High Quality Content by WIKIPEDIA articles! The geological history of Earth follows the major events in Earth`s past based on the geologic time scale, a system of chronological measurement based on the study of the planet`s rock layers (stratigraphy). Earth formed about 4.54 billion years ago by accretion from the solar nebula, a disk-shaped mass of dust and gas left over from the formation of the Sun, which also created the rest of the Solar System.