0:00:06 > 0:00:08New York City.
0:00:08 > 0:00:10Gateway to the New World.
0:00:14 > 0:00:18But also a gateway back into the distant past,
0:00:18 > 0:00:24not just of New York, but of both North and South America.
0:00:24 > 0:00:28I'm heading to the top of the tallest building in the city,
0:00:28 > 0:00:30in fact in the whole of the Americas,
0:00:30 > 0:00:34but because it's still going up, I have to have this.
0:00:46 > 0:00:51Rising 104 floors, right beside where the twin towers once stood,
0:00:51 > 0:00:54this is World Trade Center 1.
0:00:55 > 0:00:59Few people realise it, but this building and the ones around it
0:00:59 > 0:01:03have a direct connection to a mysterious past.
0:01:12 > 0:01:16There's a secret hidden in this iconic skyline.
0:01:16 > 0:01:19And deciphering it will reveal a long-lost world.
0:01:25 > 0:01:30I'm going to reach back in time to explore this lost world.
0:01:30 > 0:01:35The evidence that unlocks that ancient past is hidden all around us
0:01:35 > 0:01:39in rocks, landscapes and even animals.
0:01:43 > 0:01:47The tiniest detail can reveal the history of a vast continent.
0:01:50 > 0:01:56Those clues reveal a defining moment in the story of the Americas...
0:01:58 > 0:02:02..and show how these turning points have transformed evolution...
0:02:02 > 0:02:03It's moving.
0:02:03 > 0:02:06..created incredible economic riches...
0:02:06 > 0:02:08That feels really close.
0:02:08 > 0:02:12..and changed the human history of these two great continents.
0:02:16 > 0:02:19If you really want to understand the modern Americas,
0:02:19 > 0:02:21you have to understand the remarkable story
0:02:21 > 0:02:25of how they were born, from the wreckage of a lost world.
0:02:43 > 0:02:48You can find a clue to the origin of both American continents
0:02:48 > 0:02:50here at the top of World Trade Center 1.
0:02:52 > 0:02:56It's the way that Manhattan skyscrapers are concentrated
0:02:56 > 0:02:58in just two places -
0:02:58 > 0:03:02Downtown, where I am, and a couple of miles further north.
0:03:03 > 0:03:06And there you can see the Empire State Building -
0:03:06 > 0:03:08that patch is Midtown.
0:03:12 > 0:03:15New York skyscrapers are concentrated
0:03:15 > 0:03:18in Midtown and Downtown for a very good reason.
0:03:18 > 0:03:21One that's buried beneath each one of them
0:03:21 > 0:03:26and that puts New York at the heart of an ancient world.
0:03:31 > 0:03:35To find evidence for this ancient world, I need to explore
0:03:35 > 0:03:38the foundations of the city's skyscrapers.
0:03:38 > 0:03:40It's a bit rickety, this thing, isn't it?
0:03:40 > 0:03:46Before any building goes up high, you've got to dig down deep.
0:03:51 > 0:03:55And that takes some hard-core tools.
0:03:57 > 0:04:03Now, that is the kind of geology hammer I have always wanted to have.
0:04:16 > 0:04:20I'm looking for a particular type of rock.
0:04:20 > 0:04:24One that dates back at least 300 million years.
0:04:26 > 0:04:30Inside it, there's evidence of what this place was like
0:04:30 > 0:04:32in the long-distant past.
0:04:36 > 0:04:41A past that helps explain the mystery of New York's skyline.
0:04:51 > 0:04:53Crystal.
0:04:55 > 0:04:57High pressures.
0:04:57 > 0:05:01This rock face, it's the foundation stone on which,
0:05:01 > 0:05:03for me, modern America was built.
0:05:03 > 0:05:06If you look at it, you can see there's a whole series of lines.
0:05:06 > 0:05:09It's like bands coming through. And that's because of the crystals -
0:05:09 > 0:05:12look, you can see them glittering away here.
0:05:12 > 0:05:16They're all stacked on top of each other in a series of layers.
0:05:16 > 0:05:19You can see that when you look at it closely.
0:05:20 > 0:05:23When you zoom into this rock...
0:05:23 > 0:05:26what you see is a mosaic of crystals...
0:05:28 > 0:05:30..that are flattened in this direction
0:05:30 > 0:05:34and are elongated, strung out in this direction here.
0:05:34 > 0:05:37And that transformation, that rearrangement,
0:05:37 > 0:05:41has been done under really high temperatures, maybe 700 degrees,
0:05:41 > 0:05:44but also really high pressures.
0:05:46 > 0:05:48You get an idea of just how much pressure
0:05:48 > 0:05:51from a mineral that you actually find in here.
0:05:51 > 0:05:54It's a mineral that gives this rock a blue tinge.
0:05:54 > 0:05:56And it's a mineral called kyanite.
0:05:58 > 0:06:01Now, kyanite is a really interesting mineral.
0:06:01 > 0:06:04It's formed by pressures of four kilobars or more.
0:06:04 > 0:06:06Four kilobars doesn't seem very much,
0:06:06 > 0:06:08but if you were squeezed by four kilobars
0:06:08 > 0:06:11you'd be squeezed by a block of rock a metre by a metre
0:06:11 > 0:06:14that extends upward for 13 kilometres.
0:06:17 > 0:06:21This dense bedrock is known as Manhattan schist.
0:06:22 > 0:06:26The only way that you can generate the heat and pressure
0:06:26 > 0:06:29that you need to form the dense strength of a rock like this
0:06:29 > 0:06:32is if you produce it under an enormous weight.
0:06:32 > 0:06:34The kind of weight that's far in excess
0:06:34 > 0:06:36of anything you find around here today.
0:06:42 > 0:06:44300 million years ago,
0:06:44 > 0:06:49New York was at the foothills of a huge mountain range.
0:06:49 > 0:06:52And this rock - this rock - was buried
0:06:52 > 0:06:5513 kilometres beneath those soaring peaks.
0:06:55 > 0:06:57Imagine that!
0:07:06 > 0:07:09These mountains were the height of the Himalayas.
0:07:11 > 0:07:13But they weren't just high.
0:07:13 > 0:07:17They went on for thousands of kilometres.
0:07:18 > 0:07:22And they played a critical role in this story of the Americas
0:07:22 > 0:07:24because their formation is what brought
0:07:24 > 0:07:27North and South America together.
0:07:31 > 0:07:34430 million years ago,
0:07:34 > 0:07:37North and South America were separated
0:07:37 > 0:07:39by thousands of kilometres of ocean,
0:07:39 > 0:07:41but they were on a collision course.
0:07:41 > 0:07:44A slow-motion crash that raised giant mountains
0:07:44 > 0:07:46all along the impact zone.
0:07:48 > 0:07:52At the same time, it brought all the world's landmasses together
0:07:52 > 0:07:56in one giant supercontinent - Pangaea.
0:07:56 > 0:08:00The two American continents were at the heart of Pangaea,
0:08:00 > 0:08:03on either side of a massive mountain range.
0:08:03 > 0:08:06And New York was, in geological terms,
0:08:06 > 0:08:09at the centre of this lost world.
0:08:22 > 0:08:25It's funny. New Yorkers like to think of their city
0:08:25 > 0:08:27as the centre of the world.
0:08:27 > 0:08:30300 million years ago, it really was.
0:08:34 > 0:08:35Now, all that's left here
0:08:35 > 0:08:38of the enormous supercontinent of Pangaea
0:08:38 > 0:08:41is the rock beneath the city.
0:08:48 > 0:08:50You know, it's staggering to think
0:08:50 > 0:08:52that in the last few hundred million years,
0:08:52 > 0:08:56mountains of Himalayan stature have been eroded down
0:08:56 > 0:08:59to leave us with a dense bedrock beneath our feet.
0:09:05 > 0:09:08And that's left its legacy in this iconic skyline.
0:09:09 > 0:09:12Where the bedrock is closest to the surface
0:09:12 > 0:09:15in Downtown and Midtown
0:09:15 > 0:09:18it makes strong foundations for skyscrapers.
0:09:20 > 0:09:23Where it's been eroded away between the two,
0:09:23 > 0:09:26the foundations are weaker and the buildings are smaller.
0:09:38 > 0:09:43This icon of the modern world, the skyline of this great city
0:09:43 > 0:09:46is underpinned by the long-lost world of Pangaea
0:09:46 > 0:09:48and it's shaped much more than that.
0:09:55 > 0:09:59Pangaea's had a huge influence on the modern-day Americas,
0:09:59 > 0:10:02from their natural resources to their history.
0:10:02 > 0:10:06But Pangaea also left its mark on the whole planet.
0:10:06 > 0:10:08It played a critical role
0:10:08 > 0:10:12in one of the most important evolutionary developments
0:10:12 > 0:10:13in the story of life on Earth.
0:10:13 > 0:10:18Nothing less than the invention of sex.
0:10:31 > 0:10:35That rather significant development can only be understood
0:10:35 > 0:10:38if we journey back to the early days of Pangaea,
0:10:38 > 0:10:40before it was fully formed.
0:10:42 > 0:10:48And there's one place in North America that can take us there.
0:11:13 > 0:11:15The Grand Canyon.
0:11:18 > 0:11:21This is a portal through time,
0:11:21 > 0:11:26where you can see the history of the planet laid out before you.
0:11:29 > 0:11:33You have a strange double vision as a geologist when you come here
0:11:33 > 0:11:38because on the one hand you have this spectacular, jaw-dropping view,
0:11:38 > 0:11:40and it's absolutely beautiful.
0:11:40 > 0:11:43But as a geologist you see past that as well.
0:11:43 > 0:11:47You see...a kind of deeper significance of what it means.
0:11:47 > 0:11:52In this case, it means a huge, huge expanse of time.
0:11:53 > 0:11:56The Earth's history being unravelled by the sun
0:11:56 > 0:11:59as it exposes the deeper and deeper layers.
0:12:02 > 0:12:07The rocks down there are 1.7 billion years old -
0:12:07 > 0:12:09extraordinary number.
0:12:11 > 0:12:16The only life on the planet was single-celled algae - it was slime.
0:12:17 > 0:12:19And then, just a little bit higher,
0:12:19 > 0:12:22the rocks are 500, 550 million years old.
0:12:22 > 0:12:24That's where complex life starts growing.
0:12:24 > 0:12:27That's a time when there was great ice sheets across the planet.
0:12:32 > 0:12:37So there's 1.5 billion years of time just condensed into that view there.
0:12:37 > 0:12:40Absolutely spectacular!
0:12:46 > 0:12:49One set of layers that's important for our story of Pangaea
0:12:49 > 0:12:53is this group of rocks over here. It's called the Supai Group.
0:12:54 > 0:12:57They date from the earliest days of Pangaea,
0:12:57 > 0:13:00before it was fully formed.
0:13:00 > 0:13:03The layers are red because the rocks are packed full of iron.
0:13:03 > 0:13:05Sediments are made of silts and sands
0:13:05 > 0:13:10that have been washed off the land into coastal swamps and deltas.
0:13:10 > 0:13:15The rocks show that this early Pangaea was a watery place
0:13:15 > 0:13:20and fossils reveal the kind of life that was around at this time.
0:13:24 > 0:13:26Amphibians.
0:13:26 > 0:13:32Today amphibians, like frogs and salamanders, are relatively rare.
0:13:32 > 0:13:34But before Pangaea formed,
0:13:34 > 0:13:38amphibians were the dominant animals on the planet.
0:13:39 > 0:13:41And if you imagine frogs and salamanders,
0:13:41 > 0:13:43you realise how important water is for them,
0:13:43 > 0:13:46particularly in that early spawning stage
0:13:46 > 0:13:49and the development of the young, like tadpoles.
0:13:50 > 0:13:53And that's something that amphibians have in common,
0:13:53 > 0:13:57past and present, really, is that fundamental attachment to water.
0:13:57 > 0:14:02And that wet world of early Pangaea would have been absolutely perfect
0:14:02 > 0:14:04for these critters to flourish in.
0:14:14 > 0:14:20Before Pangaea formed, the world had lots of coastal swamps
0:14:20 > 0:14:23and wetlands for the amphibians to breed.
0:14:23 > 0:14:27But then the world changed.
0:14:28 > 0:14:32The evidence is just a short trek down from the canyon rim.
0:14:35 > 0:14:39A layer of yellow rock, called the Coconino,
0:14:39 > 0:14:42that was formed when the Americas were part
0:14:42 > 0:14:44of the great supercontinent of Pangaea.
0:14:44 > 0:14:49It reveals a landscape that would change the course of life on Earth.
0:14:49 > 0:14:52Wind.
0:14:52 > 0:14:54Sand dunes.
0:14:58 > 0:15:01These are lovely rock surfaces. They're so smooth.
0:15:03 > 0:15:06If you look at the sand grains...
0:15:06 > 0:15:10what you see is lots and lots
0:15:10 > 0:15:12of tiny, rounded grains.
0:15:12 > 0:15:16The other thing is that they're all roughly about the same size.
0:15:21 > 0:15:25What that's telling you is that the process that formed this was wind
0:15:25 > 0:15:26because wind can pick up
0:15:26 > 0:15:29only the finest sand grains and move it around.
0:15:31 > 0:15:34Actually, what's interesting about them is that they're not horizontal,
0:15:34 > 0:15:36they're actually inclined.
0:15:36 > 0:15:38And sometimes that means that they've been started off horizontal
0:15:38 > 0:15:42and then they've been tilted up, but not in this case.
0:15:42 > 0:15:45We're looking at a surface that was always at this angle.
0:15:45 > 0:15:49And this angle - it's about 33, 34 degrees - and the reason for that
0:15:49 > 0:15:53is if you take fine, fine sand and just pour it out in a heap,
0:15:53 > 0:15:57the angle that it falls at is about 33, 34 degrees.
0:15:57 > 0:16:00And that's the angle that the sand grains hold themselves together at.
0:16:04 > 0:16:06So what this is really telling us
0:16:06 > 0:16:09is that the surface that I'm standing on
0:16:09 > 0:16:12is that of an ancient desert sand dune.
0:16:12 > 0:16:15In fact, in its time if we looked around,
0:16:15 > 0:16:19it would have been just a sand sea for miles upon miles of huge dunes.
0:16:19 > 0:16:22To imagine what it would've been like, you've got to think of
0:16:22 > 0:16:26something like the Namib Desert in south-western Africa
0:16:26 > 0:16:29where you've got dunes that are maybe 100 metres or so,
0:16:29 > 0:16:34several hundred feet high. I mean, it's an extraordinary landscape.
0:16:34 > 0:16:36And you just get the hint of it here.
0:16:50 > 0:16:52We know from the Coconino layer
0:16:52 > 0:16:57that the Grand Canyon had become the western edge of a giant desert...
0:17:01 > 0:17:06..that spread across almost all of what is today the Americas,
0:17:06 > 0:17:08Africa and Europe.
0:17:13 > 0:17:18This gigantic desert was a direct result of Pangaea's formation.
0:17:28 > 0:17:34One huge landmass meant that most of the land was distant from the sea
0:17:34 > 0:17:37so rain-carrying winds couldn't reach the centre.
0:17:38 > 0:17:43250 million years ago, Earth had become a desert planet.
0:17:44 > 0:17:46Not good news for the amphibians.
0:17:48 > 0:17:54But in the heart of this arid world, one type of animal did flourish.
0:17:55 > 0:17:58Although this environment was extreme desert, it wasn't lifeless.
0:17:58 > 0:18:02The evidence is right here on the rock face.
0:18:02 > 0:18:04You can see these really odd markings.
0:18:04 > 0:18:07And what they are are footprints, a track way of an animal
0:18:07 > 0:18:10that was walking up here,
0:18:10 > 0:18:14pushing down, kind of displacing the sand.
0:18:14 > 0:18:16What is was was a reptile.
0:18:16 > 0:18:18A reptile with a tail, because you can see
0:18:18 > 0:18:22this sinuous track of this reptile that's dragged its tail up.
0:18:24 > 0:18:27To adapt to these super-arid environments
0:18:27 > 0:18:30required an evolutionary innovation that would be inherited
0:18:30 > 0:18:33by all the reptiles - by birds, by mammals...
0:18:33 > 0:18:35by you and I.
0:18:44 > 0:18:51250 million years ago, America was at the centre not only of Pangaea,
0:18:51 > 0:18:53but of a massive evolutionary change.
0:18:55 > 0:18:57I've come to see what it was
0:18:57 > 0:19:01in an ancient animal with a fearsome reputation.
0:19:03 > 0:19:04The alligator.
0:19:11 > 0:19:14It's mating season at the Colorado Reptile Park...
0:19:16 > 0:19:21..and these feisty fellas scrap for the right to breed.
0:19:24 > 0:19:28So keeper Jay Young has to tend their wounds.
0:19:30 > 0:19:35Helping him treat his injured means I can get up close and personal
0:19:35 > 0:19:38to an animal whose ancestors roamed the Americas
0:19:38 > 0:19:40when they were part of Pangaea.
0:19:45 > 0:19:47You let me know when you need this thing.
0:19:47 > 0:19:50- I'm gonna give you the stick. - Don't you need that?
0:19:50 > 0:19:52ALLIGATOR GROWLS
0:19:54 > 0:19:57Look at this. He's going to grab the tail.
0:19:57 > 0:20:00Oh, my goodness!
0:20:03 > 0:20:05Whoa! Whoa! Hissing everywhere.
0:20:05 > 0:20:07- So what do I do? - Move it...
0:20:07 > 0:20:10Agh!
0:20:11 > 0:20:14Where should I be? Your left or right as you come out?
0:20:14 > 0:20:16Either way. Ready?
0:20:16 > 0:20:18OK, now we yank and jump.
0:20:18 > 0:20:20Make sure both the hands are near her neck
0:20:20 > 0:20:22- at the same time. - No, you jump.
0:20:22 > 0:20:23I'll just stay at this end.
0:20:23 > 0:20:24ALLIGATOR HISSING
0:20:27 > 0:20:30- Yeah?- OK, come up here.
0:20:30 > 0:20:32- Are you sure?- Yeah.
0:20:33 > 0:20:36Jump on her back. That's it - all your weight.
0:20:36 > 0:20:39Put your hands right here on her neck. OK, you got her?
0:20:39 > 0:20:42- Yeah, I think so. We'll soon find out.- OK.- Hey there, honey.
0:20:42 > 0:20:44- We'll soon find out. Anariki, is it?- Yeah.
0:20:44 > 0:20:47- Hi, Anariki. Pleased to meet you. - I'm gonna get lunch.
0:20:47 > 0:20:49I'll be back in a few! HE LAUGHS
0:20:49 > 0:20:52I hope that's a joke. It's moving!
0:20:52 > 0:20:53Ooh!
0:20:54 > 0:20:57- OK, keep your hands on her neck. - I haven't got it.
0:20:57 > 0:20:59Just letting you get a sense of her power.
0:20:59 > 0:21:01- Is she strong? - It's incredible, yes, very strong.
0:21:01 > 0:21:03She heard that Scots taste like chicken.
0:21:03 > 0:21:05But very weak chicken!
0:21:08 > 0:21:11This is the closest I'm ever going to get
0:21:11 > 0:21:14to a creature from Pangaean times
0:21:14 > 0:21:17because alligators share an anatomical connection
0:21:17 > 0:21:20with the ancient reptilian fossils.
0:21:24 > 0:21:27It's this - what we call the ankle joint, it's the crural-tarsal joint,
0:21:27 > 0:21:31and it's a really distinctive adaptation.
0:21:31 > 0:21:34You can get this thing underneath your body, you can push yourself
0:21:34 > 0:21:36more upright and you can have this really fast gait.
0:21:39 > 0:21:41That looks sore, doesn't it?
0:21:41 > 0:21:45'Anariki's ancestors were hugely successful in Pangaea.
0:21:45 > 0:21:47'The way they moved was part of it.'
0:21:47 > 0:21:50- Back on her. - I think that's it.
0:21:50 > 0:21:52'But the biggest breakthrough was something
0:21:52 > 0:21:57'that perfectly equipped them for Pangaea's desert world...
0:22:00 > 0:22:03'The way they have sex.'
0:22:18 > 0:22:21Alligator sex is pretty much like human sex,
0:22:21 > 0:22:23certainly in the style of copulation.
0:22:23 > 0:22:26The key is internal fertilisation.
0:22:26 > 0:22:30Delivering the sperm inside the female and directly to the ova.
0:22:30 > 0:22:35And that process involved the invention of sex.
0:22:35 > 0:22:39Sex is the most efficient and direct way of achieving fertilisation.
0:22:39 > 0:22:44It's how modern reptiles, birds and mammals impregnate.
0:22:50 > 0:22:52Up until this innovation,
0:22:52 > 0:22:57fertilisation could only occur externally, in water.
0:23:00 > 0:23:04Amphibians were the first vertebrates to emerge onto land.
0:23:04 > 0:23:07But because they fertilised externally,
0:23:07 > 0:23:09they had to return to water to breed.
0:23:17 > 0:23:21The newly evolved reptiles did things differently.
0:23:21 > 0:23:26They fertilised and developed their eggs inside their females,
0:23:26 > 0:23:30so by the time the eggs were laid, they had hard, impermeable shells.
0:23:30 > 0:23:34These eggs didn't need water to survive.
0:23:36 > 0:23:38This is chicken egg,
0:23:38 > 0:23:41but surprisingly it's about the same size as an alligator egg.
0:23:41 > 0:23:44But what's important is what's inside.
0:23:45 > 0:23:50Because what's inside is the amniotic fluid.
0:23:50 > 0:23:54That transparent liquid,
0:23:54 > 0:23:56that's the stuff that contains the energy
0:23:56 > 0:23:57and the life-sustaining waters
0:23:57 > 0:24:01that amphibians would have found in the rivers and seas.
0:24:01 > 0:24:04This object, the egg, was the revolution.
0:24:05 > 0:24:08Mammals have taken those life-supporting fluids
0:24:08 > 0:24:12inside themselves and supplied nutrition through a placenta.
0:24:12 > 0:24:15But we're still children of that first amniotic reptile.
0:24:37 > 0:24:40The Pangaean deserts were essentially
0:24:40 > 0:24:42an impenetrable barrier to the amphibians.
0:24:45 > 0:24:48But for the reptiles it was a different story.
0:24:48 > 0:24:52The development of internal fertilisation and the amniotic egg
0:24:52 > 0:24:54allowed them to spread into and thrive
0:24:54 > 0:24:56in those arid environments.
0:24:58 > 0:25:01It's a wonderful example of how environmental change
0:25:01 > 0:25:04can be a catalyst for evolutionary advances
0:25:04 > 0:25:09and those advances would lead eventually to the evolution of us.
0:25:11 > 0:25:14It's interesting to think that the way that we have sex
0:25:14 > 0:25:17and the way that we rear our young
0:25:17 > 0:25:20have been shaped by these deserts of the distant past.
0:25:32 > 0:25:36North and South America spent almost 100 million years
0:25:36 > 0:25:38nestled together in the heart of Pangaea.
0:25:40 > 0:25:43But by 200 million years ago, there were signs
0:25:43 > 0:25:46that this gigantic landmass was about to break up.
0:25:47 > 0:25:50This break-up would have a massive influence
0:25:50 > 0:25:53on the modern-day Americas.
0:25:53 > 0:25:57It would end up creating fortunes, destroying lives
0:25:57 > 0:25:59and transforming the landscape.
0:26:04 > 0:26:09The evidence for this cataclysmic event is right under the nose
0:26:09 > 0:26:13of unsuspecting commuters, driving in and out of New York every day.
0:26:17 > 0:26:22Connecting Manhattan to New Jersey is the George Washington Bridge.
0:26:24 > 0:26:30Anchored on one side by an imposing cliff face, the Hudson Palisades.
0:26:35 > 0:26:37I've come here to find evidence
0:26:37 > 0:26:40of probably the single most important event
0:26:40 > 0:26:43in the history of the two American continents.
0:26:44 > 0:26:46The moment when they split from Pangaea.
0:26:51 > 0:26:53There's a telltale sign here
0:26:53 > 0:26:56that really shows how these rocks came into being.
0:26:58 > 0:26:59Hexagon.
0:26:59 > 0:27:03Vertical fracture.
0:27:03 > 0:27:05You can see it in the shape of these blocks.
0:27:05 > 0:27:07They've got these regular sides to them.
0:27:07 > 0:27:09And this block as well - you can see it beautifully there.
0:27:09 > 0:27:11And there's six sides -
0:27:11 > 0:27:15one, two, three, four, five, six.
0:27:15 > 0:27:18These hexagons are the flat-top surfaces
0:27:18 > 0:27:21of columns that go straight the way down.
0:27:23 > 0:27:27You can see it as vertical fractures in the cliffs
0:27:27 > 0:27:28all the way along here.
0:27:28 > 0:27:30What they are telling you
0:27:30 > 0:27:34is that this rock started off as a liquid mush.
0:27:34 > 0:27:37'A molten fluid that must have cooled rapidly.'
0:27:37 > 0:27:41And as it cools, it congealed, it contracted in
0:27:41 > 0:27:45and the most efficient way of doing that is to pull in from all sides
0:27:45 > 0:27:47and create these wonderful hexagons.
0:27:49 > 0:27:54So this rock, which is a kind of basalt, started off as hot magma.
0:28:03 > 0:28:07The magma that erupted out is thought to have been brought up
0:28:07 > 0:28:11by a current of hot rocks known as a mantle plume.
0:28:13 > 0:28:15It's not clear why they form,
0:28:15 > 0:28:18but rising mantle plumes push the land up
0:28:18 > 0:28:21like a heat blister until it cracks and fractures,
0:28:21 > 0:28:24triggering immense volcanic eruptions.
0:28:26 > 0:28:30These cool and become layers of basalt.
0:28:32 > 0:28:36Geologists have found evidence of this humungous volcanic outpouring
0:28:36 > 0:28:40in places thousands of miles apart
0:28:40 > 0:28:42If we just look at it on a modern map,
0:28:42 > 0:28:46we find that the equivalent layer of this basalt
0:28:46 > 0:28:48that we get here in eastern America
0:28:48 > 0:28:50has also been found in eastern Canada,
0:28:50 > 0:28:53it's been found in southern Britain, in Portugal
0:28:53 > 0:28:56in West Africa and in parts of Brazil.
0:28:56 > 0:29:00Now, viewed from the perspective of Pangaea 200 million years ago,
0:29:00 > 0:29:02it makes perfect sense.
0:29:08 > 0:29:13If you wind back time, all these places were joined together.
0:29:13 > 0:29:16Part of a single, huge volcanic event
0:29:16 > 0:29:19that spread across Pangaea's heart.
0:29:20 > 0:29:25A fiery inferno covering 10 million square kilometres.
0:29:30 > 0:29:32Across this huge area,
0:29:32 > 0:29:36great sheets and rivers of lava burned for thousands of years.
0:29:38 > 0:29:43Volcanic ash and gas played havoc with the planet's climate.
0:29:44 > 0:29:50Large numbers of reptiles and half of all plant species were wiped out.
0:29:56 > 0:30:01But these were also the death throes of the supercontinent itself.
0:30:01 > 0:30:04The eruptions created chasms and rifts
0:30:04 > 0:30:08that would eventually fill with water.
0:30:08 > 0:30:11Pangaea split apart
0:30:11 > 0:30:15and out of it emerged a brand-new continent...
0:30:15 > 0:30:16North America
0:30:16 > 0:30:19and the beginnings of a brand-new ocean...
0:30:25 > 0:30:27..the Atlantic.
0:30:31 > 0:30:36The mantle plume kick-started a process that is still going on today
0:30:36 > 0:30:39with major consequences for the Americas.
0:30:45 > 0:30:473,000 kilometres from land
0:30:47 > 0:30:51and 2,500 metres under the ocean,
0:30:51 > 0:30:54you find strange volcanic vents
0:30:54 > 0:30:57spewing superheated water.
0:30:57 > 0:30:59Home to deep-sea shrimps
0:30:59 > 0:31:03that feed on minerals erupting out of the Earth.
0:31:08 > 0:31:11These vents are just one tiny part
0:31:11 > 0:31:13of a huge underwater chain of volcanoes
0:31:13 > 0:31:16called the mid-ocean ridge...
0:31:18 > 0:31:22..that spreads down the middle of the Atlantic Ocean...
0:31:22 > 0:31:26along which magma is constantly emerging,
0:31:26 > 0:31:29cooling and turning into fresh rock.
0:31:36 > 0:31:40The Mid-Atlantic Ridge marks where Pangaea fractured,
0:31:40 > 0:31:43to create two new tectonic plates.
0:31:46 > 0:31:49The North American plate on one side,
0:31:49 > 0:31:52Eurasia and Africa on the other.
0:31:54 > 0:31:57And as lava continues to erupt at the ridge,
0:31:57 > 0:32:01these continental landmasses move gradually further apart.
0:32:16 > 0:32:19It's odd to think that each year,
0:32:19 > 0:32:24New York and the Americas get 2cm further west from Europe and Africa.
0:32:24 > 0:32:28The New World driven inexorably away from the old.
0:32:31 > 0:32:32It's this separation
0:32:32 > 0:32:36with newly formed plates pushing away from each other on one side
0:32:36 > 0:32:40and jostling for position with their neighbours on the other
0:32:40 > 0:32:42that's shaped the New World.
0:33:13 > 0:33:16By 130 million years ago,
0:33:16 > 0:33:20North America had fully separated from Pangaea.
0:33:22 > 0:33:25Then the action shifted south.
0:33:26 > 0:33:29Around 85 million years ago,
0:33:29 > 0:33:33the remains of Pangaea split again to form another plate.
0:33:33 > 0:33:38Moving away west, separate from both Africa and North America,
0:33:38 > 0:33:41was the newly formed continent of South America.
0:33:42 > 0:33:46It's journey was to be anything but smooth.
0:34:00 > 0:34:01Today, South America has
0:34:01 > 0:34:05some of the most spectacular landscapes on Earth.
0:34:08 > 0:34:12They're the product of a violent geological past
0:34:12 > 0:34:16that shaped an equally turbulent human history.
0:34:20 > 0:34:23This relationship between geology and history
0:34:23 > 0:34:27is revealed in the Bolivian town of Potosi.
0:34:31 > 0:34:33Once part of the Spanish Empire,
0:34:33 > 0:34:35what the conquistadors plundered here
0:34:35 > 0:34:38bankrolled their empire for three centuries.
0:34:40 > 0:34:42But at a price.
0:34:47 > 0:34:50Agh! Hey!
0:34:50 > 0:34:53- Pedro, how are you? - Good morning.
0:34:54 > 0:34:56- Thanks for doing this. - I'll give you a hand.
0:34:56 > 0:35:00Local miner, Pedro Montes Coria,
0:35:00 > 0:35:04is going to take me inside the deadliest mountain in human history.
0:35:05 > 0:35:07Cerro Rico.
0:35:11 > 0:35:15We're going to see what the conquistadors discovered here.
0:35:17 > 0:35:21But this mine also reveals why South America's movement
0:35:21 > 0:35:23has been such a violent process.
0:35:26 > 0:35:28Before entering the depths,
0:35:28 > 0:35:30miners fortify themselves
0:35:30 > 0:35:33with intoxicating coca leaves.
0:35:33 > 0:35:37- You have to chew the coca like this, one by one.- Oh, OK.
0:35:39 > 0:35:42I feel a kind of buzz on my tongue, actually.
0:35:42 > 0:35:45Just on here...zzzz.
0:35:46 > 0:35:49With coca, we are not very thirsty, hungry,
0:35:49 > 0:35:52you want maybe to sleep.
0:35:52 > 0:35:56We feel that we are stronger with the coca leaf.
0:35:56 > 0:35:58So what age do you start eating coca leaves?
0:35:58 > 0:36:02- When we come to the mine. We are ten years old.- Ten years old?- Yeah.
0:36:05 > 0:36:07- Switch on the light. - Oh, yeah.
0:36:07 > 0:36:11Not only are many of the miners school age,
0:36:11 > 0:36:15but they're entering a world where tunnels regularly give way
0:36:15 > 0:36:18and explosives are unregulated
0:36:18 > 0:36:23so the miners' first stop before the depths is to ask for protection.
0:36:23 > 0:36:27- This way.- OK.- First to visit El Tio. - Is that El Tio?
0:36:27 > 0:36:30- This is the devil in the mountain? - He is our God.
0:36:30 > 0:36:33Of course he is like a devil, but not the same devil that we have outside
0:36:33 > 0:36:37because everything here belongs to him.
0:36:37 > 0:36:39We are going to do the ritual.
0:36:40 > 0:36:43Take some coca and put in his hands,
0:36:43 > 0:36:46on his willy, his head.
0:36:46 > 0:36:49El Tio, lot of safety in the mine.
0:36:49 > 0:36:52Yes. Do you know this alcohol?
0:36:52 > 0:36:56I don't, no. It says, "Alcohol potable" so drinkable alcohol.
0:36:56 > 0:36:59It says, "96" - oh, cha!
0:36:59 > 0:37:02- "Industrial Bolivia."- Cheers to you.
0:37:07 > 0:37:12- That's...- Very nice.
0:37:12 > 0:37:14- And then good luck to me.- Yeah.
0:37:17 > 0:37:19HE COUGHS
0:37:19 > 0:37:20- That is strong.- Yeah.
0:37:20 > 0:37:22Oh, gosh!
0:37:22 > 0:37:24Oh! Whoo!
0:37:24 > 0:37:25OK.
0:37:31 > 0:37:35If anything, the rituals left me feeling even more nervous.
0:37:42 > 0:37:46- Watch with the hole.- The hole? It's deep!- Yeah.
0:37:46 > 0:37:48How far does that go down, do you think?
0:37:48 > 0:37:50It's like 80 metres down, more or less.
0:37:50 > 0:37:54This tunnel is connecting to another mine.
0:37:54 > 0:37:57OK, so the mines are all interconnected.
0:37:57 > 0:38:00All the mines - it's like Swiss cheese, full of holes.
0:38:00 > 0:38:04Every step needs to be taken very carefully.
0:38:07 > 0:38:11The miners work by digging and blasting through the rock.
0:38:11 > 0:38:15Collapses and fatalities are a fact of life
0:38:15 > 0:38:19and you never know what the other miners are doing.
0:38:20 > 0:38:21What's happening?
0:38:21 > 0:38:23- BLAST - Oh, that was close.
0:38:23 > 0:38:26- That's happening! - That was it, was it?
0:38:26 > 0:38:27Yeah.
0:38:27 > 0:38:30- BLAST - Oh!
0:38:30 > 0:38:33BLASTS
0:38:33 > 0:38:35- BLAST - Shhh...!
0:38:36 > 0:38:38That feels really close.
0:38:45 > 0:38:49- I can smell the dynamite. - Yeah.- Really strong.
0:38:51 > 0:38:56Down here is what three centuries of miners have been looking for.
0:39:00 > 0:39:01So here we are.
0:39:09 > 0:39:13OK, I see it. You see this band coming all the way down here?
0:39:15 > 0:39:19Just in amongst it all is a rather dull grey mineral, and that...
0:39:19 > 0:39:21Well, that's the silver.
0:39:21 > 0:39:24That's what miners like Pedro are after.
0:39:25 > 0:39:29And, for me, the way this precious silver is laid out
0:39:29 > 0:39:33reveals a fundamental process that's shaped South America
0:39:33 > 0:39:36and its often bloody history.
0:39:38 > 0:39:40Hot fluids.
0:39:43 > 0:39:47It's actually concentrated on these really narrow bands.
0:39:47 > 0:39:50These are called veins
0:39:50 > 0:39:53and you can actually see them all the way up across there.
0:39:53 > 0:39:56Those metals would have been laid down by hot fluids.
0:39:56 > 0:39:58And the reason the fluids were hot
0:39:58 > 0:40:02was because deep beneath my feet at the time was molten magma,
0:40:02 > 0:40:04magma that had risen up from the mantle,
0:40:04 > 0:40:08carrying with it metal elements like zinc and gold and silver.
0:40:10 > 0:40:13And as that magma rose higher and higher, it heated up
0:40:13 > 0:40:16water that was circulating through the crust
0:40:16 > 0:40:19and those waters, at several hundred degrees Celsius,
0:40:19 > 0:40:21started to pick up those metal elements,
0:40:21 > 0:40:22to carry them higher and higher
0:40:22 > 0:40:27until they just ditched their cargo, stuffing them into veins like this.
0:40:27 > 0:40:31But what's surprising is the source of that water.
0:40:41 > 0:40:45Analysing the steam that emerges from volcanic vents nearby
0:40:45 > 0:40:47reveals something unexpected.
0:40:50 > 0:40:53The steam's chemical signature is similar
0:40:53 > 0:40:57to that of water found 400 kilometres to the west.
0:41:01 > 0:41:04The waters of the Pacific Ocean.
0:41:14 > 0:41:17So the most obvious conclusion is that some of the hot waters
0:41:17 > 0:41:20that have been percolating through these rocks in this region
0:41:20 > 0:41:22started out in the Pacific.
0:41:22 > 0:41:24And that is telling us about a process
0:41:24 > 0:41:26that's going on deep beneath my feet now
0:41:26 > 0:41:29and is really at the heart of those moving continents,
0:41:29 > 0:41:32and that process is subduction.
0:41:39 > 0:41:42Subduction is the key to understanding
0:41:42 > 0:41:45how South America was changed as it moved west.
0:41:46 > 0:41:50As the South American plate moved apart from Africa,
0:41:50 > 0:41:53it collided with the Pacific Ocean plate
0:41:53 > 0:41:57and the collision is going on right underneath Cerro Rico.
0:42:00 > 0:42:04The ocean floor of the Pacific plate is sinking down,
0:42:04 > 0:42:08dragging a part of the Pacific Ocean deep underneath South America.
0:42:10 > 0:42:12This is subduction.
0:42:16 > 0:42:18The sinking rock heats up
0:42:18 > 0:42:22and minerals and water from the old ocean floor
0:42:22 > 0:42:25escape into the continental rocks above.
0:42:27 > 0:42:30It's this process that has given South America
0:42:30 > 0:42:32its incredible mineral wealth.
0:42:32 > 0:42:37From tin, copper and zinc to gold and silver.
0:42:37 > 0:42:39Hey! Fresh air!
0:42:40 > 0:42:42- Hey!- Good, my friend.
0:42:42 > 0:42:44- Thank you very much.- Yes.
0:42:44 > 0:42:46That's good then.
0:43:01 > 0:43:06In the 17th century, the town of Potosi was as big as London.
0:43:09 > 0:43:13The mines resources not only resulted in fabulous riches -
0:43:13 > 0:43:1740,000 tonnes of silver came out of this mine -
0:43:17 > 0:43:20but a terrible history of exploitation.
0:43:27 > 0:43:32During the Spanish colonial centuries, it's been estimated that
0:43:32 > 0:43:36as many as eight million indigenous people and slaves died
0:43:36 > 0:43:39working the mines of Cerro Rico.
0:43:42 > 0:43:44So the fruits of subduction
0:43:44 > 0:43:47have shaped the recent human history of this region.
0:43:48 > 0:43:51But over tens of millions of years,
0:43:51 > 0:43:55it's also created the defining feature of the continent.
0:43:58 > 0:44:02As the ocean plate pushes underneath the leading edge of South America,
0:44:02 > 0:44:05it kind of gets snagged and jarred.
0:44:05 > 0:44:08Pressure builds up and you generate these huge earthquakes
0:44:08 > 0:44:09and also open up pathways
0:44:09 > 0:44:12for magma to rise up to the surface and produce volcanoes.
0:44:12 > 0:44:15And what you get over 60 million years
0:44:15 > 0:44:18is the gradual uplift and crumpling of this whole region.
0:44:18 > 0:44:22The result, almost a by-product of subduction,
0:44:22 > 0:44:26is the longest mountain range on any continent...
0:44:26 > 0:44:27The Andes.
0:44:36 > 0:44:39The Andes stretch for more than 6,000 kilometres
0:44:39 > 0:44:43along almost the entire western coast of the continent.
0:44:44 > 0:44:46It's a long, narrow range
0:44:46 > 0:44:50because the mountains follow the boundary between the two plates
0:44:50 > 0:44:52where subduction is taking place.
0:44:54 > 0:44:57And in a strange twist of fate,
0:44:57 > 0:45:00their formation may give Bolivia the chance to gain
0:45:00 > 0:45:04some measure of compensation for the traumas of the past.
0:45:08 > 0:45:12As they have grown, the mountains have lifted one Bolivian lake
0:45:12 > 0:45:16from its original position near sea level
0:45:16 > 0:45:19to a height of nearly 4,000 metres.
0:45:37 > 0:45:42This is the Salar de Uyuni, the biggest salt flat on Earth.
0:45:44 > 0:45:46Hidden in this landscape
0:45:46 > 0:45:51is a resource worth tens of billions of dollars.
0:45:51 > 0:45:54It could have the global impact of the silver of Potosi,
0:45:54 > 0:45:57but without its tarnished history.
0:45:58 > 0:46:00FOOTSTEPS CRUNCHING
0:46:02 > 0:46:05The key to understanding this new source of wealth
0:46:05 > 0:46:09is inside something we nearly all carry in our pockets.
0:46:10 > 0:46:14Open up any mobile phone, whether it's a fancy new touch-screen
0:46:14 > 0:46:16or one of these old-style handsets
0:46:16 > 0:46:18and you'll find the battery.
0:46:18 > 0:46:22And what all these batteries have got in common is one key element.
0:46:22 > 0:46:26The active components inside here are made of lithium carbonate.
0:46:26 > 0:46:28As well as being in a mobile phone,
0:46:28 > 0:46:32lithium's in laptops and all electronic devices.
0:46:32 > 0:46:35It's used because of one quality above all.
0:46:35 > 0:46:39And that is lithium is the lightest of all the metals
0:46:39 > 0:46:42so it gives more power for its mass.
0:46:42 > 0:46:43Now here's a thing.
0:46:43 > 0:46:48Bolivia has as much as 50% of the world's lithium reserves.
0:46:48 > 0:46:51Most of it in this extraordinary landscape.
0:47:00 > 0:47:03Lithium isn't just for mobile technologies.
0:47:03 > 0:47:08It also offers a potential clean green future for cars.
0:47:13 > 0:47:17Until now, electric cars have been hampered
0:47:17 > 0:47:20by the weight of their batteries.
0:47:20 > 0:47:23But lithium makes it easier and cheaper
0:47:23 > 0:47:26to produce lightweight batteries for the cars of tomorrow.
0:47:30 > 0:47:33It's thought there's enough lithium here
0:47:33 > 0:47:38to make batteries for more than four billion electric vehicles.
0:47:38 > 0:47:42Enough to make Bolivia a Saudi Arabia of the 21st century.
0:47:46 > 0:47:50In places, the lithium is only just below the surface.
0:47:52 > 0:47:57Where the crust is thin, you can see the brine underneath.
0:47:57 > 0:48:01And if you really hammer away at it,
0:48:01 > 0:48:06then you can actually see the structure of the salt.
0:48:09 > 0:48:12Look at that. It's beautiful.
0:48:13 > 0:48:16All these symmetrical crystals.
0:48:16 > 0:48:20The white ones are sodium chloride - that's just ordinary table salt
0:48:20 > 0:48:23but this pink one here - that's potassium
0:48:23 > 0:48:28and this one, the brown-coloured one, that - that's lithium.
0:48:28 > 0:48:31So today the lithium's here at the surface in the salt
0:48:31 > 0:48:33but it started off way down deep.
0:48:33 > 0:48:36Subduction produced magma
0:48:36 > 0:48:40that rose up and erupted out of volcanoes like that over there.
0:48:40 > 0:48:43In fact, there's a whole series of them all the way around.
0:48:43 > 0:48:46So these mountains are rich in lithium.
0:48:52 > 0:48:55From the slopes of the Andes, run-off erosion
0:48:55 > 0:48:58washes the metal-rich sediments down to the lake.
0:49:00 > 0:49:05Since it's been uplifted, the lake has become surrounded by mountains
0:49:05 > 0:49:09so no river can find a way out to drain the Salar.
0:49:12 > 0:49:16The result is that the only way water leaves the lake
0:49:16 > 0:49:18is through evaporation.
0:49:18 > 0:49:22Over time, that concentrates minerals, including lithium,
0:49:22 > 0:49:24in the lake bed.
0:49:27 > 0:49:29There's now a plan to build
0:49:29 > 0:49:32a full-scale lithium extraction plant in the Salar.
0:49:32 > 0:49:35Huge multinationals want in,
0:49:35 > 0:49:38but the Bolivian government says it wants to avoid
0:49:38 > 0:49:42the foreign exploitation that marked colonial silver mining.
0:49:48 > 0:49:51Subduction and the rise of the Andes
0:49:51 > 0:49:54has given South America extraordinary mineral wealth
0:49:54 > 0:49:57and all that a consequence of that gradual drift
0:49:57 > 0:50:00of the New World away from the old.
0:50:00 > 0:50:03That process has shaped the destiny of South America in another way.
0:50:03 > 0:50:07I mean, here it's given us a landscape of jaw-dropping beauty,
0:50:07 > 0:50:09but completely lifeless.
0:50:09 > 0:50:13But elsewhere it's created some of the richest
0:50:13 > 0:50:15and most unique habitats on the planet.
0:50:23 > 0:50:28One ecosystem above all others owes its existence to the Andes,
0:50:28 > 0:50:30because as the Andes grew,
0:50:30 > 0:50:35the rivers of South America went through a series of massive changes.
0:50:37 > 0:50:41Before the Andes, it's thought the main rivers flowed
0:50:41 > 0:50:45in the opposite direction to today, into the Pacific.
0:50:45 > 0:50:50When the Andes started to rise, they diverted rivers to the north,
0:50:50 > 0:50:52where they flowed out into the Caribbean,
0:50:52 > 0:50:56creating a huge area of wetlands close to the growing mountains.
0:50:56 > 0:50:59But then further uplift blocked the route north
0:50:59 > 0:51:03and forced the rivers to converge towards the Atlantic,
0:51:03 > 0:51:05forming an enormous drainage basin.
0:51:05 > 0:51:09And that led to the creation of the Amazon rainforest.
0:51:22 > 0:51:25Meanwhile, on its western flanks,
0:51:25 > 0:51:28the Andes created a rain shadow.
0:51:28 > 0:51:31The result is the driest place on the planet...
0:51:31 > 0:51:33the Atacama Desert.
0:51:38 > 0:51:40By ten million years ago,
0:51:40 > 0:51:43both South and North America looked similar to today,
0:51:43 > 0:51:45but there was one critical difference.
0:51:45 > 0:51:47They were still separate continents.
0:51:47 > 0:51:52The stage was set for the final act in the story of the Americas.
0:51:54 > 0:51:58It didn't lead to a dramatic change in the landscape.
0:51:58 > 0:52:01But it did transform their wildlife.
0:52:13 > 0:52:17Few animals are better suited to the mountainous terrain of the Andes
0:52:17 > 0:52:18than the llama.
0:52:31 > 0:52:33Hello!
0:52:33 > 0:52:37These animals are just magnificently adapted for life at altitude.
0:52:37 > 0:52:39There's obvious things for the low oxygen -
0:52:39 > 0:52:43they've got big hearts and enlarged lungs, but there's something else.
0:52:43 > 0:52:45Can you catch one for me, Clemente?
0:52:45 > 0:52:47Just to see... There's something I want to show you.
0:52:47 > 0:52:50- HERDER WHOOSHES - OK.
0:52:50 > 0:52:52Just any one. There we go.
0:52:53 > 0:52:55OK. OK, this is nice.
0:52:55 > 0:52:59So I just want to show you the feet because unlike other hoofed animals,
0:52:59 > 0:53:02the llama's feet are split into two, they've got two toes.
0:53:02 > 0:53:06And underneath the two toes - can I just lift it up a little bit?
0:53:07 > 0:53:09It's got this thick leathery sole.
0:53:09 > 0:53:13What that means is that it's perfect for sure-footedness
0:53:13 > 0:53:15on really rough rocks.
0:53:15 > 0:53:18Just perfect for up this mountain terrain.
0:53:18 > 0:53:22And the other thing's inside - it's the blood
0:53:22 > 0:53:24because the haemoglobin,
0:53:24 > 0:53:27the red blood cells that carry oxygen through the body,
0:53:27 > 0:53:30llamas have got more haemoglobin per unit volume
0:53:30 > 0:53:32than any other mammal - it's extraordinary.
0:53:32 > 0:53:35So there's a whole series of really clever adaptations.
0:53:35 > 0:53:37They're just wonderful beasts.
0:53:37 > 0:53:39Thanks for that. Let him go.
0:53:44 > 0:53:49Since Inca times, llamas have been at the heart of Andean life.
0:53:50 > 0:53:53The animals' wool is used for making clothing.
0:53:55 > 0:53:58Its meat is a staple of local diets.
0:53:59 > 0:54:04Even the animals' blood is sacred. It's sprinkled around doorways
0:54:04 > 0:54:07to bring blessings to those who enter.
0:54:08 > 0:54:10There's something unexpected
0:54:10 > 0:54:12about this particular South American animal.
0:54:12 > 0:54:16Llamas that seem so at home in the high mountains
0:54:16 > 0:54:18aren't from this continent at all.
0:54:18 > 0:54:21They evolved in the low-lying plains of North America.
0:54:21 > 0:54:24They're living evidence of the final instalment
0:54:24 > 0:54:26in the tale of the two continental Americas -
0:54:26 > 0:54:28their joining up.
0:54:32 > 0:54:36The llamas' ancestors first appear in North America
0:54:36 > 0:54:37about 40 million years ago.
0:54:40 > 0:54:42But they don't appear in South America
0:54:42 > 0:54:44until three million years ago.
0:54:47 > 0:54:50The two continents had been edging closer together.
0:54:50 > 0:54:53Then, starting around 30 million years ago,
0:54:53 > 0:54:56volcanic islands began to combine,
0:54:56 > 0:54:59slowly building a land bridge between the two.
0:54:59 > 0:55:02By three million years ago,
0:55:02 > 0:55:06two continents that had been separate since the days of Pangaea
0:55:06 > 0:55:08were finally joined again.
0:55:10 > 0:55:12The New World was born.
0:55:19 > 0:55:24Across this narrow link has come a great intermingling of species.
0:55:25 > 0:55:30Northern mammals in particular invaded the south.
0:55:30 > 0:55:33Deer, foxes and dogs all crossed over,
0:55:33 > 0:55:37and cats that quickly became the prime predators.
0:55:38 > 0:55:43The result was to increase South America's biodiversity.
0:55:49 > 0:55:52Among the most successful arrivals, the llama,
0:55:52 > 0:55:56ironically now long extinct in the north.
0:56:00 > 0:56:03For me, the llama is the perfect symbol of the New World.
0:56:03 > 0:56:05Originating in the northern continents
0:56:05 > 0:56:08and flourishing in the southern.
0:56:08 > 0:56:12It represents both the isolation and the coming together of the Americas.
0:56:16 > 0:56:19Since that momentous joining,
0:56:19 > 0:56:23the story of the Americas has been of a single land.
0:56:25 > 0:56:28When the first humans arrived in North America,
0:56:28 > 0:56:30they quickly moved into the south.
0:56:32 > 0:56:34And when Europeans arrived,
0:56:34 > 0:56:38both Americas were seen as a single New World.
0:56:42 > 0:56:44Today, continental movement means
0:56:44 > 0:56:48the Americas continue their westward drift from the Old World.
0:56:48 > 0:56:50But on a cultural and economic level,
0:56:50 > 0:56:53you can argue the opposite is the case.
0:56:56 > 0:56:58Walk through any market place,
0:56:58 > 0:57:01even one like this in the relatively inaccessible Andes,
0:57:01 > 0:57:05and you find evidence for a connected world, old and new.
0:57:12 > 0:57:15Here, you can find electronics, designed in America,
0:57:15 > 0:57:17made in the Far East.
0:57:17 > 0:57:19English football shirts.
0:57:26 > 0:57:27And food.
0:57:27 > 0:57:30Beef and pork that came here with the Europeans,
0:57:30 > 0:57:32while potatoes and tomatoes and chocolate
0:57:32 > 0:57:37were all South American in origin, now worldwide in consumption.
0:57:49 > 0:57:53So, although the single continuous landmass of Pangaea
0:57:53 > 0:57:55no longer exists,
0:57:55 > 0:57:59our modern-day continents are linked in a different way.
0:58:00 > 0:58:05Today, our great global economy binds all the continents together.
0:58:05 > 0:58:08In essence, we've created a new Pangaea.
0:58:08 > 0:58:11A Pangaea of our own making.
0:58:11 > 0:58:14And in this Pangaea, just like the one 300 million years ago,
0:58:14 > 0:58:17the Americas are right at the heart.
0:58:42 > 0:58:45Subtitles by Red Bee Media Ltd