The Williams Lab

Human-environment interaction in prehistoric eastern North America

Humans arrived in North America at least 15,000 years ago, but our understanding of how humans have used and shaped ecosystem services is mostly limited to the period of historic record, after the arrival of Europeans in the Americas just 500 years ago. Developing an understanding of the characteristics, spatial extent and magnitude of human-caused changes to ecosystems, particularly of those in the past, would help to clarify concepts of ‘ecological baselines’, ecosystem resilience and human vulnerability to environmental change.

People involved with this project include Sam Munoz, Jack Williams, Sissel Schroeder, Steve Jackson, and David Fike

This project will use sediment cores from oxbow lakes to develop records of environmental change in the central Mississippi River valley, a region which was heavily populated during the late prehistoric period by the agricultural ‘Middle Mississippian’ culture. Mississippian communities of this region flourished during the 12th century, but were abandoned by the 14th century. Many explanations have been put forward to explain the downfall of the Middle Mississippian culture, including over-exploitation of resources, drought and social instability.

Through multi-proxy analyses (e.g. pollen, macroscopic charcoal, δ13C, and sedimentology) of several sediment cores along the central Mississippi valley, this project will clarify the role of prehistoric peoples in shaping, and being influenced by, environmental change.

Figure 1. Conical burial mounds constructed by the Middle Mississippian culture at the Cahokia site. At its peak, Cahokia was home to about 15,000 people. We are using lake sediment records near this and other prehistoric archaeological sites to understand the environmental impact of late prehistoric settlement.



Figure 2. A section of a lake sediment core from Horseshoe Lake, Illinois showing a period of fine-grained clay bracketed by two coarse-grained sandy deposits. These changes in grain size could be result of hydroclimatic variability (flooding and/or drought). We are using several techniques to understand the hydroclimatic history of this region in the context of human vulnerability to climate change.


This work is supported by the Climate People and Environment Program at the University of Wisconsin-Madison
and the National Geographic Society

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