The accumulation of oxygen on Earth began between 50 and 100 million years earlier than previously thought, according to the traces found in Australia by several American research groups. They have studied a sediment that has not been in direct contact with the atmosphere for millions of years and have discovered that in the sediments of 2.5 billion years ago there are components that reacted with oxygen, that is, that at that time there was oxygen --until now it was thought that oxygen had appeared about 2.4 billion years ago. If there was oxygen in the ocean water, it is possible that it was also in the atmosphere, although the concentration was much lower than that necessary to develop life.