0:00:02 > 0:00:05MUSLIM CALL TO PRAYER
0:00:11 > 0:00:13Istanbul.
0:00:15 > 0:00:20For more than 2,000 years it stood at the crossroads between East and West.
0:00:22 > 0:00:24The point where Europe ends
0:00:24 > 0:00:27and Asia begins.
0:00:30 > 0:00:34The two continents divided by the Bosphorus Straits.
0:00:38 > 0:00:40This is one of the great journeys.
0:00:40 > 0:00:43Stepping off the continent, leaving Europe behind.
0:00:49 > 0:00:52But crossing the Bosphorus isn't all that it seems.
0:00:56 > 0:01:00This notion that Europe and Asia are separate is a bit of a nonsense.
0:01:00 > 0:01:05From a geological perspective, they're both part of the same vast landmass.
0:01:05 > 0:01:08Eurasia stretches from the Atlantic coast of Portugal
0:01:08 > 0:01:11all the way through to Russia's Pacific coast,
0:01:11 > 0:01:14making it the biggest continent on the planet.
0:01:17 > 0:01:22To reveal how this mighty continent formed, I want to reach back in time.
0:01:27 > 0:01:33Because, if you know where to look, there are clues to its ancient past
0:01:33 > 0:01:35written into the world around us.
0:01:37 > 0:01:40Its landscapes...
0:01:41 > 0:01:43..wildlife...
0:01:43 > 0:01:45Hey! Is that karimeen?
0:01:45 > 0:01:47..and the very rock from which it's built.
0:01:49 > 0:01:53The tiniest detail can reveal the history of a vast continent.
0:01:56 > 0:02:00Evidence that shows how Eurasia was assembled
0:02:00 > 0:02:02in a series of monumental collisions...
0:02:02 > 0:02:04This just kicked off just as we got here.
0:02:04 > 0:02:07..catastrophic impacts
0:02:07 > 0:02:11that created the conditions for civilisations to rise,
0:02:11 > 0:02:14changed the course of life on Earth...
0:02:18 > 0:02:21..and left an indelible mark on the landscape...
0:02:21 > 0:02:24Just a wall of rock and ice.
0:02:24 > 0:02:28..a mountain range spanning the entire continent.
0:02:30 > 0:02:34The story of how that formed was the story of how Eurasia formed.
0:02:34 > 0:02:39A continent forged in a series of collisions that continue to this day.
0:02:41 > 0:02:46And because the process that built Eurasia is still active...
0:02:46 > 0:02:48Whoo-ho-ho!
0:02:48 > 0:02:51..the largest continent on the planet
0:02:51 > 0:02:54is merely the start of something far bigger.
0:03:16 > 0:03:21The first clue to uncovering Eurasia's past can be found here in Istanbul.
0:03:28 > 0:03:32For centuries, the city's strategic location at the heart of the continent
0:03:32 > 0:03:35has made it a major centre for trade.
0:03:40 > 0:03:43- Turkish delight.- Lovely!
0:03:43 > 0:03:45- With honey and pistachios. - Pistachios?
0:03:45 > 0:03:47- Yes, honey and pistachios. - It's lovely.
0:03:50 > 0:03:52Just as it does to this day.
0:03:56 > 0:03:58We have a present for your mother-in-law.
0:03:58 > 0:04:00There's a joke there, I'm sure.
0:04:05 > 0:04:07That's the thing about these bazaars -
0:04:07 > 0:04:09they still sell the traditional things
0:04:09 > 0:04:13that they've been selling since this city was in its infancy.
0:04:13 > 0:04:16Look at this. Exotic foods there, spices.
0:04:16 > 0:04:23Metals, spice men...jewellery, precious stones like this, ceramics.
0:04:23 > 0:04:25If you want it, it's here.
0:04:26 > 0:04:28Now smell, please.
0:04:28 > 0:04:30Wow!
0:04:31 > 0:04:36But there's one product that's shaped Istanbul's history like no other.
0:04:39 > 0:04:43In a way, this city is here because of this stuff - silk.
0:04:43 > 0:04:46Look at it, it's just gorgeous.
0:04:46 > 0:04:48If you go back to the sixth century,
0:04:48 > 0:04:51this is one of the most expensive, most sought-after commodities,
0:04:51 > 0:04:54partly because it comes all the way from China
0:04:54 > 0:04:59and also because how it was made was this closely guarded secret.
0:04:59 > 0:05:04The story goes that a delegation of monks would smuggle back
0:05:04 > 0:05:08a couple of silkworm inside a bamboo cane, brought it back here
0:05:08 > 0:05:12and then this place, Istanbul, just took off as a hub of silk production.
0:05:17 > 0:05:20And the fabric gave its name to the Silk Road,
0:05:20 > 0:05:25the network of ancient trade routes that runs across the entire continent,
0:05:25 > 0:05:29connecting China through Istanbul and onto Europe.
0:05:33 > 0:05:37And the Silk Road is crucial to the story of Eurasia today
0:05:37 > 0:05:39because beneath it lies evidence
0:05:39 > 0:05:43that reveals the origin of the continent itself.
0:05:51 > 0:05:56Evidence that can be found 500 kilometres southeast of Istanbul,
0:05:56 > 0:06:00where the Taurus Mountains reach the shores of the Mediterranean...
0:06:04 > 0:06:08..in a place that's been both a staging post on the Silk Road
0:06:08 > 0:06:13and a site of pilgrimage since the days of Ancient Greece.
0:06:18 > 0:06:21This whole landscape is steeped in myth.
0:06:21 > 0:06:26Just over the back is Mount Olympus, the home of the Greek gods.
0:06:26 > 0:06:29Actually, it's one of about 20 Mount Olympuses
0:06:29 > 0:06:32that are scattered across the ancient world.
0:06:32 > 0:06:36But the mountain that I'm climbing now is unique - Mount Chimera.
0:06:36 > 0:06:41It's named after this mythological creature that's got the tail of a snake,
0:06:41 > 0:06:44the body of a goat and a lion's head.
0:06:44 > 0:06:46Oh, yeah - and it breathes fire.
0:07:18 > 0:07:20These are the eternal flames.
0:07:20 > 0:07:25In Turkish they're called Yanartas, which is just "flaming rock".
0:07:25 > 0:07:28Look at them. Today they're maybe half a metre high
0:07:28 > 0:07:30but in ancient times they were much higher,
0:07:30 > 0:07:34so that if you were out at sea, you could see this place as a lighthouse.
0:07:39 > 0:07:44But my favourite story, though, is, because we're so close to Olympus,
0:07:44 > 0:07:47this could be the source of the first Olympic flame.
0:07:50 > 0:07:53It's such a surreal scene.
0:07:58 > 0:08:02But what fuels these flames is far more ancient.
0:08:04 > 0:08:08And analysing it takes you back tens of millions of years
0:08:08 > 0:08:10to the time Eurasia formed.
0:08:27 > 0:08:30Fossilised sea creatures.
0:08:30 > 0:08:31Plankton.
0:08:31 > 0:08:34Three to four kilometres into the Earth.
0:08:37 > 0:08:40Do you see this black residue here?
0:08:40 > 0:08:43It's soot - essentially carbon.
0:08:43 > 0:08:47That tells us that these flames are burning an organic compound.
0:08:47 > 0:08:50In this case, natural gas or methane.
0:08:50 > 0:08:53A geochemical analysis of these flames indicates
0:08:53 > 0:08:58that that gas is coming from carbon-rich rocks deep underground.
0:08:59 > 0:09:03Much of it from fossilised sea creatures, plankton.
0:09:05 > 0:09:07To transform plankton into gas,
0:09:07 > 0:09:12you have to take the long-chain hydrocarbons that make up the cells
0:09:12 > 0:09:16and you have to break them into smaller and lighter bits.
0:09:19 > 0:09:24This process happens spontaneously at around 140 degrees...
0:09:29 > 0:09:32..temperatures that can be generated by burying the rock
0:09:32 > 0:09:35three to four kilometres down into the Earth.
0:09:38 > 0:09:40The best way to do that
0:09:40 > 0:09:44is to pile layer upon layer upon layer of sediment on top of it.
0:09:44 > 0:09:47And the place where that process happens all the time
0:09:47 > 0:09:50is the bottom of the deep ocean.
0:09:53 > 0:09:56The gas here shows that millions of years ago
0:09:56 > 0:09:59this region of Turkey was underwater.
0:09:59 > 0:10:02But the evidence of a lost ocean doesn't stop there.
0:10:02 > 0:10:05It can be found all along the ancient Silk Road.
0:10:05 > 0:10:08This is Eurasia as we know it today
0:10:08 > 0:10:10and here we are down here in southern Turkey.
0:10:10 > 0:10:17Some of the biggest oil and gas fields on the planet occur east of Turkey
0:10:17 > 0:10:21in a belt through Central Asia to Afghanistan.
0:10:21 > 0:10:25But east and west of that too there's evidence of a former ocean.
0:10:25 > 0:10:29There's precious stones that started off as rocks on the ocean floor.
0:10:29 > 0:10:33Things like jade which occur in Pakistan, in Burma and in China.
0:10:33 > 0:10:38And then marble occurs in Greece, Italy and other parts of Europe.
0:10:38 > 0:10:42You also get metals that are formed on the bottom of the ocean,
0:10:42 > 0:10:46metals like copper that you get found in Cyprus.
0:10:47 > 0:10:51But the final evidence, the best evidence
0:10:51 > 0:10:54is fragments of the rock that I'm sitting on.
0:10:54 > 0:10:58These are fragments of ophiolite.
0:10:58 > 0:11:00Ancient ocean crusts
0:11:00 > 0:11:05which you find formed in a kind of belt all the way across this region.
0:11:10 > 0:11:13What all these lines of evidence add up to
0:11:13 > 0:11:16is the fact that there was once a vast ocean
0:11:16 > 0:11:19that stretched the entire length of this continent.
0:11:27 > 0:11:30The continent of Eurasia as we know it today
0:11:30 > 0:11:33didn't exist 200 million years ago.
0:11:39 > 0:11:44Where the south of the continent, Italy, Arabia and India, are today
0:11:44 > 0:11:47there was a 90 million square kilometre ocean.
0:11:49 > 0:11:51The Tethys.
0:11:57 > 0:12:00Western Europe was lost beneath its waves...
0:12:01 > 0:12:04..and Britain was a collection of tropical islands
0:12:04 > 0:12:06off its northwestern shores.
0:12:12 > 0:12:15Wrapped around its long arcing coastline,
0:12:15 > 0:12:18all the Earth's landmasses were joined together
0:12:18 > 0:12:21into one vast supercontinent.
0:12:25 > 0:12:29Called Pangaea, it was a land dominated by the dinosaurs...
0:12:36 > 0:12:40..just as fearsome marine reptiles ruled the Tethys.
0:12:50 > 0:12:53Today, all those creatures are now extinct.
0:12:53 > 0:12:57And the Tethys Ocean itself has long since disappeared.
0:12:57 > 0:13:00But what destroyed the Tethys
0:13:00 > 0:13:03and led to the extinction of many of the creatures that lived in it
0:13:03 > 0:13:08is the same geological process that led to the formation of Eurasia.
0:13:08 > 0:13:10Because the story of Eurasia
0:13:10 > 0:13:14is essentially the story of how the Tethys died.
0:13:19 > 0:13:23The mystery of how Eurasia formed from the death of the Tethys
0:13:23 > 0:13:27involves one of the greatest mass extinctions in Earth's history,
0:13:27 > 0:13:30the rise of its ancient civilisations
0:13:30 > 0:13:33and will reveal the continent's ultimate fate.
0:13:42 > 0:13:44And clues to how that happened
0:13:44 > 0:13:47can be found in the southernmost tip of India.
0:13:59 > 0:14:02These are the gentle backwaters of Kerala in southern India.
0:14:02 > 0:14:06A place famed for its spices, especially black pepper.
0:14:06 > 0:14:08One of the key staging posts
0:14:08 > 0:14:12on another of those ancient trading routes that crisscross Eurasia.
0:14:23 > 0:14:26For centuries, Kerala's lakes and waterways
0:14:26 > 0:14:29supported a traditional way of life,
0:14:29 > 0:14:34a floating existence that still survives to this day.
0:14:35 > 0:14:37I'm here to find something truly ancient,
0:14:37 > 0:14:40something that's lived in waters like these
0:14:40 > 0:14:42for over 100 million years.
0:14:45 > 0:14:48A creature that provides a direct link
0:14:48 > 0:14:52back to the most important event in the formation of Eurasia...
0:14:53 > 0:14:59..and is, for the local fishermen, these waters' most prized catch.
0:15:01 > 0:15:05A fish known here as karimeen.
0:15:05 > 0:15:06Hello!
0:15:06 > 0:15:10- How're you doing?- Hi there.
0:15:22 > 0:15:25The karimeen is tasty. Very, very tasty.
0:15:25 > 0:15:29Is there a lot? Is it all over?
0:15:29 > 0:15:31All over.
0:15:34 > 0:15:37So how do you catch it?
0:15:37 > 0:15:38Do you jump in?
0:15:39 > 0:15:40Catch it.
0:15:40 > 0:15:42You make it sound so easy.
0:15:58 > 0:16:01First, two of the fishermen use a line
0:16:01 > 0:16:05to scare the fish into the mud at the bottom of the lake.
0:16:13 > 0:16:18Then the others swim behind, making a noise to startle the fish...
0:16:21 > 0:16:24..before plucking them from the mud with their bare hands.
0:16:36 > 0:16:40Hey! Is that karimeen? Yay!
0:16:40 > 0:16:42Fantastic! Number one.
0:16:43 > 0:16:45That's fast.
0:16:48 > 0:16:50Very nice.
0:16:50 > 0:16:52Put it in there.
0:17:01 > 0:17:05This is it. This is what all the action was for. A karimeen.
0:17:05 > 0:17:08Latin name Etroplus suratensis.
0:17:10 > 0:17:16A fish whose anatomy reveals the evolution of entire continents.
0:17:19 > 0:17:21IAIN'S VOICE ECHOES: ..the anal fin...
0:17:21 > 0:17:22..shape of the skull...
0:17:24 > 0:17:26It's a type of fish called a cichlid.
0:17:26 > 0:17:30They're marked out by a couple of anatomical quirks
0:17:30 > 0:17:31that make them distinctive.
0:17:31 > 0:17:33One of them is right at the back.
0:17:33 > 0:17:35It's at his rear end, basically, the anal fin.
0:17:35 > 0:17:40Now, in most cichlids, the anal fin's got three or four spines
0:17:40 > 0:17:43but this species has many more.
0:17:43 > 0:17:46The other characteristic is at the front end.
0:17:46 > 0:17:48It's in the distinctive shape of the skull
0:17:48 > 0:17:50which relates to the swim bladder,
0:17:50 > 0:17:53that sac that controls the buoyancy of the fish.
0:17:55 > 0:17:57There's only one other group of fish
0:17:57 > 0:18:00that share these distinctive characteristics.
0:18:01 > 0:18:06The closely related Paretroplus cichlids.
0:18:08 > 0:18:12And they live over 4,000 kilometres away...
0:18:14 > 0:18:15..in Madagascar.
0:18:17 > 0:18:20Now, Etroplus can tolerate slightly salty conditions
0:18:20 > 0:18:23but they're essentially a freshwater fish,
0:18:23 > 0:18:26so one thing's for sure is they didn't swim here.
0:18:26 > 0:18:30Instead the answer is that it's not the fish that moved.
0:18:30 > 0:18:32It was India.
0:18:44 > 0:18:48This is a reconstruction of how the Earth's landmasses looked like
0:18:48 > 0:18:50120 million years ago,
0:18:50 > 0:18:53just before the emergence of the first cichlid fishes.
0:18:53 > 0:18:57You can see up here, China and Siberia fused together.
0:18:57 > 0:19:00And you can see the area here that's going to become Britain
0:19:00 > 0:19:03and this in here in blue is the Tethys Ocean.
0:19:03 > 0:19:06Then down here past the equator into the southern hemisphere,
0:19:06 > 0:19:10tucked snugly in beside Madagascar, is India.
0:19:10 > 0:19:15If I press "play" here I can simulate how the landmasses then move.
0:19:15 > 0:19:18What you find is that in 90 million years,
0:19:18 > 0:19:20India and Madagascar split.
0:19:22 > 0:19:27Then suddenly, 25 million years after they separated,
0:19:27 > 0:19:29India more than doubled its speed.
0:19:29 > 0:19:31That's dramatic stuff.
0:19:31 > 0:19:35That's a mini-continent, something like 3,000 kilometres across,
0:19:35 > 0:19:39just speeding across the globe, crashing into Eurasia.
0:19:39 > 0:19:43Fantastic! I never tire of watching this. It's great.
0:19:50 > 0:19:55India's journey north was a key moment in the formation of Eurasia
0:19:55 > 0:19:59because, as it moved, it closed the ocean in front of it,
0:19:59 > 0:20:02spelling the beginning of the end for the Tethys.
0:20:03 > 0:20:08But the big question is what caused it to speed up,
0:20:08 > 0:20:09because that led to one of
0:20:09 > 0:20:12the most catastrophic events in Earth's history.
0:20:20 > 0:20:25You can see evidence of that cataclysm in the hills outside Mumbai,
0:20:25 > 0:20:28a place known as the Deccan Traps.
0:20:30 > 0:20:31The Deccan.
0:20:31 > 0:20:35It's one of those words for a geologist that conjures up these images.
0:20:35 > 0:20:40This iconic landscape. Stepped plateaus and things.
0:20:44 > 0:20:47And yet this kind of gentle landscape holds in it
0:20:47 > 0:20:52one of the cataclysmic geological events in the planet's past.
0:20:55 > 0:20:58There's telltale signs in that cliff face there.
0:20:58 > 0:21:02You see, it looks like a set of bands. They're layers of lava.
0:21:02 > 0:21:04Molten rock that came out, solidified
0:21:04 > 0:21:06and then built up layer upon layer upon layer
0:21:06 > 0:21:11over tens, hundreds of thousands of years to form these hills.
0:21:12 > 0:21:1668 million years ago, this landscape was very different.
0:21:25 > 0:21:31Eruption after eruption poured 1.3 million cubic kilometres of lava
0:21:31 > 0:21:33across southern India.
0:21:37 > 0:21:43Enough to cover the UK in a layer of rock five kilometres thick.
0:21:53 > 0:21:58All over these hills, there's gems like these just carved into the lava.
0:22:00 > 0:22:04But there is no volcanic activity in India today,
0:22:04 > 0:22:09so the question is where's the source of these eruptions?
0:22:09 > 0:22:11And how did it speed India up?
0:22:17 > 0:22:21This whole cave is carved out of a type of lava called basalt.
0:22:23 > 0:22:25IAIN'S VOICE ECHOES: Ilmenite... magnetite...
0:22:25 > 0:22:27latitude.
0:22:27 > 0:22:30It's got really fine crystals.
0:22:30 > 0:22:35About 10% are minerals called iron oxides - rust.
0:22:35 > 0:22:37It gives us this reddy browny tint.
0:22:37 > 0:22:40Minerals like ilmenite and magnetite.
0:22:40 > 0:22:44And that's the clue, because these iron oxides are magnetic.
0:22:49 > 0:22:52Just after the lava solidifies,
0:22:52 > 0:22:56its temperature drops below 585 degrees
0:22:56 > 0:23:00and the magnetic fields of the iron oxide crystals
0:23:00 > 0:23:03align themselves with the planet's own field.
0:23:04 > 0:23:08The thing about the Earth's magnetic field is that it changes
0:23:08 > 0:23:10depending on your position on the planet,
0:23:10 > 0:23:13where you are between the South Pole and the North Pole.
0:23:13 > 0:23:14In other words, your latitude.
0:23:16 > 0:23:20It's a property known as its inclination
0:23:20 > 0:23:24and it means that the basalt contains a record of its position
0:23:24 > 0:23:27at the precise moment it solidified,
0:23:27 > 0:23:30which allows you to pinpoint exactly where it formed.
0:23:41 > 0:23:45Today, this temple is at a latitude of 18.7 degrees north.
0:23:45 > 0:23:49But the thing is, the magnetic inclination of the rock itself
0:23:49 > 0:23:53tells us that it formed at a latitude of about 20 degrees south.
0:23:53 > 0:23:57In other words, this lava formed in the southern hemisphere.
0:23:57 > 0:24:02So the thing is that the source of this volcanism isn't to be found
0:24:02 > 0:24:04deep beneath my feet here.
0:24:04 > 0:24:08Instead it's several thousand kilometres in that direction.
0:24:14 > 0:24:20If you trace India's journey back to the point it crossed 20 degrees south,
0:24:20 > 0:24:22you arrive directly over a mantle plume.
0:24:25 > 0:24:28A huge column of superheated rock
0:24:28 > 0:24:32that rises up from near the Earth's core.
0:24:35 > 0:24:40As India moved over the plume, it triggered the Deccan eruptions.
0:24:46 > 0:24:49But deep underground it had another impact...
0:24:57 > 0:25:00..something that can explain India's dramatic acceleration.
0:25:03 > 0:25:06Continents flow around the mantle like vast ships.
0:25:06 > 0:25:09Just as a hull of a ship lies below the water line,
0:25:09 > 0:25:14so the bulk of a continent, maybe 80% of it, extends deep into the Earth.
0:25:19 > 0:25:21Today, the Indian continent
0:25:21 > 0:25:24is half the thickness of the other great landmasses.
0:25:24 > 0:25:26It's thought that that's because
0:25:26 > 0:25:29as the Indian Plate moved across that mantle plume
0:25:29 > 0:25:32it melted away the base of the continental plate.
0:25:32 > 0:25:35According to that idea, that huge loss of mass,
0:25:35 > 0:25:38combined with the lubricating effect of that molten rock,
0:25:38 > 0:25:41and also maybe an extra push from the mantle plume,
0:25:41 > 0:25:46caused India to double its speed, propelling it towards Eurasia.
0:25:49 > 0:25:51It was a geological cataclysm.
0:25:52 > 0:25:56But the implications for life are even more dramatic,
0:25:56 > 0:25:59because the Deccan eruptions contributed
0:25:59 > 0:26:04to one of the greatest turning points in the history of life on Earth.
0:26:12 > 0:26:16As the plume burnt its way up through the continent,
0:26:16 > 0:26:19it pumped billions of tonnes of ash and toxic gas
0:26:19 > 0:26:21directly into the atmosphere.
0:26:24 > 0:26:26Over hundreds of thousands of years,
0:26:26 > 0:26:30this slowly choked the planet and poisoned the oceans,
0:26:30 > 0:26:34wiping out 50% of all life.
0:26:37 > 0:26:41And for the dinosaurs it led to a drawn-out decline
0:26:41 > 0:26:46until it's thought an asteroid finally finished them off.
0:26:57 > 0:27:00But the end of the dinosaurs turned out to be our gain,
0:27:00 > 0:27:03because, as one group of animals died out,
0:27:03 > 0:27:06so another rose to take their place.
0:27:09 > 0:27:11The mammals.
0:27:12 > 0:27:16In a way, the extinction was curiously selective.
0:27:16 > 0:27:18I mean, you and I would never have survived.
0:27:18 > 0:27:24In fact, no land vertebrate larger than 25 kilograms made it through.
0:27:27 > 0:27:30But back then our distant ancestors
0:27:30 > 0:27:34had just the right mix of characteristics to survive.
0:27:37 > 0:27:40And there's one modern mammal
0:27:40 > 0:27:43that's thought to have similar adaptations today.
0:27:44 > 0:27:47Because what's worked in the past
0:27:47 > 0:27:50also works on the mean streets of Mumbai.
0:28:03 > 0:28:06The city has such a large rat problem,
0:28:06 > 0:28:11it employs a small army of rat-catchers, like Rakesh Daji Mittal.
0:28:48 > 0:28:52So we think of humans as being the most successful mammal,
0:28:52 > 0:28:56but I reckon we're looking at the ultimate one here - rats.
0:28:56 > 0:28:59They've certainly got all the essential traits for survival.
0:28:59 > 0:29:03They're small enough - they can get into nooks and crannies
0:29:03 > 0:29:07and just keep themselves tucked away from harm.
0:29:07 > 0:29:10And, in food, they're voracious eaters. They eat anything.
0:29:10 > 0:29:16And that not having to rely on a single source of food is really useful.
0:29:17 > 0:29:18It's...
0:29:22 > 0:29:26And I guess the main thing is sex. These things breed like...
0:29:26 > 0:29:27rats, really,
0:29:27 > 0:29:32which is why the rat-catchers of Mumbai are struggling to keep up.
0:29:32 > 0:29:36If it's a question of who's going to survive the next apocalypse,
0:29:36 > 0:29:38my money's on them.
0:29:41 > 0:29:43It's curious to think
0:29:43 > 0:29:47that it might have been characteristics possessed by the humble rat
0:29:47 > 0:29:50that enabled our distant ancestors to survive
0:29:50 > 0:29:52where the dinosaurs had perished.
0:29:53 > 0:29:58And that it was the movement of India that ultimately paved the way
0:29:58 > 0:30:00for us to inherit the Earth.
0:30:06 > 0:30:11As it continued north, India left the mantle plume behind.
0:30:11 > 0:30:16But, now travelling twice as fast, it crashed into the rest of Eurasia...
0:30:21 > 0:30:23..changing the face of the continent
0:30:23 > 0:30:27and sealing the fate of the Tethys Ocean.
0:30:36 > 0:30:38But the demise of the Tethys
0:30:38 > 0:30:42would have another major impact on human history...
0:30:43 > 0:30:47..shaping the rise of Eurasia's civilisations.
0:30:47 > 0:30:49- Morning, Max.- Hello, sir.
0:30:49 > 0:30:50- Hey!- Welcome aboard.
0:30:51 > 0:30:53It's small, isn't it?
0:30:53 > 0:30:58To see how that lost ocean influenced our past and still affects us today,
0:30:58 > 0:31:03you need to take a closer look at the most obvious result of the collision.
0:31:03 > 0:31:06FAINT MUSIC Where's the music coming from?
0:31:06 > 0:31:08Where's your tape deck? Your CDs?
0:31:08 > 0:31:09Ah!
0:31:09 > 0:31:13I love the music. I just can't get over the music.
0:31:14 > 0:31:16Giorgio Moroder - lovely!
0:31:20 > 0:31:21Ha-ha!
0:31:26 > 0:31:28What a place you have here.
0:31:29 > 0:31:32Ah! Ah-ah-ah!
0:31:34 > 0:31:37It's a long way down.
0:31:37 > 0:31:38It is a very, very long way down.
0:31:40 > 0:31:45These are the Himalayas, the greatest mountain range on Earth.
0:31:46 > 0:31:49Ah! Now we see the mountains. Here they are.
0:31:49 > 0:31:51The Dhaulagiri's over there,
0:31:51 > 0:31:54Manaslu's over here and Annapurna's ahead of us.
0:31:54 > 0:31:57All three of those are over 8,000 metres.
0:31:57 > 0:32:0226,500 feet. That's three of the top ten mountains in the world.
0:32:09 > 0:32:12The mountains look solid and immovable.
0:32:15 > 0:32:17Ah! That's majestic.
0:32:19 > 0:32:22Just a wall of rock and ice.
0:32:26 > 0:32:28But that is just an illusion.
0:32:28 > 0:32:32These peaks are in fact a slow-motion car crash
0:32:32 > 0:32:35playing out over millions of years.
0:32:35 > 0:32:36Ah!
0:32:37 > 0:32:39And still we climb.
0:32:52 > 0:32:53Whoo-hoo!
0:32:56 > 0:32:59It's absolutely stunningly beautiful,
0:32:59 > 0:33:03but when you look at the mountains, as a geologist you see so much more.
0:33:03 > 0:33:07It's almost like you see through the obvious snow and rock
0:33:07 > 0:33:08to the inner workings.
0:33:08 > 0:33:12You can see the process of mountain building almost in action.
0:33:20 > 0:33:23I can see some folds.
0:33:23 > 0:33:28So, Max, that's those folds up there.
0:33:28 > 0:33:33See the rocks kind of wrapped around this enormous fold structure.
0:33:33 > 0:33:38You can see that it comes across, swings down like a big Z shape.
0:33:40 > 0:33:45It's not just the shape of them that's spectacular - it's the sheer size.
0:33:45 > 0:33:49You see these Zs up there? Z.
0:33:49 > 0:33:52We call them Z-shape folds.
0:33:52 > 0:33:53It's very technical, geology.
0:33:57 > 0:34:00These folds, some the size of entire mountains,
0:34:00 > 0:34:04were created as India ploughed into the rest of the continent,
0:34:04 > 0:34:10the immense power of the collision twisting and contorting solid rock,
0:34:10 > 0:34:12as if it were Plasticine.
0:34:15 > 0:34:16Ah, yeah.
0:34:17 > 0:34:20I love it! Love it!
0:34:22 > 0:34:26You might think these contorted rocks are pieces of the land
0:34:26 > 0:34:30scrunched upwards as the two continents ploughed into each other.
0:34:36 > 0:34:40But the reality is far more surprising.
0:34:48 > 0:34:52This is one of the great rivers of Eurasia, the Kali Gandaki.
0:34:52 > 0:34:54It starts up there in the north in Tibet
0:34:54 > 0:34:59and flows down through the wilds of Mustang Province of northern Nepal,
0:34:59 > 0:35:02down through here to India in the south.
0:35:02 > 0:35:06For millions of years, it's been carving its way down through the Himalayas
0:35:06 > 0:35:10to produce what down there is one of the deepest gorges in the world.
0:35:17 > 0:35:20And it's in rivers like these that you can find clues
0:35:20 > 0:35:24to the origin of the rock from which these mountains are formed.
0:35:25 > 0:35:29Curious stones, called saligrams by the locals,
0:35:29 > 0:35:33who worship them as manifestations of the Hindu god Vishnu.
0:35:41 > 0:35:45What I'm looking for is hard, black nodules,
0:35:45 > 0:35:48kind of black lumps of shale
0:35:48 > 0:35:51that's fallen out of the cliff and then been washed around
0:35:51 > 0:35:55and I'm hoping that at the heart of one of these nodules
0:35:55 > 0:35:59we're going to find a saligram, because often they enclose them.
0:35:59 > 0:36:02Need to break them open and reveal them.
0:36:06 > 0:36:09What's lovely is that when you reveal them, if you get it,
0:36:09 > 0:36:13you're exposing something that last lived in the Jurassic,
0:36:13 > 0:36:18100-odd million years ago, sort of exposed back to the world.
0:36:19 > 0:36:22And the other thing that's lovely, if you find one,
0:36:22 > 0:36:27is you're the first person in the world to ever find that.
0:36:27 > 0:36:30Cos it's been hidden away for 100 million years or so
0:36:30 > 0:36:32and then you break it open.
0:36:33 > 0:36:35It's your fossil.
0:36:39 > 0:36:41So, if you see any, tell me.
0:36:42 > 0:36:47You're looking for a natural weakness and once you get that...
0:36:55 > 0:36:56This'll be the one.
0:36:57 > 0:36:59This'll be the one.
0:37:02 > 0:37:04This geology lark's harder than it looks.
0:37:14 > 0:37:17The funny thing about it is, all the way up that road
0:37:17 > 0:37:19there's guys selling these things.
0:37:19 > 0:37:22They get them from the rock and sell them to all the tourists
0:37:22 > 0:37:25and I thought no, no, I'm going to find them for real.
0:37:30 > 0:37:32How much for this?
0:37:32 > 0:37:36- 350.- 350 rupees, OK. One...
0:37:36 > 0:37:39This is going to be a bargain. There's 300... OK?
0:37:40 > 0:37:42- OK.- OK.
0:37:43 > 0:37:47Now this... This is a saligram.
0:37:47 > 0:37:49Look at that. Absolutely beautiful.
0:37:49 > 0:37:52Geologists know it better as an ammonite.
0:37:52 > 0:37:53It's the fossilised remains
0:37:53 > 0:37:56of an extinct member of the squid family.
0:37:58 > 0:38:01The modern-day version would be the nautilus.
0:38:01 > 0:38:03The body would be in here and the head
0:38:03 > 0:38:05and tentacles would sit out here.
0:38:07 > 0:38:10The thing is, just like the modern-day nautilus,
0:38:10 > 0:38:15these creatures didn't live in the mountains - they lived in the ocean.
0:38:17 > 0:38:19That's the thing about geology.
0:38:19 > 0:38:22It's not really the rocks themselves that are important -
0:38:22 > 0:38:26this is a rather boring black mud - but it's the stories they tell.
0:38:26 > 0:38:31I mean, these ammonites were swimming around in Jurassic seas
0:38:31 > 0:38:33when dinosaurs roamed the land,
0:38:33 > 0:38:36when Eurasia was really coming together.
0:38:36 > 0:38:39That's what the story of the rocks tell.
0:38:44 > 0:38:49The walls of this valley, 2,700 metres above sea level,
0:38:49 > 0:38:53are brimming with the remains of ancient sea creatures.
0:38:54 > 0:38:57Marine fossils have been found right across the Himalaya,
0:38:57 > 0:39:00including right at the top of Mount Everest.
0:39:00 > 0:39:03It's astonishing to think that rocks that started out
0:39:03 > 0:39:07at the bottom of the Tethys Ocean are now the roof of the world.
0:39:14 > 0:39:16When India collided with Eurasia,
0:39:16 > 0:39:21the ocean floor at the margins of the Tethys was thrust upwards...
0:39:23 > 0:39:26..forming an immense barrier across the continent.
0:39:29 > 0:39:31And it's by creating that barrier
0:39:31 > 0:39:36that the Tethys has had a profound effect on the course of human history,
0:39:36 > 0:39:38and still does to this day.
0:39:42 > 0:39:46Because mountains this high can't help but interfere with the climate.
0:39:49 > 0:39:51THUNDER RUMBLES
0:39:52 > 0:39:56That is one angry sky up there, isn't it?
0:39:56 > 0:39:59That's the thing about mountains - they create their own weather,
0:39:59 > 0:40:02and the bigger they are, the bigger the weather they create.
0:40:02 > 0:40:05Somewhere round that cloud and mist
0:40:05 > 0:40:08there's the Himalayas, the biggest on the planet,
0:40:08 > 0:40:10so it's no real surprise, then, that it produces
0:40:10 > 0:40:15one of the most important weather systems on the planet - the monsoon.
0:40:16 > 0:40:18THUNDER ROLLS
0:40:18 > 0:40:22WIND AND RAIN
0:40:22 > 0:40:26The winds that bring the moist air rise up along these slopes
0:40:26 > 0:40:29and just dump rain and snow on those hills
0:40:29 > 0:40:32and you get these brutal downpours like these,
0:40:32 > 0:40:34running up to the wet season,
0:40:34 > 0:40:38that dump water in the gorges and rivers up there,
0:40:38 > 0:40:43create mudslides and landslides that just chuck it down, chuck material.
0:40:43 > 0:40:46If you can just see, there's a river down there that's flooded,
0:40:46 > 0:40:51that's full of mud and dirt that's been taken out of that mountain range.
0:40:51 > 0:40:55This is one of the most dynamic active environments in the world.
0:40:55 > 0:40:58But also one of the wettest.
0:41:01 > 0:41:04THUNDER RUMBLES
0:41:08 > 0:41:10THUNDER STILL RUMBLES
0:41:16 > 0:41:20These sediment-laden waters flow down from the mountains
0:41:20 > 0:41:25and out onto the plains of India, Pakistan and China...
0:41:30 > 0:41:33..and, combined with the monsoon rains,
0:41:33 > 0:41:39water and nutrient-rich soils from the Himalayas support three billion people.
0:41:42 > 0:41:46Nearly half the world's population.
0:41:49 > 0:41:55But the formation of Eurasia has had a much wider impact on civilisation.
0:42:01 > 0:42:06Because India's collision was only the beginning of the end for the Tethys.
0:42:10 > 0:42:15Arabia also moved north, creating the Zagros and Taurus Mountains
0:42:15 > 0:42:18that run through Iran and Turkey.
0:42:22 > 0:42:26Italy and Greece collided with northern Europe, building the Alps...
0:42:29 > 0:42:33..and completing a mountain chain that spans the entire length of Eurasia...
0:42:37 > 0:42:42..and marks the final resting place of the once-great Tethys Ocean.
0:42:54 > 0:42:58And, just as the Himalayas support Asia's population today,
0:42:58 > 0:43:02so this immense chain of mountains created the conditions
0:43:02 > 0:43:06for the first civilisations to rise across the continent.
0:43:06 > 0:43:09Oh, wow! Look at this.
0:43:10 > 0:43:12Isn't that magnificent?
0:43:21 > 0:43:24Many of the great Eurasian civilisations sprung up
0:43:24 > 0:43:28in the shadow of the mountain chains that spanned the continent.
0:43:28 > 0:43:31They occupied fertile river valleys that grew up
0:43:31 > 0:43:35on the back of sediment the water washed down from mountains.
0:43:38 > 0:43:42Following the line of the mountains and connected by trade routes,
0:43:42 > 0:43:46a chain of empires developed across the continent.
0:43:49 > 0:43:53But the mountains themselves also provided a sanctuary
0:43:53 > 0:43:57for numerous city states, like the Pisidian city of Termessos
0:43:57 > 0:44:00in the Taurus Mountains of southern Turkey.
0:44:02 > 0:44:04If you were a society that lived in the mountains
0:44:04 > 0:44:08then you had to work with the geological cards you'd been dealt.
0:44:08 > 0:44:10This is a fragmented landscape.
0:44:10 > 0:44:15Cities like this are physically hemmed in and isolated from the neighbours.
0:44:15 > 0:44:19But isolation also means independence
0:44:19 > 0:44:25and cities like this could become crucibles of invention and innovation.
0:44:25 > 0:44:28Empires like the Greeks and the Romans
0:44:28 > 0:44:31that had mountains at their heart became successful,
0:44:31 > 0:44:35because they were able to harness that ingenuity.
0:44:40 > 0:44:44So, in a way, Eurasia's long history of civilisation
0:44:44 > 0:44:47goes back not thousands, but millions of years
0:44:47 > 0:44:52to the formation of the mountains at the heart of the continent.
0:44:59 > 0:45:05Eurasia as we know it was complete around 20 million years ago.
0:45:05 > 0:45:10The landmasses that formed it had moved into their current positions.
0:45:13 > 0:45:15And with the closing of the Tethys,
0:45:15 > 0:45:20western Europe, including Britain, emerged from beneath the waves.
0:45:31 > 0:45:36But the formation of Eurasia is really just the beginning of this story,
0:45:36 > 0:45:40because the process that built it is still active today.
0:45:43 > 0:45:46And by understanding that process
0:45:46 > 0:45:51it's possible to chart the astonishing future that awaits the continent.
0:45:54 > 0:46:00This is the Mediterranean Sea, instantly recognisable on a map.
0:46:00 > 0:46:03In the west, it connects to the Atlantic Ocean
0:46:03 > 0:46:05through the narrow Straits of Gibraltar
0:46:05 > 0:46:09and then in the east it's the shores of Turkey and the Middle East that end it.
0:46:13 > 0:46:17But, just like the Tethys before it, the Med too is closing,
0:46:17 > 0:46:21as the vast African Plate moves north.
0:46:25 > 0:46:29And where it collides with Eurasia beneath the southern tip of Italy
0:46:29 > 0:46:34it's created a cluster of volcanoes that rise up from the ocean floor.
0:46:41 > 0:46:44This is Strombolicchio.
0:46:44 > 0:46:48It's actually the solidified throat of an ancient volcano.
0:46:48 > 0:46:53200,000 years ago that rock was molten, rising up to spew
0:46:53 > 0:46:56and explode out of a volcano that would have risen above our heads.
0:46:56 > 0:47:01And then, around that time, that volcanic activity switched to the south
0:47:01 > 0:47:06and this thing just crumbled and collapsed back down into the sea,
0:47:06 > 0:47:10so all that's left is a solid volcanic neck.
0:47:10 > 0:47:13The innards, the guts of an ancient volcano.
0:47:18 > 0:47:21Today, the tiny island of Strombolicchio
0:47:21 > 0:47:25lies two kilometres north of Stromboli...
0:47:36 > 0:47:40..Italy's most continually active volcano...
0:47:40 > 0:47:41Grazie.
0:47:41 > 0:47:45..in a place you can see Eurasia's destiny taking shape.
0:47:47 > 0:47:51The thing about volcanoes is that they're windows into the inner Earth.
0:47:51 > 0:47:55This particular one is a window into the most important process
0:47:55 > 0:47:57driving the movement of the continent.
0:47:57 > 0:48:00The only trouble is that to understand it,
0:48:00 > 0:48:02I have to get right up there.
0:48:15 > 0:48:19The summit towers some 900 metres above sea level...
0:48:20 > 0:48:24..casting a long shadow over the island
0:48:24 > 0:48:26and the villages that cling to its shores.
0:48:39 > 0:48:40Ha!
0:48:44 > 0:48:46Look at it steaming away.
0:48:46 > 0:48:48Oh, that's perfect!
0:49:06 > 0:49:08This just kicked off just as we got here.
0:49:09 > 0:49:14They call it "puffing" here - a big puff, and you can see all the boulders
0:49:14 > 0:49:17just rolling down the hill and the smoke there.
0:49:19 > 0:49:21We've arrived.
0:49:23 > 0:49:26BLAST Hey! Hey!
0:49:26 > 0:49:28Look at that.
0:49:28 > 0:49:30That's Stromboli for you.
0:49:30 > 0:49:32Isn't that magnificent?!
0:49:35 > 0:49:39This volcano's been doing this, exploding like this,
0:49:39 > 0:49:43every ten, twenty minutes really for the last 2,000 years.
0:49:43 > 0:49:45Whoa!
0:49:47 > 0:49:49That's a good 'un.
0:49:49 > 0:49:50That's a cracker!
0:49:53 > 0:49:56It's so hard to get an idea of the intensity of that,
0:49:56 > 0:49:59but those orange balls that are getting kicked out there
0:49:59 > 0:50:02are actually metre-sized boulders.
0:50:03 > 0:50:08And the temperature of that must be 500, 600 degrees.
0:50:08 > 0:50:12Extraordinary! You really don't want to be much closer than this.
0:50:12 > 0:50:14Well, I do, but...
0:50:21 > 0:50:25What makes Stromboli special is it doesn't really produce that much lava.
0:50:25 > 0:50:30Unlike volcanoes like Hawaii and Etna that spew out these huge lava flows,
0:50:30 > 0:50:34this volcano's eruptions are almost exclusively explosive.
0:50:36 > 0:50:40And at night, when the sun goes down and the fireworks really start,
0:50:40 > 0:50:44you really understand why it's called the Lighthouse of the Mediterranean.
0:50:54 > 0:50:57Stromboli's regular explosive eruptions
0:50:57 > 0:51:00create one of the planet's most astonishing spectacles.
0:51:08 > 0:51:12But more than that, they're a clue to understanding the process
0:51:12 > 0:51:15shaping the fate of the continent.
0:51:20 > 0:51:22Whoo-ho-ho-ho!
0:51:34 > 0:51:36IAIN'S VOICE ECHOES: ..viscous and sticky...
0:51:36 > 0:51:37..trapped gases...
0:51:37 > 0:51:39..so explosive...
0:51:40 > 0:51:42..the Tethys destroying itself...
0:51:46 > 0:51:49This crater rim is just littered with blocks
0:51:49 > 0:51:52that have been thrown out of that vent down there.
0:51:52 > 0:51:53Stuff like that.
0:51:58 > 0:52:02This material is actually made of a rock called andesite.
0:52:02 > 0:52:06Andesite is quite a light grey rock and that's cos it's got a lot of silica in it.
0:52:06 > 0:52:09Because it's got a fair amount of silica in it,
0:52:09 > 0:52:12it tends to make the magma quite sticky and viscous
0:52:12 > 0:52:14and that means it traps gases.
0:52:17 > 0:52:20It's just lots and lots of bubbles in this rock.
0:52:22 > 0:52:25And it turns out that it's those bubbles
0:52:25 > 0:52:28that's the reason why those eruptions are so explosive.
0:52:31 > 0:52:36As the magma rises to the surface, the gas trapped inside expands
0:52:36 > 0:52:40until the bubbles burst and the rock explodes.
0:52:48 > 0:52:50But the gas responsible
0:52:50 > 0:52:54isn't one you'd immediately associate with a volcano.
0:52:56 > 0:52:58It's water vapour,
0:52:58 > 0:52:59or steam.
0:53:08 > 0:53:11This rock actually explains where the water comes from
0:53:11 > 0:53:14to drive those steam eruptions.
0:53:14 > 0:53:16You might think the steam comes from sea water
0:53:16 > 0:53:18sinking into the volcano,
0:53:18 > 0:53:21but actually the water's already in the rock.
0:53:21 > 0:53:24Look at this. This is an andesite without all those bubbles
0:53:24 > 0:53:28so that you can see all the beautiful crystals, called pyroxene.
0:53:34 > 0:53:38Pyroxene crystals form at depths of five to ten kilometres.
0:53:40 > 0:53:44And as they grow they encase tiny quantities of magma,
0:53:44 > 0:53:47locking it away and carrying it up to the surface.
0:53:50 > 0:53:53Now, if you could look into those tiny specks
0:53:53 > 0:53:57of the original magma that formed this rock,
0:53:57 > 0:53:59you'd find that there was water in them.
0:54:01 > 0:54:04In other words, the water was actually in the magma
0:54:04 > 0:54:06deep down in the mantle.
0:54:08 > 0:54:13The only way water could be found so deep in the inner Earth
0:54:13 > 0:54:15was if something carried it there.
0:54:19 > 0:54:20In this case,
0:54:20 > 0:54:24it was dragged down in the rock that forms the ocean floor itself.
0:54:43 > 0:54:45Because Stromboli is a volcano
0:54:45 > 0:54:48powered by a process called subduction.
0:54:52 > 0:54:56Subduction generally happens when ocean crust meets continental crust.
0:54:56 > 0:54:59The ocean crust rocks are denser so they sit lower in the mantle
0:54:59 > 0:55:01and when they collide,
0:55:01 > 0:55:04the ocean crust gets pushed under the lighter continental crust
0:55:04 > 0:55:07descending down into the mantle. BANG
0:55:07 > 0:55:10So that eruption up there actually started off
0:55:10 > 0:55:12about 100 kilometres beneath our feet.
0:55:14 > 0:55:17Down there, water gets forced out of those ocean rocks
0:55:17 > 0:55:19and causes the rocks around them to melt,
0:55:19 > 0:55:22which rise up and eventually burst out as volcanoes.
0:55:26 > 0:55:30Subduction is the ultimate fate of all ocean crust.
0:55:33 > 0:55:37But it isn't a consequence of the continents moving.
0:55:37 > 0:55:41Subduction is the engine that drives the movement in the first place.
0:55:46 > 0:55:49As the ocean crust descends beneath the continental crust,
0:55:49 > 0:55:53it doesn't break off - it's still attached to all that ocean floor.
0:55:53 > 0:55:57And it's that vast slab of rock heading down into the mantle
0:55:57 > 0:56:03that pulls the ocean crust and in turn hauls the landmasses behind it,
0:56:03 > 0:56:06dragging the continents across the face of the Earth.
0:56:10 > 0:56:14Maybe it's because we live in the land that it's tempting to think
0:56:14 > 0:56:18that it's the landmasses moving around that closed the oceans.
0:56:18 > 0:56:22That it was the northward movement of India that destroyed the Tethys.
0:56:22 > 0:56:25But actually it's the exact opposite.
0:56:25 > 0:56:29It was the Tethys that pulled the continents together,
0:56:29 > 0:56:31destroying itself in the process.
0:56:34 > 0:56:37It was subduction that built Eurasia.
0:56:41 > 0:56:45And it's subduction that's shaping its ultimate destiny.
0:56:45 > 0:56:50For 300 million years subduction has been gradually,
0:56:50 > 0:56:54inexorably closing the Tethys, creating Eurasia.
0:56:54 > 0:56:58And as time goes on it'll close the Med too.
0:56:58 > 0:57:02Africa will continue northwards, this whole area will emerge as land
0:57:02 > 0:57:07and these islands will be the peaks of the Mediterranean mountains.
0:57:07 > 0:57:11A great mountain chain at the heart of a new supercontinent.
0:57:16 > 0:57:18As Africa ploughs northwards,
0:57:18 > 0:57:22France and Germany become ever more mountainous.
0:57:28 > 0:57:32And those peaks would look out over a vast desert
0:57:32 > 0:57:35covering the whole of central Europe and Asia.
0:57:41 > 0:57:45It's thought that 250 million years in the future
0:57:45 > 0:57:49all of those continents will once again be joined together as one,
0:57:49 > 0:57:52with Eurasia right at the heart of it.
0:57:57 > 0:58:00Australia joins up with southern China.
0:58:05 > 0:58:09The Americas crash into the shores of Africa.
0:58:14 > 0:58:18And Britain is swept up towards the North Pole.
0:58:20 > 0:58:24The formation of this vast new land, the planet's grand cycle,
0:58:24 > 0:58:26that epic break-up
0:58:26 > 0:58:29and movement of the continents across the face of the Earth
0:58:29 > 0:58:31will begin once again.
0:58:59 > 0:59:02Subtitles by Red Bee Media Ltd