The missing 500 million: Cosmic bombardment melted Earth’s first crust
via arstechnica.com
Short excerpt below. Read at the original source.
Earth is the only planet we know of with buoyant, silica-rich continents. But, despite decades of research, geologists still don’t agree on how they formed. “The continents started appearing around about four billion years ago—that’s the oldest continental rock we know about,” said Tim Johnson, a geologist at Curtin University in Perth, Australia. “The Earth […]