CANBERRA, May 17 (Xinhua) -- Australian scientists revealed evidence on Tuesday that a "huge" asteroid struck the Earth early in its life, with the impact thought to be significantly larger than anything humankind has experienced.

The researchers, from the Australian National University (ANU) in Canberra, found tiny glass beads called "spherules" in terrain in north-western Australia, and Dr. Andrew Glikson said they were formed by "vaporized material" when the massive asteroid hit Earth.

"The impact would have triggered earthquakes orders of magnitude greater than terrestrial earthquakes, it would have caused huge tsunamis and would have made cliffs crumble," Glikson,  from the ANU Planetary Institute said in a statement on Tuesday.

"Material from the impact would have spread worldwide. These spherules were found in sea floor sediments that date from 3.46 billion years ago."
Glikson said from the evidence recovered, the asteroid would have been up to 30 km in diameter, and would have created a massive crater hundreds of km wide, but said as the impact occurred more than 3.4 billion years ago, it was impossible to tell where it happened.

"Exactly where this asteroid struck the earth remains a mystery, " Glikson said.

"Any craters from this time on Earth's surface have been obliterated by volcanic activity and tectonic movements."

Terrain in north-western Australia is largely considered some of the oldest on Earth, and it allowed the scientists to accurately gauge how old the asteroid impact was.

Glikson said the sediment layer in which the spherules were found was originally on the ocean floor, but preserved between two volcanic layers, allowing the team to precisely work out when it occurred.

He added that his team was searching for further evidence of other asteroid impacts early in the Earth's life which could unlock further secrets about the history of the planet.

"This is just the tip of the iceberg. We've only found evidence for 17 impacts older than 2.5 billion years, but there could have been hundreds," he said.

"Asteroid strikes this big result in major tectonic shifts and extensive magma flows. They could have significantly affected the way the Earth evolved."