Ancient Maya ruins digitized by laser aerial survey

Archaeology in the 21st century looks radically different than what you might expect. While archaeologists still get their boots wet and perform fieldwork, trowels and picks in hand, their modern toolkit also includes artificial intelligence algorithms that reveal new hidden statistical patterns in ancient samples or state-of-the-art lasers that shoot billions of beams per minute from an aircraft onto the ground. It’s this latter combination of lasers, known as LIDAR, and AI that allowed researchers to uncover hidden ancient Maya ruins that had been obstructed by vegetation and the wear of the passing centuries.

3D image of Labna, an ancient Maya structure in the Puuc region. Credit: Proyecto Arqueológico Regional de Bolonchén.

Thanks to LiDAR (light detection and ranging) technology, archaeologists don’t have to wander endlessly through the jungle in search of artifacts and hidden ruins. By strapping LiDAR to a low-flying aircraft, it’s possible to survey thousands of square kilometers of terrain at a time.

LiDAR or 3D laser scanning was developed in the early 1960s for submarine detection from an aircraft. It works by generating a laser pulse train that can travel through the gaps of dense vegetation. By calculating the time it takes for the laser pulse to reflect back to its source, researchers can determine the elevation of the ground. This way, archaeologists can identify human-made features on the ground, such as walls, roads, and buildings.

Archeologists have put LIDAR to good use while surveying Mayan sites before. In 2018, LIDAR revealed more than 60,000 hidden Maya structures at the site of Tikal in Guatemala. In 2020, the laser-based tech led to the discovery of the largest and oldest Maya monument, found in the Mexican state of Tabasco.

Now, LIDAR has been deployed to the northern Yucatán Peninsula, at an area of limestone hills and valleys known as the Puuc region, in present-day Mexico. Appropriately, Puuc is the Maya word for “hill”.

It was at Puuc that one of the greatest Mayan cities, Uxmal, evolved, reaching its apogee between AD 600 and 900. William Ringle, a professor emeritus of anthropology at Davidson College in North Carolina, has spent over 20 years doing groundwork in the Puuc region, which is home to four large acropolises that had been documented since the 1940s. But thanks to a few LIDAR aerial surveys in 2017, Ringle’s team discovered more about the Maya site than in the past two decades.

Ruins of a two-story Maya palace. Credit: Proyecto Arqueológico Regional de Bolonchén.
Another Maya ruin from Puuc. Credit: Proyecto Arqueológico Regional de Bolonchén.
A ruined structure that used to divide the Plaza Icim from the Plaza Yaxche in the Puuc region. Credit: Proyecto Arqueológico Regional de Bolonchén.

Writing in a study published this week in the journal PLOS One, Ringle and colleagues described how they identified over 1,200 ovens, about 8,000 platforms for dwellings, artificial reservoirs, terraces for farming, and a rock quarry for construction materials.

3D overview of Labna palace at Puuc. Credit: Proyecto Arqueológico Regional de Bolonchén.
A ruin east of Kiuic built by the Maya in Puuc. Credit: Proyecto Arqueológico Regional de Bolonchén.

According to the researchers, a large number of circular ovens were likely used to heat sandstone in order to extract lime, an essential material used for mortar and to help soften maize. Before the LIDAR survey, archaeologists identified around 40 ovens. “Now, with lidar, we have a sample of over 1,230,” Ringle told Live Science.” They’re all over the place. And that indicates that it was a pretty big industry in the Puuc.” 

The area was also home to a burgeoning stoneworking industry. Most of the buildings identified by the researchers were masonry houses, suggesting that Puuc was highly prosperous. These included civic buildings known as early Puuc civic complexes, which involved several buildings with a plaza that were connected via elevated causeways.

LIDAR of houses at the Maya sites of Acambalam (B) and Kiuic (C). Credit: Ringle et al, PLOS ONE.
LIDAR of Middle Preclassic civic instructures. Credit: Ringle et. al, PLOS ONE.

The civic and religious structures erected had a distinctive style: stone facades embellished with mosaics and friezes and the prolific depiction of Chac, the Mayan rain god. 

One by one, after about AD 900, the Puuc cities were abandoned and swallowed up by the forest until they were“discovered” by later explorers and archaeologists.

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