Cold Lava? The East African Rift Valley was created about 25 million years ago as a divergent (moving away from each other) tectonic plate boundary formed as the Somalian plate moves away from the Nubian plate. The East African Rift (EAR) Valley, noted by Astronauts, is the most significant physical detail on the Earth’s surface from space. Our continental lithosphere (Earth’s crust and upper mantle) is typically 93 miles (150km) thick! The formation of the Rift thinned the c