Doubts crept in around Greenland, which looked so good it was frankly suspicious, and questions soon spread all over the map: about the wormholes, the handwriting and, most important, the weirdly crumbling ink.
For over half a century, scholars have fought over the authenticity of the Vinland Map, which Yale University unveiled to the world in 1965, calling it at the time evidence of Viking explorations in the western Atlantic, the first European depiction of North America and a precious medieval treasure.
Yale now says someone duped a lot of people.
"The Vinland Map is a fake," Raymond Clemens, the curator of early books and manuscripts at the Beinecke Rare Book and Manuscript Library at Yale, said in a statement this month. "There is no reasonable doubt here. This new analysis should put the matter to rest."
The university said that a team of conservators and scientists, analyzing the elements in the map's lines and text, found high levels of a titanium compound used in inks that were first produced in the 1920s. Clemens said the team hoped to publish an article in a scientific journal. Ars Technica, Smithsonian Magazine and Gizmodo, among other news outlets, reported the conclusion this month.
Elizabeth Ashman Rowe, an associate professor of Scandinavian history at the University of Cambridge, said it was "deeply satisfying to have the strongest possible scientific confirmation of the historians' longstanding arguments that the Vinland Map had to be a forgery."
Experts in the field, she said, had long since determined that the map was a forgery along the lines of the Kensington Runestone, a carved stone on a Minnesota farm that scholars found to be a 19th-century hoax. But the debate over the map persisted, with decades of competing claims.
"It went on and on, like a tennis match over 20 years or more," said William Fitzhugh, the curator of North American archaeology at the Smithsonian National Museum of Natural History. He praised the Yale team's work as thoughtful and well done, adding, "We need to put a lid on this can."
The researchers also found that a Latin inscription on the back of the map was overwritten with modern ink, which Clemens called "powerful evidence that this is a forgery, not an innocent creation by a third party that was co-opted by someone else."
The map can be traced at least to 1957, after Laurence Witten, an antiquarian in New Haven, Conn., acquired it from an unknown source in Europe. He sold the parchment to philanthropist Paul Mellon, who donated it to Yale.
In 1965, Yale revealed the map to the public, with stories appearing in major newspapers, including on the front page of the New York Times. At the time, the school's experts believed the map was compiled around 1440, about 50 years before Christopher Columbus sailed west.
Archaeologists and scholars have no doubt that a small number of Norse people reached the area of Newfoundland and the Gulf of St. Lawrence around A.D. 1000, with evidence both in 13th-century sagas about the journeys and the archaeological remains of a Viking settlement at a site called L'Anse aux Meadows, in Newfoundland.
There were probably fewer than 100 people on the largest of those voyages, and the travelers landed on shores where Native people lived in large numbers, said Gisli Sigurdsson, a professor of Norse studies at the Árni Magnússon Institute in Iceland.
When the Vinland Map appeared in 1965, not long after the Newfoundland discovery caused a sensation, scholars quickly raised doubts about the parchment. While the curator of maps at Yale's library at the time saw the "amazingly accurate" drawing of Greenland as evidence of Viking exploration, others saw it as the mark of an artist looking at a 20th-century map.
Greenland's northern coast was drawn "suspiciously similar to what you can see on modern maps," Sigurdsson said. "Greenland is so close to the real Greenland, it's hard to believe anyone in the Middle Ages would have drawn a map like that."
It also seemed unlikely for a medieval scribe to know Greenland — drawn for centuries as a peninsula — was an island.
Cartographers raised other questions. They noticed that its ink was crumbling off "in a very strange way that medieval map ink doesn't crumble," Fitzhugh said.
Scholars also raised questions about whether holes in the map matched wormholes in an authentic medieval volume that was thought to be the source of the map's calfskin parchment.
"No one in the actual field of Norse studies or Vinland studies has believed in the authenticity of the map for a long time," Sigurdsson said.
Clemens said the map would remain in Yale's collection, calling it a "historical object in and of itself" and "a great example of a forgery that had an international impact."