Read aloud Around fifty years ago, a mysterious world map appeared in Europe: it was supposed to be from the time before Christopher Columbus and shows the coastline of North America. Allegedly, the map was drawn on the occasion of a council that met between 1431 and 1449 in Basel. Two research groups have now examined the map using the most modern methods. The card is a fake, claims one group from London. The map is real, say scientists from the American Tucson. On the document, which is supposed to reflect knowledge of Vikings, America is called "Vinland". The Norwegian conqueror Leif Erikson gave this name to the continent about a thousand years ago, which could mean either "wine country" or "pasture land". The arrival of the Vikings in America has now been proven beyond doubt. The name "Vinland" is also typical of Erikson and his men, who knew how to put their discoveries to contemporaries in a favorable light. Previously, Leif's father Erik the Red had given the name "Green Land" or Old Norse "Greenland" to a glacier island.

The Vinland card, which is said to be worth $ 20 million, was nevertheless quickly labeled as a fake: it showed a world that did not meet medieval expectations, argued historians. In addition, the coastline of Norway was so inaccurately recorded that they did not want to attribute it to the seaworthy Vikings.

In the ink chemists also found the titanium oxide anatase that can only be produced since 1923. In contrast, chemists argued that anatase could have been found in medieval inks containing iron compounds and bile. In fact, researchers later found the link in other medieval documents as well. On the Vinland card, the medieval ink seems to have turned yellowish on the paper. This is typical of old inks if they contain iron compounds. However, the Vinland card had a skilled counterfeiter, this could have imitated the effect.

Robin Clark of the College College in London and his colleagues have therefore studied the ink and the yellow edges of the ink closer. With highly sensitive laser spectroscopy they found anatase only in the yellow margins. However, the ink itself contains no iron but a carbon-based dye, they write in the journal Analytical Chemistry, (vol. 74, p. 3658). On an original there should have been no yellow edges, argue the researchers. This proved that the map was created after 1923. display

Meanwhile, chemists at the University of Arizona used the radiocarbon method to study the age of the parchment on which the map is recorded. The result of their study they describe in the August issue of the journal Radiocarbon, (Vol 44, p 45): The parchment dates from the period of 1423-1445. The researchers point out that the radiocarbon method in medieval documents particularly reliable is working.

ddp / bdw - Andreas Wawrzinek

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