4.4bn years ago, the Earth was a barren, flooded world

9 May 2017

Image: Vadim Sadovski/Shutterstock

New research into what Earth looked like billions of years ago has revealed that our planet was once a barren, alien-like world.

While Earth today is undergoing its own environmental challenges, spare a thought for what it would have been like around 4.4bn years ago.

A team of researchers from Australian National University decided to imagine just that, analysing zircon mineral grains preserved within ancient sandstone found in Western Australia, so far the oldest known fragments of Earth ever found.

By looking at the fragments under powerful microscopes and conducting analyses, the team led by Dr Antony Burnham discovered that during this period, the planet resembled a world alien to our own.

If you were to see it today, it would be something like a water world, with only a few islands dotted across its flat surface due to a complete lack of continental collisions during the first 700m years of formation.

Zircon material

Zircon crystals, some of the oldest known fragments of Earth ever found. Image: Stuart Hay/ ANU

Earth took a long time to evolve

“The history of the Earth is like a book with its first chapter ripped out, with no surviving rocks from the very early period, but we’ve used these trace elements of zircon to build a profile of the world at that time,” Burnham said.

“Our findings also showed that there are strong similarities with zircon from the types of rocks that predominated for the following 1.5bn years, suggesting that it took the Earth a long time to evolve into the planet that we know today.”

Describing the zircon grains as clues in a crime scene, the team was able to come to these conclusions by finding that the zircon was formed by melting older igneous rocks rather than sediments.

“Sediment melting is characteristic of major continental collisions, such as the Himalayas, so it appears that such events did not occur during these early stages of Earth’s history,” he said.

It was only a few hundred million years later that the first known forms of life emerged, 3.8bn years ago.

The team’s research has been published in the journal Nature Geoscience.

Colm Gorey was a senior journalist with Silicon Republic