Geoarchaeology and the search for the first Americans

Research into the origins and subsequent development of the first American cultures (“Paleoindians”), in particular the timing and place of their arrival, has provoked heated, contentious debates in North American archaeology since the 19th century. Many of the questions in this archaeological puzzle are fundamentally geological and thus many of the answers have come from the geosciences, including geology, geography, and soil science, and at a wide range of spatial scales. Stratigraphy, perhaps the most basic principle in both archaeology and geology, first established the antiquity and chronology of the earliest artifact assemblages at sites such as Folsom and Clovis in New Mexico by demonstrating clear association of artifacts and Pleistocene fauna. Geologists and paleontologists further provided age estimates of sites in the absence of other forms of numerical age control. Geologists also were prominently involved in developing the radiocarbon method and applying it to Paleoindian sites. Many Paleoindian sites also yielded not only extinct fauna, but stratigraphic records with evidence of markedly different depositional environments in the past. These sites were inviting to geologists because many investigators had backgrounds in Pleistocene paleontology. The ancient fauna and the striking contrasts between past and present depositional environments drew the attention of archaeologists and earth scientists alike who recognized the paleoenvironmental implications. At regional, subcontinental scales the peopling of the New World has been a question revolving around lowered seas levels and fluctuating glacier margins. Modeling sea-level changes and the paleogeography of the “Bering Land Bridge” and the high-precision dating of ice retreat over Canada is helping to understand the environmental conditions faced by Native American forbears in Beringia and the environment, route(s), and timing of their entry into North America.