Abstract: A 5 page paper discussing changes in the Earth's atmosphere over the last several million years. It is possible that the secondary atmosphere (the first was probably lost) contained even more carbon dioxide than that of today. Volcanic activity was much more pronounced, and there likely were not as many photosynthetic ocean organisms available to use it. The one change we can be certain of is that there is more oxygen now than when it first began to be a standard element of the atmosphere. Bibliography lists 7 sources.