The impact event occurred less than 5 million years ago.

Many impact events occur without being observed by anyone on the ground.

It is the largest impact event on or near Earth in recorded history.

This estimate is based on evidence of five to ten large impact events in the last 10,000 years.

It was one of the largest known impact events to have happened in North America.

It has clearly undergone significant erosion since the impact event.

The most likely cause for this to happen are impact events.

To date there have been several known and suspected impact events.

Such impact events occur on average around once per 10,000 years.

This could happen during impact events on the surface of the parent body.