Massive icebergs once ran aground in Greenland sometime within the last 800,000 years, according to a new study, providing scientists with a new understanding of the dynamics of the Ice Age and the extent of the Arctic ice sheet thousands of years ago.
Scientists from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI), have found scours between Greenland and Spitsbergen left behind on the sea bed by gigantic icebergs. These five lineaments were located at a depth of 1,200 meters, making them the lowest-lying iceberg scours yet to be found on the Arctic sea floor.
"Whenever icebergs run aground, they leave scours on the seabed. Depending on their depth and location, those markings may continue to exist over long periods of time," lead author Jan Erik Arndt explained in an AWI news release.
Researchers discovered such traces on the Hovgaard Ridge, a plateau in the deep Arctic Sea located 400 kilometers off of Greenland's eastern coast.
"Such scours are a window into the past. Thanks to these iceberg scours we now know that a few very large, but also many smaller icebergs, passed across the Hovgaard Ridge," Arndt added.
Arndt and her colleagues uncovered the lineaments when conducting work for unrelated research in 1990. But do to the lack of more advanced technology then, the scientists weren't able to analyze their data until now. They can, however, roughly estimate the period within which the icebergs scoured the ridge crest to sometime in the last 800,000 years. They also know that the height of the iceberg had to be approximately 1,200 meters - about three times the height of the Empire State Building - in order to create such long-lasting marks.
The scientists refer to these types of gigantic icebergs as megascale icebergs. They theorize that two areas off the northern coast of Russia are most likely where these large objects came from.
The discovered scours not only reveal the enormity of these icebergs, but also indicate that they played a more important role in the export of fresh water from the Arctic into the North Atlantic.
The study's findings were published in the journal Geophysical Research Letters.