As a result oxygen was allowed to build up in the atmosphere and enable oxygen-breathing life to evolve and flourish. When the newly emerged land eroded, it produced sediment that washed into the oceans and buried the organic matter, preventing further reactions with oxygen, the scientists believe. The transition may help explain why oxygen levels in the atmosphere rose at this time in the Earth’s history, say the researchers led by Dr Nicolas Flament from the University of Sydney.ĭuring the waterworld era, any oxygen produced by photosynthesising bacteria would have been quickly used up through reactions with decaying organic matter in the oceans. New Scientist magazine reported: “As the mantle cooled, land would have gradually appeared as the oceans became deeper and regions of high relief on the continental crust formed.” The continental crust would also have spread, making it lower and flatter and more vulnerable to floods. A hotter mantle would have thickened and buoyed up the Earth’s crust beneath the oceans, creating shallower basins and leading to the flooding of what is now land. The Australian scientists who produced the new computer simulation believe that billions of years ago the Earth’s deep mantle was 200C hotter than it is today.
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