Evidence that the Vinland Map is medieval

The Vinland Map has been proposed to date to the mid-fifteenth century and is significant in showing the north Atlantic area of what is now North America about 50 years before the voyages of Columbus. It has been confirmed by radiocarbon dating that the map was drawn on a fifteenth century parchment; however, controversy regarding the ink of the map has persisted. Analytical studies of the ink of the map have been interpreted to show that the map is a twentieth century forgery because of the presence of carbon and anatase in the ink. However, carbon is known to have been added to medieval iron gallotannate inks, and the presence of anatase in a medieval ink can be explained by examining the process of making medieval inks.