LiDAR Reveals Ancient Amazon Cities
For centuries, archaeologists and historians viewed the Amazon rainforest as a pristine, sparsely populated wilderness. The dense canopy made it nearly impossible to see what lay beneath the forest floor. However, a revolutionary technology called LiDAR (Light Detection and Ranging) has recently stripped away the trees digitally to reveal a shocking truth. The Amazon was once home to massive, complex urban societies that rivaled the Maya in sophistication.
The Discovery in Ecuador’s Upano Valley
The most significant breakthrough occurred recently in the Upano Valley, located in the eastern foothills of the Andes in Ecuador. A team of researchers led by archaeologist Stéphen Rostain discovered a sprawling network of ancient cities that dates back roughly 2,500 years.
Published in the journal Science in early 2024, the findings document a dense system of urban centers constructed by the Upano people (specifically the Kilamope and later Upano cultures). These settlements were inhabited roughly between 500 BCE and 300 to 600 CE.
This was not a collection of small, isolated huts. The LiDAR survey covered approximately 300 square kilometers (115 square miles) and revealed over 6,000 rectangular earthen platforms. These platforms were arranged around plazas and connected by a highly advanced network of roads.
Key Architectural Features Found
- Earthen Platforms: The scans show rectangular mounds measuring about 20 meters by 10 meters. These likely served as foundations for wooden houses or ceremonial buildings.
- Central Plazas: The platforms are organized around central squares, indicating a planned community structure rather than random expansion.
- Monumental Complexes: Some areas contain much larger platforms, suggesting civic or religious centers that would have required collective labor to build.
How LiDAR Technology "Sees" Through the Jungle
To understand the magnitude of this discovery, it helps to understand the tool that made it possible. LiDAR is a remote sensing method that uses light in the form of a pulsed laser to measure ranges (variable distances) to the Earth.
When researchers fly an aircraft equipped with LiDAR over the Amazon, the sensor shoots hundreds of thousands of laser pulses per second toward the ground. While most of these pulses hit the tops of trees, a small percentage penetrate the gaps in the leaves and hit the forest floor.
By filtering out the data points that hit the vegetation, computers can generate a precise 3D map of the ground surface. This reveals “anomalies” that are invisible to the naked eye, such as unnatural straight lines, mounds, and depressions. What would take an archaeologist decades to map on foot with a machete can now be surveyed in a few days of flight.
The Great Road Network
Perhaps the most startling revelation from the Upano Valley data is the complexity of the road system. The LiDAR images show long, straight roads connecting different urban clusters.
These were not simple footpaths. The main roads were up to 10 meters (33 feet) wide and stretched for 10 to 20 kilometers. The straightness of these thoroughfares suggests the Upano people possessed advanced engineering skills and a centralized system of governance to plan and maintain them.
The connectivity implies distinct social relationships. Different settlements were linked physically, likely facilitating trade, military movement, and religious gatherings. The scope of this infrastructure challenges the long-held belief that Amazonian societies were small and disconnected.
Agriculture and Land Management
The “Garden Cities” of the Amazon relied on sophisticated agriculture to support a large population. The laser mapping revealed extensive drainage fields and canals interspersed among the residential areas.
The soil in this region is fertile due to volcanic activity from the nearby Sangay volcano. The ancient inhabitants modified the landscape to manage water runoff and maximize crop yields. They likely grew maize, manioc (cassava), and sweet potatoes.
This level of agricultural intensification is evidence of a sedentary lifestyle. These people did not roam the forest as hunter-gatherers; they stayed in one place for centuries, reshaping the land to feed a population that researchers estimate could have reached into the tens of thousands—comparable to the population of London during the Roman era.
Connecting the Dots: The Bolivian Finds
While the Upano Valley discovery is the current headline, it connects with previous findings to form a larger picture. In 2022, distinct LiDAR research in the Llanos de Mojos region of Bolivia revealed the Casarabe culture (500 to 1400 CE).
The Bolivian sites feature massive earthen pyramids up to 22 meters tall and causeways raised above the seasonal floodwaters. Like the sites in Ecuador, these findings prove that high-density urbanism was not unique to the Andes (like the Incas) or Central America (like the Maya). The Amazon basin itself was a cradle of civilization.
Why Did These Cities Disappear?
If these civilizations were so large and advanced, their disappearance requires explanation. In the case of the Upano Valley, there is a significant gap in the archaeological record after roughly 600 CE.
Researchers suspect that the very geography that made the land fertile also caused their downfall. The nearby Sangay volcano is one of the most active in the world. It is highly probable that a series of violent eruptions blanketed the region in ash or triggered lahars (mudflows), forcing the population to abandon their urban centers.
For other Amazonian societies, the arrival of Europeans brought diseases like smallpox and influenza, which traveled along trade routes faster than the explorers themselves. These pathogens likely decimated populations before written records could be made, leaving the jungle to reclaim the cities until lasers brought them back to light.
Frequently Asked Questions
What is LiDAR? LiDAR stands for Light Detection and Ranging. It is a technology that uses laser pulses from an aircraft to create detailed 3D maps of the ground, effectively “seeing” through dense vegetation.
Where represent the largest ancient Amazon cities found? The most recent major discovery is in the Upano Valley of eastern Ecuador. Significant urban centers have also been mapped in the Llanos de Mojos region of Bolivia.
How old are these Amazonian cities? The cities in the Upano Valley date back to around 500 BCE and were inhabited for over a thousand years. This makes them roughly contemporary with the height of the Roman Empire.
Did the Amazon cities have stone pyramids? Unlike the Maya or Incas who built with stone, Amazonian civilizations built primarily with earth and wood. They constructed massive earthen platforms and pyramids, which are harder to identify without technology like LiDAR because they blend into the landscape when overgrown.
How many people lived in these cities? Estimates vary, but researchers believe the Upano Valley network could have supported a population of at least 10,000 people, and potentially up to 30,000 at its peak.