快猫短视频

Earth 4.4 billion years ago was flat and almost entirely covered in water with just a few small islands, new research suggests.

快猫短视频s came to the conclusion after analysing tiny zircon mineral grains from a region of Western Australia containing the oldest rocks ever found.

鈥淭he 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鈥檝e used these trace elements of zircon to build a profile of the world at that time,鈥� says lead researcher Antony Burnham, from the Australian National University.

鈥淥ur research indicates there were no mountains and continental collisions during Earth鈥檚 first 700 million years or more of existence 鈥� it was a much more quiet and dull place,鈥� he says. 鈥淭here are strong similarities with zircon from the types of rocks that predominated for the following 1.5 billion years, suggesting that it took the Earth a long time to evolve into the planet that we know today.鈥�

The team conducted a forensic study of the grains looking for clues to their formation.

They found that the zircon was created by melting old igneous rocks rather than sediments.

鈥淪ediment 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鈥檚 history,鈥� says Burnham.

The zircon grains, preserved in sandstone rocks in the Jack Hills, date back to when the Earth was only 160 million years old.

The new research fits in with the 鈥淐ool Early Earth鈥� theory that suggests a cool, quiet period followed the extreme conditions of Earth鈥檚 earliest history.

It pre-dated the Late Heavy Bombardment 4.1 to 3.8 billion years ago when the Earth was pummelled by comets and asteroids.

Bacterial life is thought to have emerged on Earth at the end of the bombardment around 3.8 billion years ago.