Deep inside Earth are rocks that date back to the first 50 million years of the Solar System's history. The discovery suggests that, even as internal heating mixes most of Earth's interior, some primordial material still survives today.
A team led by Hanika Rizo of the University of Quebec in Montreal, Canada, analysed lava that erupted off the coast of northern Canada and the southwest Pacific Ocean, and then cooled to form basalt rock (pictured). Both places are thought to tap deep and ancient sources of lava.
The scientists found that levels of tungsten-182 — an isotope created early in Earth's history by the radioactive decay of hafnium-182 — were higher in the Canadian and Pacific rocks than in those from other parts of the world, confirming that the rocks contained ancient materials.