A sheep ranch in the remote Jack Hills region of western Australia has yielded a huge discovery — tiny zircon crystals that scientists have now confirmed are the oldest known materials formed on Earth. A team of researchers used two different techniques to date the crystals, which were extracted in 2001 from a rock outcrop of sandstone that formed an ancient beach 3 billion years ago. According to their findings, published in the journal Nature Geoscience, the crystals are fragments of the Earth’s crust and date back some 4.4 billion years, just 100 million years after the formation of the planet itself.
Due to plate tectonics and weathering, very little of the Earth’s early surface remains for scientists to study. With a few exceptions, the vast majority of surface rocks on the planet are relatively modern, dating back less than a few hundred million years old. For this reason, the tiny zircon crystals found worked into newer sandstone rocks in the Jack Hills region in 2001 provide a vital clue in the mystery surrounding Earth’s earliest history.
A team of researchers led by geoscience professor John Valley of the University of Wisconsin originally determined the age of the crystals by looking at a small sample and measuring how much of the element uranium had decayed into lead. . .