It’s been a long time: welcome back any and all reading this. Since we last met I’ve been off writing another blog/book, False Steps: The Space Race as it Might Have Been, and the last little while has been spent revving up for a science fiction novel. In honor of the Passing Strangeness book being published (finally!) however, I felt it was time to dust things off here and start writing about what old and weird corners of history I’ve encountered since the last post here. Feel free to take a peek at the book’s webpage, visit the sister site linked above, poke around in the archives, or just scroll down a bit to read what may become the first essay of Passing Strangeness, vol. 2.
There have been three nuclear power plant meltdowns that have captured worldwide attention and left the general public with the opinion that nuclear power is too dangerous to rely upon. The most dangerous have been the meltdowns at Chernobyl in 1986 and Fukushima in 2012, both of which have left large areas where no-one can live. Three Mile Island is the other name to conjure with, though it was considerably less disastrous than the other two (it rates a 5 on the INES scale of accident severity, while the other two are a 7). To this we can add the Windscale Fire, also a 5, which was covered in secrecy at the time but became a rallying point for opposition to nuclear power in Britain after it became known in later decades.
There have been several other meltdowns and partial meltdowns besides these, few even as severe as Three Mile Island, and in many cases they occurred in the early days of nuclear power when reactors were experimental and so correspondingly more dangerous. Most were clear of fatalities, but the SL-1 meltdown in 1961 killed three people. What’s particularly unusual about SL-1 is that it was at the very least a case of egregious operator error, and there exists the possibility that it was a bizarre case of murder suicide.
In 1954 the US Army began a project to evaluate nuclear reactors for use in the Arctic, as they were ramping up to build the DEW line in the extreme north of Canada and Greenland. Their requirements were strict: small, simple, low maintenance, and able to be flown in by air. They were also to be stationary (as opposed to naval submarine reactors) as well as low-power (200 kW of electricity and 400 kW of heating), hence the initials SL. The idea was to be able to set one up and forget about it, giving very isolated military installations reliable power. By 1957 they contracted the Argonne National Laboratory, near Chicago, to build them an prototype reactor that met their needs; by the end of October 1958 it was built and operational on the National Reactor Testing Station, in the wide-open spaces of southeast Idaho about forty miles from Idaho Falls.
Army personnel, mixed with some Navy, began training on SL-1. What one of these trainees would have encountered on leaving the reactor’s support building and climbing the stairs to the top of the small, cylindrical building containing the reactor was something a bit like a missile silo. There was a circular working area, the center of which was taken up by the top part of the reactor where the control rods could be manipulated. The reactor and its water cooling mechanism were beneath this, descending to the ground level.
On December 21st, 1960 the reactor was shut down for maintenance, recalibration, and the installation of instruments for monitoring the neutron flux in the reactor core. Work to get the reactor back up and running began on January 3rd, 1961. On that day the reactor was configured for less power than it was designed for, 3 MW, with only 40 of 59 possible fuel assemblies in place and five (of nine) control rods. It did mean that the reactor would be more sensitive to manipulation of the control rods, though, and in particular the “one stuck rod” rule—that it should still be possible to shut down the reactor even with one rod stuck in the “completely out” position—was contravened.
In the evening of January 3rd the personnel working on the reactor were two Army Specialists, Richard L. McKinley and John A. Byrnes, and a Navy Seabee, Richard C. Legg. At 9:01, Byrnes was performing a part of the restart that required him to manually pull up the central control rod by 10 centimeters to reattach it to its drive mechanism, which was disconnected as part of the shutdown before Christmas. Post-incident calculations showed that instead the rod was abruptly lifted by 66.7cm. At 58.4cm the reactor went prompt critical. In the split second it took for the rod to travel the remaining 8.3cm, the reactor spiked to 20 GW, 6300 times its safe operating capacity.
Just prior to the spike the recommissioning protocol had dictated that the reactor be largely drained of water. Under the influence of the immense surge of power the remaining fluid caused a water hammer that that traveled through the air separating it from the top of the reactor vessel and hit it at 175 km/h. The resulting pressure smashed the entire top of the reactor into the ceiling of the reactor building at high speed.
Nine minutes later the first responders appeared, on-site fire personnel reacting to a fire alarm. They’d been dealing with false alarms most of that day and expected more of the same. At first all they saw was some vapor rising from the building, which was normal given the extreme cold (the low the night previous had been -6°, measured in Fahrenheit, which works out to about -20 Celsius). Instead their radiation detectors spiked as they climbed the stairs of the reactor building. From there the reaction to the incident steadily escalated until at 10:45 PM sufficiently protected rescue personnel managed to enter the badly damaged control room to retrieve Byrnes, who was dead, and McKinley, who was still alive but was contaminated to the point that he was emitting 500 roentgens per hour. He succumbed to head trauma shortly after, but could not have possibly survived the dose of radiation he had received even if he hadn’t died of his wounds. Fifteen minutes later they found Legg, also dead—he had been impaled to the ceiling by one of the plugs used to seal the unused control rod channels. When he was finally retrieved six days later he showed little sign of decay; the radiation had sterilized him and the immediate area of any possible microbes that might have done the job.
At first a regular explosion was suspected, and the assumption was that the high radiation levels detected were incidental after the reactor’s fuel was spread around the building, but analysis of Byrne’s gold watch showed that it was laced with highly radioactive 198Au, which was only possible if the reactor had gone critical and bombarded the watch with neutrons (that particular isotope being precisely one neutron heavier than regular, stable gold).
The question then became “Why was the central control rod moved so far?”. Ultimately the investigators settled on the theory that it had stuck in its channel when Byrnes tried to lift it, and that he was moving it back and forth to unstick it. He succeeded while pulling too hard, the rod came loose, and the three were dead before he even had an idea of what he had done.
Countering this is the fact that, while there were incidents of control rods sticking in SL-1’s past, they had all happened while the reactor was operating. The reconnecting maneuver Byrnes performed on the cool reactor had never once produced a report of a stuck rod.
Apart from their favored hypothesis, the investigators felt that they could not rule out two other possibilities: suicide, or murder-suicide on the part of Byrnes. Operators of the reactor knew the consequences of pulling out the central rod of the reactor. In a history of the Idaho nuclear reactor test range published in 2012, former operators were quoted as saying that, informally, they’d decided to do just that in the event of a Russian invasion, destroying SL-1 to deny it to the enemy.
There was probably tension on the reactor site when the three began their work shift at noon that day. Byrnes had been assigned to the program the same month as Legg, October 1959, but he’d been surpassed by his classmate and January 3rd was the first day where Legg was Byrnes’ supervisor. Things got much worse for Byrnes at 7:00 when he received a call from his wife, Arlene. Their marriage had been in trouble for some time and the Christmas break had made things worse. Over the phone she asked him for a divorce.
At the very least Byrnes was probably not focusing as well as he could when 9:01 rolled around. An accident is certainly possible, but so too is suicide. In the absence of any living witnesses to testify to his state of mind in the last two hours of his life, it’s impossible to tell. Whether it was also murder depends on how much credence you want to lend to the idea that Byrnes wanted to take Legg with him. As it happens, their new job situation was not just a source of tension between them but the latest. Several sources cite them coming to blows at a party the previous year.
One way or another, three men died in an instant. Legg is buried in Arlington National Cemetery, though his remains are in a lead-lined casket inside a metal vault with a concrete lid. Parts of all three men were so radioactive that, after they were autopsied they were not buried religiously but rather treated as dangerous waste and moved with other dangerous residue of the accident to a site 500 meters northeast of SL-1’s former site—it being deemed too dangerous to move all of it by public highway for 26 kilometers to the site normally used for radioactive waste. Along with those mortal remains of the men killed by the only fatal reactor accident in US history, the ultimate reason for the explosion lies sandwiched between native basalt bedrock and tons of rip rap in a dry and dusty part of rural Idaho, never to see the light of day again.
Meltdown: The SL-1 Nuclear Accident, a contemporary training film presenting the accident the nuclear professionals, now on YouTube. Contains a great deal of footage of the cleanup effort.
Proving the Principle – A History of the Idaho National Engineering and Environmental Laboratory, 1949-1999. A free book (in PDF format) outlining the history of the whole time and place, including one chapter devoted to SL-1 both before and after the accident. Page 149 is the source of the information that the operators knew what would happen if the central control rod was removed.
Ladies and gentlemen, I’m happy to say that the Passing Strangeness e-book is nearly ready to be published. I’ll have more details for you within a few weeks.
As it starts to wrap up and I wait out a variety of bureaucratic processes, I’ve begun a new book project False Steps. As before, work will be posted beforehand in a blog, which can be found here. In it I hope to trace a variety of ways in which the Space Race (which I’ve generously expanded outside of the usual 1957-1969 time frame to 1939-Present Day) might have gone. If you liked the Passing Strangeness posts Orbital Longshot and The Ghost Rockets, it just might be your cup of tea. Regardless, I invite you to come on over and check it out — Paul Drye
Beneath Land’s End and Scilly rocks
Sunk lies a town that Ocean mocks.
– Unattributed rhyme from Legend Land, Volume 2, George Basil Barham, published in 1924
The Isles of Scilly barely enter into history. About the only major event associated with them was the Scilly Naval Disaster of 1707, when the gloriously named Admiral Sir Cloudesley Shovell sailed a significant fraction of the British Navy into their shallow waters, losing four ships and approximately 1,400 sailors’ lives—including his own. The disaster led to the solution of the Longitude Problem by means of naval chronometers, and as these precise clocks spread they and their descendants revolutionized war, industry, trade, and science. Thank Admiral Shovell when the alarm clock wakes you tomorrow morning. However, the other particularly interesting thing about the Isles of Scilly looks back into the past rather than forward into the Industrial Age.
Britain is lousy with towns and even entire lands lost to the sea. H.P. Lovecraft was influenced by the story of Dunwich in Suffolk: one of the most important towns in medieval England, it was progressively swept into the ocean after a storm surge hit it in 1286. A bit further east the central part of the North Sea covers Doggerland, which was above sea level during the last Ice Age and only submerged about 6500 BC; the author owns a chunk of mammoth tusk dredged up from the area. The effect of the Ice Age on Britain hit Scilly too, but in a less obvious way. The southern half of Britain is further underwater than it should be after accounting for the melting of ancient ice caps, while the north is, in places, actually higher than it was at the Last Glacial Maximum, 20,000 years ago. This is because one of the ice caps was actually on Scotland and Northern England, and the weight of the ice pressed that section of the island down. Now that the ice has been removed, Britain has been slowly rebalancing itself, and the southern reaches are subsiding as the north rebounds, like a great tectonic see-saw.
This post-glacial rebound is continuing even as we speak, so the Isles of Scilly—literally the most southern point of England—have changed well into the last couple of millennia. It’s worth looking at the British Admiralty’s depth charts for the waters around the islands. The rather small brown areas are the present-day Isles, while the green represents flats that can become exposed if the tide is low enough. The blue area is a rough approximation of what Scilly would have been like some time in the past, with a depth of four meters or less. As you can see, this produces a single large island (sometimes called Ennor after a castle on the largest of the present islands, St. Mary’s) out of most of the plural, 21st century Scillies. The main difficulty here is knowing just when this island existed. Charles Thomas, emeritus Professor of Cornish Studies at Exeter University has suggested it disappeared some time around 1600 BC, but others have suggested that it existed until more recently—possibly as late as 500 AD. It’s worth noting that the Roman name for the Isles, Scillonia insula, is singular.
If the latter is true then Ennor existed well into the Celtic period of Britain, which is interesting because there are several legends about drowned lands in Celtic mythology. Readers who know their Thomas Malory (or Jack Vance) are aware of Lyonesse, home of the Arthurian Tristan, and Lyonesse has long been associated with the Isles of Scilly. However, there are signs that the association is a 16th-century invention. The first known mentions of Lyonesse in literature are just variations on Lodonesia, which is the Roman name for Lothian in Scotland; “Tristan” itself is just a variant, via Latin, of the Pictish royal name “Drust″. The identity of Lyonesse and Scilly (or, rather, the Seven Stones Reef , deathbed of the Torrey Canyon, to the northeast) wasn’t entirely cemented until Alfred, Lord Tennyson got his hands on it in his mid-19th century Idylls of the King.
All is not lost, however. The Celtic legends go deeper than Lyonesse, to stories such as Brittany’s Ker-Is (or Caer Ys, if you prefer the more common Welsh or Narnian spelling to the Breton). It too is a sunken land, this time placed in Douarnenez Bay south-east of Brest. There is even a potential connection between it and Scilly: Mont Saint-Michel is not too far away on the border between Brittany and Normandy and it was the sister house of the remarkably similar-looking St. Michael’s Mount in Cornwall—right where the British coast is closest to Scilly and where a drowned forest can be seen at low tide. It doesn’t take a lot of imagination to suppose a Breton monk, familiar with the story of Ker-Is, being transferred to St. Michael’s Mount when it was gifted to the Norman monastery in the 11th century and him making the obvious inference when he saw what was in the water.
On the other hand, the story may be entirely native. The Welsh have a similar legend, Cantre’r Gwaelod, which is supposed to be a drowned hundred in Cardigan Bay. If it comes down to it, the story could even be both native and imported. After all, Brittany was colonized by Britons from Wales and Cornwall in the 4th and 6th centuries (a trek legendarily led by a Welsh prince whose name hits two fantasy heroes in one blow, Conan Meriadoc). Ker-Is may just be the colonists’ version of Cantre’r Gwaelod, 1500 years on.
The main difficulty with fitting Ennor to any of these stories is that they’re all of sudden inundation. Most are about sinful lands suffering the wrath of God and feature a single survivor literally galloping his horse away from the clawing waves—a myth memorialized in the coat of arms of the Trevelyan family of Cornwall. The flooding of Scilly’s central plain would have taken many years; a snail could have escaped, let alone a horse. Still, this isn’t a fatal rupture of the connection between the two. Human beings have a knack for making stories more interesting, and it’s not too difficult to see a folk tale that “once there were farms under the bay” slowly turn into a story of dash and adventure, especially under the influence of the biblical story of Noah.
Ultimately, we’ll learn more about Ennor only through archaeological investigation. Surprisingly for the heritage-mad United Kingdom there’s never been a large-scale investigation of the waters around the present-day isles. But the so-called Lyonesse Project began in 2009, and is to run until 2011. Its goal is to determine what the Isles of Scilly were like prior to inundation. Results are expected in the next few months.
In the history of astronomy up to 1992 there were only two people who could cleanly claim to have discovered a planet: William Herschel found Uranus and Urbain Le Verrier can claim Neptune; if you’re feeling somewhat charitable, you can give half of Neptune to John Couch Adams. For almost eighty years Clyde Tombaugh was in this group, but Pluto was famously demoted in 2006. The discoverers of the first four asteroids (Giuseppe Piazzi who discovered Ceres; Pallas’ discovery by Heinrich Olbers; Karl Harding who claimed Juno; and Olbers again with Vesta) had a similar fate. For close to forty years they were planet-discoverers. All their “planets” were discovered between 1801 and 1807, and were considered important enough for the title because they were the only known planetoids until Astraea was discovered in 1845. But that discovery signaled a rash of new inhabitants for the Asteroid Belt—eighteen more by the end of 1852, and a total of 62 by 1860; it became clear that the previously lonely four were something quite different from planets and so they were downgraded.
Since the 1990s, though, a variety of new techniques has uncovered more than 500 more planets to date—the difference now being that increases in instrument sensitivity make it possible to see planets outside of the Sun’s system, in the systems of the much more distant stars. For a little while in the 1960s and early ’70s, though, one other astronomer made a plausible claim that he’d discovered a planet, and it too was outside the Solar System.
That astronomer was Piet “Peter” van de Kamp, from 1937 to 1972 the director of Sproul Observatory of Pennsylvania’s Swarthmore College. Van de Kamp’s claim needed to be taken seriously because his specialty was the tiny motions of stars in the sky and the announcement depended on just that.
It seems that while studying the proper motion of 18,000 stars he started considering the possibility that he could find a planet or planets around Barnard’s Star. Barnard’s Star is notable for two main reasons: it is the second closest star system to the Earth (third, if you count the Sun), and it has the largest proper motion of any star. In other words, it changes its position in the sky faster than any other, taking “only” 173 years to cover a width equal to the full Moon’s. Van de Kamp’s insight was that while planets themselves were invisble to the technology of the time, no star with planets would move in a straight line. Instead, the planets would tug it this way and that as they orbited the star, causing it to make tiny loops in the sky. As Barnard’s Star was so close, the loops would be relatively large and easy to see.
Of course, “relatively” is the key word here. Barnard’s Star was already making little loops because of the Earth’s own motion around the Sun, and they would be about 100 times larger than the ones caused by any planet orbiting the distant star. Depending on exactly how big the hypothetical planet was, and how far away it was from the star, the displacement it caused would be on the order of a micrometer (one one-millionth of a meter) on Sproul Observatory’s photographic plates. Nevertheless, van de Kamp thought he could pull it off.
He began his observations shortly after moving to Sproul in the spring of 1937, and kept them up for 26 years before announcing that he had in fact discovered a planet around Barnard’s Star. By his calculation it was about 60% bigger than the planet Jupiter, and it orbited the star at a distance of 4.4 AU (a bit shy of Jupiter’s distance from our own Sun). His discovery made quite a splash, as being the first to see an extra-solar planet (even indirectly) was a major coup. Other scientists had a hard time duplicating his results, but this was no great surprise: it relied on the Sproul Observatory’s 24-inch refractor, a kind of photographic telescope that was being mothballed in other observatories in favour of spectroscopic ones; furthermore van de Kamp had needed more than two decades of observations to be sure. It was going to take time for anyone else to check his results.
The first sign of trouble came after van de Kamp announced planets around other stars too: Epsilon Eridani, 61 Cygni, and one he’d mooted back in 1951, Lalande 21185. Another astronomer, Bob Harrington, noticed that the shape of the planetary wobbles was the same for all three, and for Barnard’s Star too—as if it were the photographic plates that were moving, not the stars. That turned out to be the case. When it was first made the Sproul Observatory telescope van de Kamp was using had had one of its lenses inserted the wrong way, and while the effect on its operation was very small, in 1949 it had been removed and reset the proper way. The slight change in the lens had made a slight change in the way light focused on photographic plates taken with the telescope, and by bad luck the change was about the same size as what van de Kamp had been expecting to see from his planets. He agreed that all of his data prior to 1950 was now suspect, but still argued that everything taken since then still supported his discovery.
With the idea of instrument error now in the open, though, another astronomer by the name of George Gatewood published a paper in 1973 which demolished van de Kamp’s planets. The consensus is now that there was a cycle causing the image of the stars to move, but that it was down here on Earth. The telescope underwent regular maintenance, and every time it did its focus shifted ever so slightly and made any star it observed appear to have moved. Ironically, Gatewood eventually changed his mind about one of van de Kamp’s claims, Lalande 21185, but this too has turned out to be instrument error
After retiring, van de Kamp returned to his native Netherlands, where he died on May 18th, 1995. To the end he believed he had found at least one planet around Barnard’s Star, and maybe two. One real set of planets, orbiting the pulsar PSR 1257+12, had been discovered in 1992 but they were a peculiar case having probably formed after a supernova and not giving any real insight into planets in the universe as a whole. The Golden Age of Extra-Solar Planets began when Michel Mayor and Didier Queloz announced they had discovered 51 Pegasi b (AKA Bellerophon) just under five months after van de Kamp passed away. Its existence, as well as that of hundreds of others of new planets since then, has been demonstrated conclusively using two new techniques called the Doppler Method and the Transit Method. Van de Kamp’s photographic method is now considered a dead end.
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.