'Massive meteorite impact crater discovered in Greenland'

Scientists have discovered a 31-kilometre wide meteorite impact crater buried beneath the ice-sheet in the northern Greenland.

This is the first time that a crater of any size has been found under one of Earth's continental ice sheets, said researchers from the University of Copenhagen in Denmark.

The researchers worked for last three years to verify their discovery, initially made in the 2015.

The crater measures more than 31 km in diameter, corresponding to an area bigger than Paris, and placing it among the 25 largest impact craters on Earth, according to the study published in the journal Science Advances.

The crater formed when a kilometre-wide iron meteorite smashed into northern Greenland, but has since been hidden under nearly a kilometre of ice.

"The crater is exceptionally well-preserved, and that is surprising, because glacier ice is an incredibly efficient erosive agent that would have quickly removed traces of the impact," said Professor Kurt H Kjaer from the Natural History Museum of Denmark.

"But that means the crater must be rather young from a geological perspective," Kjaer said.

"So far, it has not been possible to date the crater directly, but its condition strongly suggests that it formed after ice began to cover Greenland, so younger than 3 million years old and possibly as recently as 12,000 years ago -- toward the end of the last ice age," he said.

The crater was first discovered in July 2015 as the researchers inspected a new map of the topography beneath Greenland's ice-sheet.

They noticed an enormous, but previously undetected circular depression under Hiawatha Glacier, sitting at the very edge of the ice sheet in northern Greenland.

"We immediately knew this was something special but at the same time it became clear that it would be difficult to confirm the origin of the depression," said Kjaer.

The 20-tonne iron meteorite sits in the courtyard at the Geological Museum in Copenhagen.

"It was therefore not such a leap to infer that the depression could be a previously undescribed meterorite crater, but initially we lacked the evidence," said Associate Professor Nicolaj K Larsen from Aarhus University in Denmark.