How Old are the Oldest Rocks on Earth?
As of 2008, the oldest rocks on Earth known are 4.03 billion years old, from the Acasta Gneiss in the Northwest Territories of Canada. These rocks were found in the Canadian Shield, a very ancient section of the Earth’s crust. Originally the rock was part of a very old mountain chain, the core of which was exposed over billions of years due to glacial activity. The rock formed during the Hadean period, the oldest geologic division of time on Earth, which began at the planet’s formation 4.57 billion years ago and continued until the dawn of the Archean, 3.8 billion years ago. Many of the world’s oldest rocks are from this era.
