Scientists trying to decipher the early history of the Earth are like people who arrive late for a movie, after the basic story line and characters have been established. Like tardy moviegoers, geologists are frustrated by the absence of any preserved geological record from the Earth's early years, the “Hadean Interval,” which extended from about 4.6 billion years ago, when the solar system formed, to about 3.8 billion years ago, when rocks started to be preserved.
It is in this Hadean Interval that much of the basic character of the Earth was established. A metal core formed, a magnetic field developed, the first lavas erupted, continental nuclei possibly formed, and there may have been the first stirrings of plate tectonics. Oceans and an atmosphere formed, prebiotic chemical evolution took place, and the first primitive life forms may have appeared.