The evolution of Earth's atmosphere GapFill

There are many theories about Earth's early atmosphere and what it contained. Many people think that  1.2 billion200 million4.6 billion7.5 billion580 million2.7 billion years ago when Earth was formed, the atmosphere contained mainly  water vapouroxygencarbon dioxidemethanesulfuric acidnitrogen. One of the most well-supported theories for the development of the early atmosphere is that  volcanoeshumanssandstormstornadoesmeteorsearthquakes were the main contributor of the gases, as well as in forming the oceans from condensed  carbon dioxideoxygenwater vapouralkalisacidsnitrogen. In addition to nitrogen, there may have been small proportions of  methane and ammoniamethane and oxygenoxygen and sulfurammonia and argonargon and sulfurammonia and oxygen released.

Levels of carbon dioxide slowly decreased due to the increased rate of  pollinationanaerobic respirationfermentationaerobic respirationcombustionphotosynthesis in  animalsvirusesinsectsfungibacteriaalgae and plants. This also contributed to  fluctuatingincreaseddecreasedconstantoverwhelmingnegligible levels of oxygen, starting around  5 billion1 billion200,00040 million2.7 billion2 million years ago, and allowing the evolution of  virusesfungimicrobesanimalshumansbacteria. Carbon dioxide was also removed from the atmosphere by the action of the oceans, where it dissolved to form  carboxidescarbonatesphosphatesammoniumacidshydroxides. These precipitated out into  shalegraniteslateigneoussedimentarymetamorphic rocks such as limestone, and fossil fuels were also formed as organic material was buried under damp conditions.

The atmosphere of today's Earth has been around in much the same form for about  10004.7 billion10,000200 million2 billion5 million years. The composition of gases present is about  60%20%80%90%70%50% nitrogen, with the majority of the rest being  carbon dioxideargonammoniamethanewater vapouroxygen, although there are small amounts of other gases present too.