Cities under the trees

Seeing through the trees

Lidar stands for light detection and ranging. A scanner in an aircraft maps the ground with laser light, and it can see through thick forest canopy to the shape of the earth beneath.¹ A mound that is a buried house, or a ridge that is a buried wall, shows up even where the trees hide it.

The survey covered more than 2,100 square kilometres of the Maya Biosphere Reserve in northern Guatemala. A team of 18 scholars from the United States, Europe and Guatemala studied the scans, with the help of PACUNAM, the Mayan Heritage and Nature Foundation, and published what they found in the journal Science in 2018.¹

What was under the forest

• 61,480buildingsFrom houses to palaces and pyramids, in the parts of the forest that were scanned.¹
• 362 km²of terraces and reshaped fieldsLand the Maya had changed to farm it.¹
• 952 km²of good farmlandLand that could be farmed.¹
• 106 km²of causewaysRaised roads joining cities to the land around them.¹
• Manydefensive earthworksLarge banks and ditches, a sign of war. The report does not count them.¹

The archaeologists said the scans showed in “a matter of minutes” what would have taken years of work on foot.¹ Lidar does not replace digging, though. Someone still has to walk to a sample of the places to check that a mound is really a building, and to date it.

How many Maya?

From the number of houses, the team estimated that 7 to 11 million people lived in the Maya lowlands at the busiest time, the Late Classic period, AD 650 to 800.¹ That is a guess built on a count: it depends on how many houses were lived in at the same time, and how many people lived in each.

The roads and fields matter as much as the temples. They show that Maya cities were not lonely islands in the jungle, but the centres of farmed, connected countryside. The causeways and earthworks also show, the researchers said, the scale of Maya warfare.¹