Rivers may have operated on a global scale around 3.5 billion years ago.
The new find comes courtesy of ancient rocks in China and South Africa. A change in rock chemistry around that time provides the earliest known chemical evidence for the weathering of Earth’s continents and the subsequent delivery of nutrients from land to ocean, geobiologist Kurt Konhauser and colleagues report December 12 in Geology.
Water chips away at rocks on land, removing minerals and washing them away. “As soon as you get weathering, you’ve got a nutrient influx to the oceans, which can lead to … life thriving in coastal waters,” says Konhauser, of the University of