Summer 2018: By David Malakoff
In the fall of 2005, Hurricane Wilma, a powerful storm packing 120-mile-an-hour winds, smashed into the Ten Thousand Islands, a fifty-mile-long maze of mangrove-ringed islets on the Florida’s southwestern coast. Once the storm had passed, the National Park Service dispatched one of its staff scientists, Margo Schwadron, to assess how dozens of archaeological sites on public lands in the remote region had fared.
“We didn’t know much about what was out there; for the most part, the sites were just dots on a map,” Schwadron recalled. But given a boat and some enthusiastic assistants, she began a systematic survey and was stunned by what she found. “We’d pull up to an island and see this bank of oyster shells rising eight or ten feet out of the water. Then you’d climb up and realize there was so much more” beneath the tangled vegetation: enormous sculpted mounds, ridges, ramps, plazas, basins, and canals that sometimes covered more than 100 acres. “There were entire islands, whole landscapes, that people had constructed from shell,” she said. “It was mind boggling.”
The experience prompted Schwadron to launch an ambitious, years-long study of some of the world’s largest and most complex prehistoric constructions made from shells. She and her colleagues have mapped more than a dozen major shellworks in the Ten Thousand Islands, as well as more than forty smaller shell structures. They have recovered nearly 50,000 artifacts, including ceramics and tools made from animal bones and shell. Radiocarbon dating of shell fragments and other materials indicates that people began creating the shell structures in the Ten Thousand Islands at least 3,500 years ago, during the Late Archaic period.
The findings are helping reshape how scholars perceive North America’s prehistoric hunter-gatherers, and the numerous mounds of oyster, mussel, and snail shells they often left behind.
Read More in our SUMMER 2018 Issue of American Archaeology, Vol. 21 No. 1. Browse Content of this Issue: SUMMER 2018.
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