Ecocide at Cahokia?

How do you prove ecocide – the human destruction of the environment?

For years, scholars investigating the great Mississippian ceremonial center at Cahokia near St. Louis, Missouri, USA, have argued that the city was abandoned between AD 1050 and 1150 after rapid population growth, also escalating demand for both firewood and construction timber, which led to the deforestation of the uplands surrounding the American Bottom. Soil erosion increased, causing severe floods on the plain below. In other words, the Cahokians destroyed their environment.

The Cahokia ecocide scenario has survived without definitive proof, buttressed with more nuanced theories, also without definitive proofs. Now we have the first evidence that the ecocide theory may be wrong.

A new generation of research is combining sedimentological studies of ancient land-use practices with geomorphological survey near Cahokia’s North Plaza, which floods seasonally. Kaitlin Rankin and her colleagues combined core borings with excavation down to the original ground surface under a mound at the lowest elevation of the central precincts dating to about AD 1050-1400. By using data from cores and excavation, combined with radiocarbon dates, they showed that deposits laid by flowing water lay under the occupation layers. The inhabitants responded to floods by modifying the landscape, not moving. They were successful. The surrounding landscape remained stable until the Industrial Revolution brought coal mining and deforestation. Nor was deforestation a catastrophic problem. So it now seems unlikely that people left Cahokia because of ecocide.

Image: Artist’s recreation of central Cahokia.