what happened 4.0 billion years ago ?
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https://www.britannica.com/science/Hadean-Eonhttps://www.britannica.com/science/Hadean-Eon Hadean Eon | Start, Timeline, & Facts | Britannica Hadean Eon, informal division of the Precambrian occurring between about 4.6 billion and about 4.0 […]
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