Using Lasers to Reveal the Secrets of Lost Civilizations

ON THE ISLAND of Rapa Nui—more commonly known as Easter Island—the monolithic statues known as moai rest on the slopes of a collapsed volcano called Rano Raraku. Native inhabitants carved these figures between the 13th and 16th centuries, archaeologists believe, as sacred embodiments of departed ancestors. Nearly nine hundred moai exist on the island, and many were moved long distances from the Rano Raraku quarry site, positioned as if to protect the land.

Today, you can still go visit the Easter Island statues, reveling in the effort it must have taken to construct and move them to their current positions. Other ruins, though, you may never have the chance to see with your own eyes. In recent months, ISIS has essentially bulldozed the ancient Assyrian city of Nimrud, destroying artifacts that date back to the 13th century BC. And they’re currently knocking on the door of the 2,000-year-old Syrian city of Palmyra.

In a world that consistently threatens humans’ valuable archaeological heritage, new digital preservation technologies can offer a small (very, very small) comfort.CyArk, a nonprofit organization in California, has digitally captured many sites and objects, including those ancient maoi on Rapa Nui, through LiDAR (light detection and ranging) data. The three-dimensional scanned images are helping the island’s modern inhabitants record their cultural history for posterity—and aiding researchers in their study of the past.

LiDAR isn’t so different from radar or sonar—it sends out pulses of electromagnetic radiation (in this case light, in the visible spectrum or very close to it) and analyzes it as the beams return. That analysis can detect the elevation of surfaces within a few centimeters. LiDAR is used to spot damage from natural disasters, to estimate the amount of carbon stored in an Alaskan forest and even to see London in new and weird ways.

It’s possible that these records will become crucial historical documents, if researchers can store them frequently enough. Consider the moai again: Accounts from Western explorers, recorded 50 years apart, indicate thatlife and politics on Rapa Nui changed dramatically during the 18th century. The island suffered intense civil wars, as deforestation and overpopulation took their toll. In the strife, moai were toppled and defaced, and thousands of people were killed. So much more of island’s ancient Polynesian history could have been preserved if LiDAR images were collected before that period of devastation.

Archaeologists have increasingly turned to LiDAR in recent years to survey their areas of interest, and some are explicitly working to make sure that they have a record of places that seem in imminent danger of being destroyed. As valuable as the work is, it’s no replacement for preservation in the first place. A point cloud just doesn’t quite match the real thing.
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Reference:

Venton, Danielle. 2015. “Using Lasers to Reveal the Secrets of Lost Civilizations”. Wired. Posted: May 20, 2015. Available online: http://www.wired.com/2015/05/lidar-archaeology/