A series of mysterious lines etched into the seabed off North Carolina’s Outer Banks has been identified as “very unexpected” evidence that icebergs once filled the horizon along the East Coast.
The huge chunks of ice are thought to have drifted up to 5,000 miles from Canada and could be seen as far south as the Florida Keys, according to research supported by the US Geological Survey.
“When you think of the Florida Keys, icebergs probably aren’t the first things that come to mind,” the USGS wrote on Facebook. “But more than 30,000 years ago, towering chunks of bright white ice drifted south from Hudson’s Bay in Canada, past Cape Hatteras in North Carolina, and into the Florida Keys. … These icebergs were huge. Measuring about 300 meters, they had a stature similar to the Eiffel Tower.”
The research, published June 16 in Nature Communication, used high-resolution seafloor mapping to find nearly 700 iceberg “washouts” embedded in the seabed. Photos show that the lines are reminiscent of ancient geoglyphs carved 2,000 years ago in Peru’s Nazca Desert.
They appeared at depths of 557 feet by 1,246 feet, according to The Woods Hole Oceanographic Institution, which worked with the USGS on the search.
“To understand when and why these icebergs ended up in unexpected waters, a team of researchers sailed on a boat to South Carolina and dug long, skinny tubes of sand, mud and shells from the seafloor.” , reported the USGS.
“Scientists used radiocarbon dating on the tiny shells (foraminifera) in the sediment to determine when icebergs left their mark on the seabed.”
The rough estimate of the date is around 31,000 years ago, during a “period of massive iceberg discharge known as the Heinrich 3 event,” the report said.
Among the most mysterious parts of the discovery is the fact that the icebergs were flowing south against the Gulf Stream, the report said. This led the researchers to conclude that a “large-scale but brief” flood of melted icy water was powerful enough to wash away the ice.
The freezing current also helped icebergs survive long enough to reach the subtropics, the study found.
“What our model suggests is that these icebergs are caught in currents created by meltwater from the glaciers and essentially surf along the coast,” said Alan Condron, a climate modeler at the Woods Hole Oceanographic Institution. who worked with USGS geologist Jenna Hill. on research.
“When a large glacial lake dam breaks and releases huge amounts of fresh water into the ocean, there is enough water to create these strong coastal currents that essentially move icebergs in the opposite direction to the Gulf Stream, which is not an easy task”. said Condon.
The data suggests melting icebergs could have a big impact on climate change, the report concludes. An overabundance of cold water carried by the ocean current could “significantly weaken…the amount of heat carried northward by the ocean (current)…increasing the odds that Europe will become much colder,” the researchers wrote.
Icebergs drifting from Canada to South Florida
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