Shock and thaw? Earth’s oldest asteroid impact may have helped lift the planet out of a deep freeze

By Eric Hand Barlangi Rock, an ancient hill in the outback of Western Australia, is dimpled by the quarries of Aboriginal people who chiseled its fine-grained rocks into sharp tools. Now, geologists have added a much deeper layer of history to those rocks by showing they were forged 2.229 billion years ago, when an asteroid …