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Unearthing History: How Technology Is Transforming Archaeology


Legend has it that the rainforest of Mosquitia hid La Ciudad Blanca, the White City. For centuries, explorers tried to find the fabled city in the jungle of Nicaragua and Honduras. Protected by white water, coral snakes, stinging plants and brutal topography, the White City remained an archeologist dream. But with a new application of recent technology, a documentary filmmaker, not an archeologist, found the White City.

In The New Yorker magazine, Douglas Preston tells the story of Steve Elkin's amazing discoveries. Doug Preston is an author and contributing writer at National Geographic, The Atlantic and Smithsonian magazine. His piece, "The El Dorado Machine," is in the May 6th edition of The New Yorker, and he joins us from his home in Santa Fe. Welcome to TALK OF THE NATION.


CONAN: And the El Dorado Machine, well, it turns out it's an old Cessna with a new piece of equipment in it.

PRESTON: That's right. It has a huge box that they call the LiDAR machine which basically can pierce through the jungle's foliage and map whatsoever on the ground underneath.

CONAN: And this LiDAR machine can penetrate even triple canopy rainforest.

PRESTON: It's absolutely incredible. It strips it out completely. And you can actually see something as small as a meter on a side, sitting on the ground underneath this incredibly dense rainforest.

CONAN: And this rainforest, it turns out even sites that had been discovered by archeologists before that the LiDAR technique from the air found vastly more than the archeologists ever suspected.

PRESTON: It's absolutely incredible. It's a revolution in archeology that, for example, they recently mapped the Mayan city of Caracol in Belize. And archeologists had been mapping this city for 25 years and they flew - for five days they flew this machine over the city of Caracol and they found that the archeologists had missed 90 percent of what was there. The archeologists had missed temples, pyramids, roads, terracing, caves, tombs - it was unbelievable what the LiDAR machine was able to see that the archeologists had missed.

CONAN: Well, that brings us to the story of the White City which had been, well, an archeologists dream as we suspect - as we said, for centuries. And well, it's sort of a legend in Guatemala.

PRESTON: Well, it really is a legend. In fact, most archeologists really didn't believe it existed. It was first mentioned by Cortez when he was exploring the coast. He heard about golden provinces in the interior. There are a lot of Spanish rumors. And in the early part of the 20th century, a number of American explorers and adventurers went into the jungles of Honduras looking for the White City. They also called it the Lost City of a Monkey God. And there are a bunch of explorers who claim to have found it actually but they were just finding large ruins.

So about 20 years ago, or 15 years ago, a scientist at the jet propulsion laboratory in Pasadena noticed from looking at satellite imagery that this very remote valley in the mountains of Honduras showed what he thought were unnatural curvilinear and rectilinear features that might hide a city. And - but no one has ever been able to get to this valley. It's absolutely - it's almost impossible to get there. The jungle is so thick, the mountains are so high and there's so much, you know, dangerous animals and white water and so forth. So no one was able to explore this valley.

So Steve Elkins managed to persuade the National Center for Airborne Laser Mapping which is a group at the University of Houston, financed by the National Science Foundation, to explore the city from the air and map it or map the valley from the air to see if anything was there.

CONAN: And that raises a question. Some of the scientist you talk to sniffed contemptuously that this was an adventure, an Indiana Jones-type. This wasn't real science.

PRESTON: Well, there's a lot of controversy now in archaeology over the use of LIDAR. I mean, LIDAR is an extremely expensive technology. It cost half a million dollars to survey this valley, and archaeologists are a very impecunious group. They don't have a lot of money. They don't have the kind of financing that some of the other scientists get. So they look at LIDAR as being too expensive. It's a technology that they don't understand - some of them. Engineers run it, not archaeologists. So there was a - so a number of archaeologists look askance at this search. They didn't think that anything would be found. Or if they find something, it wouldn't be very important.

CONAN: Tell us a little bit about Steve Elkins.

PRESTON: Well, he's a filmmaker. He's an amazing person. He's one of these - he's a true adventurer. I guess he's sort of a kid who never grew up. I'm kind of like that too. I mean, I never stopped dreaming about finding lost cities and being the first one in Egyptian tombs and that sort of thing. And he's sort of like that. And he had fallen in love 20 years ago with this whole White City legend and had been trying to find a way into this valley where this JPL Scientist has been seeing something for 20 years.

And he organized an expedition. It was washed out by Hurricane Mitch. And then he heard about LIDAR, and he said, wow, this is the way to find stuff in the jungle. Instead of sliding on the ground, let's fly over this valley and see if there's anything in there. So he called me up and he said, hey, do you want to be part of this expedition?

CONAN: And you, of course, agreed and ran down to Central America and ended up as, well, I guess, extra cargo in the back of a very rickety old plane.

PRESTON: Well, you know, I have to be honest with you. I really didn't believe that they were going to find anything in this valley. It was such a crazy idea. I mean - and when I looked at the images that the JPL scientists had been looking at, to me, they look like a Rorschach test. I mean, you stared at it long enough and you could see anything in there. I mean, I could see Jimmy Hoffa's body if I looked long enough. But - so I didn't think we're going to find anything.

But I thought, well, gee, you know, I'm a journalist, like, you know, I got to do my job. So they jammed me in the back of this plane. There was no place for me. They actually had to remove some safety equipment to get me in there. And we took off. We were flying out of the island of Roatan, which is off the coast of Honduras, deep into the interior mountains, absolutely, incredibly remote.

I just couldn't believe how remote this was. And so, you know, we flew to the mainland and inland and then picked our way through the mountains and then pretty soon arrived at this valley which has never been explored. There's no evidence that anyone has ever been in there - and started mapping.

CONAN: And it is amazing because the LIDAR shoots billions of bursts of energy down to the ground. And then there's computer magic that can measure exactly how far off the surface of the ground the signal is returned so it can eliminate all the leaves and the wood from the trees and that sort of thing and then give you a picture of the ground.

PRESTON: That's it. It's a very interesting technology. It shoots this - 125,000 laser pulses a second down at the rainforest canopy. Now - and then it measures the reflections. Now, 99 percent of what's reflected comes off leaves. But here and there, there are tiny gaps in the canopy where a laser beam can reach the ground, bounce off and go back up to the plane. And then with massive software processing, they're able to remove all the reflections from leaves, leaving only the ground.

And it's just incredible to see these scientists at work. I mean, you see this impenetrable rainforest canopy. And then with a press of a button, it disappears and you see everything on the ground. It's absolutely amazing.

CONAN: Well, it's a little more complicated than that. They have to then process the signals that they receive back from the ground. As you say, most of them come back from leaves. And I think, what, they handed you the disc and you flew it out and gave it to the computer guy.

PRESTON: Well, that's right. And in fact, it is very complicated. The LIDAR machine has inside it a highly classified thing called an IMU, an Inertial Measurement Unit that was developed for the military for use in guided missiles. And in order to get an export permit for the plane, the State Department required that the plane be guarded by armed soldiers at all times when it was on the ground because this is a very highly classified piece of equipment. Because it's important to locate the plane in the air in three dimensions as it's flying to within an accuracy of about a centimeter. I mean, that's incredible.

CONAN: Mm-hmm. So you rushed this data off to the computer guy and he did his magic. How did you - what did you - when did you actually see the picture?

PRESTON: Well, I brought it back from that evening on the island of Roatan, and he processed it. He had to crunch the data. There was also data that had to come from Houston that had been collected by them, and all those had to be combined to make this map. And he was working till the wee hours of the morning making these maps. And then the Internet connection was down so he went to bed. His name is Michael Sartori, by the way. He was a really fascinating guy.

But then he uploaded those images in the morning to Houston and the - one of the directors of NCALM, this organization, the National Center for Airborne Laser Mapping, a guy named Bill Carter, was the first one to look at the images and he was in West Virginia. He was about to go out and buy a refrigerator or something, and this email came in with these images attached.

He looked at them, and he said, oh, my God. He was thunderstruck. He almost immediately saw in this valley pyramids, structures, buildings, plazas, terracing, roads. He saw this incredible amount of archaeological features that he recognized immediately even though he's not an archaeologist.

CONAN: So not just a lost city, a lost civilization?

PRESTON: That's right. He emailed Michael back in Roatan, and I'll never forget we were returning from breakfast and this normally phlegmatic kind of skeptical scientist who is rolling his eyes at the whole idea that there is going to be lost city comes running out of his room, racing in his flip-flops, waving his arms and yelling, there's something in the valley. My God, I don't know what it is, but you've got to come and look at it. So we all went rushing over to this room and looked at these images. And I looked at them and I was actually thunderstruck myself. I mean, there is no mistaking what we were looking at.

CONAN: We're talking with Doug Preston, an author and contributing writer at National Geographic, The Atlantic and Smithsonian magazines. He also writes for The New Yorker. "The El Dorado Machine" is in the May 6th edition. You're listening to TALK OF THE NATION from NPR News.

And eventually, other target areas were also mapped and also revealed enormous structures - entire cities.

PRESTON: Well, that's the thing. Three areas we've looked at - covering about 55 square miles of the jungle - target one, target two and target three. And the first one was target one, and we found these all these archeological features. They covered hundreds of acres, maybe even thousands of acres, and this is gigantic. And then they moved on to target two, and they marked that, and then they moved on to target three. And target three showed even more striking features.

And we've - an archaeologist has been looking at them and a guy named Chris Fisher, who is an archaeologist at the Colorado State University, who's an expert on LIDAR, and he tells us that there is a city in T3 that is comparable in area to the city of Copan. It's absolutely enormous. The track is two square - five square kilometers.

CONAN: And if these valleys are so remote, how did these civilizations develop in this unforgiving area?

PRESTON: Well, that's the thing. We're only now starting to realize that this so-called virgin or impenetrable jungle in prehistoric times was anything but. It was very heavily settled. There were many thousands of people living in these areas, and it wasn't virgin jungle. It was more like a tended garden. They cleared huge areas for farming. They terraced. They built irrigation canals. They built roads. They built enormous pyramids and structures.

And the idea that the rainforest of Central and South America - the soils were too poor to support major agriculture and large populations turns out to be a false idea. In fact, even in Amazonia, they're now realizing that these supposedly impenetrable jungles in Amazonia were, in fact, heavily settled by people in prehistoric times.

CONAN: And they are remote today, but not too remote to be of interest to loggers.

PRESTON: Well, that's the unfortunate thing. Illegal logging is destroying huge areas of the rainforest and Honduras is, you know, because these mountains are so difficult to get into, the rainforest has been sort of protected by the geography. But, you know, a single mahogany tree can be worth hundreds, even thousands of dollars and people are very poor. And so when we flew into these mountains they could see incredible amounts of illegal logging, you know, plumes of smoke rising as far as the eye could see.

Now, when we actually flew into these valleys, there was no illegal logging, it hadn't been touched yet. They didn't seem to have been penetrated by human beings. But all around, surrounding it, you could see where illegal logging was just eating away at the jungle and exposing these areas to looting and, you know, destruction.

CONAN: And, in fact, you wrote that this city discovered in the T3 area, well, it might be gone and destroyed by logging before it can be surveyed by archaeologists.

PRESTON: Well, that's right. These areas are very vulnerable. These ruins, as soon as loggers get in there, they open them up and there's looting, destruction, fires, you know, they burn, slash and burn. There's agriculture taking place. And, you know, Chris Fisher, the archaeologist working with us said, gee, you know, we've got to get into these areas right away because who knows how long they're going to last.

CONAN: And are there plans to send people in on the ground? And if so, are you going with them?

PRESTON: Yes. As a matter of fact there's a major expedition planned to one of these lost cities. They'll go in by helicopter, probably, in the early part of 2014. And I'll be - they promised me a berth on the chopper so I'll be one of the - one of those guys setting foot into the lost city for the first time in a thousand years.

CONAN: Well, good luck and bring out pictures.

PRESTON: Well, thank you. I'm looking forward to it.

CONAN: Doug Preston is a fiction and non-fiction writer, and author, and fellow of the Royal Geographic Society. His piece "The El Dorado Machine" is featured in this week's edition of The New Yorker. He joined us by Skype from his home in Santa Fe.

Tomorrow, Gwen Thompkins and Trombone Shorty will join us to talk about New Orleans, it's long recovery from Katrina and its future with jazz. I'm Neal Conan. Join us for that conversation. I'm the TALK OF THE NATION from NPR News. Transcript provided by NPR, Copyright NPR.