• A team of researchers has brought to light a Mayan archaeological site using lidar technology, a laser remote-sensing technique.
• The ruins are located in the state of Campeche, in Mexico, and comprise more than 6,000 structures.
• This technology promises to uncover numerous other historical sites that remain unknown to this day.

The buried past is speaking to us again, revealing ancient civilisations: a team of archaeologists has identified thousands of previously unknown ancient structures, including pyramids, hidden in the dense Mexican jungle. In the southern state of Campeche, on the Yucatán Peninsula, more than 6,600 structures linked to Mayan civilisation have come to light. The experts used lidar, a technology that allows the ground to be scanned from above using lasers, revealing the presence of buildings and settlements beneath the thick vegetation.

Mayan civilisation discovered thanks to laser technology

Mayan civilisation reached its peak between 300 and 900 AD, and the descendants of this ancient culture still inhabit the region. The pre-Columbian civilisation, one of the most powerful in the Mesoamerican area, built cities with ceremonial temples and magnificent stone pyramids in what are now Mexico, Honduras, Guatemala and El Salvador. "For a long time, our knowledge of Mayan civilisation was limited to a few hundred square kilometres, mapped by archaeologists who, with great effort, explored every square metre by cutting paths through the vegetation," one of the researchers explained. However, instead of sending teams into the field, his team analysed existing cartographic data covering an area of approximately 122 square kilometres.

The discovery was made by Luke Auld-Thomas, an anthropologist at Northern Arizona University. Auld-Thomas and his fellow researchers managed to map the city beneath the jungle using airborne laser scanning, better known as lidar (light detection and ranging), a remote-sensing technique that uses pulsed lasers and other data collected via overflights to generate accurate three-dimensional models of surface features, revolutionising the way archaeologists explore the hidden past.

The team discovered three sites in total, within a survey area the size of Edinburgh. As Auld-Thomas explained to the BBC, the discovery came about almost "by chance", while the archaeologist was browsing data online: "On page 16 of a Google search, I found a laser survey carried out by a Mexican organisation for environmental monitoring." Once the data had been processed with lidar, Auld-Thomas saw what others had not: an enormous ancient city that may have been home to between 30,000 and 50,000 people at its peak from 750 to 850 AD. The findings were subsequently published in the journal Antiquity and highlight a vast and diverse complex of Mayan settlements not yet studied, scattered throughout the region.

Among these discoveries, one entire city stands out, named Valeriana by the team in reference to a nearby freshwater lagoon. This urban centre comprises two main clusters of "monumental architecture", connected by continuous settlements and landscape engineering works.

"We didn't only find rural areas and small settlements," researcher Auld-Thomas stated. "We also identified a large city with pyramids right next to the only motorway in the area, near a village where people have been farming among the ruins for years."

As recently as last year, a Mexican team had identified an ancient Mayan city dating back to around 1000 AD in the same area. But unlike the American researchers, that group had no access to lidar technology and trekked 60 km through dense vegetation to reach the site.

The complete absence of any knowledge of these settlements, on the part of both the government and the scientific community, suggests there are many more discoveries waiting to emerge. New laser technology will certainly play a crucial role in this ongoing exploration of the past.