One of the key features of Earth is that continents are constantly on the move. They move because of the intense heat in the Earth's core that causes molten rock in the mantle to move. Some scientists believe that tectonic plates began moving only a billion years ago, but others also think that the whole process started when Earth was only an infant, which happened nearly four billion years ago.
Since they are two conflicting views, scientists agreed somewhere in between. Today, it is commonly known that the movement of Earth's tectonic plates began around 2.8 billion years ago. During that time, the interior of the planet was just the right temperature to allow for the formation of 15 rigid plates.
But still, the disagreement between the two timelines is hard to prove since direct evidence from these times is hard to come by. Now, some of the ancient rocks on Earth suggest that the prediction on Earth's movements may have been more than 400 million years off the mark.
Ancient rocks from Australia
Harvard and MIT scientists analyzed the magnetism in ancient rocks found in Australia and South Africa. The researchers claim that tectonic plates began moving at least 3.2 billion years ago-and maybe earlier than that.
Alec Brenner, the paleomagnetics researcher at Harvard University said that that this discovery is one piece of geological evidence to extend the record of Earth's plate tectonics farther back in the planet's history.
"Based on the evidence we found, it looks like plate tectonics is a much more likely process to have occurred on the early Earth and that argues for an Earth that looks a lot more similar to today's than a lot of people think," Brenner said.
One of the oldest slices of Earth's ancient crust, the Pilbara craton contains fossils for some of the earliest organisms on our planet. This chunk of the ancient crust was formed as early as 3.5 billion years ago, stretching nearly 500 kilometers or 300 miles.
Known as the Honeyeater Basalt, the researchers drilled into a portion of the craton using a state of the art magnetometers and demagnetizing equipment to reveal the magnetic history of the region.
Continental drift
Published on the Science Advances, their research reveals a shift from one point to another. Roughly 3.2 billion years ago, the Earth's plate tectonics seemed to have a latitudinal drift of 2.5 centimeters a year. As the researchers put it, "a velocity comparable with those of modern plates."
Brenner told MSN that it is very comparable to the speeds of plate motion that is observable on the modern Earth. More so, it is also the most ancient sample of a piece of Earth's crust drifted long distances over the surface that the humans have.
But that is all that the scientist can conclude for now. It is still unclear whether the shift was caused by the local effects or the Pilbara craton's rotation or it could be a combination of both. Previous scientists believed that before the modern movements began, the tectonic plates moved in episodes of starts and stops that lasted for many billion years.
Though the authors of the study think that the timing hints otherwise, it could still explain the movement in Pilbara between 3.35 and 3.18 billion years ago.
