[Lee Stewart]

The oldest known materials of any kind on the planet are zircon crystals found in western Australia's Jack Hills region that are 4.4 billion years old. Elements in these zircons suggest they came from water-rich, granite-like rocks. The presence of quartz as well as the result of isotopic studies of the materials suggests that continental crust was forming very early in Earth's history and that tectonic activity was occurring as well.