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Thursday, February 07, 2008

The real facts about Earth

The Earth's surface is exceptionally young. In the relatively short (by astronomical standards) time of 500,000,000 years or so erosion and tectonic processes destroy and restructure most of the Earth's surface and thus eliminate almost all traces of earlier geologic surface history (such as impact craters). Thus the very before time on history of the Earth has mostly been erased. The Earth is 4.5 to 4.6 billion years old, but the oldest recognized rocks are about 4 billion years aged and rocks older than 3 billion years are rare. The oldest fossils of presented organisms are less than 3.9 billion years old. There is no evidence of the critical period when life was first getting in progress.

The Earth's environment is 77% nitrogen, 21% oxygen, with draws of argon, carbon dioxide and water. There was perhaps a very much bigger amount of carbon dioxide in the Earth's atmosphere when the Earth was first created, but it has since been nearly all incorporated into carbonate rocks and to a smaller extent dissolved into the oceans and consumed by living plants. Plate tectonics and biological processes now keep a frequent flow of carbon dioxide from the atmosphere to these various "sinks" and back over again. The little amount of carbon dioxide occupant in the atmosphere at any time is very important to the maintenance of the Earth's surface temperature through the greenhouse effect. The greenhouse consequence raises the average surface temperature regarding 35 degrees C above what it would if not be (from a frigid -21 C to a comfortable +14 C); without it the oceans would freeze and life as we know it would be impossible.

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