The ancient supercontinent of Rodinia turned inside out as the Earth swallowed its own ocean some 700 million years ago, new research suggests.
Rodinia was a supercontinent that preceded the more famous Pangea, which existed between 320 million and 170 million years ago. In a new study, scientists led by Zheng-Xiang Li of Curtin University in Perth, Australia, argue that supercontinents and their superoceans form and break up in alternating cycles that sometimes preserve the ocean crust and sometimes recycle it back into Earth’s interior.
“We suggest that the Earth’s mantle structure only gets completely reorganised every second supercontinent [or every other cycle] through the regeneration of a new superocean and a new ring of fire,” Li wrote in an email to Live Science. The “Ring of Fire” is a chain of subduction zones around the Pacific, where the crust of the ocean grinds underneath the continents. Volcanoes and earthquakes are frequent around the Ring of Fire, lending it its name.