Radiometric dating has determined that earth is approximately
The ages of these single zircon grains are at least roughly 100 million years older than those of the oldest known intact rocks.
Earth’s secondary atmosphere began to develop at the time of planetary differentiation, probably in connection with volcanic activity.
This chemical process of melting, separation of material, and outgassing is referred to as the Earth’s interior (or its mantle) was hot and liquid, it would have been subjected to large-scale convection, which may have enabled oceanic crust to develop above upwelling regions.
Rapid recycling of crust–mantle material occurred in convection cells, and in this way the earliest terrestrial continents may have evolved during the 300-million-year gap between the formation of Earth and the beginning of the rock record.
It is known from direct observation that the surface of the basaltic lavas caused by the impact-induced melting of the lunar mantle.
Many of these basalts have been analyzed isotopically and found to have crystallization ages of 3.9 to 4 billion years.
Earth and the meteorites thus have had similar lead isotope histories, and so it is concluded that over a period of about 30 million years they condensed or accreted as solid bodies from a primeval cloud of interstellar gas and dust—the so-called solar nebula from which the entire solar system is thought to have formed—at about the same time.
This mineral is the oldest dated material on Earth.
The rocks from which the zircons in the quartzites and conglomerates were derived have either disappeared or have not yet been found.
To understand this little-known period, the following factors have to be considered: the age of formation at 4.6 billion years ago, the processes in operation until 4.3 billion years ago, the bombardment of Earth by meteorites, and the earliest zircon crystals.
It is widely accepted by both geologists and astronomers that Earth is roughly 4.6 billion years old.