The 10 Geologic Eras (explained and described)

Let's see what are the Geological Eras and their most important events throughout time.

The Eras are one of the units of time that divide the history of the planet Earth taking into account its geological characteristics.

The period of division of each Era is neither determined nor constant, it presents a great variation of time between each one of them, depending on the end and therefore the beginning of another one of the occurrence of a relevant fact or event that involves a change in the development of the planet or living beings.

In each time 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 the different organisms, 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 the Geological Eras are, listing and developing the different types of Eras that divide the history of the Earth..

What are the Geologic Eras?

A Geologic Era is a unit of time that refers to the different divisions of the Earth's history according to its geologic characteristicsthat is, according to its structure and composition.

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

The Eras 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 important events and events that mark the beginning and the end of each of these units of time, being therefore irregular between them.

Types of Geological Eras

Thus, Geologic Time is divided into different temporal units, one of these being the Eras, of which ten different types are distinguished coming from three different Eons. Thus, the Phanerozoic includes the Paleozoic, Mesozoic and Cenozoic Eras; the Proterozoic is made up of the Paleoproterozoic, Mesoproterozoic and Neoproterozoic Eras; and finally the Archean is made up of the Eoarchaic, Paleoarchaic, Mesoarchaic and Neoarchaic Eras.

The Phanerozoic refers to the most recent Eon, being the Cenozoic the current Era. At the other extreme we will have the Eoarchean Era, which will be considered the first, placing its beginning about 3600 million years ago, since no older rocks are preserved.

Although there are no older Eras, there is an Eon before the Ark. there is an Eon before the Archean, which is the Hadic, although since there are no rock specimens dating from this time interval, its duration is not known.. However, it is estimated that it lasted a relatively short time.

We will now give a more detailed description of each Era.

The Archaic Aeon

Within this first Aeon we find the following Geological Eras.

1. The Eoarchaic Era

The Eoarchaic Era began 4000 million years ago, being considered the oldest Eoarchaic Era, and ended 3600 million years ago, lasting 400 million years.and ended 3600 million years ago, thus lasting 400 million years.

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

In the same way, it is worth mentioning the formation of the Earth's magnetic field the formation of the Earth's magnetic fieldIt is believed that in it appeared the first unicellular organisms such as batteries, although there is no evidence of it.

2. The Paleoarchaic Era

The Paleoarchaic Era began 3600 million years ago and lasted for 400 million years.It lasted 400 million years and ended about 3200 million years ago.

The fossils of the first living beings date back to this era, such as the case of bacteria that carried out photosynthesis (but in a different way than today, since oxygen was not produced by this process, it was therefore an anoxygenic process). In the same way, these unicellular organisms used asexual reproduction to reproduce themselves, i.e. no two living beings were needed.

3. The Mesoarchaic Era

The Mesoarchaic Era began 3200 million years ago and ended 2800 million years ago.It also lasted 400 million years.

This era marked the separation of the supercontinent formed in the first era, the Vaalbaran, and an expansion of the oceans took place. 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 Neoarchaic Era

The Neoarchaic Era began 2.8 billion years ago and lasted 300 million years. ending 2500 million years ago.

It is in this Era when the microorganisms like the bacteria begin to make oxygenic photosynthesis, process by which oxygen is obtained from the carbon dioxide, increasing this way the quantity of this chemical element in the atmosphere and allowing the development of the alive beings, thanks to the stabilization of the temperature.

The Proterozoic Eon

This Eon 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, making it the longest era of the Paleoproterozoic Era.The Paleoproterozoic Era began 2500 million years ago and ended 1600 million years ago.

The most remarkable events of this era were the stabilization of the continents for the first time. stabilization of the continents for the first timeThe formation of the supercontinent Columbia, and the massive production of oxygen through the process of photosynthesis (this led to the extinction of anaerobic organisms that did not consume oxygen).

6. The Mesoproterozoic Era

The Mesoproterozoic Era began 1600 million years ago and ended 1000 million years ago.thus covering a period of 600 million years.

As remarkable facts, after the division of the Columbia, the supercontinent Rodinia was formed, and living beings began to reproduce sexuallyThis means that the offspring had genetic material from both parents and therefore this led to a more complex evolution and development of organisms.

7. The Neoproterozoic Era

The Neoproterozoic Era began approximately 1000 million years agoIt was the first ice age, with an approximate duration of about 539 million years, so we can know that it ended about 541 million years ago.

This Era is divided into three periods, being in the Cryogenic when the longest recorded glaciation of the Earth took place. 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 following reasons the appearance of the first multicellular animals, the first aquatic animals developedand the development of the first aquatic animals.

The Phanerozoic Eon

The last Eon contains the following Geological Eras.

8. The Paleozoic Era

The Paleozoic Era began about 541 million years ago and ended about 252 million years ago; it lasted about 290 million years.It lasted about 290 million years. This Era spans from the division of the supercontinent Pannotia to the creation of the great supercontinent Pangaea, which consisted of the largest land area of the planet.

As far as the evolution of the fauna is concerned, at the beginning of this temporal unit animals with shells and exoskeletons began to develop, appearing at the end of this time unit.and at the end of this Era, the great reptiles appeared.

We can divide the Paleozoic into the Lower Paleozoic (with a warm climate at the beginning, although it ended with a glaciation that led to a great mass extinction); the climate recovered and the Middle Paleozoic began, this being much more stable and ending with the extinction of most 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 Dinosaurs, began 251 million years ago, lasted 186 million years and ended 66 million years ago.. As already mentioned, the Paleozoic Era ended with the appearance of the first reptiles, which were the most characteristic animals of this new era, not only because of the presence of dinosaurs, but also turtles and crocodiles.

During this era, the supercontinent Pangea began 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 era, a meteorite collision the collision of a meteorite against the Earth caused climatic conditions to change, decreasing the amount of food and thus affecting the large reptiles, resulting in a mass extinction, called the Cretaceous-Tertiary Mass Extinction, with birds and mammals surviving and gradually evolving.

10. The Cenozoic Era

The Cenozoic Era is the current. It began 66 million years ago and is also known as the Age of mammals. The Homo sapiensour species, has its origin 200,000 years ago.

In the Cenozoic is when the continents definitively acquired their current location, although tectonic movements continue to occur.although tectonic movements continue to occur; this means that the continents continue to move.

The climate progressively cooled and, as we have already mentioned, after the extinction of the dinosaurs, it was the mammals that became stronger, evolving and finally giving rise to the genus Homo.