A cosmic event recorded in ancient trees all over the planet allowed to date exactly when the Vikings were in America. Researchers do not know when they arrived or how long they remained, but the wooden rings of various objects show that the Norse settled in what is now northern Canada in 1021, exactly a millennium ago.
Apart from the Icelandic sagas, part of the oral history of the Nordic peoples, there are not many references to the Viking presence in America. The most consistent evidence is the archaeological site of L’Anse aux Meadows (Jelly Inlet), located on the island of Newfoundland in the far northeast of Canada. In excavations, carried out in the sixties of the last century, evidence was found that these houses had been built by the Vikings. One such evidence is the sharp, angular cut in the wood, something that could only have been done with axes or other metal tools. And the original inhabitants of the region were unaware of metallurgy. Due to the oral tradition and architectural style of the buildings, historians believe that L’Anse aux Meadows was built around the end of the first millennium. But until now the exact date was unknown.
Taking advantage of a solar storm that hit Earth in the year 992, a group of scientists managed to date not when the Vikings arrived in America, but when they were already there. The innovative and original way of finding out is explained by Michael Dee, a researcher at the University of Groningen (Netherlands) and research director: “Trees absorb carbon from the atmosphere and incorporate it into their rings during their growth”, says this professor of chronology by isotopes. This discipline relies on the fact that various elements of the periodic table vary their atomic composition (isotopes) upon radiation at a known rate. “Part of that carbon is radiocarbon,” says Dee. And that year the levels soared.
Details of the survey were published in the latest issue of the journal nature. “There are records of rings all over the world formed by wood from millenary trees, or preserved in swamps or peat bogs, without knowing exactly the year of growth of each ring”, explains Dee. This is the basis of a science known as dendrochronology, which uses rings as time markers. Thus, the age of a tree is not only known. By capturing environmental conditions, the logs can tell stories about past glaciations, volcanic eruptions, when the magnetic poles reversed or what’s happening with climate change. Recently, says Dee, “a peak in the concentration of radiocarbons in the ring was discovered in the ring corresponding to the year 993”, that is, the year following the solar storm, whose cosmic rays would have raised the concentration of carbon-14 in the atmosphere.
What they did at their Isotope Research Center was to analyze three pieces of cut wood found at L’Anse aux Meadows. The three are from different trees (a Christmas pine, a juniper and a cypress) and all three have the 993 anomaly engraved. ring is 993. We only had to count to the edge of the bark to determine when the last ring was formed, that is, when the tree was cut down. We applied the same method to three different pieces of wood from three different trees, and they all returned the cut date of 1021″, explains the Dutch scientist.
Dendrochronologist Raúl Sánchez-Salguero, from the Pablo de Olavide University, recalls that several carbon isotopes coexist in the atmosphere (carbon 12, carbon 13, carbon 14). “Solar storms disturb the Earth’s magnetism, modifying the atmospheric composition, disturbing the relationship between 12 and 14, for example. During the photosynthesis process, the trees capture these variations”, he explains. “The year 992, like the year 774, was a brutal cosmic event recorded by trees all over the planet, hence the precision of the dating of Viking wood,” he adds.
Although Vikings arrived in America nearly 500 years before Columbus, their presence did not extend far beyond Jellyfish Cove, not even in time. The Dutch researcher sums it up: “Scientifically we can’t say much more about how long they stayed. They spent a year or several times on short stays. Or maybe they stayed a little longer, maybe a decade. All archaeological evidence suggests that his stay was relatively short”.
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