Climate Change and the Archaic to Woodland Transition (3000–2500 Cal B.P.) in the Mississippi River Basin

Abstract

Archaeologists frequently assume the cultural transition from Archaic to Woodland (ca. 3000–2500 cal B.P.) in the Mississippi River basin is a gradual process. In the lower Mississippi Valley, however, there is an abrupt gap in the archaeological sequence at this time and pronounced differences between Late Archaic and Early Woodland archaeological remains. Elsewhere in the basin, this transition is marked by an occupation hiatus or decline and is accompanied by significant changes in settlement and material culture organization. In most parts of the floodplain of the Mississippi River and its tributaries there are few sites dating to this interval suggesting the river bottom was abandoned for several hundred years as a location for sustained habitation. High-resolution climate data demonstrates an episode of rapid global climate change involving significant alterations in temperature and precipitation in the period ca. 3000–2600 cal B.P. The proximate cause of this global climate occurrence is change in galactic cosmic ray intensity and solar irradiation possibly amplified by variations in the earth"s geomagnetic field. Global climate changes led to greatly increased flood frequencies and magnitudes in the Mississippi River watershed during the shift from Late Archaic to Early Woodland. In northeast Louisiana, increased flooding led to major fluvial reorganization that caused settlement abandonment and is associated with the demise of Poverty Point culture. Climate change and associated flooding is implicated as one cause of major cultural reorganization at the end of the Archaic throughout much of eastern North America.