2 billion years ago (The Archean Eon )
Huge quantities of steam shot out of blow holes and splitting seams. The (Earth)lay covered in a darkening fog of carbon gases and sulfurous fumes. Showers of icy comets and carbonaceous meteorites bombarded teh planet, burning through the atmosphere to the weak and unstable surface, further rupturing the crust. Carbon and water came with them from space in sufficient quantities to add to the Earth's own supplies of what were later to become the staples of life. As the Earth's surface continued to cool, the clouds of steam filling the atmosphere could finally condense. Torrential rains fell for perhaps a hundred thousand years without cease, creating hot, shallow oceans. Submerged plate boundaries, rich in chemicals and energy, steadily vented hydrogen-rich gases into the seas. Water hitting the boiling lava in rifts and volcanoes evaporated, condensed, and rained down again. The waters began to erode the rocky landscape, smoothing out the pockmarks and wounds made by the constant belching of volcanoes and powerful impacting of meteorites. The waters round off the mountains as they were created, washing minerals and salts into the oceans and land pools. Meanwhile, in an event sometimes called the Big Belch, tectonic activity released gases trapped in the Earth's interior to form a new atmosphere of water vapor, nitrogen, argon, neon, and carbon dioxide. By this time much of the ammonnia, methane, and other hydrogen-rich gases of the primary atmosphere had been lost into space. Lightning struck. The sun continued to beam heat and ultraviolet light into the Earth's thickening atmosphere, as the fast-spinning planet spun in cycles of five-hour days and five-hour nights. The moon too had condensed from the sun's nebula. Since some 15 percent of the moon is material of Earth origin, the moon may have arisen when a planetoid crashed into the Earth's surface but could not completely escape Earthly gravity, going into orbit. Talk about trapped! Our faithful natural satellite, rather large for a puny inner planet like the Earth, from the beginning pulled rhytmically on the great bodies of water, creating tides. It is from this Archean Eon, from 3,900 to 2,500 million years ago, that we have found the first traces of life. Learn More Take me to the Early Proterozoic
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