Discovered from the Air: Lost Cities of Amazon

Amazon is one of the last great wildernesses on the planet.

Discovered from the Air: Lost Cities of Amazon

Amazon is one of the last great wildernesses on the planet. However, legends persist that there were once cities hidden deep in the Amazon. Many Spanish explorers were lured away from the map by the search for El Dorado (a city of gold), but some never returned. Percy Fawcett, a British explorer, searched for the Lost City of Z as early as the 20th century. He disappeared into the jungle, adding his unfinished chapter to a story that began 600 years earlier.

Scientists have now discovered that Amazonian ancient cities do exist. It is still difficult to find urban ruins in dense, remote forests. But a key technology has changed the game. Scientists sat in a helicopter at 650 feet and used light-based remote sensing technology (lidar), to digitally clear the canopy and identify ancient ruins of an abandoned urban settlement in the Bolivian Amazon. It was located around Llanos De Mojos, which was established 600 years ago. These new images show the Casarabe Culture, which is complex and socially important, clearly in its final form (500-1400 C.E.). Urban centers are known for their monumental platforms and pyramid architecture. Raised causeways linked a series of suburban-like settlements that stretched for miles across a landscape that was shaped and controlled by massive water distribution systems with reservoirs, canals, and other infrastructures. This site was described in Nature this week. It is the most striking evidence that Amazon's rainforest "wilderness" was in fact heavily populated. In some places, it was quite urbanized for centuries before the recorded history of the area began.

Heiko Prumers (German Archaeological Institute) is co-author. He cites an old Spanish proverb that says no one is as blind as someone who doesn't want it to be. He says, "It's a myth created by Europeans who actually spoke of a forest and vast areas untouched by human beings." "So many people didn't want the discovery that there are archaeological sites that deserve exploration.

He adds, "I'm certain that in the next ten or twenty years we'll have a lot more of these cities and some bigger than those we present in our paper."

Michael Heckenberger, an Anthropologist at the University of Florida was not involved in the research, but has been studying urbanism and pre-Columbian Amazon for almost two decades. He noted that some elements of Llanos de Mojos' settlement, such as moats and causeways and modified landscapes of parklands and working forests, can be found elsewhere in the Amazon. The new research reveals something entirely new. The Upper Xingu region in Brazil, where Heckenberger is a member of the Kuikuro Nation, has been an example of urbanism in Amazon. These settlements could be described as a network of villages. Experts argue that they are not technically urban because they lack defined centers with monumental architecture such as platform mounds or U-shaped temples. Llanos de Mojos has these urban centers. Heckenberger says that this is the best example of an urbanized Amazonian landscape. It's an amazing piece of work. It shows the incredible range of human activities that were done in the past to manage their landscapes, and work with larger populations.

Remote-sensing and previous archaeological work had previously revealed hundreds of sites on more than 1,700 acres of the Llano de Mojos area. These included settlements that were inhabited all year by the Casarabe who hunted and fished for staple crops such as maize. There were 600 miles of canals and causeways that had been identified. However, the logistical difficulties of mapping them in remote tropical forests hampered attempts to connect the dots and determine if or how they were related.

It is difficult to find the remains and explore the remote forest area. Prumers says that there is no way to see what's below the ground until you reach it. Once you're there, you will have trouble finding and orientating the sites.

The team carried out airborne lidar mapping in six areas. These ranged from 4 to 32 square miles and gave them a bird's-eye view of the area that was the heartland for Bolivia's Casarabe culture, which occurred between 500 and 1400 C.E. A lidar system is a device that fires infrared beams from an aircraft. Each beam bounces back with a distance measurement when it strikes anything on the Earth's surface. This creates a huge cloud of data points that can be fed into computer software to create high-resolution images. Scientists can then digitally deforest Amazon. The maps are created by removing trees and revealing the Earth's surface as well as the archaeological features. The images showed 26 sites that were unique, 11 of which were previously unknown.

Two large urban centers, Landivar (and Cotoca) were among the 26 sites. Although they were known to exist, the new maps revealed their complexity and immense size (1.2 and 0.5 miles, respectively). Each large center is surrounded with successive rings of rampart and moat fortifications. These sites feature artificial terraces, large earthen-platform buildings, and conical pyramids that reach 70 feet high. Scientists believe that all these magnificent civic and ceremonial buildings are also oriented towards the north-northwest. This is consistent with a cosmological view seen elsewhere in the Amazon at ancient sites.

Two centers were revealed in the aerial view, with all trees removed. Each center was anchored by a network of regional settlements linked by many causeways. These passageways extend for many miles from the center like spokes of a wheel. These passageways connect sub-urban settlements. They can be found from closer settlements to the center to smaller, more remote sites that could have been used for temporary camping. Canals connect to the main centres and to Laguna San Jose, which may have brought water to Cotoca.

Chris Fisher, an archaeologist at Colorado State University who is not involved in this study but specializes in Mesoamerica, says that "essentially they reshaped the landscape in terms their cosmology which is mind blowing." This architecture was built from mud brick. It was a stunning looking structure at the time, but the Maya monuments survived because they had limestone. These were not as durable.

The Casarabe are certainly not as well-known as the Maya. Who were they? Their culture has been revealed by a decade of archaeological research in the region. It was more likely that they lived in an area with riverside forests and an annual flooded savannah than in the unbroken timber stands one finds today.

Andean cultures are not far from the Andes, with their prominent monumental platforms mounds, temples, and other structures. Prumers says that the urbanization of these areas was not due to an Andean influx or their influence. "The Andes have been very well studied, and you won’t find any sites of this nature in the Andes. So we can confirm it’s not something that originated from the Andes." It is unique Amazonian.

It is not clear what happened to the Casarabe or their settlements, but dates at the sites suggest that their occupation ended in 1400 C.E., just before European arrivals in the Amazon. Prumers speculates that widespread drought could have been the cause. His team discovered large reservoirs of water storage at various locations, something that isn't typical in an Amazon region with abundant rainfall.

He says, "Officially, we don’t know if they were for a water supply or to farm fish and turtles, but we are very curious that we have them." We know there have been severe droughts in the Amazon region several times throughout history. This could have also happened to this culture. You only need to lose one or two years' worth of crops before people can move.

Although it was a tragic end, the Amazon's culture survived and is now proving that the Amazon is not a great wilderness area. It wasn't an unbroken forest up until fairly recent times.

Paleoclimate research has shown that much of Amazon's forest may be older than previously thought. It also suggests that large areas of the Amazon were open savannah environments long before Europeans arrived in Americas. This environment would have allowed for landscape engineering, which is becoming increasingly apparent. Many Amazonians likely lived in urban and suburban settlements that had high levels of sociopolitical organization.

Michael Heckenberger spent decades working in Brazil's Xingu area. There, dozens of communities he called 'garden city' have homes, plazas, and palisade walls. Although the sites do not have large monumental centers like those in Bolivia, they are connected by a network of roads, bridges, and canals. They are all located in an engineered landscape of fields and fish farms, and other features. It is interesting to note that this low-density urban culture, which was more like a cluster of suburb communities without an urban centre, was found in the same area where Percey Fawcett disappeared in search of the Lost City of Z.

Although they are difficult to find in the forest, geoglyphs, which are clearly human-made earthworks, have been discovered in many other Amazon locations. Scientists using satellite images discovered that large areas in Brazil's Mato Grosso State had been populated by villages and strangely-shaped geoglyphs. Many hundreds of villages could have accommodated up to a half million people between 1250 C.E. and 1500 C.E., even though they are far from the large rivers. This area is only about 7 percent the size of the Amazon basin. These populated areas could have been anchored by larger urban centers, but they are not yet identified.

These settlements were discovered through hard work. Despite the presence of large, sophisticated populations who once lived here, it has been difficult to find any evidence of urbanism in the densely forested Amazon. Future discoveries will be accelerated by lidar technology. Chris Fisher says that lidar technology has had a transformative effect on archaeology. This work is an excellent example. He says that the researchers were able see patterns that aren't visible from the ground. The pattern clearly showed two large settlements that were embedded in a settlement system with a level that isn't possible in the Amazon. It's amazing."

Although the Amazon may have once been a hub of human activity, Prumers points out that many ancient sites have remained relatively unaffected for over 500 years. This is a huge advantage. He says, "The area has a very low population density. That means we are finding almost unaltered the relics pre-Spanish culture over there."

However, the Amazon is rapidly changing. To promote agriculture, ranching, energy production, and roads and dams that facilitate such endeavors, forests are being removed. Many of these areas will be lost, as they contain hidden histories of past cultures. Fisher calls for large-scale lidar scanning of Amazon and other areas through an Earth Archive project that aims to capture what remains of the past, before it is lost.

He says, "We are running out of time as we lose the Amazon." "And we're about to lose things we didn't know were there. That's a tragedy to me."