Some Future Consequences of Plate Tectonics

Some Future Consequences of Plate Tectonics - reducing...

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Some Future Consequences of Plate Tectonics Plate tectonics is still an active process, and will drastically reshape the face of the Earth over the next 50 million years or so. A few consequences of plate tectonics based on projections of present motion include: Portions of California will separate from the rest of North America. The Italian "boot" will disappear. Australia will become linked to Asia. Africa will separate from the Near East. As a consequence of plate tectonics (supplemented by wind and water erosion), we live on the surface of a geologically active planet that has obliterated most of its early geological history. The Earth's Atmosphere The present atmosphere of the Earth is probably not its original atmosphere. Our current atmosphere is what chemists would call an oxidizing atmosphere , while the original atmosphere was what chemists would call a
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Unformatted text preview: reducing atmosphere . In particular, it probably did not contain oxygen. Composition of the Atmosphere The original atmosphere may have been similar to the composition of the solar nebula and close to the present composition of the Gas Giant planets, though this depends on the details of how the planets condensed from the solar nebula. That atmosphere was lost to space, and replaced by compounds outgassed from the crust or (in some more recent theories) much of the atmosphere may have come instead from the impacts of comets and other planetesimals rich in volatile materials. The oxygen so characteristic of our atmosphere was almost all produced by plants ( cyanobacteria or, more colloquially, blue-green algae). Thus, the present composition of the atmosphere is 79% nitrogen, 20% oxygen, and 1% other gases....
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