Evaluating narratives of ecocide with the stratigraphic record at Cahokia Mounds State Historic Site, Illinois, USA

摘要

Narratives of ecocide, when a society fails due to self-inflicted ecologic disaster, have been broadly applied to many major archaeological sites based on the expected environmental consequences of known land-use practices of people in the past. Ecocide narratives often become accepted in a discourse, despite a lack of direct evidence that the hypothesized environmental consequences of land-use practices occurred. Cahokia Mounds, located in a floodplain of the central Mississippi River Valley, is one such major archaeological site where untested narratives of ecocide have persisted. The wood-overuse hypothesis suggests that tree clearance in the uplands surrounding Cahokia led to erosion, causing increasingly frequent and unpredictable floods of the local creek drainages in the floodplain where Cahokia Mounds was constructed. Recent archaeological excavations conducted around a Mississippian Period (AD 1050-1400) of earthen mound in the Cahokia Creek floodplain shows that the Ab horizon on which the mound was constructed remained stable until industrial development. The presence of a stable ground surface (Ab horizon) from Mississippian occupation to the mid-1800s does not support the expectations of the wood-overuse hypothesis. Ultimately, this research demonstrates that pre-Colombian ecological change does not inherently cause geomorphic change, and narratives of ecocide related to geomorphic change need to be validated with the stratigraphic record.