Mega Icebergs Scoured the Ocean Floor Near Greenland 800,000 Years Ago
Scientists have found new evidence of massive icebergs that ran aground near Greenland. They've discovered scours left behind by the giant chunks of ice at a depth of an impressive 1,200 meters, revealing a bit more about the dynamics of the Ice Age and the extent of the Arctic ice sheet thousands of years ago.
"Whenever icebergs run aground, they leave scours on the seabed," said Jan Erik Arndt, one of the researchers, in a news release. "Depending on their depth and location, those markings may continue to exist over long periods of time."
In this case, the researchers found scours on the Hovgaard Ridge, which is a plateau in the deep Arctic Sea. The five lineaments are the deepest iceberg scours found to date, and are as much as four kilometers long and 15 meters in depth. The evidence of these scours was actually present in data collected from 1990, but researchers only noticed the scours now due to better data analysis.
The icebergs scoured this ridge about 800,000 years ago. Since the sea level during the glacial period at this time was about 120 meters lower than today, the icebergs reached a depth at least 1,080 meters below sea level. This means that the icebergs had a height of about 1,200 meters, which is three times the height of the Empire State Building.
The findings don't just show that these large icebergs existed, though. They also provide an explanation as to how fresh water was transported from the Arctic and into the Atlantic Ocean. The scours show that large icebergs may have drifted southward through the Fram Strait, carrying large volumes of frozen fresh water into the North Atlantic.
"The fact that icebergs of this order of magnitude were drive from the Arctic is clear evidence that icebergs played a more serious role in freshwater imports than what we had previously assumed," said Arndt.
The findings are published in the journal Geophysical Research Letters.