4.6billion years ago, it had almost no atmosphere. The surface was molten. After about half a billion years, Earth’s surface cooled and solidified enough for water to collect on it.
The Archean Eon (4 to 2.5 billion years ago) Methane droplets in the air covered the young Earth in a global haze. There was no oxygen gas on Earth. Oxygen was only in compounds such as water.
Oxygen at Last (2.6 billion to 400 million years ago) Two billion years ago, the methane haze cleared and the sky turned blue.
Between 700-550 million years ago, in the late Proterozoic, oxygen levels in the oceans and atmosphere increased dramatically.
The Age of Oxygen (400 million to 290 million years ago) As plants became established on land, life once again had a major effect on Earth’s atmosphere during the Carboniferous Period.
Modern Atmospheres (290 million years ago to now),Earth was much warmer than it is now.In these warm climates, many types of plants and animals lived.
