Dendrochronology and Accelerator Mass Spectrometry (AMS) Carbon 14 Dating: A Novel and Potent Combination

Over the past several decades the use of dendrochronology, or tree-ring dating has become a mainstream buildings archeology tool to firmly establish when framing timbers of historic structures were felled. While not every building tested can or has been successfully dated, a vast majority do allow dating using this method. As a result, dendrochronology has been instrumental in our rethinking of the architectural evolution of many historic building practices. One of the hurdles encountered when conducting such studies is having to work in areas where dated master chronologies are lacking, thus requiring testing against more far-flung masters which may, or may not, yield consistent alignments. One such case involved the supposedly 17th century Hancock-Mitchell house located in Chilmark on Martha’s Vineyard, an island off the coast of Cape Cod, Massachusetts, first settled by Europeans in 1641. While initial dendrochronological testing did not yield conclusive results, further sampling in this house as well as in three others on the island resulted in a provisional oak master chronology for the island. In an attempt to confirm the accuracy of this master, a novel use of Accelerator Mass Spectrometry (AMS) Carbon 14 dating was employed whereby two rings, carefully selected based on their provisional dates in conjunction with the Carbon 14 recalibration curve, were sampled from one timber fragment. The results of these tests proved unequivocally that the dendrochronology dating was correct and the house was in fact constructed in the mid 18th century, and not in the mid 17th century as has been long believed.