The 10 Geological Ages (explained and described)

Ages are one of the units of time that divide the history of planet Earth, keeping in mind its geological characteristics.

The division period of each Era is not determined nor is it constant, it presents a great variation of time between each one of them, depending on the end and therefore the beginning of another of the event of a relevant fact or event that supposes a change in the development of the planet or of living beings.

In each temporary unit there will also be a characteristic type of climate, appearing in the same way a representative fauna and flora, thus allowing to observe and understand the evolution of different organisms, thus being able to study, for example, from the appearance of the first bacteria to the emergence of the first homo sapiens.

In this article we will see what are the Geological Ages, listing and developing the different types of Ages that divide the history of the Earth.

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What are Geological Ages?

A Geological Age is

a unit of time that refers to the different divisions of the Earth's history according to their geological characteristics, that is, according to its structure and composition.

There are different geological times or geochronology, specifically 6 different ones, the Era is the second, between the Aeon which is the longest temporal unit and the Period, followed by the Epochs, Ages and the Cron.

Ages are not a constant and determined division of time; This means that each Era will not be constituted by the same period of time, but its division will depend on events and important events that mark the beginning and end of each of these units of time, being therefore irregular between they.

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Types of Geological Eras

Thus, Geological Time is divided into different temporal units, one of these being the Eras, of which ten different types are distinguished. coming from three different aeons. In this way the Phanerozoic encompasses the Paleozoic, Mesozoic and Cenozoic Era; The Proterozoic is made up of the Paleoproterozoic, Mesoproterozoic and Neoproterozoic Era; and finally the Archaic is made up of the Eoarchic, Paleoarchic, Mesoarchic and Neoarchic Era.

The Phanerozoic refers to the most recent Aeon, with the Cenozoic being the current Era. At the other extreme we will have the Eoarchic Era, which will be considered the first, placing its beginning about 3.6 billion years ago, since older rocks are not preserved.

Despite not having eras older, yes that There is an Aeon before the Archaic, which is the Hadic, although since there are no rocky specimens dating from this time interval, its duration is not known.. However, it is estimated to have lasted for a relatively short time.

Next we will go on to make a more detailed description of each Era.

The Archaic Aeon

Within this first Aeon we find the following Geological Eras.

1. The Eoarchic Era

The Eoarchic Era had its beginning 4000 million years ago, considering the oldest Era, and ended 3,600 million years ago, thus lasting 400 million years.

It is in the Eoarchy when the earth's surface begins to solidify giving rise to the supracortical belt of Isua in Greenland, being the oldest rock formation that is preserved today and also the constitution of the first supercontinent called Vaalbara.

Similarly, it is worth noting from this Era the formation of the earth's magnetic field, and it is believed that the first unicellular organisms such as batteries appeared in it, although there is no evidence of this.

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2. The Paleoarchic Era

The Paleoarchic Era places its beginning 3.6 billion years ago, and lasted 400 million years, ended about 3.2 billion years ago.

The fossils of the first living beings date from this Era, as is the case of bacteria that carry out photosynthesis (but in a different way to the current one, since oxygen was not produced through this process, it was therefore an anoxygenic process). In the same way, these unicellular organisms used asexual reproduction to reproduce, that is, it does not need two living beings.

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3. The Mesoarchic Era

The Mesoarchic Era began 3.2 billion years ago and ended 2.8 billion years ago, also lasting 400 million years.

This Era highlighted the separation of the supercontinent formed in the first Era, the Vaalbará and there was an expansion of the oceans. In reference to the climate, the first glaciation took place, which is believed to have been a consequence of the metabolism of the first microorganisms.

4. The Neoarchic Era

The Neo-Archean Era began 2800 million years ago and lasted 300 million years. thus ending 2,500 million years ago.

It is in this Era when microorganisms such as bacteria begin to carry out oxygenic photosynthesis, a process by which oxygen is obtained from carbon dioxide. carbon, thus increasing the amount of this chemical element in the atmosphere and allowing the development of living beings, thanks to the stabilization of the temperature.

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The Proterozoic Aeon

This Aeon is characterized by the appearance of the first complex life forms, as we will see.

5. The Paleoproterozoic Era

The Paleoproterozoic Era lasted 900 million years, thus being the longest Era, having its beginning 2,500 million years ago and ending 1,600 million years ago.

The most notable events of this Era were the stabilization of the continents for the first time, forming the supercontinent Columbia, and the massive production of oxygen thanks to the process of photosynthesis (this fact meant that anaerobic organisms that did not consume oxygen were extinguished).

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6. The Mesoproterozoic Era

The Mesoproterozoic began 1.6 billion years ago and ended 1 billion years ago, thus welcoming a period of 600 million years.

As notable events, after the division of the Columbia the supercontinent Rodinia was formed, and living beings began to reproduce sexually; This means that the offspring had genetic material from their two parents and therefore this entailed a more complex evolution and development of organisms.

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7. The Neoproterozoic Era

The Neoproterozoic started approximately 1 billion years ago, with an approximate duration of about 539 million years, in this way we can know that it ended about 541 million years ago.

This Era is divided into three periods, being the Cryogenic when the most extensive ice age recorded on Earth developed. At the end of this era the earth's surface would form a new supercontinent called Pannotia.

In reference to organisms, this Era stands out for the appearance of the first multicellular animals, also developing the first aquatic animals.

The Phanerozoic Aeon

The last Aeon contains the following Geological Eras.

8. The Paleozoic Era

The Paleozoic Era began approximately 541 million years ago and ended 252 million years ago.; it lasted about 290 million years. This Era spans from the division of the Supercontinent Pannotia to the creation of the great supercontinent Pangea, which was made up of the largest land area on the planet.

Regarding the evolution of the fauna, at the beginning of this temporary unit shell and exoskeleton animals begin to develop, already appearing at the end of this Era the great reptiles.

We can divide the Paleozoic into a lower one (with a warm climate at the beginning, although it ended with an ice age that led to a great mass extinction); the climate was recovering and beginning the Middle Paleozoic, being this much more stable and ended with the extinction of most of the vertebrates; and finally the Upper Paleozoic, in which glaciations also appeared, although these were more extreme than the previous ones, concluding with another mass extinction.

9. The Mesozoic Era

The Mesozoic Era, Also known as the Age of the dinosaurs, it began 251 million years ago with a duration of 186 million years, it ended 66 million years ago. As we already mentioned, the Paleozoic Era ended with the appearance of the first reptiles, these being the animals most characteristic of this new Era, not only for the presence of dinosaurs, but also for turtles and crocodiles.

Throughout this Era, the supercontinent Pangea begins to divide, thus acquiring a distribution of continents more similar to the current one. In reference to the climate, it was warmer than we have today, presenting higher temperatures.

It is believed that at the end of the Mesozoic the collision of a meteorite with the Earth caused the climatic conditions to change, reducing the amount of food and thus affecting large reptiles, leading to a mass extinction, called Cretaceous-Tertiary mass extinction, surviving birds and mammals that little by little were evolving.

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10. The Cenozoic Era

The Cenozoic Era is the current one. It had its beginning 66 million years ago and is also known as the Age of Mammals. The Homo sapiens, our species, has its origin 200,000 years ago.

In the Cenozoic is when the continents definitely acquire their current place, although tectonic movements continue to occur; This means that the continents continue to shift.

The climate progressively cooled and as we have already said after the extinction of the dinosaurs were the mammals that gained more strength, evolving and finally giving rise to the genus Homo.