A weathered sign in the Minnesota River Valley proudly proclaims: “World’s Oldest Rock.” Erected in 1975, it marks a 3.8-billion-year-old gneiss — or so scientists thought.

A team of geologists have conducted a survey of likely candidates to identify the oldest rock in the United States. Their ...

(via Be Smart) The oldest rocks on Earth are more than just ancient—they’re time machines, holding clues to Earth’s missing history and revealing what happened in the unknown times after the Big Bang.

The rock was limestone ... The Chazy Reef is the oldest reef in the world built by a community of organisms (a few older reefs are made up of one species only). Its foundation was built by ...

Australian scientists have recently discovered the oldest known meteorite impact crater in the world, which could ... The research team examined the rock layers in the North Pole Dome and found ...