Evidence of giant asteroid strike may be buried under Wyoming
Excerpt: Some 280 million years ago, before the rise of the Rocky Mountains—or even the dinosaurs—a 2.5-kilometer-wide asteroid smashed into the supercontinent of Pangaea, near the eastern border of present-day Wyoming. The impact’s heat and shock wave would have killed anything within 400 kilometers, making it one of the largest asteroid strikes in North American history. ...And there the crater may sit, kilometers down, even to this day. That’s the scenario painted in new work. Researchers haven’t found the crater itself, but they have identified a series of 31 smaller craters, each no wider than a U.S. football field. These “secondary” craters would have been formed by boulders ejected by the impact, landing up to 200 kilometers away. It is the first time a secondary crater field—commonly seen on other planetary bodies, including the Moon—has been discovered on Earth. ...The craters’ pattern was similar to the rays and streaks of small craters that surround large craters on the Moon, like Tycho. They provide clear evidence that such formations are possible on Earth, the researchers conclude this month in the Geological Society of America Bulletin.…