Eons

The Hadean eon (4,540 – 4,000 mya) represents the time before a reliable (fossil) record of life.
Temperatures were extremely high, and much of the Earth was molten because of frequent collisionswith other bodies, extreme volcanism and the abundance of short-lived radioactive elements.
A giant impact collision with a planet-sized body named Theia (approximately 4.5 billion years ago) is thought to have formed the Moon.
The moon was subjected to Late Heavy Bombardment(LHB – lunar cataclysm – 4 billion years ago).
During the LHB phase, a disproportionately large number of asteroids are theorised to have collided with the early terrestrial planets in the inner Solar System, including Mercury, Venus, Earth, and Mars.
Volcanic outgassingprobably created the primordial atmosphere and then the ocean.
The early atmosphere contained almost no oxygen.
Over time, the Earth cooled, causing the formation of a solid crust, leaving behind hot volatiles which probably resulted in a heavy CO₂atmosphere with hydrogen and water vapour.
Liquid water oceans existed despite the surface temperature of 230° C because, at an atmospheric pressure of above 27 atmospheres, caused by the heavy CO2 atmosphere, water is still liquid.

The beginning of lifeon Earth and evidence of cyanobacteria date to 3500 mya.
Life was limited to simple single-celled organisms lacking nuclei, called Prokaryota.
The atmosphere was without oxygen,and the atmospheric pressure was around 10 to 100 atmospheres.
The Earth’s crust had cooled enough to allow the formation of continents.
The oldest rock formations exposed on the surface of the Earth are Archean.
Volcanic activity was considerably higher than today, with numerous lava eruptions.
The oceans were more acidicdue to dissolved carbon dioxide than during the Proterozoic.
By the end of the Archaean, plate tectonicsmay have been similar to that of the modern Earth.
Liquid water was prevalent, and deep oceanic basins are known to have existed.
The earliest stromatolites are found in 3.48 billion-year-old sandstone discovered in Western Australia.
The earliest identifiable fossilsconsist of stromatolites, which are microbial mats formed in shallow water by cyanobacteria.

It is the last eon of the Precambrian “supereon”.
It spans for the time of appearance of oxygenin Earth’s atmosphere to just before the proliferation of complex life (such as corals) on the Earth.
Bacteriabegin producing oxygen, leading to the sudden rise of life forms.
Eukaryotes (have a nucleus), emerge, including some forms of soft-bodied multicellular
Earlier forms of fungi formed around this time.
The early and late phases of this eon may have undergone Snowball Earthperiods (the planet suffered below-zero temperatures, extensive glaciation and as a result drop in sea levels).
It was a very tectonically activeperiod in the Earth’s history.
It featured the first definitive supercontinent cycles and modern orogeny (mountain building).
It is believed that 43% of modern continental crust was formed in the Proterozoic, 39% formed in the Archean, and only 18% in the Phanerozoic.
In the late Proterozoic (most recent), the dominant supercontinent was Rodinia (~1000–750 Ma).

Started about 541 million years ago and continues to the present is known as the Phanerozoic Eon.
This eon can be divided into 3 Eras.
These 3 eras are the Paleozoic, Mesozoic, and Cenozoic.
Each of these Eras can be subdivided even further into Periods.