Among the oldest known exposed rock on Earth, this found-image shows a fragment of the Acasta Gneiss.

A meteorite strike 4 billion years ago created the oldest rocks on Earth by raising temperatures enough to melt the planet's crust. Mysterious minerals older than any others found on the planet were formed by the strike in the early days of Earth's formation: extraterrestrial rocks so hot they melted the Earth's still forming crust, hitting our homeworld around half a billion years after the planet formed. They created an area of unique geology in Northern Canada around four billion years ago: the Acasta River rocks, also known as the Acasta Gneiss outcropping.