May 5, 2015
Floods at Cahokia May Have Doomed the City
New evidence at Cahokia taken from lake bottom sediment cores dating back 2000 years show evidence of eight major floods in the central Mississippi river valley. Cahokia became a major metropolis during an arid and flood free period. The research team collected cores from two lakes to see if the information was consistent. By 900 CE, people in the Cahokia area were cultivating maize and the population exploded. Larger buildings and structrues were constructed. But at 1200 CE, there was a major flood and a population decline. A defensive wall was built around Cahokia and other material changes. By 1400 CE, Cahokia was deserted. The cores show a rise in the Mississippi by 33 feet above base elevation, which would have flooded out crops and food stores.
The research is published in the Proceedings of the National Academy of Sciences.
Popular Archaeology has the report here;
Mike Ruggeri’s Ancient Southwest/Mound Builders News Magazine