Cahokia was a very important settlement in the 1100s. The ancient city was founded by a sophisticated cultural group that managed to build sweeping plazas and tall mounds.
The Native American ancient town was located near where St Louis, Missouri is now.
The town was inhabited by tens of thousands of people and started to decline around the year 1200.
According to the experts, by year 1350, Cahokia had become a deserted place.
No one really knows for sure what caused the ancient city’s decline. However, a recent research study published in the Proceedings of the National Academy of Sciences points out to the fact that Cahokia was destroyed by a massive flood caused by the Mississippi River around 1200.
Samuel Munoz, a geography expert from the University of Wisconsin–Madison and his team of researchers conducted the new study.
They analyzed samples of sediments taken from Horseshoe Lake, which is located at about 5 km from Cahokia.
The scientists managed to extract sediment cores up to 5 m in length from the lake bed. According to them, this represents approximately 2,000 years of deposition.
Munoz said that while digging for the sediments, a series of light stripes of fine sediment started to surface as they started their work.
One of the researchers named these fine sediments “lake butter”, due to their extremely fine and silky textures.
The team of experts believes that this type of sediment may have entered the lake during a massive flood along the Mississippi River.
Munoz said that the river is called “Big Muddy” for a good reason. According to him, this sediment is what makes the river water brown and muddy.
The researchers were able to date the “buttery” sediments using radiocarbon methods; this technique helped them confirm and refine some of the dates by analyzing the cores from another lake located at about 200 km down the river.
The team concluded that massive floods took place around AD 280, 490, 580, 1200, 1400, 1510, 1590 and 1800.
Munoz said that flooding might have been responsible for the ancient city’s total decline. However, the researchers cannot really say for sure if the massive flood that occurred in 1200 caused the settlement’s decline. They can only confirm that there the floods correspond with the Cahokia’s abandonment.
Larry Benson, an anthropologist at the University of Colorado Boulder’s Natural History Museum, said that the ancient city might have been destroyed by drought, but doesn’t exclude the possibility that flooding could also contributed to the city’s disappearance.
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