IT’S such a simple idea that it’s surprising no one seems to have thought of it before. Did a massive asteroid or comet impact kick-start plate tectonics on Earth?
For much of our planet’s history, rocky plates have been sliding over a viscous, molten mantle, colliding to build mountain ranges or spreading apart to make way for oceans. In a neat piece of recycling, an oceanic plate dives, or “subducts”, underneath a less dense continental plate, and eventually melts into the hot mantle.
Geologists estimate that plate tectonics began during the Archean period, between 2.5 and 3.8 billion years ago…
