The evolution of Earth's atmosphere GapFill

There are many theories about Earth's early atmosphere and what it contained. Many people think that  580 million1.2 billion2.7 billion4.6 billion years ago when Earth was formed, the atmosphere contained mainly  carbon dioxidemethanewater vapoursulfuric acid. One of the most well-supported theories for the development of the early atmosphere is that  volcanoessandstormstornadoesearthquakes were the main contributor of the gases, as well as in forming the oceans from condensed  water vapouralkalisoxygennitrogen. In addition to nitrogen, there may have been small proportions of  argon and sulfuroxygen and sulfurammonia and oxygenmethane and ammonia released.

Levels of carbon dioxide slowly decreased due to the increased rate of  anaerobic respirationphotosynthesisaerobic respirationpollination in  algaefungiinsectsviruses and plants. This also contributed to  decreasedoverwhelmingincreasedconstant levels of oxygen, starting around  2 million1 billion2.7 billion40 million years ago, and allowing the evolution of  microbesbacteriavirusesanimals. Carbon dioxide was also removed from the atmosphere by the action of the oceans, where it dissolved to form  phosphatesammoniumcarboxidescarbonates. These precipitated out into  shaleigneoussedimentarygranite 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  5 million200 million10,0001000 years. The composition of gases present is about  70%60%80%50% nitrogen, with the majority of the rest being  ammoniaoxygencarbon dioxidewater vapour, although there are small amounts of other gases present too.