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The date when the Earth's atmosphere became oxygen-rich and suitable for life – known as The Great Oxidation Event –  was thought to have occurred around 2.4 billion years ago.

But now geologists from Ireland have found evidence of an earlier short-lived oxidation event which took place 600 million years earlier.

And they say their other research suggests the first oxygen-producing lifeforms began flourishing on Earth 60 million years earlier than first believed.

Pictured is a sample of a 3.02 billion years ago ancient soil - or paleosol. Here, they found evidence of chemical weathering of rocks leading to soil formation that occurred in the presence of oxygen

They claim these lifeforms were responsible for adding oxygen to our atmosphere, which laid the foundations for more complex life to evolve.

Scientists working at in India found evidence of chemical weathering of rocks leading to soil formation that occurred in the presence of oxygen. 

Using the naturally occurring uranium-lead isotope decay system, which is used to determine the age of substances, geologists claim this took place at least 3.02 billion years ago.

The pattern of chemical weathering preserved in the ancient soils - or paleosols - is compatible with higher atmospheric oxygen levels at that time, said scientists at Trinity College Dublin.

The soil came from the Singhbhum Craton of Odisha (pictured), and was named the 'Keonjhar Paleosol'

The soil came from the Singhbhum Craton of Odisha, and was named the 'Keonjhar Paleosol' after the nearest local town.

These high oxygen levels could only have been produced by organisms that were capable of photosynthesis. 

'This is a very exciting finding, which helps to fill a gap in our knowledge about the evolution of the early Earth,' said Professor Quentin Crowley at Trinity College, who led the study.

'This paleosol from India is telling us that there was a short-lived pulse of atmospheric oxygenation and this occurred considerably earlier than previously envisaged.'

The early Earth was very different to what we see today. Our planet's early atmosphere was rich in methane and carbon dioxide and had only very low levels of oxygen.

The widely accepted model for evolution of the atmosphere states that oxygen levels did not rise significantly until about 2.4 billion years ago.

This 'Great Oxidation Event' event enriched the atmosphere and oceans with oxygen, and heralded one of the biggest shifts in evolutionary history.

Micro-organisms were present before three billion years ago but they were not likely capable of producing oxygen by photosynthesis, scientists claim.

Pictured is a simplified map of the southern part of the Singhbhum Craton in India. It shows the distribution of sediments overlying the Keonjhar Paleosol 

Up until very recently however, it has been unclear if any oxygenation events occurred before the Great Oxidation Event and the argument for an evolutionary capability of photosynthesis has largely been based on the first signs of an oxygen build-up in the atmosphere and oceans.

'It is the rare examples from the rock record that provide glimpses of how rocks weathered,' added Professor Crowley.

'The chemical changes which occur during this weathering tell us something about the composition of the atmosphere at that time.

'Very few of these paleosols have been documented from a period of Earth's history prior to 2.5 billion years ago.

'The one we worked on is at least 3.02 billion years old, and it shows chemical evidence that weathering took place in an atmosphere with elevated oxygen levels.'

There was virtually no atmospheric oxygen present 3.4 billion years ago, but recent work from South African paleosols suggested that by about 2.96 billion years ago oxygen levels may have begun to increase.

Professor Crowley's finding moves the goalposts back at least 60 million years, which, given humans have only been on the planet for around a tenth of that time, is a significant change.

There was virtually no atmospheric O2 present 3.4 billion years ago, but recent work from South African paleosols suggested that by about 2.96 billion years ago O2 levels may have begun to increase. Pictured is the inghbhum Craton in India