Scientists have found the traces of two giant meteorite impacts that indicate a "double strike" occurred in Sweden 460 million years ago.
The "globally unique" craters, which were discovered in Jämtland, are composed of one enormous impression that measures in at over four miles in diameter and another that is about one-tenth of the size, the University of Gothenburg reported.
"The two meteorite impacts occurred at the same time, 458 million years ago, and formed these two craters," said Erik Sturkell, Professor of Geophysics at the University of Gothenburg.
During the period in which the meteorites are believed to have struck, two large asteroids collided in the asteroid belt between Mars and Jupiter, causing fragments to be thrown into new orbits. The researchers noted that when the strikes occurred, Jämtland was under 1,640 feet of water. The findings mark the first simultaneous meteorite strike to be conclusively proven in the history of Earth.
"Information from drilling operations demonstrates that identical sequences are present in the two craters, and the sediment above the impact sequences is of the same age. In other words, these are simultaneous impacts," Sturkell said.
When the impacts occurred the water covering the land was pushed away, leaving the craters completely dry for almost two minutes.
"The water then rushed back in, bringing with it fragments from the meteorites mixed with material that had been ejected during the explosion and with the gigantic wave that tore away parts of the sea bed," Sturkell explained.
About 90 meteorites have also been found in red limestone slabs around Kinnekulle, Sweden.
"Small meteorites survive the fall, while large ones explode and disintegrate. In Jämtland we have only found minerals from the meteorites, small grains of chromite," Sturkell said.
