The Early Atmoshpere

The Earth's first atmoshpere was formed/composed by(of) gases produced from' volanoes''. It contained large amounts of carbon dioxide and water vapour, hardly any oxygen '''and small amounts of other gasess.

At first the Earth was very hot, and there were not oceans because the water vapour hadn't yet cooled. But over time the Earth began to cool down, and the water vapour in the atmoshpere condensed  to liquid water. This liquid became the oceans.

Scientists cannot be certain about the composition of the early atmosphere. This was because there was no humans around this time, the only evidence is: Questions to ask Myself:
 * The gases that are made from present volcanoes. This tells us what gases there was ack then.
 * The atmospheres of other planets and moons in our solar system, where the atmosphere hasn't been affected (changed) by living things.
 * Iron compounds that have been found in very old rocks that can only form if there was no oxygen present (around).

What gases come out volcanoes?

What 1 thing shows us that the early atmosphere had no or a little amount of oxygen?