Earth took billions of years to become habitable.
These years included a number of natural phenomena that destroyed and created entire landscapes. Earth’s tectonic plates sitting under the crust also played a major role in transforming the ancient grounds, creating the mountains and the continents we now know.
Now, billions of years later, scientists have found the oldest direct evidence that gives an estimate about when Earth’s ground began to shake.
The planet’s tectonic plates were moving as far back as 3.5 billion years ago, a discovery that will reshape our understanding of how our planet became the living world it is today.
The findings, published March 19 in the journal Science, come from a Harvard University team that spent years analysing ancient rocks in western Australia.
Their work pushes back the known timeline of plate movement and sheds new light on one of geology’s biggest unsolved questions.
WHAT DID ROCKS REVEAL?
The researchers studied more than 900 rock samples from over 100 sites in a region called the North Pole Dome, part of the Pilbara Craton, which is one of the oldest and best-preserved rock formations on Earth.
Using paleomagnetism, a technique that reads fossilised magnetic signals locked inside ancient minerals, the team could track where the rocks were located on the globe when they first formed, essentially using them as prehistoric GPS units.
The results were unexpected.
“There has been a huge range of ages suggested for timing,” said lead author Alec Brenner, who conducted the research at Harvard. “With this study, we’re able to say three and a half billion years ago, we can see plates moving around on the Earth surface.”
WHY DOES IT MATTER FOR OUR PLANET?
Plate tectonics is not just about earthquakes and volcanoes. It is deeply connected to the conditions that made life possible.
These are the movements that shaped continents, regulate climate, and drove the recycling of nutrients essential for living organisms.
“Almost everything unique about the Earth has something to do with plate tectonics at some level,” said senior author Roger Fu, professor of Earth and Planetary Sciences at Harvard. “At some point, the Earth went from something not that special, just another planet in the solar system with similar materials, to something very special. A very strong suspicion is that plate tectonics started Earth down this divergent track.”
The team also uncovered the oldest known case of a geomagnetic reversal. It’s an event where Earth’s magnetic field flips, making compass needles point south instead of north. The finding suggests these reversals happened less often in Earth’s early history than they do today.
“We took a really big gamble,” Brenner added. “Demagnetising thousands of cores takes years. And boy, did it pay off! These results were beyond our beyond our wildest dreams.”
