A recent study published in Nature Communications has reported on iceberg scouring marks on the ocean floor in the Atlantic Ocean off the coast of the United States from North Carolina to the Florida Keys. The grooves were made as the bottom side of icebergs scratched the marine sediments on the ocean floor during the last glaciation period, thousands of years ago.

What makes this particularly interesting is that these marks are where the Gulf Stream is located today, suggesting not only that these waters were much colder than at any time in the recent past, but also that the northeastward flowing Gulf Stream either did not exist then, or was located somewhere else. It is likely that this occurred around 8,200 years ago, as a huge volume of glacial Lake Agassiz catastrophically drained northward into Hudson Bay and out the Labrador Sea, flushing huge icebergs into the Atlantic Ocean.

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