Earth older than thought

Core samples originally taken for gold mine exploration may change the scientifically accepted date of the Earth’s formation.

Iron-rich rock formations dating to 2.3 billion years ago suggest that the Earth’s land mass was covered with living things at least a billion years earlier than previously thought.

“Until now, the earliest accepted date for land-based life was 1.2 billion years ago, but now we can push that back at least another billion years,” says Hiroshi Ohmoto, professor of geoscience and director of the Penn State Astrobiology Research Center.

In collaboration with Nicholas Beukes of Rand Afrikaans University in Johannesburg, Ohmoto investigated laterites — iron-rich deposits that form when organic acids (acids created when living things decay) leach iron from upper layers of rock and deposit them as oxides in layers below. Normally, a laterite consists of three bands: an iron-deficient layer covered by an iron-rich layer that, in turn, is covered by another iron-deficient layer.

Says Ohmoto: “Since we have now traced these laterites to 2.3 billion years ago, there must have been an atmospheric oxygen and terrestrial life at that time.”

Although he began his research by studying formations in Waterval Onder, near Pretoria, South Africa, his work was hampered because the iron-rich layer and upper iron-poor layer had eroded away. The researchers then studied core samples taken by miners who drilled through these layers looking for gold and uranium ores buried much farther down. “We looked at two cores in South Africa and one in Botswana that showed the complete series of rocks,” says Ohmoto. The core samples will be studied further.

— The preceding an excerpt from an article published in Gold News.