Summary: the geological time scale is a way to organize and divide Earth’s history based on significant geological events such as mass extinctions, climate changes, and the appearance of new species. Geologists use this scale to understand and predict the behavior of the planet, as well as to identify natural resources such as oil, gas, and minerals. The scale is divided into eons, eras, periods, and epochs, with each division based on important geological events that occurred during Earth’s history. While the scale is not based on equal time intervals, it provides a framework for understanding the history of our planet.
What is the geologic time scale?
The geological time scale is the way geologists and geoscientists divide time since planet Earth was formed. This scale arose from the need to organize all the geological events that have occurred during the life of planet earth.
Thus, the geological time scale is subdivided taking into account various events such as mass extinctions, climate changes, appearance of new species, formation of continents, mountains, and various other events.
What is the significance of the geologic time scale?
Its importance lies in the fact that it helps geologists and scientists to correlate various past events to try to predict the behavior of the planet now and in the future.
Furthermore, all these past geological events are directly related to natural resources such as the formation of oil, gas and mineral deposits that are currently used for economic development. Thus, this scale is also used by mining engineers.
Therefore the geological time scale is the division of the earth’s history taking into account several important geological events.
Division of the geologic time scale
Those in charge of dividing this scale are geologists, who have not done so taking into account only days and hours. This scale is divided even with time intervals greater than millions of years and its subdivisions are varied, that is, they do not have an equal time limit in all divisions.
This is because geologic time is divided using important events in Earth’s history.
Example of division of the geologic time scale
For example, to set the limit between the Permian and Triassic, it is done taking into account a global extinction that occurred that ended a large percentage of the life of animals and plant species on earth.
Another interesting example is the limit between the Precambrian and the Paleozoic, which is delimited by the appearance of the first animals with hard parts in their body structure.
General structure of the geologic time scale
Eons
The eons are those intervals in the larger scale or with more geological time duration, generally representing a separation of hundreds of millions of years. If you look at the geological time scale in pdf, you will be able to notice that the Phanerozoic eon is the most recent and its beginning was delimited 500 million years ago.
Ages
The eras are the subdivisions that are made to the eons. Likewise, in the geological time scale in pdf, it is observed, for example, that the Phanerozoic is divided into eras: the Cenozoic, the Mesozoic and the Paleozoic eras. These eras are divided equally by major and rare events that occurred on the planet.
Periods
The eras are the small divisions that are made to the periods. The periods are delimited with geological events that are not as important or relevant as those of the eras and eons. The geologic time scale pdf shows that the Paleozoic is subdivided into the Permian, Pennsylvanian, Mississippian, Devonian, Silurian, Ordovician, and Cambrian periods.
Times
Epochs are much finer subdivisions of time, however keep in mind that the Cenozoic periods are often subdivided into times. This type of subdivision is done only for those most recent slices on the time scale.
This occurs because the oldest rocks have undergone various geological processes such as deformation, burial, metamorphism, alteration and for this reason they cannot be clearly interpreted.