LiDAR Reveals Vast Ancient Cities Hidden in the Amazon

For centuries, historians and archaeologists believed the Amazon rainforest was a pristine wilderness sparsely populated by small, nomadic tribes. Recent technological advancements have shattered this assumption. A groundbreaking study published in the journal Science uses laser imaging technology to reveal a massive, sophisticated network of ancient cities in Ecuador’s Upano Valley, proving that complex civilizations thrived in the Amazon more than 2,000 years ago.

The Discovery in the Upano Valley

The most significant recent finding comes from the foothills of the Andes in eastern Ecuador. A team led by archaeologist Stéphen Rostain, a director of research at the French National Center for Scientific Research (CNRS), uncovered a dense urban network that dates back roughly 2,500 years.

While Rostain and his team had been excavating in the Upano Valley for decades, the density of the vegetation made it impossible to see the big picture. Ground-level digging could only reveal small sections at a time. The breakthrough came when the team employed LiDAR (Light Detection and Ranging) technology. This remote sensing method uses a plane to fire thousands of laser pulses per second at the ground. These pulses penetrate the thick canopy and bounce back to the sensor, allowing researchers to digitally strip away the trees and map the earth’s surface in 3D.

The resulting images revealed a landscape that had been hidden for millennia. The scan covered approximately 115 square miles (300 square kilometers) and exposed more than 6,000 earthen platforms arranged in a geometric pattern.

Anatomy of a Lost "Garden City"

These were not simple villages. The data shows five major settlements and ten smaller ones, all interconnected by a complex infrastructure that rivals ancient civilizations in Mexico and Guatemala. The researchers describe this urban layout as “garden cities” because of the seamless integration of residential areas with agricultural zones.

Earthen Platforms and Plazas

The core structures of these cities are rectangular earthen platforms. These mounds measured about 66 feet by 33 feet and stood roughly 6 to 10 feet high. Researchers believe these platforms supported wooden houses that have long since decomposed.

• Residential Units: Most platforms served as homes.
• Ceremonial Centers: Larger, monumental platforms were found in the center of the settlements, likely used for civic or ritual functions.
• Plaza Formation: The platforms were generally arranged in groups of three to six around a central, low-lying plaza.

The Road Network

Perhaps the most stunning revelation is the road system. The LiDAR scans show a highly organized network of straight, wide roads connecting the various urban centers.

• Dimensions: Some roads were up to 33 feet wide and stretched for 6 to 12 miles.
• Construction: The builders dug into the earth to create level paths, piling the soil on the sides to elevate the roads slightly above the surrounding terrain.
• Significance: The straightness of the roads suggests advanced planning and central coordination. They connect the settlements to one another and the wider region, indicating a unified society rather than isolated tribes.

Who Built This Civilization?

The civilization is attributed to the Kilamope and later the Upano cultures. Radiocarbon dating suggests the sites were occupied starting around 500 BCE and remained inhabited until between 300 CE and 600 CE.

This timeline is crucial. It places this Amazonian society in the same era as the Roman Empire in Europe. While the Romans were building London, the people of the Upano Valley were constructing a metropolis in the rainforest.

Population Estimates

Estimating ancient populations is difficult, but the density of the structures suggests a massive society.

• Conservative Estimates: Researchers believe at least 10,000 people lived in the Upano Valley area.
• Peak Estimates: At its height, the population could have reached 15,000 to 30,000, with some experts suggesting numbers as high as 100,000 for the broader region.

This level of population density requires intensive agriculture. The LiDAR images reveal extensive drainage fields and canals designed to manage water and cultivate crops in the fertile volcanic soil. The region is located in the shadow of the Sangay volcano, which provided rich soil but likely contributed to the civilization’s eventual decline due to increased volcanic activity.

Challenging the "Green Hell" Myth

For a long time, Western science viewed the Amazon as a “Green Hell” (a trap for humans) or a “Counterfeit Paradise” (lush looking but possessing soil too poor to support farming). This discovery drives a nail into the coffin of those theories.

The Upano Valley find proves that ancient Amazonians were distinct urban planners. Unlike the Maya or Aztecs who built with stone, these cultures built with earth. In the humid tropics, stone is rare, but earth is abundant. The lack of stone ruins is why these cities remained “lost” for so long; once the people left, the jungle reclaimed the mud structures, hiding them under vegetation until laser technology brought them back to light.

This discovery joins other recent finds, such as the Casarabe culture in Bolivia (found in 2022) and the geometric earthworks known as geoglyphs in Brazil. Together, they paint a picture of the Amazon not as the last frontier of untouched nature, but as a region that was once heavily managed, farmed, and urbanized by millions of people.

Frequently Asked Questions

What is LiDAR and how does it see through trees? LiDAR stands for Light Detection and Ranging. A specialized sensor attached to an aircraft sends out laser pulses. While many pulses hit leaves and trees, a small percentage reach the forest floor. By filtering out the data points returned by the vegetation, computers can create a precise 3D topographic map of the ground beneath the canopy.

Why did this civilization disappear? While there is no single confirmed cause, strong evidence points to volcanic activity. The Sangay volcano is nearby, and geological records indicate increased eruptions around the time the sites were abandoned (300-600 CE). This would have covered agricultural fields in ash and made the region uninhabitable.

Are these cities open to tourists? Currently, the sites are not developed for tourism in the way Machu Picchu is. The structures are made of earth and covered in vegetation. However, the recognition of their significance may lead to conservation efforts and educational centers in Ecuador in the future.

How does this compare to the Maya or Inca civilizations? The scale is comparable, but the materials are different. The Maya and Inca used stone, which survives well. The Upano culture used earth and wood. In terms of complexity, the road networks and urban planning in the Amazon show a level of societal organization similar to the great empires of Central and South America.