American map of 1434 is a modern fake, scientists claim

Two London University researchers claim today that the celebrated Vinland Map, purportedly drawn in the mid-15th century showing the New World as discovered by Nordic explorers, is a fake from the early 20th century.

The claim, to be detailed in the journal American Chemical Society, will rekindle debate over the authenticity of the map, which is owned by Yale University. Three American institutions believe the parchment is genuine.

Robin Clark, a professor at University College, and a colleague, Katherine Brown, said inspection of the ink under a Raman microscope, which uses a laser beam to scatter molecules as radiation with different colours, showed it was made after 1923. "The results demonstrated the great importance of modern analytical techniques in the study of items in our cultural heritage," Professor Clark said.

Believers have long claimed that the parchment is the first map of the western hemisphere known to exist and that it predates Christopher Columbus by 50 years. It would prove that he was not the first European to reach America.

The map was found in a medieval travelogue that purportedly depicts the discovery of the New World, named as Vinland, by a Nordic explorer, Leif Eiriksson, around the year 1000. It was donated to Yale in the Fifties and is valued at more than $20m (£12.8m).

Research by the Smithsonian Institution in Washington DC concludes that the map's parchment was produced in 1434.

But Professor Clark said that the black ink of the parchment did not contain iron gallotannate, which was found in medieval inks.