When a stone sits on the Earth’s surface, cosmic rays quietly pepper it, leaving behind rare isotopes like tiny time stamps.

Africa's ground is shifting. Tectonic forces are tearing the continent apart along the East African Rift. Satellites and GPS show this separation is happening now, widening by millimetres annually.

The changes are most visible in the Afar region of northeastern Ethiopia. Scientists say that the Gulf of Aden and the Red ...