Building Monks Mound, Cahokia, Illinois, a.d. 800–1400

Cahokia (a.d. 800–1400), located near the confluence of the Mississippi and Missouri rivers, was the largest settlement in ancient North America. Monks Mound occupies the center of Cahokia and provides both a modern and ancient focal point for the site. Past investigations of Monks Mound explored issues of mound chronology and use. Recent soil coring around the perimeter clarifies the geological context and degree of preparation necessary before the mound was built. The results suggest that the mound is not optimally positioned for stability and its location may ultimately accelerate deterioration. Moreover, evaluation of the mound features and fill indicates that maximization of the geotechnical potential of sediments was not a primary concern for the Cahokians. Although poorly engineered relative to modern standards, the suitability of the mound as a platform may have been secondary to other design choices made while building the largest single mound in ancient North America.