May 8 (UPI) — Ancient rocks in Australia suggest early Earth was flat, barren and mostly under water. The vast seas were interrupted by only a handful of small islands 4.4 billion years ago.
Researchers determined the composition of early Earth by analyzing zircon mineral grains trapped in ancient sandstone, the oldest rock fragments recovered by scientists.
“Our research indicates there were no mountains and continental collisions during Earth’s first 700 million years or more of existence — it was a much more quiet and dull place,” Antony Burnham, an earth scientist at Australian National University, said in a news release.
“Our findings also showed that there 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,” Burnham added.
Zircon grains are to geologists and earth scientists what DNA is to a paleontologist.
Scientists were able to link zircon composition with different magma and rock types, recreating a timeline of geologic conditions during Earth’s earliest millennia.
Because zircon is created by the melting of older igneous rock, they serve as evidence of major magmatic events.
“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,” Burnham said.
The new study — detailed in the journal Nature Geoscience — relied upon a wealth of previous research.
“The samples of zircon from Jack Hills have been collected over the course of several decades by many people, while chemical analyses carried out by an ANU research group 20 years ago have proved invaluable,” Burnham said.
