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Researchers believe land would have been scarce some 3 billion to 4 billion years ago.
Alec Brenner/Harvard University
Ancient Earth was a water world
Mar. 9, 2021 , 9:00 AM
Across the ages, sea levels have risen and fallen with temperatures—but Earth’s total surface water was always assumed to be constant. Now, evidence is mounting that some 3 billion to 4 billion years ago, the planet’s oceans held nearly twice as much water—enough to submerge today’s continents above the peak of Mount Everest. The flood could have primed the engine of plate tectonics and made it more difficult for life to start on land.