid.

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Bacteria.

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An inland sea.

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What I love about opal is it forms through this peculiar set of conditions.

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You need two raw ingredients for it. One of them is silica...

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..and the other's acid.

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Now, the silica's pretty simple,

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it comes from minerals in the rock around here.

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But for the acid, you need a really strong acid like sulphuric acid,

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and the sulphur for that comes from bacteria

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that eat sulphur when oxygen's not around.

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Bacteria that live in the mud at the bottom of a stagnant sea.

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To turn that sulphur into sulphuric acid,

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you essentially need to put oxygen into it.

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So, you need to take the sea away, exposing it to the air.

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So, now you've got sulphuric acid, and what that does is,

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it just leaches its way through the rock, picking up the silica

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and concentrating it into these narrow bands.

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What all that complicated chemistry tells us

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is that there used to be an inland sea here,

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but actually, down here, in a few places,

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the opal's preserved far more obvious evidence of that sea.

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Now, look at that - sea shells.

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You don't get much clearer evidence than that.

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It's hard to imagine now,

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but here in the dry, dusty interior of Australia,

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there existed, for just a while, an inland sea.

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This sea was created by an event of epic proportions -

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the break-up of Gondwana.

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Around 180 million years ago,

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huge upwellings of hot rock began to rise from the mantle,

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deep below the Earth's crust.

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These plumes wore away at weak spots in that crust...

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..until finally, 150 million years ago, they gave way.

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This was the beginning of the break-up of Gondwana.

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As the continents separated,

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new sea floor was created between them.

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This new material was hot,

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which made it expand and displace the seas above it.

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This was what caused global sea levels to rise

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so that water rushed into the flat centre of what would become Australia,

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creating the inland sea.

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And it lasted for over 35 million years.

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When it retreated, the sea left in its wake

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the specific conditions for the formation of opals.

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But the break-up of Gondwana also created something else extraordinary,

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something which would help people survive here millions of years later.

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The interior of Australia is harsh. Forbidding.

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When the Europeans first came here, over two centuries ago,

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they realised the key to settling this land

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was to find water.

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From the time the Europeans arrived in Australia, they had an obsession

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and that was to get in to the country's interior.

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They were absolutely convinced that somewhere in this vast landscape

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there had to be an inland sea.

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After all, all the other continents that they explored had one -

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the Great Lakes in the US, Caspian in Asia.

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Why should this place be any different?

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They were, of course, 100 million years too late to find Australia's inland sea.

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But they didn't know that

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and such was the importance of finding water

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that they kept on trying.

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From 1813, they launched a series of expeditions

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that aimed to chart rivers and find the inland sea.

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But time after time, the expeditions ended in failure and even death.

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The place names that they came up with gives you a sense of their desperation.

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There's Dismal Plain, Lake Disappointment, Mount Hopeless.

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But, of course, there was a people who had lived here for many thousands of years,

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and they knew a source of water that the Europeans didn't.

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These people had ways and means of finding that water in the desert.

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They saw it in the land.

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And they remembered it with the stars.

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And with their songs.

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..it's not difficult.

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Dean Ah Chee is an elder of the Lower Southern Arrernte people,

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and was schooled from earliest youth in the Aboriginal ways of finding water

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in this dry land.

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So, what is a songline?

0:27:320:27:34

So, is it like a kind of...an aural map?

0:27:470:27:49

Is it like a map of the landscape, but told?

0:27:490:27:51

Right.

0:27:510:27:53

And so do all the songlines relate to water?

0:28:100:28:13

So, how far can you navigate on a songline? Is it...?

0:28:190:28:23

So, how do you find it? Tell me the secrets!

0:28:260:28:29

Ah!

0:28:350:28:37

Right.

0:28:370:28:38

Really? So, it's that important?

0:28:400:28:41

It's that crucial that it's almost kept like a secret?

0:28:410:28:46

Secret law.

0:28:470:28:49

The Aboriginal people,

0:28:590:29:00

for thousands of years, have used these songlines

0:29:000:29:03

to lead them to a reliable source of water in the desert...

0:29:030:29:07

..water that emerges from underground into what's called mound springs.

0:29:110:29:15

So, is it cold or is it hot? It's hot water.

0:29:200:29:23

It's hot? Yeah.

0:29:230:29:25

Oh, it is! Ah-ha-ha! I tell you, it's the mud.

0:29:250:29:28

Ah! That's a lovely temperature. No crocs, yeah?

0:29:280:29:32

You sure?

0:29:320:29:34

Whoa!

0:29:360:29:38

Oh, that is lovely.

0:29:380:29:41

Ah, yeah... Oh, yeah!

0:29:430:29:45

I can feel... Look at this.

0:29:450:29:47

What the Aboriginal people couldn't know

0:29:540:29:56

was how their songlines, linking up one mound spring to another,

0:29:560:30:01

echoed the geology below.

0:30:010:30:04

Because deep in the ground, all these mound springs were linked,

0:30:040:30:08

in a vast reservoir of water.

0:30:080:30:11

What's really intriguing about these springs is just how many there are.

0:30:110:30:15

In this area there's a handful, but across the region, there's something like 700.

0:30:150:30:21

What's even more remarkable

0:30:210:30:22

is that I'm swimming above this enormous reserve of water

0:30:220:30:26

that's deep down there

0:30:260:30:28

and extends beneath almost a quarter of Australia's land surface.

0:30:280:30:32

This reserve is called the Great Artesian Basin

0:30:400:30:44

and, incredibly, it holds enough water to fill

0:30:440:30:47

26 billion Olympic-size swimming pools.

0:30:470:30:51

It's a giant aquifer - porous rock under the ground which holds water -

0:30:560:31:02

and a key part of it exists here thanks to the ancient inland sea.

0:31:020:31:06

Even before Gondwana began to break up,

0:31:110:31:14

the first element of the Great Artesian Basin was in place.

0:31:140:31:18

Deep underground, there were layers of porous sandstone rock.

0:31:220:31:26

But any water which got into that rock would quickly escape again

0:31:260:31:31

because there was nothing to contain it.

0:31:310:31:33

The inland sea brought, and left behind,

0:31:380:31:41

the crucial ingredient needed to trap the water inside.

0:31:410:31:44

Mud.

0:31:460:31:47

The mud hardened into a lid of impermeable rock,

0:31:490:31:53

which lay across the top of the sandstone.

0:31:530:31:56

So, when rainwater fell,

0:31:560:31:58

it could trickle around the edges of the lid and get into the sandstone,

0:31:580:32:02

but, crucially, that same lid prevented the water from evaporating away.

0:32:020:32:08

At a few places, where the lid's broken, the water escapes.

0:32:150:32:20

These are the mound springs that have sustained the Aboriginal people

0:32:200:32:24

for thousands of years.

0:32:240:32:26

And because these springs provide the only reliable source of water

0:32:260:32:31

for much of inland Australia,

0:32:310:32:33

they're a vital lifeline for wildlife here,

0:32:330:32:37

as well as the great sheep and cattle stations of the Australian outback.

0:32:370:32:42

It's an extraordinary thought that the muddy remains of a long-lost sea

0:32:450:32:50

still provide water that sustains life here today.

0:32:500:32:53

By around 100 million years ago, Gondwana had broken apart

0:33:010:33:06

but Australia still didn't exist as a separate continent.

0:33:060:33:10

There was one big split yet to come.

0:33:110:33:14

One that would transform Australia,

0:33:170:33:18

and lead to the evolution

0:33:180:33:20

of one of the most spectacular animals on the planet.

0:33:200:33:24

This is the Great Australian Bight,

0:33:320:33:37

over one thousand kilometres of coastline on the southern edge of Australia.

0:33:370:33:41

It's just vast.

0:33:440:33:46

The cliffs themselves are 80 metres high, falling away to the sea.

0:33:460:33:51

If I'd been walking along here 90 million years ago, then...

0:33:570:34:02

there would have been no cliff, there would have been no ocean.

0:34:020:34:06

Instead, I would have been able to take a single step from here,

0:34:060:34:11

directly onto Antarctica.

0:34:110:34:13

This is how the coastline of Antarctica and Australia joined up.

0:34:230:34:28

Despite the inevitable erosion, it's still a neat fit to this day.

0:34:280:34:32

Although these two continents are now almost opposites,

0:34:390:34:42

back then, the story was very different.

0:34:420:34:46

They were effectively identical twins.

0:34:480:34:51

Both, temperate, forested lands,

0:34:510:34:54

which lay together near the South Pole.

0:34:540:34:57

And, like all twins, they weren't easy to separate.

0:35:000:35:04

Although Gondwana was gone,

0:35:040:35:06

Australia and Antarctica stayed close together for many millions of years.

0:35:060:35:11

But the process that transformed them into radically different lands

0:35:160:35:20

also had another consequence -

0:35:200:35:22

the evolution of the largest group of animals that ever lived on the planet.

0:35:220:35:27

Those great Leviathans of the sea.

0:35:310:35:33

The filter-feeding whales.

0:35:350:35:37

I'm off looking for whales.

0:35:400:35:42

It's the perfect weather, perfect time of year, August,

0:35:420:35:45

which is breeding season, so hopefully, fingers crossed,

0:35:450:35:49

we'll see some mums and calves.

0:35:490:35:50

Helping me locate them is local guide Rod Keogh.

0:36:000:36:03

Oh, there's one. Can you see that, just over there?

0:36:170:36:19

The black in the water. A black strip.

0:36:190:36:21

Oh, there's two. A fin to the side of it.

0:36:210:36:24

Oh, look, look, look! Look at the face!

0:36:240:36:26

Can you see that? Yeah! Yeah! It's great!

0:36:260:36:29

Just encrusted with barnacles, just coming up.

0:36:320:36:35

WHALE CALL

0:36:370:36:39

Did you hear that? "Hooonnn." That's the sound of a whale.

0:36:390:36:44

Oh! Look at that!

0:36:450:36:48

That was incredible.

0:36:480:36:49

That was one of the mothers flicking her tail. That's Scottie.

0:36:500:36:54

Scottie from the Antarctic, is that it?

0:36:540:36:55

Yeah. She was...

0:36:550:36:58

She was named short for "S-cot no friends" cos she was always by herself.

0:36:580:37:03

And now she's back, she's still got no friends.

0:37:030:37:06

So, I still call her Scottie. That's great.

0:37:060:37:09

Now she's got a calf.

0:37:090:37:10

Oh, yeah, see that.

0:37:100:37:12

These whales spend most of the year in Antarctica feeding

0:37:140:37:18

but at this time of year, August,

0:37:180:37:21

they journey over 2000 kilometres here to breed.

0:37:210:37:25

These are southern rights, third largest whale species on the planet.

0:37:280:37:32

You're only seeing about 10% of the animal.

0:37:340:37:36

The bulk of it, 90%, is underneath.

0:37:360:37:38

These whales can grow up to 15 metres in length.

0:37:380:37:42

And they can reach such a size because of what they eat,

0:37:420:37:45

scooping up two to three tonnes of food each day -

0:37:450:37:48

millions and millions of miniscule krill.

0:37:480:37:52

How these great animals came to survive on these tiny creatures

0:37:550:37:58

is a direct consequence of Australia's geological history...

0:37:580:38:03

..and its separation from Antarctica.

0:38:050:38:07

90 million years ago,

0:38:130:38:15

something happened to finally separate Australia from Antarctica.

0:38:150:38:19

Volcanic activity from deep within the Earth's mantle

0:38:220:38:25

forced up a new ocean crust between them,

0:38:250:38:27

creating a mid-ocean ridge which broke them apart.

0:38:270:38:31

Australia was, at last, a separate island continent.

0:38:350:38:39

And that left Antarctica sitting all alone over the South Pole,

0:38:440:38:48

still temperate and forested.

0:38:480:38:50

That was, until the isolation of Antarctica

0:38:520:38:55

created an unusual effect in the waters around it.

0:38:550:38:59

Normally, the wind drives surface currents,

0:39:030:39:06

pushing the water onto shores like these, where the energy dissipates.

0:39:060:39:10

But thousands of kilometres over there is Antarctica,

0:39:100:39:13

and there, the situation's slightly different.

0:39:130:39:16

The water goes round and round that huge mass, building up the flow.

0:39:160:39:21

And without land to get in the way to disrupt it,

0:39:210:39:24

the current just gets stronger and deeper.

0:39:240:39:27

The oceans were free to flow all around Antarctica

0:39:330:39:36

driven by the winds.

0:39:360:39:38

And this was the beginning of the Circum-Antarctic Current.

0:39:400:39:45

Its effect on Antarctica was profound...

0:39:450:39:47

..cutting off the continent from the warm waters to the north.

0:39:490:39:53

In just one million years,

0:39:580:40:01

Antarctica was transformed from a temperate forested land...

0:40:010:40:05

..to one entombed in ice.

0:40:070:40:10

From now on, Antarctica would be a land of desolation...

0:40:130:40:16

..inhabited by nothing bigger than a penguin.

0:40:200:40:23

But in the ocean, this new current had a more positive effect,

0:40:310:40:35

playing a significant role

0:40:350:40:37

in the evolution of all filter-feeding whales,

0:40:370:40:40

the southern right whale among them.

0:40:400:40:43

The motion of this current forced up water from the depths of the ocean

0:40:440:40:48

to the surface, carrying with it nutrients which support tiny creatures

0:40:480:40:53

such as phytoplankton and krill.

0:40:530:40:55

This was a rich source of food, just waiting to be scooped up.

0:41:050:41:09

And, sure enough, around the time the current appeared

0:41:210:41:24

sea-dwelling mammals began to develop a new way of eating,

0:41:240:41:28

filter-feeding those vast volumes of krill.

0:41:280:41:32

Giant whales to this day feed in the same way.

0:41:390:41:42

I could watch them all day, just doing their stuff out there.

0:41:500:41:54

It's lovely to think that it's the Circum-Antarctic Current

0:41:540:41:57

that played such an important role in allowing these giants to develop.

0:41:570:42:02

And also keeps them fed today.

0:42:020:42:03

In a way, these whales are the last remaining link between two continents

0:42:050:42:09

that started as twins and have grown so far apart.

0:42:090:42:13

Australia's fate was to be very different to that of Antarctica.

0:42:180:42:23

It too would change dramatically, but in almost the opposite way.

0:42:230:42:27

While Antarctica turned to ice, Australia was turned to dust.

0:42:380:42:43

It continued moving northwards

0:42:470:42:50

and around 20 million years ago, Australia pushed into warmer latitudes.

0:42:500:42:55

And this would have significant consequences for this land

0:42:590:43:03

and anything trying to live on it.

0:43:030:43:04

The forest died away, save for a few tiny pockets.

0:43:090:43:14

It was replaced with bare, red land

0:43:170:43:20

and the one tree that thrived in these new arid conditions -

0:43:200:43:23

the eucalyptus.

0:43:230:43:24

A tree that now accounts for almost 80% of the forest in Australia.

0:43:280:43:33

For the animals, it was a brutal case of "adapt or die."

0:43:360:43:40

Only a few were able to evolve quickly enough to survive.

0:43:450:43:48

KOALA GRUNTS

0:43:500:43:53

And a classic case of that rapid evolution

0:43:560:43:59

is this fellow.

0:43:590:44:01

(WHISPERS) He's big.

0:44:090:44:10

He's really big.

0:44:100:44:12

I'm assuming you wanted the big koala!

0:44:120:44:13

Yeah, big koalas are good. I could have got a female.

0:44:130:44:16

I didn't have, necessarily, a preference.

0:44:160:44:18

OK. Just don't move, cos it can climb across.

0:44:180:44:21

Over this way, sweetheart. Hiya.

0:44:210:44:22

Good boy. Under his bum. He's not sure.

0:44:220:44:24

Yeah, I've got him. Gosh! He's heavy.

0:44:240:44:26

What's that? Did you say 11 kilos?

0:44:260:44:29

About 11 and a half, Hank is, yeah.

0:44:290:44:30

It's just...! Good boy.

0:44:300:44:32

This feels really nice, actually.

0:44:360:44:39

He's quite heavy, like a toddler size,

0:44:390:44:43

and the fur feels absolutely lovely.

0:44:430:44:46

It reminds me of holding the kids when they were young, actually.

0:44:460:44:49

It's quite nice. I've not done that for years, and they're too big.

0:44:490:44:52

Wow! Yeah, you go for it! Erm...

0:44:530:44:57

I think koalas are great, actually, now.

0:44:590:45:01

I mean, you know they're supposed to be cute...

0:45:010:45:04

They do, they look cute.

0:45:040:45:06

Looks like your iconic teddy bear, doesn't he?

0:45:080:45:11

But he's not actually a bear at all.

0:45:110:45:14

The koala's teddy bear features

0:45:140:45:16

and the anatomy that underpins them

0:45:160:45:18

are the result of having only the eucalyptus tree to munch on.

0:45:180:45:21

A very chewy tree at that...

0:45:220:45:24

..as palaeontologist Mike Archer showed me.

0:45:270:45:30

This is a modern koala. Ah.

0:45:300:45:32

Most of this head has to do with smelling, eating, hold the teeth,

0:45:320:45:37

and the muscles that drive the powerful jaws because these trees are hard to eat.

0:45:370:45:43

So, basically, their head's a chewing machine.

0:45:430:45:45

Exactly. Now, if you look at some of the fossils,

0:45:450:45:48

these fossils are 20 million years old. Ah, cool!

0:45:480:45:52

You've got an animal here that's about half the size of the modern koala.

0:45:520:45:55

Yeah. So, this thing has become gigantic.

0:45:550:45:58

It's a bigger and bigger face.

0:45:580:45:59

The Eucalyptus trees didn't change only the koala's machinery for eating

0:46:020:46:06

but also for communicating.

0:46:060:46:09

This bubble of bone here is an echo-locating chamber.

0:46:090:46:13

That's very good at picking up low-frequency vibrations.

0:46:130:46:16

A low frequency sound? Yes.

0:46:160:46:18

That weird sound they make transmits long distances, and they have to,

0:46:180:46:23

because where they live here, the trees are far apart. Yeah.

0:46:230:46:26

KOALA CALLS

0:46:260:46:29

So, koalas have made this kind of alliance with this tree, really.

0:46:290:46:33

I think so. And then eventually,

0:46:330:46:34

that little niche is the one that then spreads.

0:46:340:46:37

So, they're the lucky ones. They lucked out!

0:46:370:46:39

They were the furry parasite that lucked out.

0:46:390:46:41

The koala's face reflects the dramatic climate shift

0:46:440:46:47

that Australia has undergone...

0:46:470:46:50

..turning from verdant forest to mostly red, dry desert.

0:46:520:46:57

The drying out of Australia is just one more phase in the changing history

0:47:000:47:05

of this continent...

0:47:050:47:06

..that was born in the arms of the giant Gondwana...

0:47:080:47:12

..was flooded by sea when that supercontinent broke up

0:47:170:47:22

and spent much of its life attached to an unlikely twin...

0:47:220:47:26

..before finally becoming an island.

0:47:300:47:33

Throughout all that, Australia has been relentlessly moving northwards

0:47:350:47:41

and it's still going

0:47:410:47:43

which means Australia's transformation isn't over yet.

0:47:430:47:47

An unexpected fate awaits.

0:47:470:47:49

You can already see signs of that future by looking beyond Australia

0:47:540:47:59

to the Indonesian waters of the Banda Sea.

0:47:590:48:02

Hi.

0:48:020:48:03

Hi.

0:48:030:48:04

Can I come in?

0:48:040:48:06

This is Mang, a member of the Bajau, so-called sea-gypsies

0:48:060:48:11

and masters of these waters.

0:48:110:48:14

He's taking me on a fishing trip into the seas which are his home.

0:48:140:48:18

He's completely gone.

0:48:280:48:29

Mang makes it look effortless.

0:48:450:48:48

And the Bajau can almost reach out and take all they need from the sea.

0:48:500:48:55

Because with over 2,000 species of fish

0:49:030:49:06

and over 600 species of coral, these waters,

0:49:060:49:09

known as the Coral Triangle, are the most bio-diverse and productive in the world.

0:49:090:49:15

That was great! Ahh!

0:49:270:49:30

Fish caught,

0:49:330:49:35

Mang takes me to his village, home to over a thousand Bajau people,

0:49:350:49:39

all living off the fruits of the sea.

0:49:390:49:41

So, there's lots of little fish swimming around.

0:49:450:49:48

Hello.

0:49:510:49:55

Hello.

0:49:550:49:58

I love this place. I mean, once you get past the obvious oddity of it -

0:49:580:50:01

all the houses are on stilts,

0:50:010:50:03

and you get these treacherous planks that you walk across -

0:50:030:50:06

what you get is this feeling of a real lively community.

0:50:060:50:09

All these kids, it's fantastic.

0:50:090:50:11

You just forget you're actually on the water.

0:50:110:50:15

CHILDREN SHOUT

0:50:150:50:16

But it means that all sorts of things turn up in your back yard.

0:50:160:50:19

There is a snake. Andwa.

0:50:190:50:21

Andwa? It's a snake, then? Yeah.

0:50:210:50:24

Although Mang seems to relish that.

0:50:240:50:26

CHILDREN SHOUT

0:50:280:50:30

He's got the snake!

0:50:310:50:32

It's not aggressive, but ten times more poisonous than a rattlesnake.

0:50:320:50:36

Well done, sir. That's extraordinary.

0:50:360:50:39

I'm not going to point out any other sea snakes from now on.

0:50:390:50:42

But sea snakes can't faze a man

0:50:440:50:45

who's spent more of his life at sea than on land.

0:50:450:50:49

So, does anyone on this island not like fish?

0:50:500:50:54

There's no vegetarians or vegans or something?!

0:50:580:51:01

To find out why the waters here are so rich,

0:51:050:51:08

and what this can reveal about the future of Australia,

0:51:080:51:11

I'm going ashore, to the nearby island of Wangi Wangi.

0:51:110:51:16

The Bajau villages are strung out

0:51:190:51:21

all the way along the coast on this island.

0:51:210:51:24

But I've come inland, up here into the hills,

0:51:240:51:27

to look for something rather peculiar.

0:51:270:51:29

Because, strangely, the key to understanding the richness

0:51:310:51:35

of the waters down there

0:51:350:51:37

is the rock on this hill up here.

0:51:370:51:41

This is what I've been looking for here. It's coral.

0:51:410:51:45

You can see a whole kind of colony of polyps.

0:51:450:51:47

There's another one here and there's another...

0:51:470:51:49

I mean, essentially, all of the grey rock you can see is coral.

0:51:490:51:53

Which is hardly something you expect to see at the top of a hill.

0:51:530:51:56

And that's because this is an ancient coral reef

0:51:560:51:59

that's been uplifted above the sea.

0:51:590:52:01

It's absolutely spectacular.

0:52:010:52:04

And by looking at this fossilised coral,

0:52:060:52:08

I can find crucial clues to the future of Australia.

0:52:080:52:12

Strontium.

0:52:130:52:16

Three million years.

0:52:160:52:19

A layer cake.

0:52:190:52:20

The clams and corals in this reef

0:52:210:52:23

are absolutely exquisitely preserved. Beautiful.

0:52:230:52:26

But what's really interesting is the age of them.

0:52:260:52:29

Scientists have dated these corals with a form of element called strontium,

0:52:290:52:34

which builds up over time.

0:52:340:52:37

And the age that they get is less than three million years,

0:52:370:52:41

which makes this reef a geological infant.

0:52:410:52:44

This means that this whole island came up above the waves

0:52:480:52:51

no more than three million years ago.

0:52:510:52:54

But the biggest surprise is what lies beneath this reef.

0:52:550:52:59

A layer cake of ancient strata.

0:52:590:53:01

Beds of sand and mud

0:53:030:53:04

that have built up gradually over time

0:53:040:53:07

in conditions of tranquillity and stability.

0:53:070:53:09

Those conditions just aren't found, really,

0:53:100:53:13

in the crumple zone of Southeast Asia.

0:53:130:53:15

Instead, they're absolutely typical of one place -

0:53:150:53:19

Australia.

0:53:190:53:20

The implication's intriguing.

0:53:230:53:26

These Wakatobi islands are in Indonesia,

0:53:260:53:28

so you just assume that they're part of Asia.

0:53:280:53:32

In fact, they're a fragment of the Australian continent.

0:53:320:53:35

It all points to one thing -

0:53:420:53:44

that Australia has moved so far north that it's colliding with Asia.

0:53:440:53:50

Continent is now grinding directly against continent.

0:53:500:53:53

The reason why the collision of these two continents creates such a bounty of fish

0:54:020:54:06

for the Bajau here, is all down to the effect it has on the sea bed.

0:54:060:54:10

As they smash together, the crust gets fragmented and broken

0:54:120:54:16

because some parts are denser, stronger than others

0:54:160:54:20

and the result is that the sea floor around here

0:54:200:54:23

turns into this uneven patchwork of highs and lows.

0:54:230:54:25

In a way, the sea bed around here's a bit like this.

0:54:270:54:29

If I pour some water in to create a sea...

0:54:290:54:32

When the sea level's low, you get a series of isolated pockets

0:54:340:54:37

and each one of those has different conditions

0:54:370:54:40

and so different species.

0:54:400:54:41

But if sea level rises and the water spills across

0:54:410:54:46

then everything gets mixed.

0:54:460:54:48

The thing is, the sea floor around here is constantly shifting,

0:54:480:54:51

constantly going up and down,

0:54:510:54:52

and so you're always revealing new pockets.

0:54:520:54:56

And it's that separation, mixing, separation, mixing,

0:54:560:54:58

that drives evolution here so fast.

0:54:580:55:01

And that's what, in turn, creates these phenomenally rich seas

0:55:060:55:12

and a way of life for these people.

0:55:120:55:14

CHILDREN SHOUT

0:55:140:55:18

Being in this place, here, now, it's kind of a rare moment in time -

0:55:190:55:24

a time when two continents are starting to directly collide into each other.

0:55:240:55:29

But the effects of Australia's move north

0:55:340:55:36

are much, much bigger than the fabulous haul of fish around these islands.

0:55:360:55:42

They're visible all along the boundary where these two continents meet

0:55:420:55:46

as a startling variety of dramatic natural phenomena.

0:55:460:55:50

It's forced up many of the volcanoes of Indonesia, even whole islands

0:55:580:56:03

such as Timor.

0:56:030:56:04

And on the Pacific side, in Papua New Guinea,

0:56:090:56:13

it's thrust up entire new mountain ranges as high as Europe's Alps.

0:56:130:56:17

And the action isn't over,

0:56:250:56:27

not by any means,

0:56:270:56:29

because this is Australia's future.

0:56:290:56:32

To effectively become a part of Asia.

0:56:320:56:35

It's impossible to tell exactly how that collision will pan out

0:56:380:56:42

but a likely version of events

0:56:420:56:44

is that Australia crushes the islands of Indonesia into Vietnam,

0:56:440:56:49

pushes on into China and sideswipes Japan.

0:56:490:56:52

One thing's for sure -

0:56:540:56:55

Australia's brief existence as an island continent

0:56:550:57:00

is coming to an end.

0:57:000:57:01

Australia's destiny is to become much more like this place -

0:57:070:57:10

Indonesia.

0:57:100:57:13

No longer isolated and with a lush climate once again.

0:57:130:57:18

What's happening now is the biggest change in the history of Australia,

0:57:250:57:29

and it's happening right before our eyes.

0:57:290:57:32

Of course, eventually, all of this will be utterly transformed.

0:57:320:57:37

For a geologist, it makes it just so exciting

0:57:370:57:39

because this is one of the most dynamic places on the planet.

0:57:390:57:44

And it's all down to the slow and steady movement of the one continent

0:57:490:57:52

that's always been considered quiet and stable.

0:57:520:57:57

For so long, Australia was thought of as dry, unchanging, isolated,

0:57:570:58:01

but its story is so very different from that.

0:58:010:58:04

In the past, it was twinned with Antarctica.

0:58:040:58:06

And its future's in the making as it merges with Asia

0:58:060:58:09

to become this tropical land of forest and mountains.

0:58:090:58:13

That's why, for me, Australia is the most surprising continent of all.

0:58:130:58:18

Subtitles by Red Bee Media Ltd

0:58:410:58:44

Professor Iain Stewart uncovers the mysterious history of Australia, and shows how Australia's journey as a continent has affected everything from Aboriginal history to modern-day mining, and even the evolution of Australia's bizarre wildlife, like the koala.

Iain begins searching for the platypus - a strange creature that is half mammal and half reptile. 200 million years ago reptile-like mammals were found across much of the world because at this time Australia was just one part of a huge landmass called Gondwana, that dominated the southern hemisphere.

Piecing together evidence from fossils found in a sea cliff outside Sydney and rocks recovered from Captain Scott's expedition to the South Pole, Professor Stewart shows that Gondwana was covered by a forest of now extinct trees called glossopteris. This was the habitat of the ancestors of today's platypus.

To discover the fate of Gondwana, Iain visits an unusual mining town called Coober Pedy where many of the buildings are underground in dug-out caves. The opals that are mined here enable him to recreate the breakup of Gondwana, and also show how Australia's formation led to the creation of a vast underground aquifer. This source of hidden water sustained the Aboriginal people as they criss-crossed the otherwise arid Australian interior.

Iain travels to the cliffs of the Australian Bight to show how Australia was once joined to Antarctica, and how their split led to the evolution of the biggest group of mammals on Earth - the filter feeding whales.

Australia's journey away from Antarctica has also left its mark on the koala. Its big, round face and fluffy ears are a result of adaptations to the climate change that Australia has undergone on its northwards journey.

Finally Iain travels to Indonesia to meet the Bajau people of the Banda Sea - sea gypsies who glean almost all they need to live from the waters around them. Contained within these waters is evidence that shows Australia's eventual fate. Over the next 50 million years, Australia will collide with Asia, its isolation will be over, and it will become forested and lush once again.