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Terra Preta, or, The Lost Cities of Amazonia

December 17, 2010
The Ingá Stone

The Ingá Stone, a possibly pre-Columbian set of petroglyphs found in Paraíba State, Brazil. It's one of several pieces of evidence that the Amazon once held civilizations which were wiped out by disease after contact with Europe. Public Domain image by Jp. Juarez, from Wikimedia Commons.

One of the many inexplicable statements in historical literature is Gaspar de Carvajal’s description of his travels down the Amazon River with Francisco de Orellana. He says in numerous ways that the banks of the Amazon were stuffed with people, literally village after village for most of its length. No-one else reported this. All subsequent expeditions found the Amazon Basin much as it is today—thinly inhabited. Indeed it had to be this way, as Amazonian soils are notoriously poor for farming. The tragedy of modern-day deforestation of the jungle there is that the poor Brazilian farmers doing the cutting end up with farms that can’t support them for more than a few years before the soil’s nutrients are gone. Even the native Amazonians have to resort to slash-and-burn agriculture, clearing an area then moving on after a while to let the soil recover rather than settling in villages. De Carvajal, like many early explorers, must have been embellishing his tale to the point of lying.

Except maybe not.

De Orellana’s expedition was the first to reach the deep Amazon jungle, in 1541. Surprisingly he began from the west coast of South America, crossing the Andes from the Spanish conquests in Peru and then working his way down to the mouth of the river where the Portuguese had a presence. In between was terra incognita to Europeans. From the end of this expedition in 1542 until until 1637 there were no other trips up or down much of the Amazon (barring the bizarre Pedro de Ursúa and Lope de Aguirre episode two decades later).

Pedro Teixeira was responsible for that new expedition, and he reported a green desert: trees and rampant foliage, and no villages worth mentioning let alone entire civilizations. So it’s been down to the present day: if de Carvajal were telling the truth, the ninety-five years between the two expeditions concealed the death of literally millions of people and an entire way of life.

As archaeology climbed out of pseudo-science during the 19th century, its practitioners developed a hard-nosed attitude about lost civilizations. The Mayans may have been disappeared but Chichen Itza remained; we don’t even know what the Indus Valley people called themselves, but Mohenjo Daro is a monumental testament to their existence. Atlantis and the Lost Tribes of Israel, though? Well….

Until recently, Amazonian civilization fell into the latter category, and may end up there still. For a long time, De Carvajal’s account was the lonely piece of evidence that it ever existed, and since early travel accounts brought us such non-existent wonders as the gold-digging ants of Central Asia, archaeologists were skeptical.

A major problem is the Amazonian environment itself. As we’ve discussed elsewhere, archaeology is easiest in cold, dry environments where all sorts of artifacts can survive. Incan civilization’s remains include beautiful items made of cloth and wood thanks to the high desert in which many Incas lived. But the Amazon presents the opposite conditions: rampant moisture and life literally eat anything other than metal or stone. Worse, the Amazon is extremely short on stone, and no metals besides gold and silver (and a little copper in the Andes) were used south of Panama. Of the wood, bone, plant materials, cloth, and ceramic that could have been the foundation of Amazonian civilization, only the latter could have survived.

This leads to terra preta de Indio, or just “terra preta” for short, the Brazilian Portuguese name for an unusual phenomenon. Good farming soils have many silicate particles, which trap the nutrients a growing crop needs. Amazonian soils are low in silicate and high in aluminum and iron oxide; those oxides have the opposite effect to silicate, making nutrients susceptible to leaching when the rain comes down.

But here and there through the Amazon are patches of terra preta (“black soil”) that are extremely fertile despite being low in silicates as well. A high fraction of carbon particles from burned trees and plants, which also have nutrient-trapping properties, take their place. Furthermore, the carbon is buffered from rain by large amounts of crushed pottery mixed all throughout the soil. Some argue that terra preta patches are the remnants of Amazonian waste dumps and so happened by accident; the potsherds are just the broken leftovers of everyday items. Others argue that there’s just too much of it mixed in with the soil—that pre-Colombian Amazonians deliberately made pottery for the sole purpose of smashing it and using it to make farmable plots.

The final answer to this question depends on just how much terra preta there is, and for the moment we just don’t know. Estimates have varied between 6,300 square kilometers spread over the whole Amazon (in which case it’s reasonable to think its creation was an accident) to one hundred times that—in other words, the size of the entire Ukraine, the country with the fifth largest amount of arable land in the world.

Even if we accept that this question is nowhere near answered, though, we can understand something about pre-Colombian Amazonian life from terra preta. With one notable exception (the ancient Jōmon culture of Japan), pottery is only known in settled cultures: heavy and fragile, it’s just too much trouble for hunter-gatherers to carry around. Modern Amazonians aren’t settled in the present day, so the obvious inference is that their culture must have been settled the past and then changed for some reason.

There’s even another clue in a similar vein. An aristocracy, or even a simple chiefdom, depends on a surplus of goods, usually food (land aristocracies like “The Duke of So-and-So” are as they are because the land is worked by farmers). Permanent social hierarchies don’t develop until agriculture develops. Hunter-gatherer cultures or slash-and-burn agriculturalists are invariably egalitarian—there is no surplus of anything for a chief to hoard, and in the event someone starts trying to impose on the rest of his group, his prospective subjects can just walk away. Within limits any bit of land is as good as any other for gathering food or a new slash-and-burn plot.

But some Amazonian tribes do have aristocracies. The Yurimagua were known to have a “high king” of sorts into the 1700s, a time when the tribe was living at a hunter-gatherer level. Even in the modern day many tribes (for example, the Kuikuro) have complex social hierarchies, which is unique for societies that don’t engage in settled farming.

We even have evidence of one relatively advanced Amazonian culture, which was at the mouth of the river on Marajó Island. While not up to the standards of the Aztecs or Inca, the Marajoara culture raised funeral mounds full of pottery and built canals and weirs to raise fish.

So what happened? There’s still argument about when the Marajoara culture disappeared, with some saying before Columbus about 1400 AD and some saying as late as 1650. If the latter, it’s not unreasonable to assume that it gave way under the same pressure as destroyed the similarly unencountered central North American civilizations: the introduction of several European diseases to which Native Americans had no resistance.

The gap of 95 years between de Orellana and Teixeira is what makes this a workable hypothesis. If Europeans accidentally introduced smallpox, measles, and others to the central Amazon basin, they had time to repeatedly devastate the population to the point that they’d be reduced to hunter-gathering. The passing decades would have given enough time for the non-durable products of their civilization to decay and the passing generations would have blurred the Amazonians’ memory of their ancestors. Come the explorations of Europeans from 1650 onwards, there’d be little clue that Amazonians had lived any differently.

There are now increasing signs that this theory is correct. Starting in the late 80s and much more so in just the last few years a mixture of forest clearing and satellite surveying in the upper reaches of the Amazon have found evidence of a fairly advanced native culture in the uplands between stretches of Amazonian flood plain. Gaspar de Carvajal’s account is not the only evidence any more.

7 Comments leave one →
  1. December 18, 2010 2:36 AM

    Dear Mr. Dyre,

    I appreciate your additional cultural context telling the Terra Preta story.
    May I suggest to your readers ;
    The Biochar Solution : Carbon Farming and Climate Change
    by Albert Bates
    His work knits Orellana story with the New Genetic / demographic data, Archeological / Paleoclimate data that leaves your jaw on the floor.
    The missing pieces of Anthropogenic Climate Change fall into perfect order.
    Albert puts you in the canoes, fearing the next woman warrior attack or wondrous visions
    of plenty.
    Cutting edge Satellite research
    It ‘s main focus however is Biochar soil technology at Big, medium & small scale, here there and everywhere.

    In the “Annals of the Association of American Geographers”,
    I’m glad this work by Dr. Dull is getting attention. Together with Dr. William Woods and citing Bill Ruddiman’s work at UVA, the pieces of anthropogenic climate change fall into place.

    The Columbian Encounter and the Little Ice Age: Abrupt Land Use Change, Fire, and Greenhouse Forcing

    The implications are really important. Dull, et al, argue that the re-growth of Neotropical forests following the Columbian encounter led to terrestrial biospheric carbon sequestration on the order of 2 to 5 GtC, thereby contributing to the well-documented decrease in atmospheric C recorded in Antarctic ice cores from about 1500 through 1750. While the paper does not extend to the medieval maximum, from charcoal in lake bed studies it documents increased biomass burning and deforestation during agricultural and population expansion in the Neotropics from 2500 to 500 years BP, which would correspond with atmospheric carbon loading and global warming 1100 to 650 years BP.….608.2010.502432

    The charcoal & pollen evidence is hard to ignore.

    This NASA will settle how many acres and thus ..How many people.
    NASA’s Space Archaeology; $364K Terra Preta Program

    • Paul Drye permalink*
      December 18, 2010 9:08 AM

      I appreciate the further resources, thank you!

      I left out the modern efforts to reproduce terra preta as “not really part of the story”, but other readers interested in more about it are well-advised to look into bio-char. It’s an intriguing approach to increasing world food supplies, and one that gets a lot less press than, say, genetically modified foods or mechanization of farming in underdeveloped countries. It’s one of the few places where archaeology just might end up having a big effect on the future.

  2. December 18, 2010 11:12 PM

    Several years ago I proposed to the sim city and , IIRC, spore or spawn interactive video game creators to run biochar soil tech , “Terra Preta Nova” systems , feedstock scenarios , etc. After no repley.
    just wanted to stick this bug in your gamers ear.

    That effort however, lead me to write a screenplay outline;
    “The Biochar Script We Need”

    I sent that to PBS, Discovery channel shows on climate (with just plain stupid geo- engineering concepts,) and the producers of “Dirt” the movie. Some nice ..”but no budget” replies.

    Two months ago the special effects director of AVATAR, sent an email that He’s going to Cameron with the idea, making Biochar the Star of Avatar 2 or 3, He also wants to make a documentary around my screenplay outline, “The Biochar Script We Need”

    I can only imagine the follow on news stories about biochar’s reality in-context to the science fiction film.
    HEAD LINES; UnObtainium Now Obtainable
    Avatar 2 comes Down to Reality with Climate Change Solution.
    Un-Obtainium No longer Un-Obtainable

    I got a feeling that this black snowball is starting down the hill.

    Keeping my Braids crossed,

  3. new_biochar_land permalink
    February 1, 2011 2:12 PM

    You want to know all the secrets about biochar ?
    This book will help !

    Here practice and theory merge under a single cover of “The Biochar Revolution” and reveals hidden secrets of science called Biochar

  4. hren bzeettet permalink
    June 19, 2011 3:33 PM

    this is fucking fascinating, amazing write-up

  5. February 23, 2016 1:42 PM

    Reblogged this on The Stoker's Blog and commented:
    I love this kind of research. Combine it with a FFW into the future and you get all excited. I have mentioned at the other shops that we ought to consider universal constants of physics as not so much fixed permanently but hyper viscous and subject to transients from near and afar. My favourite for a good transienting being the Newtonian gravitational constant. Makes megaliths not so megalith. Anyway now that NA has intervened to kill off Europeans in large numbers this passed century, the meeting of the Argentenian Jesuit Babylonian Fish worshipper and the Muscovite Patriarch in Hispaniola this passed week or so dooms Europe to intervention from South America to save us from the enemy again by destroying the village Vietnamstylee. Expect more race change in Europe through dead Europeans again. It has been this way for at least 3000 years. Go tell the Etruscans and SA megalith builders.


  1. The NEW Hollow Earth Insider » Retro: Terra Preta, or, The Lost Cities of Amazonia

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