Earth’s first continents may have appeared three-quarters of a billion years earlier than previously thought
Earth’s first continents may have emerged from the oceans roughly 750 million years earlier than previously thought, rising from the seas in a manner completely unlike modern continents. These early masses of solid rock may have floated buoyantly atop magma welling up from below, a new study finds.
Unlike any other known planet, Earth possesses both continents and oceans on its surface. The emergence of land from sea greatly influenced Earth’s atmosphere, oceans, climate and proliferation of life. For instance, the runoff from continents is the primary source of a number of key nutrients for the oceans, such as phosphorus, which is needed to create DNA and other biological building blocks.
“The delivery of these essential nutrients to the oceans on the early Earth was critical in establishing and maintaining the earliest life forms,” said study co-author Priyadarshi Chowdhury, a geologist at Monash University in Melbourne, Australia. “The emergence of the first landmasses was therefore a pivotal event in our planet’s history.”
When and how Earth’s earliest continents, the cratons, first rose above the oceans remains uncertain. Previous research suggested this emergence began roughly 2.5 billion years ago and was driven by plate tectonics — the drifting, crashing and diving of the giant plates of rock that now make up Earth’s surface. [Continue reading…]