Lying on the Indo-Australian Plate, the mainland of Australia is the lowest and most primordial landmass on Earth with a relatively stable geological history. The landmass includes virtually all known rock types and from all geological time periods spanning over 3.8 billion years of the Earth's history. The Pilbara Craton is one of only two pristine Archaean 3.6–2.7 Ga (billion years ago) crusts identified on the Earth.