Scientists agreed the rocky outcrops in a remote part of Quebec, Canada, were ancient. But were they really Earth’s oldest?

In this case, it’s a piece of schist, a type of metamorphic rock made of easily identified grains or flakes. Its presence often marks places where continents collided millions of years ago. “Sometimes ...

What they were after was a type of metamorphic rock called gneiss (pronounced “nice”). It forms when igneous rocks like granite undergo intense heat and pressure, changing their structure and ...

What they were after was a type of metamorphic rock called gneiss (pronounced “nice”). It forms when igneous rocks like granite undergo intense heat and pressure, changing their structure and ...