Scientists led by the University of Copenhagen's Centre for GeoGenetics at the Natural History Museum of Denmark have found an ancient meteor crater under the Greenland ice cap that's larger than Paris. Discovered using ground-penetrating radar data gathered by NASA, the possibly three-million-year-old impact crater is 19 mi (31 km) in diameter, about 1,000 ft (305 m) deep, and is buried under 3,200 ft (1,000 m) of glacial ice.
Until now, Greenland was thought to be devoid of impact craters. With its permanent shroud of ever-moving glaciers, the giant island was considered too erosive for any craters to survive for long before being ground away. However, the discovery of the crater under the Hiawatha Glacier shows that not only does the region have impact craters, it also has one of the 25 largest impact craters on Earth.
According to the team, what is now called the Hiawatha Crater was likely formed less than three million years ago and possibly as little as 12,000 years ago, when an iron meteor about a half-mile (800 m) wide hit the ground. This makes it one of the youngest impact craters found on Earth and helps explain why it has survived. Over the millennia, it eventually filled with ice until only the outline of the rim of the glacier as seen from the air gives any hint as to what lies beneath.
According to NASA, the Danish scientists first suspected the existence of the crater in 2015 when they were using radar data from NASA's Operation IceBridge and earlier airborne missions to map the topography of the land beneath the ice cap. When they came to the Hiawatha Glacier at the edge of the northwest Greenland ice sheet, they found a circular depression in the earth.
Follow up studies using satellite imagery from the Moderate Resolution Imaging Spectroradiometer instrument on NASA's Terra and Aqua satellites and another aerial survey in May 2016 from Germany's Alfred Wegener Institute with a new ice-penetrating radar from the University of Kansas provided a more dense and focused dataset that confirmed the crater's circular rim, central uplift, disturbed and undisturbed ice layering, and basal debris.
In addition, expeditions in 2016 and 2017 uncovered geological evidence supporting the meteor hypothesis.
"Some of the quartz sand coming from the crater had planar deformation features indicative of a violent impact; this is conclusive evidence that the depression beneath the Hiawatha Glacier is a meteorite crater," says associate professor Nicolaj Larsen of Aarhus University in Denmark.
The team is continuing its study of the crater and hopes to learn more on how its formation affected the Earth's climate.
The research was published in Science Advances and the video below discusses the Hiawatha Crater.
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