背景
Around 50,000 years ago, an iron meteorite struck present-day Arizona, forming the roughly 1.2-kilometre-wide Barringer crater, also known as Meteor Crater. The well-preserved crater became an important research site for identifying impact structures on Earth. Meteorite fragments and shocked minerals support the impact explanation. Its geological age is approximate; the month and day in the sorting date are not historically known.
資料來源： NASA — Meteor Crater, Arizona