Exploratour - Evolution of the Solar System
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Image from: USGS, courtesy of Volcano World
Scientists think that the secondary atmosphere came from the many volcanic eruptions which took place in Earth's early history, and which continue today. The formation of the early ocean was also important to the forming of the secondary atmosphere. Nitrogen may be a big part of Earth's atmosphere now because it could not be dissolved in the waters which formed the early oceans. The atmosphere would be all nitrogen today exscept for the activity of plant life which provides oxygen.
We will talk more about the changes in Earth's atmosphere later.
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