4-Billion-Year-Old Earth’s Crust as Big as Ireland Found in Australia

Scientists at Curtin University in Australia have uncovered a portion of the Earth's crust that is 4 billion years old.

The piece, about the size of Ireland and located under the South-West of Western Australia, was spotted by experts using "lasers smaller than a human hair."

Researchers directed the lasers onto beach sand minerals collected from individual grains.

The report details the discovery that researchers released in June, CNet reported. The lasers revealed the grains' geological history and locations where they were first eroded.

4-Billion-Year-Old Piece of Earth Crust Found in Australia

Experts found the oldest minerals on Earth close to where the concealed chunk of ancient crust resides. Researchers have found tiny crystals called zircons that date back 4.4 billion years in Australia's Jack Hills.

In their report made online on June 17 in the journal Terra Nova, the researchers stated that the ancient crust spans at least 38,610 square miles (100,000 square kilometers).

These minerals have persisted despite the erosion of the rocks that initially contained them. The Narryer Terrane, the rocks surrounding the Jack Hills, are also not novices: A few are 3.7 billion years old.

"When comparing our findings to existing data, it appears many regions around the world experienced a similar timing of early crust formation and preservation," said study coauthor Maximilian Droellner, a doctoral student at Curtin University in Australia, in a statement. "This suggests a significant change in the evolution of the Earth some four billion years ago, as meteorite bombardment waned, crust stabilized and life on Earth began to establish."

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How Researchers Dug into Earth's Crust

According to geochemical indications found in sediments near this area (per Live Science), a much older crust may be hidden beneath younger rocks and sediments at the surface.

To evaluate the zircons in sediments from the Scott Coastal Plain, south of Perth, Droellner and his colleagues made this decision. Erosion exposed the deeper rocks that make up the plain on the Australian continent.

To achieve this, the scientists used strong lasers to melt the zircons. They then examined the chemical makeup of two pairings of radioactive elements that were liberated-lutetium and hafnium and uranium and led by the lasers.

Over billions of years, the versions of these elements locked in these zircons deteriorate.

Researchers can "clock" the age of the zircons using the relative proportions of each version, or isotope, which reveals how long the elements have been degrading.

According to the dating, the rocks containing these minerals developed between 3.8 billion and 4 billion years ago.

The researchers used information gathered by Earth-orbiting satellites to understand more about the origins of these minerals. Gravity changes somewhat on Earth's surface due to variations in the thickness of the crust.

The thickness of the crust may be calculated by monitoring these differences in gravity at various sites. This gravity measurement showed a thick section of crust in Western Australia's southwest, which is probably where the old crust that is buried there is located.