The evolution of Earth's atmosphere GapFill

There are many theories about Earth's early atmosphere and what it contained. Many people think that  4.6 billion580 million2.7 billion1.2 billion years ago when Earth was formed, the atmosphere contained mainly  water vapourcarbon dioxidemethanesulfuric acid. One of the most well-supported theories for the development of the early atmosphere is that  volcanoessandstormsearthquakestornadoes were the main contributor of the gases, as well as in forming the oceans from condensed  nitrogenwater vapouroxygenalkalis. In addition to nitrogen, there may have been small proportions of  ammonia and oxygenmethane and ammoniaoxygen and sulfurargon and sulfur released.

Levels of carbon dioxide slowly decreased due to the increased rate of  anaerobic respirationaerobic respirationphotosynthesispollination in  insectsalgaefungiviruses and plants. This also contributed to  increaseddecreasedoverwhelmingconstant levels of oxygen, starting around  2.7 billion1 billion40 million2 million years ago, and allowing the evolution of  animalsmicrobesbacteriaviruses. Carbon dioxide was also removed from the atmosphere by the action of the oceans, where it dissolved to form  carbonatescarboxidesammoniumphosphates. These precipitated out into  granitesedimentaryshaleigneous 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  1000200 million5 million10,000 years. The composition of gases present is about  60%50%70%80% nitrogen, with the majority of the rest being  oxygenwater vapourammoniacarbon dioxide, although there are small amounts of other gases present too.