Gray rocks uncovered in northern Nunavik, Quebec, Canada may be the ultimate primordial find. The stones date back 4.16 billion years to the Hadean era and are the oldest known rocks on the planet. They are described in a study published June 26 in the journal Science .

Yet some regions are far enough from tectonic plate boundaries to contain rocks that have remained unchanged for billions of years. One of these is in northeastern Canada, and its most ancient part is the Nuvvuagittuq Greenstone Belt (NGB). Scientists agree that this outcrop is at least 3.8 billion years old.

Geologists have long debated whether a stony formation in Canada contains the world’s oldest rocks – new measurements make a compelling case that it does