A remote outcrop in Canada harbors rocks that are at least 4.16 billion years old, researchers report June 26 in Science. If true, these rocks would be the oldest known on Earth and the first to date to the planet’s earliest and most mysterious eon.
The finding is the latest salvo in a debate that began in 2008 about the reliability of geochemical methods used to assess the age of this outcrop. In the new study, the scientists bolster their oldest-rock claim by using two distinct methods based on the radioactive decay of elements to date ancient magma that intruded into even older parent rocks. Both methods provided the