How the Earth was Formed

March 21, 2019

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How the Earth was Formed

            The earth is considered as the living planet. However, looking at it today, it seems that the living planet is slowly turning into a dead planet. Pollutions surround the planet like it was made to kill each and every species in the planet. Before turning to the worst case scenario, let us see the earth long before it became a part of the solar system.  The table below illustrates the shows the complete time scale of the earth from Precambrian eon up to the present:

Table 1: Geologic Time Scale: A Time Line for the Geological Sciences

Source: “Geologic Time Scale: A Time Line for the Geological Sciences.” 2005. 25 October 2008. <>

Precambrian Eon

The Precambrian eon is divided in three eons, namely, Hadean time, Archean time, and Proterozoic time. The Precambrian eon comprises the biggest part of the history of the earth. The Precambrian eon spans from 4.5 billion years to 542 million years ago. No form of life had existed during this time of the earth. Many layers of sedimentary rocks beneath the earth’s surface have uncovered the past of the earth.(Appenzeller).

According to an article from the National Geographic, 4.6 billion years have already past since the beginning of the earth’s existence. The earth slowly began to form from particles that surrounded the young sun. These particles, which were mainly rocks and ice, formed into huge balls of planetary rocks. These huge planetary bodies collided with each other, creating the planets of the solar system, including the earth. During the creation of the planets, a body as big as the mars which had the energy of trillions of atomic bomb bumped into the earth. The collision made the earth into a ball of magma and vaporized earth’s rocks into the orbit, leading to the birth of the earth’s moon. After the creation of the moon, the cooling of the earth’s surface started. During the first 700 million years of the earth, rocks that moved towards the earth melted like ice because of the extreme temperature brought about by the earth’s surface. The reaction produced gases which soon covered the planet with a prehistoric atmosphere. This atmosphere deprived the earth with oxygen, making it cooler. Shortly after, steam condensed and turned into early rain which filled the basins (Appenzeller).

However, the filled basins were short lived due to the chunks of rock that the planets of the solar system produced. The early earth attracted these big pieces of rock. These chunks of rock bombed the earth ruthlessly, boiling away the once filled up basins. Due to this happening, the earth started all over again with its cooling process. However, the impacts were not long lived. Around 1.2 billion years since the earth began, the impacts came to a halt. The halt gave way to the formation of liquid water in the basins of the early earth. The formation of the liquid water also produced reactions that led to the creation of complex molecules (Appenzeller).

Around 3.5 billions years ago, the archean time rose. During this time the single-celled, blue green cyanobacteria bloomed like flowers in the early oceans of the archean time. The blue green cyanobacteria trapped the suns energy in order to create their own food, giving off oxygen which soon helped to form the atmosphere. The atmosphere contained breathable air that opened the gates for life forms in following years to come (Appenzeller).

Multicelled organism first existed in the proterozoic time of the Precambrian period. Fossil records showed evidences that this organism had existed 600 million years ago. The organism was called Ediacarans. Ediacarans were said to have little resemblance to the organisms of the modern world. They were also believed to live in sea beds. They did not have any mouth, head, or digestive system. After that, Ediacarans became a mystery to researchers. Experts speculated that Ediacarans may have evolved, or they may have been extinct. Other early organisms of the Precambrian period include sponges, cnidarians, and annelids (Appenzeller).

Widespread ice age embarked the end of the Precambrian period. The ice age caused the wide extinction of the organisms in the eon (Appenzeller).

Phanerozoic eon

The Phanerozoic eon is divided into three main eras. The eras were named Paleozoic, Mesozoic, and Cenozoic. The three main eras were also divided into many periods. The range of time of the Phanerozoic eon is from 542 million years ago to present. The Cambrian period embarked the start of the paleozoic era of the phanerozoic eon. The range of the Cambrian period was from 542 million to 488 million years ago. In this period, the explosion of the most extreme organisms occurred. The diversity of life in the Cambrian period was so intense that the major animal groups such as the chordates started to rise (“Cambrian Period”).

            The Paleozoic era was the period of the shelled organisms, amphibians, vertebrates and reptiles. The whole Paleozoic era ranged from 542 million years to 248 million years ago. The Mesozoic era was the era of the dinosaurs. The era ranged from 248 million years to 63 million years ago. The Mesozoic era is divided into three periods, namely, Triassic, Jurassic, and Cretaceous period. The Triassic period marked the existence of the first dinosaurs (“Triassic Period”). Meanwhile, the Jurassic period’s most important note was the break up of the super continent Pangaea. The break up of the continent gave way to new oceans and mountain ranges which were very important to organisms of that time, as the creation of new oceans and mountain ranges provided the Jurassic organisms with more habitats (“Jurassic Period”). Finally, the Cretaceous period’s most important event was the extinction of half of the life forms in the planet (“Cretaceous Period”).

            The Cenozoic era is the epoch of the mammals and the humans. This era extends from 65 million years to present time. The era was subdivided into three periods: Paleocene, Neocene, and the Quaternary eras. Dinosaurs became extinct during this era, but the reason of their massive wipe out is still unknown. One of the suspected reasons of the extinction of dinosaurs was the climate change, specifically the global cooling. The Paleocene period marked the start of the Cenozoic era. This period started 65 million years ago and ended 23 million years ago. In this era, big dinosaurs and giant marine reptiles were no longer living on earth. Mammals started to populate the earth after the end of the dinosaur era. Mammals of different kinds began to grow and diversify because of the lack predators like the dinosaurs. Also, the continents further moved away to each other. Oceans started to widen as the Europe continent began to cut its last attachment from the North America. The rest of the Cenozoic era was all about the development of the mammals and also the development of the modern human(“Paleogene Period”).


The history of the earth’s formation suggests that it is truly a living planet. The long process of formation gives us an idea that the early earth rose from nothing then turned into a living planet. Hence, if humans will not take care of this living planet, it may turn into a dead planet, and it will take another billion of years just to create a planet that is similar to earth.

Works Cited

Appenzeller, T. “Earth in the Beginning.” National Geographic Society. (December 2006). 25 October 2008 <>

 “Cambrian Period.” National Geographic Society. 2008. 25 October 2008 <>

“Cretaeceous Period.” National Geographic Society. 2008. 25 October 2008 <>

“Jurassic Period.” National Geographic Society. 2008. 25 October 2008 <>

“Paleogene Period.” National Geographic Society. 2008. 25 October 2008 <>

“Triassic Period.” National Geographic Society. 2008. 25 October 2008 <>