The puzzle pieces of Earth’s rocky crust are slowly and steadily moving — a process known as plate tectonics. These dynamic movements helped to create the habitats and climate that fostered the emergence of life on our planet, but exactly when the geological process first emerged has been a matter of scientific contention for decades.Now, scientists say they have found the earliest direct evidence of plate tectonics on Earth — the only known planet to have the geological process. The findings suggest that the phenomenon was already shaping the planet billions of years ago.“Why do you have mountains? Why do you have oceans? It only makes sense with plate tectonics,” said Roger Fu, a professor of Earth and planetary sciences at Harvard University who led the research for a new study that was published in the journal Science on March 19. “So, trying to understand when it happened on early Earth is a fundamental question. It makes everything else make sense,” he said.AdvertisementAdvertisementToday, Earth’s seven major and eight minor plates, which are on average 125 kilometers (about 80 miles) thick, move at a steady rate of several centimeters per year. Each plate is in motion, either pulling away from or growing closer to its neighbors, and volcanic activity and earthquakes typically cluster at these margins.Volcanic activity, seen at the Sundhnúkur crater row in Iceland, is more likely to occur where tectonic plates meet. – John Moore/Getty ImagesSome in the scientific community contend plate tectonics began 4.4 billion years ago while others suggest they only started in the last 1 billion. Whether modern plate tectonics arose directly from the hellish magma ocean that once covered early Earth or whether intermediate stages, such as plates that moved intermittently or one single, unbroken lid, were at play is also unclear, the study authors noted.The latest research reveals the plates were shifting as early as 3.5 billion years ago — during the Archean Eon — when the planet was already home to early microbial life. In pushing back the timeline for active tectonic plates, the analysis could offer clues about Earth’s early history and the conditions that supported early life, according to the study.Rocks capture Earth’s early historyFu and his colleagues analyzed rock samples from East Pilbara Craton, a geological formation rich with fossil evidence of early organisms such as stromatolites, in Western Australia’s Pilbara region.AdvertisementAdvertisement“If you don’t get too close, it actually looks like really friendly, beautiful scenery because it’s got these low rolling hills, but once you start walking around, you realize it’s, it’s full of very spiky grasses with sharp …
