- 1 hour ago
Earth became a water-rich world through a mix of water trapped in early planetary building blocks, volcanic release, and asteroid impacts.
水——至少是地球庞大储量中那极小一部分可饮用水——对野生生物至关重要. 水的可获取性在很大程度上也决定了人类人口的规模, 尤其是在农业发明之后 :-- 农业的发展还催生了诸如灌溉和深井开凿等收集与利用水资源的巧妙方法, 此外水在航运, 气候现象及自然灾害方面也扮演着重要角色.
水——至少是地球庞大储量中那极小一部分可饮用水——对野生生物至关重要. 水的可获取性在很大程度上也决定了人类人口的规模, 尤其是在农业发明之后 :-- 农业的发展还催生了诸如灌溉和深井开凿等收集与利用水资源的巧妙方法, 此外水在航运, 气候现象及自然灾害方面也扮演着重要角色.
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TVTranscript
00:07Our planet is full of incredible natural wonders.
00:15It has immense power.
00:21And yet, that's rarely mentioned in our history books.
00:28This series looks at four powerful planetary forces that have shaped our history.
00:36The power of fire that fuelled great technological breakthroughs.
00:49Wind.
00:50Wind.
00:53That has influenced the rise and fall of empires.
00:58Water.
01:05Our struggle to control it has fuelled human progress.
01:13But this time, I'm looking inside the Earth itself.
01:20It's an unknown world, hot and extreme.
01:28It's provided the raw materials for our conquest of the planet.
01:33But at a price.
01:38This is the great untold story of human history.
02:01Hidden, unseen within the planet, extraordinary geological forces are at work.
02:09Forces that have shaped our history.
02:14To really understand and appreciate them, you have to go deep into the Earth itself.
02:26This is the Naica mine in northern Mexico.
02:30The starting point for a journey to one of the most spectacular and extreme places on, or in, the planet.
02:40So what I'm going to do is I'm going to get ready.
02:42I'm going to wear my coat suit.
02:44I'm going to get ready for the encounter with UD.
02:49Geologist Victor Torres Roldan is preparing himself for a journey so dangerous that he's risking his life even attempting it.
02:56We need a little help because it's a little heavy and it's a little cumbersome.
03:04With temperatures exceeding 55 degrees Celsius and nearly 100% humidity, he needs a full bodysuit and mask to survive.
03:14This is to assist him with ice in it and air comes through here and it comes cold.
03:19And with this ice suit, I should be able to stay there for maybe 20 minutes.
03:24If I don't, come for me.
03:27Come get me.
03:31Victor is entering a chamber that reveals the power of the inner Earth to influence human affairs.
03:42It's a geological wonder of the world.
03:56It is truly beautiful.
03:58It's sublime.
04:01It's a place like nowhere else.
04:15This is La Cueva de los Cristales, the most spectacular cave of crystals discovered anywhere in the world.
04:27This is a place that we found by chance after a hundred years of mineral exploration in thousands and thousands
04:36of feet that were drilled.
04:38All of a sudden we came into this beautiful geode of gigantic size.
04:48The crystals are about sizes of trees, the big trees, and it's unique because it has the largest crystals in
04:56the world to be found so far.
05:11These crystals are made of gypsum, normally a very ordinary material, best known as household plaster.
05:32This strange world is shaped by forces that have had a profound impact on human civilization.
05:43If you are familiar with the hot places like tropical rainforests, like steam baths, it is nothing like that.
05:51It is much, much hotter.
05:52It's about 55 degrees.
05:56It's so hot because only about five kilometres below the cavern is an area of the Earth's crust that is
06:08superheated molten rock.
06:12This heats water, which dissolves minerals from the surrounding rock.
06:19Phenomenal pressure forces this mineral-rich water up through cracks in the rock and fill this giant cavern.
06:28Here, the conditions were perfect for the minerals to slowly crystallise back out of the water.
06:35The cave lay unsturbed for over half a million years, so the gypsum crystals just kept growing until the miners
06:45broke through and the cave was drained.
06:51But the hot inner Earth has done far more than create these crystals.
06:59It's also the driving force for powerful geological events that have shaped the fate of peoples throughout history.
07:15This is the Timna Valley in Israel's Negev Desert.
07:22Today, it's pretty well deserted.
07:25But over 6,000 years ago, this place witnessed one of the world's first great scientific breakthroughs.
07:38Our ancestors realised the rock here contained a secret.
07:44Like the gypsum inside the crystal cave, these green bands of malachite formed when volcanic fluids rose from deep inside
07:52the planet and leaked into the rocks.
08:02But unlike gypsum, when malachite is heated up, it does something special.
08:11It releases a metal.
08:14It releases a metal.
08:17Copper.
08:21It was a discovery that would change a relationship with the planet.
08:35Today, we take that process for granted.
08:38But for archaeologist Dr. Uzi Avner, this was an innovation unlike anything that had gone before.
08:48They had to know how to extract the metal out of the rock or how to turn a rock to
08:53a metal.
08:53And this was a big, not only a leap forward, but a real technological revolution.
09:02You can still see evidence of the ancient smelting pits at Timna.
09:10But the copper workers left behind a more striking memorial to their work.
09:19They were using stone hammers held by two hands, and this is how they hit the rock.
09:25A very hard work.
09:30They used to dig first of all vertically into the rock, and then connect them, and wherever
09:37they saw greenish layers, indicating the presence of copper, they followed it and extracted the
09:45copper nodules.
10:00Their legacy is a network of hundreds of tunnels.
10:07This was the first large-scale mining anywhere on the planet.
10:21They probably didn't know it, but those industrious miners were changing man's relationship with
10:26the world around them in a profound way.
10:32Up to this point, all tools had been made out of things that were lying around.
10:37Stone, bone or wood.
10:39But now, for the very first time, people were transforming Earth's natural resources into
10:45something entirely new.
10:49This is one of the types of implements that the ancients used to make from copper.
10:55The advantage of this is that they could make just the shape that they wanted by preparing
11:02a right mould and casting, and then they could sharpen it.
11:05They could make it also harder by hammering, and they could resharpen it whenever necessary.
11:14And copper was just the start of things to come.
11:23About 5,000 years ago, tin was added to copper to form a new, more durable metal alloy, bronze.
11:37By 3,000 years ago, refinements to the smelting process meant iron could be smelted out of rock.
11:48Metal tools became the foundation for human civilisation.
11:59So it's clear we owe a huge debt to those first copper miners at Timna.
12:06But we also owe a debt to the deep earth.
12:13The key to Timna's role in early history is its location.
12:23The Earth's crust is divided into huge pieces called plates.
12:29Where they meet are cracks known as fault lines.
12:34Timna is next to the Dead Sea Fault, which separates Africa from Arabia.
12:41But this fault also connects Timna to the deep, hot interior of the Earth.
12:51It's this hot interior that is ultimately the source of all the metals that have so radically changed our history.
13:01Fault lines allow them to rise to the surface.
13:10Just as they did at the Crystal Cave in Mexico.
13:22But fault lines began affecting human history even before the discovery of metals.
13:29In fact, we've been strangely drawn to these boundary zones ever since the dawn of civilisation.
13:39And you can see the reason why in the Lut Desert of eastern Iran.
13:46The landscape is covered in hundreds of holes, arranged in rows.
13:51These holes in the desert help explain our ancient attraction to fault lines.
14:02Each of these shafts is over 50 metres deep.
14:06And everyday workers like Hossein Mehdi Dua descend into them to carry out maintenance.
14:12It sounds simple, but the technique for going down is not for the faint hearted.
14:33The shaft is barely wider than the human body, making the journey uncomfortable and claustrophobic.
14:52For over 2,000 years, local people have been digging shafts like this by hand.
14:58And the reason for this perilous work is apparent as soon as you reach the bottom.
15:07The essential ingredient of every civilisation on Earth.
15:13Cold, fresh drinking water.
15:22This is what made this remote corner of the Lut Desert one of the few places in the region that
15:28could sustain towns and cities.
15:36This tunnel leading off the shaft is called a kanat.
15:45It's one of many in this region, hacked out of solid rock to capture ground water that's stored deep below
15:52the desert.
16:06underground water exists beneath most deserts, but it's usually so far down there's no practical way of getting at it.
16:14The difference is here.
16:16The difference is here, there's a fault line.
16:22The fault is full of thick clay produced by the grinding of the surrounding rocks as they rub along the
16:29fault line.
16:30This forms a clay dam.
16:33Water flowing down from the mountains pools against the dam, creating an underground reservoir.
16:42Through which a kanat is dug to channel the water.
16:47gravity does the rest.
17:06gravity does the rest.
17:08Kanats were an ingenious early example of a mains water supply.
17:14The shaft is simply a way to get access to the tunnel carrying the water so it can be repaired.
17:21Today the kanats still carry water from underneath the Lut Desert into the nearby city of Balm.
17:27As well as irrigating the date orchards for which this area is famous.
17:39But this place isn't a one-off.
17:45In fact, if you look back at the ancient world, you see a strong link between fault lines, water and
17:54the growth of some of the first cities.
17:58More than 2,000 years ago, Petra in Jordan was the most important trade hub in the Middle East.
18:12It was built along a branch of the Dead Sea Fault and was entirely dependent on natural springs which rose
18:21along the fault and fed its irrigation system.
18:35Nearby is Jericho, said to be the oldest city in the world.
18:40It was first settled 10,000 years ago because deep ground water rose along fault lines to create fertile pastures
18:49in the desert.
18:57More unusual is the ancient Roman city of Herapolis.
19:01It was built next to these terraces of white rock.
19:11Here, it wasn't just water that was important.
19:14Minerals carried in the water were thought to have revitalizing powers.
19:22So, Herapolis became an important healing center in the Roman Empire.
19:35Whether it was minerals, metals or water, ancient civilizations were repeatedly drawn to the resources that fault lines brought up
19:45from the deep earth.
19:51It's a connection which led 11 of the 13 most important civilizations of the ancient world unknowingly to build their
19:59cities close to a plate boundary.
20:08As the earliest civilizations developed, so the relationship between fault lines and human history became more sophisticated.
20:16They even played a role in the establishment of the most advanced early civilization of all.
20:264,000 years ago, in the Bronze Age, the island of Crete was home to the Minoans.
20:45Canadian archaeologist Sandy McGillivray has spent many years studying the significance of Minoan culture.
20:52Here, at their most important cultural monument.
20:58This is Knossos, the heart of Europe's first great civilization.
21:03It made a very, very fine masonry, and obviously designed by a very, very clever architect.
21:10This was the heart of the Minoan Empire.
21:20There was running water, a sewage system, and large stores of food and wine.
21:33It all allowed the Minoans to create a new kind of society.
21:43You have to visualize the Minoans as people who were writing poetry and composing theatre.
21:50They were really a very, very luxurious society.
21:57The Minoans had created the world's first leisure society, and they took their pioneering responsibilities in this area very seriously.
22:12This is the heart of this great architectural complex.
22:15What you have to imagine around you now is very brightly colored painted, at least two-story buildings.
22:22At least the second story had great windows or terraces, and it was from these terraces that people could look
22:29out on the spectacle that was taking place here in the central court.
22:41One of the theories of what was going on in this court was that bulls were brought up, brought into
22:46the courtyard, and young athletes would leap over it.
22:51And what we see in Minoan art is a young man in the front approaching, grabbing the horns of the
22:56bull, flipping over the back and being aided by someone who catches them on the other end.
23:03Either you made it or you didn't.
23:05And if you made it, well, you were that much better, you were that much stronger.
23:10No one knows why the Minoans leapt over bulls, but this bizarre sport was a forerunner to bullfighting.
23:26But the real legacy of the Minoans was how they made their wealth.
23:35This was the Bronze Age.
23:39To make bronze, you need two metals, copper and tin.
23:46The problem was finding them.
23:55For the Minoans, copper was relatively near at hand in Cyprus, thanks to the fault line beneath it.
24:08Tin was trickier.
24:11Inside the Earth's crust, only two parts per million are tin, so it's much rarer.
24:20The hunts for tin led to distant lands that were at the edge of the then known world.
24:32One such place was so full of tin that it was called the Cassiterides, the Tin Islands.
24:42Today, we know it as Britain.
24:50But the centres of Bronze Age civilisation were in the Mediterranean, 3,000 kilometres away.
24:58Tin was also found in other far-flung locations, like Spain, Central Europe and even Iran.
25:06Which meant tin had to be traded.
25:09And for this, Crete was perfectly positioned.
25:18The exploitation of the deep earth by their neighbours was key to the Minoan success.
25:25Their position at the crossroads of many different trading routes enabled them to become the world's first maritime superpower.
25:40By the time of the Minoans, fault lines had been a crucial factor in the success of many early civilisations.
25:53But the Earth extracted a price for these riches.
25:59It was a price paid in full by the Minoans.
26:05At the heart of the story was a small archipelago, 100 kilometres north of Crete.
26:14Today, that island chain is known as Santorini, famous for its pretty white houses and rugged coastline.
26:31At the time of the Minoans, this was a busy port that was the key to their trading empire.
26:43But Santorini held a deadly secret.
26:49Unknown to the Minoans, it sat above one of the Earth's major plate boundaries.
26:59Santorini formed when the African plate started sliding below the European plate.
27:06As the African plate melted inside the deep earth, molten rock rose back to the surface to create what is
27:14actually a volcano.
27:22Around three and a half thousand years ago, this volcano did what volcanoes tend to do.
27:27It blew up.
27:40Unluckily for the Minoans, it was the biggest eruption of the last 10,000 years.
27:47Today, you can still trace why the eruption was so devastating in the cliffs around Santorini.
27:58For volcanologist Dr Georges Vougiokalakis, climbing this cliff helps understand a disaster that was unlike anything anyone had ever seen
28:08before.
28:09Because these cliffs don't just hold subtle clues about the eruption.
28:13They are the eruption.
28:16They are the eruption.
28:17These 150 foot high cliffs are built entirely from the events of a single catastrophic day three and a half
28:23thousand years ago.
28:46The first five meters of this cliff are made entirely from the powder and pumice from the first five hours
28:52of the eruption.
28:55This fine ash is as sharp as glass and would have sliced open the lungs of anyone who breathed it
29:02in.
29:08But more was to come.
29:20Here we are in the second phase of the Minoans.
29:23We have the place of the pyraclysmic waves.
29:26We have the very arctic waves.
29:29We have the arctic waves.
29:31We have the arctic waves.
29:33We have the very large waves.
29:35We have the waves.
29:45The temperature of these racing clouds exceeded 400 degrees Fahrenheit, burning everything in their path.
29:54As these clouds of hot gas and lava fell back to Earth, they engulfed the outer edges of the island.
30:08But incredibly, the worst was still to come.
30:14Once the volcano had spewed out everything in its guts, the weight of it collapsed into the void below, producing
30:21an enormous blast.
30:27That sudden collapse created a gigantic tsunami, which quickly spread out across the Aegean towards Crete.
30:44For a civilisation whose strength was in their navy, the tsunami would have been devastating.
31:03This was a catastrophe from which the Minoans would never recover.
31:22The eruption of Santorini was an extreme event.
31:26But ancient history is littered with tales of cities destroyed along plate boundaries.
31:38And it's not just volcanoes that do the damage.
31:44Fault lines are also home to another deadly force of nature.
31:58Earthquakes.
32:08Over the past 10,000 years, many cities first established to take advantage of fault lines have been flattened.
32:21Heropolis, with its famous health spa, was destroyed by a giant earthquake in AD 60.
32:33Jericho, the oldest city in the world, has been hit over 15 times by large earthquakes.
32:39Some believe it was this that famously brought its walls tumbling down.
32:46Likewise, Petra was abandoned after an earthquake demolished its irrigation system in AD 360.
32:59And it continues to this day.
33:02In 2003, the city of Bam, famous for its canats, was devastated by a massive earthquake which killed over 30
33:11,000 people.
33:24It makes you realise that, in effect, much of human history has centred on a bargain between us and the
33:31inner Earth.
33:34Plate boundaries provide access to resources from deep inside the planet.
33:43But live near one, and every now and then, you take a hit.
33:53But even the most advanced of our ancestors had no way of explaining the strange coincidence.
34:01In fact, it's only in the last 50 years that scientists have finally understood the bargain that was inadvertently struck
34:08all those years ago.
34:10You can see the theory in action in the middle of the Pacific Ocean.
34:19This is Kilauea, on Hawaii's Big Island.
34:29It's one of the most active volcanoes on the planet.
34:35Because it's fed by a chamber of magma deep inside the Earth, called a hotspot.
34:45The hotspot has effectively punched a hole in the Pacific Plate, the piece of the Earth's crust on which Hawaii
34:52sits.
34:53But remove the ocean around Hawaii and something strange is revealed.
35:00A chain of mountains stretching along the seabed for over 5,000 kilometres.
35:06This line of extinct volcanoes is explained when you realise that the Pacific Plate is continually on the move.
35:18As the plate drifts over the stationary hotspot, a volcano forms.
35:24But after about a million years, the moving plate pulls a volcano away from the hotspot.
35:31Meanwhile, another eruption begins, forming a new island.
35:42Today, Kilauea is still growing, but it hasn't got long to go.
35:47In a few thousand years, it will drift away from the hotspot and eventually disappear beneath the waves.
36:05The Hawaiian island chain is a beautiful demonstration of a big idea that explains why plate boundaries bring us extraordinary
36:16benefits and terrible hazards in equal measure.
36:21It's called plate tectonics.
36:28The key is that all the plates which divide the Earth's surface are continually on the move.
36:36Where they collide, they crumple the land to form great mountain ranges like the Himalayas.
36:46Where they pull apart, oceans form in the gap.
36:55The friction of this continual movement means that plate boundaries become melting zones where minerals are concentrated and are able
37:04to rise towards the surface.
37:09But the flip side is that huge amounts of energy are concentrated along the plate boundaries.
37:18When one plate slides underneath another, volcanoes form.
37:34When two plates lock together and then suddenly break free, the jolt causes devastating earthquakes.
37:48So we now know that plate boundaries are so rich in resources for exactly the reasons they are so dangerous.
37:59Yet the strange thing is, this groundbreaking discovery has made little difference to where we live.
38:12If you look at the plate boundaries, it's clear that many cities are located close by.
38:21In fact, 10 of the 20 largest cities in the world are next to dangerous fault lines.
38:29So why are we still building next to these danger zones?
38:35In the rugged hills of central California is part of the answer.
38:43And heading into the skies to see it is geologist, Dr. Mary Lou Zobak.
38:49And heading into the skies to see it is geologist, Dr. Mary Lou Zobak.
39:21Mary Lou Zobak is heading out to perhaps the most famous geological feature on the planet.
39:38This is really an extraordinary view.
39:43This line of hills with a trench cut through the middle is the San Andreas Fault.
39:48I've seen the fall many times on the ground, but you never get this kind of perspective, this sort of
39:54overview.
39:56And you really get the sense that you're in the fault zone itself because we're flying right along this very
40:01sharp, narrow valley.
40:05This huge scar that we're flying along is the boundary between two major tectonic plates.
40:12To the right, I've got the North American plate.
40:16And to the left, I have the Pacific plate.
40:20For 25 million years, they've been grinding past each other to create the largest earthquake fault in North America.
40:32We're looking at a small portion of the San Andreas Fault here.
40:36The fault itself runs more than 700 miles through California.
40:40Yeah. It's running adjacent to roughly 25 million people.
40:49If there was ever a fault line that cuts through the very fabric of a modern society, it's this one.
40:58But a good reason why over 20 million people carry on living so close to this danger zone
41:04is that this plate boundary has made California rich.
41:13It began with the Californian gold rush.
41:21These nuggets of gold might have been found in streams, but the gold originally rose in hot, mineral-rich fluids,
41:29forced up between the plates.
41:34In fact, almost everything that makes California wealthy is at least partly related to the San Andreas Fault.
41:44Take, for example, the scenery.
41:48It was the colliding plates that forced up mountains along the Californian coast.
41:56And this dramatic landscape attracts thousands of tourists every year,
42:01who spend an estimated $2 billion on sightseeing alone.
42:07Then there's the wine.
42:10That's partly down to the San Andreas too.
42:14California is mostly desert, but when moist air rolls in off the ocean and hits the mountains,
42:20it rises to form rain that irrigates this otherwise arid landscape.
42:28It's a microclimate that has made this one of the most productive farming regions in America.
42:37But the ultimate gift of the San Andreas is this.
42:51Oil.
42:53Black gold.
42:59Over the years, around 200,000 oil wells have been sunk into the Californian desert.
43:08In fact, more than 700,000 barrels are still drawn out of the ground every day,
43:15making California one of the world's biggest oil producers.
43:23So the San Andreas Fault has brought California some serious economic benefits.
43:30Its shaping of the land has created the conditions for oil, agriculture, wine and even tourism.
43:37But how much is that really worth?
43:48The money men have done the sums.
43:51They reckon this state earns around $100 billion every year because of the San Andreas Fault.
44:02But an earthquake causing $250 billion worth of damage is only likely to strike LA once every 100 years.
44:12So over a century, that's a gain of over 40 to 1.
44:18California's geology is a license to print money.
44:2710,000 years after our ancestors first settled along plate boundaries, the benefits of living along a fault line are
44:35as potent as ever.
44:38In pure economic terms, we're still financially better off living along a fault line than not, even when it's one
44:46of the most active in the world.
44:49But life's not just about money.
45:05Istanbul, the only city in the world to straddle Asia and Europe.
45:11This location at the crossroads of two continents has made it a trading hub for centuries.
45:22It's a vibrant, bustling, cosmopolitan place.
45:29But Istanbul's location also brings with it great danger.
45:41Nearby lies the North Anatolian Fault, one of the most seismically active plate boundaries on the planet.
45:48Scientists reckon a major earthquake is due here any time.
45:56For Turkish geologist Dr Jalal Sengur, who lives and works in the city, the signs aren't good.
46:04In the next half a century to 30 years, it is about 70% possibility that an earthquake larger than
46:14seven will hit.
46:16Now that's serious. That's really serious.
46:20Major destruction in the city and loss of human life.
46:23Major destruction in the city and loss of human life.
46:27Therefore, you are vitally interested in knowing what might happen, when it might happen, so that you can get prepared.
46:47Below the waters of the Bosphorus, the channel that separates Europe from Asia, is a clue to the solution.
46:59At 35 metres below sea level, this tunnel will one day link Asia and Europe, and it's the deepest tunnel
47:07of its kind on Earth.
47:10And yet it runs alongside one of the most dangerous earthquake faults in the world.
47:19The engineers building it are confident that they've got the risks covered.
47:25The tunnel is designed to flex, absorbing the vibrations of even the largest of earthquakes.
47:36This technology won't allow us to stop earthquakes.
47:40But it shows that if we really want to protect against their consequences, we can.
47:47You can do things to minimize the damage it's going to do to the city.
47:52Because we will lose a lot of things that we consider precious.
47:57Anywhere between 60 to 100,000 people will die.
48:02So, is it worth all that money we're going to spend? Is it worth all the effort?
48:05The answer is yes.
48:09The irony is, Istanbul already has a building that has survived earthquakes for centuries.
48:22This is the Hagia Sophia.
48:26For the tourists that come here, it's a fitting symbol of Istanbul's reputation as a crossroads of different civilizations.
48:34In its 1,500-year history, it's been a church, then a mosque, and now a museum.
48:44The Hagia Sophia has stood through more than a dozen earthquakes without the benefit of modern technology.
48:51It was built on such a massive, monumental scale that even the biggest earthquakes never managed to knock it down.
49:06Today, we have the technology to protect every building.
49:11Whether it's flats, factories or offices.
49:17If we choose to.
49:30For 10,000 years, we've lived with the benefits and the dangers of fault lines.
49:40And it's clear that people are going to continue to live along fault lines, probably for the next 10,000
49:47years.
49:48But now, we have two clear options.
49:52Stick with the old regime and take our chances.
49:55Or embrace the new and take some kind of control.
50:01For the very first time in human history, that choice is ours.
50:16To be continued...
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