Ancient rocks reveal when rivers began pouring nutrients into the sea
The 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 Group