It's weird to imagine giant hunks of ice floating in the waters off Miami. But that may have happened.
When the massive North American ice sheet from the last Ice Age began to melt 20,000 years ago, fresh water pooled in lakes, which were blocked in by glaciers and debris. But eventually, the lakes flooded over those barriers, and the waters carried icebergs into the northern Atlantic Ocean. While modeling studies by scientists in the past suggested that those icebergs drifted east toward Europe, a just-published article in Nature Geoscience provides evidence that the big pieces of ice drifted southward instead.
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Some of the icebergs that reached Florida were nearly 1,000 feet thick, according to researchers Jenna Hill of Coastal Carolina University and Alan Condron of the University of Massachusetts.
The researchers' computer modeling is substantiated by the presence of massive scars that have been found on the ocean bottom off the continental shelf. Those marks were left by icebergs running aground, according to an analysis of Hill's and Condron's findings in Nature.
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The researchers found that the icebergs drifted south because ocean currents are different today than they were tens of thousands of years ago. Today, most icebergs produced in the Arctic only drift as far as Newfoundland, where they encounter warmer currents and rapidly deteriorate, according to this primer on iceberg movement in the north Atlantic by the U.S. Coast Guard.
But back then, glacial floodwater running off North America formed a narrow current just about 62 miles thick, which flowed from Newfoundland southward toward Florida. It would have transported the icebergs.