60 Minutes Presents: Great Adventures

Welcome to 60 minutes presents. Tonight, we'll end Thanksgiving weekend, when so many people travel, with three "great adventures" of our own. We'll soar with eagles high above Mongolia, then cruise across the Pacific to visit Easter Island.

What lies 2 miles below Earth's surface?

We begin our adventures with a trip deep below ground. Over the years at 60 Minutes, we have been in more than a few tunnels. We explored Mexican drug lord El Chapo's subterranean escape routes, burrowed through a Roman villa buried by Mount Vesuvius and traveled the depths of the New York City Subway. But nothing prepared us for a place called Moab Khotsong, a South African gold mine that extends nearly two miles beneath the surface. As we first reported last November, in their pursuit of gold, South Africans have dug the deepest holes on Earth. The country was the world's top gold producer for decades. Now the gold is running out, just as these ultra-deep mines have attracted a new breed of miner on a very different quest. We went along for the adventure.

In the early morning light, tall mine shafts loom over the Vaal River basin two hours southwest of Johannesburg. This once was a booming gold field, now most mines lie abandoned but Moab Khotsong is bustling. Long before the sun rises, thousands of miners start lining up for the triple-deck elevator called "the cage." It's jammed but more always push on, and early one morning, so did we.

We're packed in as tight as sardines, the electric bells signal we're ready, and the cage drops. Slowly at first, then picks up speed fast. We plunge 450 stories straight down. It's the longest elevator ride on Earth.

The cage rattles and whistles as we descend, the air gets more humid the deeper we go. Our lifeline to the surface is a machine called the manwinder, massive coils of steel rope two inches thick that attach to the cage and unspool faster and faster. We dropped two miles in a couple of minutes and emerged in an underground city.

To get to the gold, miners must walk miles through a vast maze of dimly lit tunnels. Sometimes you're lucky and can catch a ride, but mostly you just walk. For Leroy Lee, it's in the blood. His father worked in the mines. Now it's his turn. His family depends on his job.

The gold in these ultra-deep mines is found in narrow veins, laced through the rock. Some are no wider than a pencil. It's cramped at the rock face and we crouch alongside the miners as they work hunched over in the dark. The noise from the drills is deafening. Massive air conditioners cool the tunnels but it can still reach 120 degrees down here.

At the end of the shift, we had to rush not to miss the elevator back up. It doesn't wait for anyone.

And here's where all that breaking rock pays off: the smelter. The ore is smashed and pulverized in a grinder before being fed into a furnace. Monga Kasongo, who runs the operation, told us we were the first TV crew to film the weekly ritual they call "the pour." We all had to wear these special pajamas with no pockets so we couldn't steal anything. The heat was intense as the furnace reached almost 2,000 degrees. The gold turned to liquid and poured down into the moulds.

Monga Kasongo: When I saw it the first time, I was like "wow." That's something that keeps me going. When you hear people who have never seen gold or touched it, I feel like I'm more privileged.

These bars will be refined again to 99.99 percent purity before they're sold for coins and jewelry. The mine used to process about 60 tons of gold a year. Now it's just a quarter of that. Still, the day we watched the pour, there was a pretty good haul.

Bill Whitaker: Wow, this is quite heavy…

Monga Kasongo: Yes, it is.

Bill Whitaker: How much is this?

Monga Kasongo: 11 million rand.

Bill Whitaker: In U.S. dollars, we're talking seven and a half to eight million U.S. dollars for what you poured today?

Monga Kasongo: Yes, definitely.

Bill Whitaker: That sounds like a good day?

Monga Kasongo: It's a good business.

It's one thing to come here for the gold but now this harsh environment has attracted others: scientists hunting for what they call extreme life.

Tullis Onstott: We've found water that's a billion years' old

Bill Whitaker: A billion years old?

Tullis Onstott: A billion years' old

Bill Whitaker: In these caves?

Tullis Onstott: Right.

An international team, led by Princeton geoscientist Tullis Onstott and Belgian biologist Gaetan Borgonie, are pioneers in the search for life buried in the rock where no one thought it could survive. Borgonie says his colleagues thought he was crazy when he took a sabbatical to try to prove there was life deep underground.

Gaetan Borgonie: Oh, come on they said. You're going to go to South Africa for a year, you're gonna go look for something that does not exist there.

They've lost count of the number of trips to the bottom of the mines searching for life hidden in the ancient water, seeping through the rock.

Gaetan Borgonie: This is a completely different world down there. There are different rules.

Bill Whitaker: How so?

Gaetan Borgonie: The temperature is different; the pressure is different. I mean, it's a tough world down there for life.

The next day we went along with them to the deepest level of the mine. For them it was just another day at the office, for us it was an eye-opener.

With just the light from our headlamps, we waded through a tunnel that had been flooded with cold water to cool it down. Then we grabbed a chairlift cut through a channel of rock, except this one went down.

Picture five of New York's World Trade Centers stacked on top of each other. That's how deep in the Earth we are.

When the chairlift stopped suddenly we had to hike down the last 50 yards to the bottom. Then, at the end of an abandoned tunnel our scientists found something amazing.

Tullis Onstott: I've been looking for 20 years for a salty water deposit like this. Never found it until now.

White patches on the wall turned out to be salt.

Bill Whitaker: Is that edible?

Bennie: I don't know, he's tried it.

Bill Whitaker: This is ancient salt?

Tullis Onstott: That's the question. Has to be-- has to be ancient salt.

Bill Whitaker: Very salty. Salty salt.

And the source? This dripping salt water.

Bill Whitaker: What does that tell you?

Tullis Onstott: It tells me this water is extremely old. Cause in these rock formations they were formed three billion years ago. There weren't salt deposits back then.

They believe this water could be all that's left of an ancient ocean and where there's water, there can be life.

Tullis Onstott: We could be looking at something which has never seen the life that has evolved on the surface of the planet.

Bill Whitaker: All from this cave two miles down in South Africa?

Tullis Onstott: All from gold mines in South Africa. Exactly.

In 2011 they found what no one thought possible: these tiny worms living in a pocket of water 5,000 years old. What you're seeing is magnified. These worms are no bigger than a human hair. It was a species never-before-seen. It survives without sunlight, deep in the hot underworld, so they called it Mephisto or, "the devil."

Gaetan Borgonie: That's where my worms live. They eat bacteria.

Bill Whitaker: The first worm you found was in something like that?

Gaetan Borgonie: Yeah

Using an endoscope camera, they were the first to film this deep inside the earth's crust. This is the devil worm's home. Before this, no one thought animal life could exist this deep.

Bill Whitaker: You've made a big discovery.

Gaetan Borgonie: For me it is big, because for me personally, I had to fight quite a lot of people to be able to do this. On a personal level, that was the biggest victory for me. In the total grand scheme of things, it's just a worm.

Bill Whitaker: It's just a worm ...

Gaetan Borgonie: It's just a worm.

They were surprised to find other living creatures too, so many they called them a zoo. A crustacean, about one sixty-fourth of an inch. An arthropod, a flatworm, and single-cell bacteria. It set off a storm of speculation about where else extreme life might exist, perhaps even on Mars. NASA helped fund their research.

Gaetan Borgonie: If there is life here in the deep, then you should definitely dig on Mars because if life was ever there you will find some life form, I believe very strongly, still on Mars.

Bill Whitaker: So the Martians we meet in the future could be these single-cell organisms you're--

Gaetan Borgonie: I think that would be the--

Bill Whitaker: --you're talking about.

Gaetan Borgonie: --that is-- yes, indeed. I think that would be the most likely. But be prepared to be surprised, I would say.

South Africa's gold mines are now so deep they might as well be on another planet.

Bernard Swanepoel: I'm not sure that we really want to send human beings much deeper.

Bernard Swanepoel started his career underground and ended it as the CEO of Harmony Gold, which now owns Moab Khotsong.

Bernard Swanepoel: If you are in a successful mining team, it must be like a successful sports team. I mean mining is one of those activities where at the end of every shift you know whether you won or lost.

Gold was the lifeblood of South Africa. The way it's dug out has changed little since apartheid when underpaid black miners often worked in mortal danger. At its worst, more than 800 workers a year died in mining accidents. No coincidence the struggle that led to apartheid's defeat started underground.

Bill Whitaker: Gold and gold mining seem to be in the DNA of South Africa.

Bernard Swanepoel: South African gold mining especially has always been at the center of all political and other activities in our country. I mean our bad apartheid history is intertwined with gold mining. I mean a lot of the-- a lot of the legislation to dispossess black people of land was in order to create cheap labor for South African gold mines.

Bill Whitaker: You grew up in a small mining town, during the era of apartheid. What are your strongest memories?

Bernard Swanepoel: Well, ultimately I'm a privileged person that, because I was white and I was male, those were the two requirements at the time to become a mining engineer.

Bill Whitaker: So are you the new face of South African mining?

Monga Kasongo: I will say yes. We are the new generation in the mining.  

Just a dozen years after apartheid ended, engineer Monga Kasongo started managing the smelter. He told us he chose to move here from the Congo to work in the mines.

Bill Whitaker: Has that wound in South Africa been healed?

Monga Kasongo: Not 100 percent healed. But there is some healing happening, there is some healing, yes because you have a different-- different people working in the mines and the mindset has been changing.

Now safety is paramount. You'll find women underground and blacks are senior managers. Once some of the lowest-paid laborers are now among the highest. But this generation of gold miners know they may be the last. Of the 11 gold mines that once flourished around here, only three still operate. The mines are now so deep, it's becoming too expensive to get the gold out. The story of the ultra-deep mines is nearing its final chapter. To dig the riches from such astounding depths took grit and brute force. Now South Africa's resolve must be deployed to solving the next challenge: what to do when the gold runs out.

Produced by Heather Abbott. Associate producers, Sarah Carter and LaCrai Mitchell.

Hunting with eagles in Mongolia

Falconry - the art of hunting with birds of prey - was born in the forbidding Altai Mountains of Central Asia. As we first told you last year, hunters there still loft golden eagles into the sky in a partnership of man and bird that predates recorded history. We say 'man' but, in truth, one of the best hunters in Mongolia today is a woman from Oklahoma City. Lauren McGough took Scott Pelley to one of the most remote places on earth to meet the hunters who trained her. And, before the next few minutes are through, you will know what it's like to fly like an eagle.

The Mongolian steppe is the greatest expanse of grassland unaltered by humankind. It endures because human existence has narrow odds between the widest climate extremes on earth: 104 degrees in summer, 50 below in winter. Nomads depend on the animals that yield nearly all of their food, fiber, clothing and fuel. And, one of the oldest bonds in nature is an alliance of survival among hunters, horses, and golden eagles.

Lauren McGough: This is the most ancient form of falconry in the world. This is where it all began. It's the cradle. So, several thousand years ago-- we don't know precisely when-- a man saw an eagle catch a rabbit or a fox and had the ingenious idea to hunt in partnership with it. It blows my mind that it's even real. It's like something out of "Lord of the Rings." But you can do it.

Lauren McGough was in high school when she dedicated her life to raptors. She traveled with us to the place she calls the "cradle."

6,000 miles led us first to the Mongolian capital of Ulaan Bataar. This civilization conquered the known world in the 13th century. The Mongols ranged from Asia to Europe – the largest contiguous empire of all time. From here, we flew another 800 miles to Bayan-Ölgii, where Mongolia, Russia, China and Kazakhstan meet. This was the end of the road, but not the end of our journey. We crossed the open steppe, past wild Bactrian camels with two humps, a vanishing species with only about 1,000 left in the world. Our destination was a camp of nomads, people who introduced Lauren McGough to the golden eagle.

Lauren McGough: Hello.

They hadn't seen her in two years.

Lauren McGough: It feels like I never left. I, just in a few minutes of seeing everybody. Such a magical place.

Scott Pelley: Now, how did a woman from Oklahoma end up out here, in Mongolia?

Lauren McGough:  Ah well, I read a book on falconry. And it's like the fire was lit. I just knew I had to do it. And, as I was researching, I went to the library, and I found this old book that had black and white photos of eagle hunters from Mongolia. So, you know, this beautiful shaggy horse and this man with a giant eagle and a fox pelt on his horse. And it just looked like the most incredible thing. And I thought, "I have to see it. I have to do it."

At the age of 17, her father, a former Air Force stealth pilot, brought her to Mongolia. Lauren returned five years later with funding from a Fulbright Scholarship. Then she earned a Ph.D. based on her work with the eagle hunters.

Lauren McGough: These are the people that can talk to animals. Because they have relationships with goats, sheep, horses, camels, eagles. They have intimate knowledge of where snow leopards are and foxes are. There's no agriculture here because the land's not arable. So, they've ingeniously learned to domesticate animals and then build these unique relationships with wild animals.

It's a relationship that she learned from people who endure the life of 19th century ranchers. They are Kazakhs, who make up just four percent of Mongolians. They have no running water, no electricity. They survive on meat and milk and burn dung as fuel. The nomads live in clusters of a half-dozen families or so. The boys mind the flocks while the men ride in search of foxes to make furs for sub-zero survival.

Scott Pelley: In all the years you've been doing this, what have you learned about these animals?

A hunter named Chukan gave us an answer we never saw coming.

Chukan (Translated): As they said in the old times, if the horse makes your name famous, in a race, once a year, the eagle makes your name famous a hundred times a year. If I gift to people many foxes, they will say it was Chukan who gifted us the foxes. Eagle hunting is more about your name being spread far and wide among the people.

So, if eagle hunting is about the ego of men, we wondered how they saw Lauren McGough.

Chukan (Translated): She had her mind set on learning to hunt with the eagle. Her motivation came from deep in her heart. We just couldn't say no.

When Lauren first came to Mongolia it took her two weeks to catch an eagle she could call her own.

Scott Pelley: How do you catch a golden eagle?

Lauren McGough: Yes. So, you have a dead hare that you lay out with a crow or a raven steaked nearby. And you encircle it in a net. So, the eagle on migration looks down and sees this hare that only a crow has possession of. And it thinks, "Ah, I can easily bully that crow out of that rabbit and have a free meal to myself." So, it comes in. And, when it tries to grab the dead rabbit the net enfolds around the eagle.

The eagle is taught to feed at the hand of the hunter. And, as long as the meals are regular, the eagles are calm, content and come back for more. They perch on the hunter's arm with a rawhide leash called a jess tied to their legs.

They train the birds with a fox pelt tugged by a rope. This is what happens when the eagle zeroes in on a fox. After the bird makes the kill, the hunters ride in, strip the pelt, and give the meat to the eagle. It's a technique well over a thousand years old.

We may not know exactly when it started, but you don't have to be here in Mongolia very long to figure out why it began. In an area as vast as this, with game so rare, it helps to have a hunting partner that can see seven times better than a human and cover all of this at about 50 miles an hour.

What is that like? The eagles were kind enough to show us. We custom-built a soft, rubber camera harness and learned how to fly.

Golden eagles are abundant all around the Northern Hemisphere. In terms of survival as a species, conservationists call golden eagles an animal of "least concern."

Lauren McGough: This is a ten-pound bird. Which, don't be fooled if that doesn't sound like a lot. They have hollow bones, and they're mostly feathers. So, ten pounds on a bird is an enormous bird. They have a six-foot wingspan. They usually have lovely amber eyes. And the name "golden eagle" derives from the beautiful golden feathers on their nape. And then, the rest—

Scott Pelley: Yes, around the neck?

Lauren McGough: They're incredibly effective at killing, which is what they're built for. They're a modern-day Velociraptor. A perfect product of evolution. I will never be tired of a golden eagle flying. Every time, it thrills me.

The eagle's talons can close on its prey with a bone crushing force of 900 pounds per square inch, a fun fact that is no fun to know.

Scott Pelley: Come on, sweetheart.

Lauren McGough: Perfect. Very good. And then, go ahead and stand up. And then, to secure the eagle, place your jesses between your thumb and the rest of your fingers.

Scott Pelley: Right here? OK.

Lauren McGough: Yes. The noise that the eagle recognizes is "kah, kah" whenever you're ready, just take off her hood.

Scott Pelley: Remove the hood?

Lauren McGough: Yes. Kah. kah-kah.

Lauren McGough: Good girl.

Scott Pelley: Oh, God, what a feeling. Oh.

Notice she said, "good girl." The only eagles worthy of partnership are female. They're larger, stronger, better hunters. Ironic, since the human partner is traditionally male.

Scott Pelley: Of all the eagle hunters you've known, how does Lauren rate? How good is she?

Chukan (Translated): She is at the same level as men. She could compete with them.

Lauren, at 32, is considered one of the best falconers in the world. She has brought the ancient ways to Oklahoma, where she rehabilitates raptors and trained with her own eagle named Miles.

Scott Pelley: What is the career of one of these eagles?

Lauren McGough: So an eagle is trapped the first year, second year, maybe third year, on its migration. And then, it has a time with an eagle hunter, which could be as short as a year or as long as six, seven, eight years, eventually, they return that eagle back to the wild.

Scott Pelley: It is part of the tradition to let them go?

Lauren McGough: Yes. They firmly believe that an older eagle should be in the wild.

Scott Pelley: What do you say to some people who might watch this and think that the eagles are being abused? That they shouldn't be caught?

Lauren McGough: I would encourage anybody that has doubts to go out with a falconer in this country or in the United States or anywhere. We only encourage their natural instincts. The only difference is you are right there. You have a front-row seat to see this incredibly million-year-old predator-prey relationship.

Scott Pelley: Do you worry that, one day, there will be no more eagle hunters?

Ouni (Translated): No. It is an essential art that Kazakhs are born with. Since Kazakhs have come to the earth, they have been practicing this tradition. It will not disappear. Also, each of us has a young person that we teach, like this boy. It passes from generation to generation.

Scott Pelley: What's at stake if this tradition is lost?

Lauren McGough: This is where man first figured out that he could have a relationship with a raptor. And what a loss would it be for humanity if it was gone. We can take an individual eagle and bring it-- from the spectrum of wild all the way to tame, and then wild again. And we get to see what they're capable of-- up close and in person. Man, if that understanding of eagles and animals were to leave, that's not a world I want to live in.

The boy, named Bekka, is the hope of his family's traditional world. He's learning horsemanship and falconry. And it was with Bekka that we discovered the most endangered species on the steppe, the nomads themselves. There may be only 300 eagle hunters left, a rare breed of human still speaking the language of the wild.

Produced by Nicole Young and Katie Kerbstat.

Easter Island's moai statues

Now we take you on a journey to Easter Island. It's one of the most remote inhabited islands in the world, far into the Pacific, 2200 miles due west from the coast of Chile.  

Dutch explorers gave it its name after they spotted it on Easter Sunday in 1722. What they found has fascinated and confounded the world ever since -- giant stone statues that tower over the island's landscape. They're called moai, and as Anderson Cooper first reported last spring, there is nothing quite like them anywhere else in the world.

When dawn breaks on Easter Island, it is the moai that first feel the sun.   

These 15 moai at a site called Tongariki are perhaps the most famous. Carved out of volcanic rock, they're placed on a stone platform called an ahu. The tallest is nearly 30 feet. They stand, strange silent sentinels, facing away from the sea, watching over the land and its people. 

At least a thousand moai can be found scattered across this island, which is about the size of Washington DC. Many more moai remain buried underground. To the descendants of those who built them, these are more than statues made of stone, they are immortal branches of an ancient family tree.

Pedro Edmunds Paoa: The moai represent an ancestor. And we believe in ancestor that goes beyond this life but is helping us, guiding you.

Anderson Cooper: Is a moai a distinct individual ancestor? Or can it also be the family line of that ancestor?

Pedro Edmunds Paoa: Both.

Pedro Edmunds Paoa is the longtime mayor of the only town on Easter Island.  

Anderson Cooper: So when you see the moai today, it's not just something from the past. It's something that is alive that has power right now?

Pedro Edmunds Paoa: Yes. We indigenous people from this island believe in that.

The indigenous people here believe their ancestors and family lines are represented by specific groups of moai. Mayor Edmunds Paoa says his are at a site called Tahai. 

Pedro Edmunds Paoa: My genealogy traces to all the way to that site 85 times.

Anderson Cooper: It goes back that far?

Pedro Edmunds Paoa: Yes. More than a thousand years.

That is entirely possible. No one knows for sure the exact date the first people came here, but it's believed to have been somewhere around 800 to 1200 years ago. Archaeological evidence indicates they sailed, from an unknown island in Polynesia, a dangerous journey across more than 1,000 miles of open ocean.

Those first settlers brought with them their tradition of carving, but they made much smaller statues. They also brought a belief in a mystical force called mana.

Anderson Cooper: How do you describe mana? What is mana?
Pedro Edmunds Paoa: Mana is- is- is- is beyond description. If we were to describe it of today's language, is knowledge.

Anderson Cooper: Knowledge?

Pedro Edmunds Paoa: Could be interpreted as wisdom as-- an energy that gives you strength.

Anderson Cooper: Do the Moai still have mana?

Pedro Edmunds Paoa: Sure. It has soul. It has life.

Anderson Cooper: They're alive?

Pedro Edmunds Paoa: Absolutely.

According to legend, when important islanders died, their mana flowed out of their bodies into the moai.

Pedro Edmunds Paoa: The mana is here. The mana is here.

Anderson Cooper: It's a hard concept for my small mind to imagine.

Pedro Edmunds Paoa: for human like you guys from the city, you don't understand these things 'cause you worry about working, like, disciplined animals. 

Those who believe in mana say it's not just in the moai, it can be found in everything here -- in the waves that constantly crash ashore, in the rocky soil and in the green grass that blankets the island.

Jo Anne Van Tilburg: These objects in the middle of what looks like a barren landscape. They speak to you. They draw you in. They-- they make you want to-- to know more. I think that that's the power of them.

Jo Anne Van Tilburg is a UCLA professor of archaeology. She has been coming here for nearly 40 years, working with local researchers and artists, excavating and cataloging the statues, trying to understand the mysteries, and what she calls, the magic of the moai. 

Jo Anne Van Tilburg: They're tight-lipped, these statues.

Anderson Cooper: They don't give up their secrets easily--

Jo Anne Van Tilburg: They-- they don't give up their secrets easily. And they don't give 'em up to outsiders easily.

To learn the moai's secrets, you have to start where nearly all of them were made. Around the vent of a dormant volcano, this is the ancient quarry of Rano Raraku. There are some 400 moai here, more than in any other spot on the island. The largest one, never raised upright, is almost 70 feet long and weighs at least 250 tons, as heavy as some passenger jets.

Based on excavations Jo Anne Van Tilburg and other archaeologists have done, and analysis of soil samples and objects found around the statues, Van Tilburg believes the height of moai construction was around 1300 to the mid 1400s. Though moai did continue to be carved until or just after the first contact with Europeans in 1722.

Anderson Cooper: I mean, is it not possible with carbon dating or other scientific techniques to know exactly when--

Jo Anne Van Tilburg: Unfortunately not. You can't date stone, this stone in that manner.

When the first archaeological survey was done on the island in 1914, all the moai except those in the quarry were found lying on the ground.

There are several plausible theories how they got there. Certain statues may have simply fallen from neglect, others were knocked over in earthquakes and some were intentionally toppled during fighting between competing family groups.

Today some moai are only partially visible, just their famous faces stick out of the ground, the rest of their bodies are buried under sediment that's naturally built up over the centuries.

Jo Anne Van Tilburg: This one is at least-- only about one third above ground.

Anderson Cooper: Wow. So two thirds of this are actually below ground.

Jo Anne Van Tilburg: Yes, yes.

At first glance the moai all look alike, but Van Tilburg says no two are the same.

Anderson Cooper: How are they different? 

Jo Anne Van Tilburg: Well they're different in the line of their mouth. They're different in, of course, their size and shape. They're different in their expressions. Whether their head is tilted up, or lowered slightly, or to the side. 

Anderson Cooper: These two moai -- they're unfinished?

Jo Anne Van Tilburg: They're unfinished.

Visitors here have long debated how the moai were made, given the stone age conditions on the island, when the statues were being carved. Van Tilburg says, the answer is all around. There are thousands of stone-carving tools scattered throughout the quarry.

Jo Anne Van Tilburg: This was a handheld instrument that was used. And if you hold it you can-- actually feel where people may have put their fingers.

Anderson Cooper: Wow.

Jo Anne Van Tilburg: Which was actually used to rough out the sculpture.

Anderson Cooper: You can actually feel the-- sort of the-- the hand--

Jo Anne Van Tilburg: Yeah, you can.

Anderson Cooper: Wow. That's amazing.

Jo Anne Van Tilburg: Isn't that cool?

Anderson Cooper: I mean -- and this was literally just laying ten feet away. I mean--

Jo Anne Van Tilburg: And you put it in your hand, and you can feel where the other person's hand was who-- who ac-- who actually-- used this.

Anderson Cooper: That's incredible.

Jo Anne Van Tilburg: When you talk about mystery and magic, that's it, right there. 

But magic alone couldn't move the moai from the quarry to sites on the coast, in some cases, more than eight miles away. That took muscle and ingenuity. Van Tilburg has tested a theory she believes. That moai were placed horizontally on sleds, and dragged over logs. 

Island legend says the statues walked, and some archaeologists have tested that theory as well, moving them upright, carefully wobbling them back and forth. 

You may have also heard an out of this world theory about space aliens making and moving the moai. It may sound ridiculous but it's still believed by many visitors today.

Anderson Cooper: You must have people asking you about extraterrestrials--

Jo Anne Van Tilburg: Yes.

Anderson Cooper: --building these.

Jo Anne Van Tilburg: Yes, I do.

Anderson Cooper: So, I mean, I just have to ask, any possibility of that? You don't believe it though.

Jo Anne Van Tilburg: No, I don't believe it.

Easter Island was annexed by Chile in 1888. Half of the 8,000 people who now live here are Chilean immigrants. The other half are modern descendants of those original Polynesian settlers.  They call themselves, and the island, Rapa Nui. In 2017, Chile finally gave them control of the national park where the moai and other important archaeological sites are located. The park covers more than 40 percent of the island.

The island of Rapa Nui was formed out of volcanic rock starting some 3 million years ago. There are now 3 dormant volcanoes that dominate the landscape. This one is called 'Rano Kau.' No one knows exactly how many archaeological sites there are on the island but this place is like a living museum, constantly battered by the sun, the wind and the rain.
 
Those three elements are, over time, destroying the moai.
 
These statues may look as though they're solid stone, but they're actually quite porous. Jo Anne Van Tilburg showed us a small piece of the soft volcanic rock called tuff that the moai are made from.  
  
Jo Anne Van Tilburg: Tuff has really special qualities that-- where it can be carved and it can be polished quite easily.
 
Anderson Cooper: It's good for sculpting because it-- it's-- with a harder stone, it's able to be chipped away easily.
 
Jo Anne Van Tilburg: Correct. Correct.
 
Anderson Cooper: So the very material which made-- made these statues possible-- also, long term, makes them vul-- very vulnerable.
 
Jo Anne Van Tilburg: Exactly.
 
Rainwater and airborne seeds get into the pores of tuff, gradually breaking it apart. The wind whittles the stone away over time, and further damage is done by birds, and an organism called lichen.
 
Some moai are in worse condition than others. Take a look at this one called Tukuturi. This photograph is from 1955, when it was unearthed. This is how Tukuturi looks today.
 
Jo Anne Van Tilburg: The stone breaks very easily. It is just not stable.
 
Anderson Cooper: Essentially, I mean, they're dissolving.
 
Jo Anne Van Tilburg: Yeah, they are. I mean, if they're standing out in the rain, they're melting like sugar cubes.
 
Anderson Cooper: Like sugar cubes in the rain?
 
Jo Anne Van Tilburg: Exactly. It's that dramatic.

In the 1990s, with help from the Japanese government, the 15 moai at Tongariki, which had fallen or been toppled over, were reconstructed along with the stone platform they now stand on.

The UN has declared Easter Island a World Heritage Site, and efforts to slow the disintegration of the statues with a chemical sealant have been underway for decades, but so far only about 20 moai have been treated.  

The process is expensive, money the island doesn't have. It's also not a permanent solution. The sealant only delays the inevitable. One day these moai will likely disappear.

Anderson Cooper: Is there a plan? A-- conservation plan? An environmental plan for long term, in the future?
 
Pedro Edmunds Paoa: No.
 
Anderson Cooper: There's not?
 
Pedro Edmunds Paoa: None. None at all.

Mayor Pedro Edmunds Paoa is frustrated. There is a lack of consensus among the Rapa Nui about how to preserve the moai. And the island's infrastructure is under pressure from all the tourists who want to come see the statues.

A few decades ago there were only two incoming flights a week.
 
Now there are two almost everyday.
 
Cruise ships also make regular calls, just long enough for passengers to get off the boat, grab some souvenirs and snap a few selfies. In all, 120,000 tourists visited last year.
 
Pedro Edmunds Paoa: That's too much.

Anderson Cooper: If tourism continues to grow, is that sustainable here?

Pedro Edmunds Paoa: No-- it's not sustainable.

Cristian Moreno Pakarati is a historian who earns his living training tour guides.

Anderson Cooper: Do you have concerns about the impact of tourism?

Cristian Moreno Pakarati: So in material terms-- the community has never been better. But in general it's much less friendly than it was some time ago.

He says the more the island caters to tourists, the less like home it is for the people whose ancestors built the moai.

Cristian Moreno Pakarati: Today we are kinda forced to see the statues from far away, just like the tourists that come here. People of my generation, right, we could go there and touch the statues, and-- and be part of the statues, and hug the statues. How can I explain to my son today that my son cannot do that?

Despite no longer being able to touch them, he still feels the same sense of wonder he's always experienced when visiting the moai.

Anderson Cooper: You've been here probably thousands of times.
 
Cristian Moreno Pakarati: A thousand times. Yeah. No, it's still awesome. It's something that you-- you still feel awe when you're here.

Cristian Moreno Pakarati supports the efforts to preserve the moai, but believes it will take more than mana and money. He has his own, somewhat radical idea on how to ensure the moai keep standing.

Cristian Moreno Pakarati: The only way to keep them alive is to keep alive the art of making and moving statues.
 
Anderson Cooper: So you would like to see the people of Rapa Nui making new moai.
 
Cristian Moreno Pakarati: That's right. Because these will disappear one day. So if the art of making them is still alive, we will never lose the statues.

Produced by Keith Sharman. Associate producer, Alex J. Diamond.