The Norwegian archaeologists Helge and Anne Stine Ingstad's famous identification, in 1961, of a Viking settlement at L'Anse aux Meadows, Newfoundland, from just after A.D. 1000 is, of course, a notable exception, no longer in dispute. But that discovery has so far gone nowhere. The Norse settlers, who may have numbered as many as 160 and stayed for three years or longer, seem to have made no lasting impression on the aboriginal skraellings that, according to Norse sagas, they encountered, and to have avoided being influenced in turn. The traditions of the Micmac people, modern-day inhabitants of the area, have...