1957
A New Haven, Conn., rare-book dealer buys the Vinland Map from an Italian book seller for $3.6K.  Provenance suspicious but this is normal for discoveries of this sort.

1965
After 7 years of study, map scholars from the British Museum and from Yale declare the map to be genuine, in articles published in The Vinland Map and the Tartar Relation, Yale University Press 1965.  The The Beinecke Library at Yale University acquires the map, with Paul Mellon providing the purchase price (reputed to be $1M). 

1966
An international conference, organized at the Smithsonian Institution in Washington, DC, reviews the authenticity of the Map extensively and recommends that it be studied scientifically.

1974
Yale engages the leading analytical chemist Walter McCrone to study the Map.  McCrone presents a report to the Yale Library, summarizing his study, by polarized light microscopy,  of microsamples taken from the Map.  He found anatase (titanium dioxide) in the ink, in a form available only after 1920.   On the basis of the McCrone Report, the Yale Library announces that “the famous Vinland Map may be a forgery.”

1976
McCrone publishes a brief account of his 1974 study in Anal. Chem.

1982
A report to the Yale Library by Kenneth Towe (a geologist at the Smithsonian) raises questions about the McCrone study but does not challenge its conclusions.

1987
Yale seeks a second opinion, using a different technique.  At U.C.Davis, Cahill subjects the map to an elemental analysis using PIXE (particle-induced X-ray emission), finding only trace amounts of titanium and challenging McCrone's findings in an article in Anal. Chem.

1988
McCrone publishes a full account of his 1974 study in Anal. Chem. and argues that Cahill's findings do not invalidate McCrone's conclusions.

1990
Towe reviews the McCrone and Cahill studies in Accounts of Chemical Research   and argues that Cahill's study supports McCrone's conclusions.

1996
A second edition of The Vinland Map and the Tartar Relation is published by the Yale University Press.  It contains a contribution from Cahill but McCrone was not invited to contribute.  The new edition stops just short of declaring the map to be genuine.

A symposium is convened at Yale to discuss the map to which McCrone is not invited.   He shows up anyway and hands out copies of the report he would have given had he been asked: The Vinland Map, Still a 20th-Century Fake. 

 An article, Tales of the Un-Fake, in the May issue of the Yale Alumni Magazine rehabilitates the map. “The reputation of a map donated to the Beinecke Library and later suspected of being a fraud has been rehabilitated …”

July, 2002
A study backs the Yale expert's belief the map is a fake. [Brown and Clark in Analytical Chemistry]

August, 2002
A study uses carbon dating to analyze the parchment, and concludes the parchment is authentic. [Donahue in Radiocarbon]

November, 2003
A study considers the methods of medieval ink makers, and concludes the map is authentic. [Olin in Analytical Chemistry]