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Researchers: Major floods coincided with desertion of Cahokia Mounds

The people who built and lived among the tall, sculpted mounds now preserved at Cahokia Mounds Historic Site have long presented a mystery to archeologists.One of the biggest mysteries: Why did they leave? A team of UW-Madison geographers studying pollen deposits buried in the sediment under Horseshoe Lake may have stumbled upon new evidence that helps explain Cahokia’s decline.