The structure of the earth's gas shell 2.7 billion years ago was quite unusual, scientists from Australia and Great Britain believe.
Experts say that at that time there was no less oxygen in the upper layers of the earth's atmosphere than it is now, but in the immediate vicinity of the earth's surface, oxygen was completely absent.
In fact, on one planet, there were simultaneously two non-mixing atmospheres (one above the other) with different chemical compositions.
Scientists have known for a long time that before the oxygen catastrophe, which occurred 2.4 billion years ago, there was hundreds, or even thousands of times less oxygen in the Earth's atmosphere than today.
However, recent research has shown that billions of years ago, the planet's gas envelope was something of a nesting doll.
That is, meteorites that hit the Earth passed through the upper layers of the atmosphere and, accordingly, were oxidized, scientists find their particles in different places on our planet.
But the absence of traces of oxygen in geological deposits can be explained by the fact that these rocks were at sea level.
However, it still remains a mystery why the two layers of the atmosphere billions of years ago did not mix. Scientists have yet to answer this question.
Promotional video: