NewsEarthAncient rocks reveal when rivers began pouring nutrients into the seaThe discovery sheds light on the origins of continents and life on our planet This open pit mine in Anshan, China, contains rocks from the Archean Eon, 4 billion to 2.5 billion years ago, that help pinpoint when rivers began operating on a global scale. Second Geological Brigade/Hebei Bureau of Geology and Mineral Resources, Luanxian Sijiaying Iron Mine Co., Ltd./Hebei Iron and Steel GroupBy Lucas Van Wyk Joel9 seconds agoRivers 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 Earths 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, youve got a nutrient influx to the oceans, which can lead to life thriving in coastal waters, says Konhauser, of the University of Alberta in Edmonton, Canada.