Cratons are pieces of ancient continents that formed several billions of years ago. Their study provides a window as to how processes within and on the surface of Earth operated in the past. Cratons preserve relics of our young Earth as they host a variety of rock assemblages such as greenstones and granites. Greenstones are rock assemblages that are primarily composed of sub-marine volcanic rocks with minor sedimentary rocks. They are the best archives to study early Earth surface processes.
Click here for original story, Study shows South Africa, India and Australia shared similar volcanic activity 3.5 billion years ago
Source: Phys.org