Material Evidence: Donahue

This accelerator measured the age of the parchment of the Vinland Map. It separates the carbon-14 from the rest of the carbon and measures its relative amount.


The parchment is dated to AD 1434.
Donahue, D. J., Olin J. S. and Harbottle, G. 2002 Determination of the radiocarbon age of parchment of the Vinland Map, Radiocarbon 44-1, 45-52.


All carbon in living matter contains the radioactive carbon isotope, carbon-14, to the extent of 1 part in 1012. All the time, carbon-14 is being formed, as cosmic rays bombard our atmosphere; and eventually the carbon-14 enters our bodies through the food chain. At the same time, carbon-14 in our bodies is disappearing by radioactive decay. A balance is achieved. Input (cosmic rays) equals output (radioactive decay). The balance is a carbon-14 content of 1 part in 1012.

Map Sample
A minute sliver of the Map was removed from a corner that contained no writing.

When we die, the input ceases and our carbon-14 content decreases in a known way. After 5730 years, it is halved. So by measuring the carbon-14 content of a dead body, we can determine when it died. The carbon-14 content of the Vinland Map reveals the date when an animal was slaughtered — the animal whose skin was used as the parchment of the Vinland Map.

Until 1980, radiocarbon dating required large samples - the size of a pocket handkerchief - which were, of course, destroyed. Subsequently, a new technique - accelerator mass spectrometry - uses samples smaller than a postage stamp. At that point, the dating of the Vinland Map became feasible. A sample, 30 mg, was cut from the VM in 1995. The results were difficult to interpret and were only published in 2002.


  • The parchment is dated to AD 1434 +/- 11.
  • The date is obtained only if, first, the parchment is drastically cleaned with acetone to remove an unknown contaminant that constitutes 30% of the sample.
  • Sample
    The sample weighed 29 mg. The experimenters claimed that the sample was worth $50,000 (assuming, of course that the Map was worth $25M).
  • Inexplicably, the contaminant is found to be more radioactive than living matter.


  • Nobody questions the date of the parchment. It is the date we expect if the VM is genuine.
  • Any forger must have used parchment of the right age, perhaps a blank sheet from one of the two companion volumes, TR or SH.
  • What is the contaminant? Why is it there? Why is it radioactive? When was it added? Its measured radioactivity suggests a date between 1950 and 1957. Was the VM forged at that time? This bizarre finding promises fresh insight into the elusive origin of the Vinland Map.


  • Does the date of the parchment limit in any way the date of the Vinland Map?