Canada: 4.16 Billion Years, The Age of the Oldest Rocks on Earth

For a long time, the famous "Acasta Gneiss" held the title of the oldest known rocks on Earth. Discovered along the banks of the Acasta River in the Northwest Territories of Canada, these rocks, which are fine-grained and have a brownish-gray color, have been dated to be at least 4.03 billion years old (Natural Resources Canada).

However, for over 15 years, a team of scientists has claimed that the oldest rocks are actually located at the other end of the continent, in northern Quebec. "Our previous research suggested that the age of these rocks could be as much as 4.3 billion years, but there was no consensus," recalls Professor Jonathan O’Neil from the University of Ottawa.

A researcher in the Department of Earth and Environmental Sciences at the University of Ottawa, he recently co-authored a new study published on June 26 in the journal Science. This research might finally convince the scientific community due to its robust methodology (C. Sole et al. 2025).

Two 'Chronometers' to Estimate the Age of the Rocks

In 2017, the team returned to the field to collect rock samples near the municipality of Inukjuak in Nunavik (northern Quebec).

After a preliminary analysis of these so-called "intrusive" rocks, which penetrate volcanic formations, further studies were conducted by the universities of Ottawa and Carleton (Canada), with the contribution of the now-deceased French geochemist Jean-Louis Paquette (University of Clermont-Auvergne / CNRS).

To establish an age, the researchers combined petrology, the science of rock formation, and geochemistry. Using two dating methods that rely on samarium and neodymium isotopes, functioning as two distinct "chronometers," they obtained consistent results: 4.16 billion years. This dethrones the venerable Acasta Gneiss!

To the Origins of the Earth

According to the authors of the study, this discovery opens an "exceptional window" into primitive Earth: "This confirmation positions the Nuvvuagittuq belt as the only place on Earth where rocks formed during the Hadean Eon can be found, which covers the first 500 million years of our planet’s history," states Jonathan O’Neil from the University of Ottawa.

Indeed, for the scientist, "Understanding these rocks is a journey back to the very origins of our planet. It allows us to better comprehend how the first continents formed and to reconstruct the environment in which life may have emerged."

Finer than the rocks they are embedded in, some minerals are even older. For example, the age of a zircon from Australia has been estimated at 4.374 billion years (John W. Valley et al., Nature Geoscience, 2014).