Luminescence dating of Enigmatic rock structures in New England, USA

Enigmatic rock structures in the form of walls, chambers, tunnels, and cairns are common archaeological features in northeastern United States, but the age of their construction is mostly unknown. Debate persists as to whether they are colonial or pre-colonial in age. Luminescence dating was applied at several sites to sediments underneath the rocks or to the rocks themselves. Sediment ages obtained from potassium feldspars using IRSL place their construction in the late 16th century, just before sustained colonial settlement. Sediment ages obtained from quartz using OSL place their construction later, but the much weaker quartz signals have issues, primarily the prevalence of a slower bleaching component. These raise questions on the credibility of the quartz ages. The age from one rock, also using IRSL, supports the K-feldspar sediment ages. The evidence suggests a pre-colonial construction, by ancestors of modern native Americans.