http://www.newsweek.com/san-francisco-sized-crater-huge-meteor-impact-discovered-beneath-greenland-1215341

An international team of scientists has uncovered a vast, 19-mile-wide impact crater hidden deep below the ice sheets of Greenland.

The crater—which is bigger than the city of Paris—is thought to have been produced by a kilometer-wide (0.6 mile-wide) iron meteorite that collided with the Earth somewhere between 3 million and 12,000 years ago, although it has not been directly dated yet.