Modern-like tectonic plate motion on the early Earth
An enduring question in geology involves the question of when the tectonic plates of the Earth’s crust began pushing and pulling in a process that formed the planet’s continents, oceans, and other landforms. Some researchers theorize it happened about 4 billion years ago. Others say it was closer to 1 billion. Clues can be found in very old rocks. Looking at some, a team led by Harvard researchers show that these plates were moving at least 3.2 billion years ago on the early Earth. In a portion of the Pilbara Craton in Western Australia, one of the oldest pieces of the Earth’s crust, scientists found a latitudinal drift of about 2.5 centimeters a year. They found the motion went back 3.2 billion years and confirmed it using a novel magnetic microscope. The researchers believe this shift is the earliest proof that modern-like plate motion happened between 2 and 4 billion years ago, suggesting...