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Tree pollen disappears and crop pollen appears in the year 450 CE. -
The earliest habitation of the city of Cahokia is believed to be 700 CE. -
Remnants of corn left over from the year 900 CE. Corn starch found in old pottery and corn husks scattered on the ground. -
Burials found of individuals and mass graves indicate a class system and perhaps mass human sacrifice in Cahokia. Artifacts found in burial sites indicate quality craftspeople at work. -
Long, tube-like samples of sediment show layers of different types of sediments in and around Cahokia. These include wooden posts, smoothed limestone, and clay. -
Meat remains indicate a stratified society where the upper class and lower class were strictly separated. -
Different material reacts differently to the Earth's magnetic field. Old walls, ditches, and construction can be found without digging anything up. -
Fecal remains from Cahokians that indicate how many people lived there - possibly up to 20,000. It also indicates when population began to decline. -
Strontium isotopes found in bone and teeth indicate how many people were coming to Cahokia as outsiders - up to 30% of the population came from somewhere else at its height. -
The city of Cahokia seems to have been largely abandoned by 1350 CE. Some people think internal or external conflict are to blame, others think flooding or climate change a likely reason.