Eras geologic of the Earth

Geological history of Earth

Diagram of geological time scale.

The geological history of Earth is believed to have begun 4.567 billion years ago^[1] when the planets of the Solar System were formed out of the solar nebula, a disk-shaped mass of dust and gas left over from the formation of the Sun. Initially molten, the outer layer of the planet Earth cooled to form a solid crust when water began accumulating in the atmosphere. The Moon formed soon afterwards, possibly as the result of a Mars-sized object with about 10% of the Earth's mass,^[2] known as Theia, impacting the Earth in a glancing blow.^[3] Some of this object's mass merged with the Earth and a portion was ejected into space, but enough material survived to form an orbiting moon.
Outgassing and volcanic activity produced the primordial atmosphere. Condensing water vapor, augmented by ice delivered by comets, produced the oceans.^[4]
As the surface continually reshaped itself over hundreds of millions of years, continents formed and broke up. The continents migrated across the surface, occasionally combining to form a supercontinent. Roughly 750 Ma (million years ago),^[5] the earliest-known supercontinent Rodinia, began to break apart. The continents later recombined to form Pannotia, 600–540 Ma,^[5] then finally Pangaea, which broke apart 180 Ma.^[5][6]
The present pattern of ice ages began about 40 Ma,^[5] then intensified during the Pleistocene about 3 Ma.^[5] The polar regions have since undergone repeated cycles of glaciation and thaw, repeating every 40,000–100,000 years. The last glacial period of the current ice age ended about 10,000 years ago.^[7]
The geological history of the Earth can be broadly classified into two periods: the Precambrian supereon and the Phanerozoic eon.

Precambrian

Precambrian includes approximately 90% of geologic time. It extends from 4.6 billion years ago to the beginning of the Cambrian Period (about 570 Ma). It includes three eons, the Hadean, Archean, and Proterozoic Eons.