Scientists may have found world’s oldest glacier which dates back to 2.9 billion years

Scientists have discovered traces of the world’s oldest-known glaciers hiding near gold deposits in South Africa. The glacial sediments, according to the researchers, date back to 2.9 billion years. The study published in the journal Geochemical Perspectives Letters also suggests the presence of continental ice caps at the time or that the area was closer to the Earth's poles.

How was the study conducted?

The study was conducted by researchers, Professor Axel Hofmann of the University of Johannesburg and Professor Ilya Bindeman from the University of Oregon. The scientists unearthed shale deposits and analysed core samples from the rocks sitting under the world’s largest gold deposits in South Africa.

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The samples collected from the field sites from the Kaapvaal Craton, South Africa were said to be a part of the Pongola Supergroup which is known to be some of the most extensive and well-preserved volcano-sedimentary successions formed in the Mesoarchaean era (between 3.2 billion to 2.8 billion years ago).

The researchers also analysed the core samples from the same region to determine the climatic conditions at the time when sediments were formed for which they used triple oxygen isotope analysis. This method measures three different forms of oxygen or isotopes present in the sediment.

About their findings

The scientists found that certain isotopes in their samples matched those common in icy temperatures, which suggests that the climate must have been cold when the rocks were deposited which indicates the presence of ice.

They also discovered the world’s oldest known fossilised glacial moraines, which is “basically the debris left by a glacier as it gradually melts and contracts,” explained Bindeman, adding “These are the oldest moraine deposits ever found.”

What else does the study suggest?

The presence of this glacial material could give us clues about Earth’s climate and geography during this period. One of the theories that the study’s authors present is that this area of South Africa may have been close to one of the poles 2.9 billion years ago.

“Another possibility is that the whole Earth was in a ‘snowball Earth’ period,” said Hofmann, adding that this period was marked by low atmospheric concentrations of greenhouse gases like carbon dioxide and methane and led to a “reverse greenhouse effect,” causing much of the planet to freeze.

“Scientists believe that this may have happened on a couple of occasions in the more recent past. If so, this would be the earliest much global cooling period recorded. Either possibility is scientifically interesting,” Hofmann added.

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