Cinematographer Steve Elkins announced last week that by using LiDAR (light detection and ranging), he discovered "what appears to be evidence of archaeological ruins in an area long rumored to contain the legendary lost city of Ciudad Blanca." The phrasing "lost city" is problematic, however: it's hard to lose a city when the city itself is a myth.

The mapping project, conducted over 40 hours split between seven flights during April and May, was led by Elkins' group, UTL Scientific. Participants include the thriller writer Douglas Preston, who is the former editor at the American Museum of Natural History. The project took place in conjunction with the government of Honduras with the help of technicians from the National Science Foundation's National Center for Airborne Laser Mapping and professors from the University of Houston.

The tech

The LiDAR survey covered the history-rich northeastern Mosquitia region of Honduras. They overflew the area, sending "25 to 50 laser pulses per square meter—a total of more than four billion laser shots" to the ground, according to the University of Houston, and capturing differences in elevation of as little as four inches. This process can look underneath forest canopies, producing a 3D map of areas in hours or days that an overland, machete-hacking expedition might take years to do.

The UTL survey employed an Optech Gemini Airborne Laser Scanner aboard a Cessna 337 Skymaster plane overflying 923 square kilometers at a height of 600 to 1,000 meters above the ground. According to UTL, 4 billion LiDAR "shots" were fired at a pulse rate of 125KHz.

Modern, high-intensity LiDAR is a recent innovation. The first archaeologists to use it to startling effect were Arlen and Diane Chase at Caracol in Belize, mapping more ground in four days, they said, than they had in their previous 25 years of exploration of the area.

Chris Fisher, as we detailed in a previous article, used it to extend the breadth and establish the importance of the Purepechan city of Sacapu Angamuco in western Mexico.

The problem

Now comes Ciudad Blanca, and the conflation of the ruins of the city the group found with a mythological city is ringing some alarm bells with a number of archaeologists.

Berkeley archaeologist Rosemary Joyce titled her post on the discovery "Good science, bad hype, bad archaeology." Making the rounds in the scientific community, Joyce's post takes the principals to task for not making archaeologists with a history in the area part of the team. The archaeologists, she claims, would never allow such implications to be released. However, Elkins denies that he has done so.

"I have never claimed to have discovered the legendary city of Ciudad Blanca," Elkins told Ars. "I have only stated that we found what appear to be significant archaeological ruins in an area that (according to legend) could be the location of the fabled site.... More often than not, legends have a kernel of truth in them. Perhaps one day someone will be able to say conclusively whether or not (or to what degree) there is any factual credence to the stories about Ciudad Blanca."

So perhaps all the blame for that trope lies with journalists. Certainly a lot of it does. However, it's hard to imagine that Mr. Elkins included mention of the mythic city in his press release with no idea that it would find a purchase in the public imagination. His above statement seems to indicate it has found some purchase in his.

Ground truthing

Although Professor Joyce makes a good case for the utility of her profession's exacting standards, she also comes close to dismissing the technology involved. "LiDAR can produce images of landscapes faster than people walking the same area, and with more detail. But that is not good archaeology, because all it produces is a discovery—not knowledge," she wrote. "If it’s a competition, then I will bet my money on people doing ground survey. And I will be betting less money: LiDAR is expensive. And I question the value you get for the money it costs."

Fisher and the Chases, who have used the technology, have made the case for LiDAR marking a "tipping point" in archaeology. They contend that it is far from just another technology, subordinate to the tyranny of pick and shovel. And if archaeologists can find more in four days of LiDAR flyovers than they could in 25 years on the ground, as Chase asserted, it is demonstrably cheaper.

Elkins said he hopes future steps in his organization's exploration will include "ground truthing" the LiDAR data, as per Joyce's admonition.

"We are hoping to organize a multi-disciplinary scientific ground exploration of some of the areas we have surveyed in cooperation with the Honduran government. Archaeologists will be an integral part of the team and it will be up to them to decide what it is the LiDAR imagery revealed."

Technology is making it possible for those with a passionate interest in history—but no grounding in the rigors of archaeology as a discipline—to make huge-scale discoveries. But those folks can also allow their imaginations to take the lead. Elkins and the Ciudad Blanca situation are reminiscent of the filmmaker Simcha Jacobovici ("The Naked Archaeologist"), who regularly announces discoveries made and mysteries solved, despite the disagreement of many, if not most, in the scientific community.

So it might also be accurate to say that, just as the technology can overwhelm those without the necessary knowledge to evaluate it, it can also allow non-specialists to push past the threshold of reliability.