Beaverhead impact structure

The Beaverhead impact structure is the second-largest impact structure within the U.S. It lies within the states of Idaho and Montana. Estimated at in diameter, it is among the largest List of [impact craters on Earth|impact structures on Earth].
With an estimated age of 600 million years, the impact's original shatter cones along the impact structure's perimeter provide some of the structure's only remaining visible evidence.
It is named for the Beaverhead region of southwestern Montana in which it was first discovered.