Within the science we know as geology, there is a more specialized branch that is responsible for studying and analyzing all the modifications that occur on our planet. This branch of geology is known by the name of historical geology. This branch aims to study all the changes that are taking place on our planet and that range from its formation to the present.
In this article we are going to tell you all the characteristics and importance of the historical geology.
Key features
This branch of science aims to study the modifications that the geological part of the planet has on Earth since it was formed approximately ago 4.570 million years to the present. As we know, the land relief is not constant over time. Our Earth's crust is made up of tectonic plates. These plates have a movement known as continental drift and that is propelled by the convection currents of the Earth's mantle.
In addition to all the things we have mentioned, there are several geological agents external factors that modify and alter the relief as we know it. This means that the geology of the terrain is not stable over the years. In each it was geological There are numerous geomorphological reliefs and landscapes that have predominated depending on the flora, fauna, climate and other factors on our planet.
In order to determine the time frame relative to each geological change, geologists have relied on the great events that have occurred on our planet. In this way it has been possible to order rocks in a continuous sequence of planetary-scale chronostratigraphic units. It must be borne in mind that since in order to measure the time that occurs on the planet at a geological level, we must count by means of the geological time. This means that the landscape is not going to be transformed in a matter of years, not even on a human scale. A human being usually lives on average about 80-100 years, and during this time the alterations in the relief are not noticeable.
Historical geology and geological processes
Historical geology is the branch that tries to analyze each of the geological processes and events that have occurred throughout the geological history of the planet. These geological events are recorded in the rocks. This is how we can obtain the authentic memory of the planet so to speak. It is valuable information that reveals to us how the geological landscape of the planet has evolved.
The main task of geologists who study historical geology is to date and identify all these processes over the geologic time scale. These geological processes are characterized by their slowness. As we mentioned before, these geological processes do not occur in a matter of days, months, or even years. They occur over thousands and millions of years. This slowness can leave a sensation of staticity and permanence for the human eye., although it is true that there are geological processes that occur more suddenly. An example of this is a volcanic eruption, an avalanche, an earthquake, among others.
These geological processes have a speed that can be perceived on a human time scale. Furthermore, they are processes capable of dramatically altering the terrain and relief over a long period of time. Previously, it was thought that our planet formed in a span of six days and that it was no more than 6 years old. This belief is closely related to the Catholic religion and has been refuted thanks to information obtained through the scientific method.
One of the ideas about the formation of our planet was that sudden processes were the only ones that could modify the Earth's relief on a long-term scale. However, science has shown that external geological agents such as wind, precipitation, weathering, etc., are what have gradually moderated the Earth's surface until it reached its current configuration. We also know that it will continue to modify the relief continuously and imperceptibly for humans.
Geological time and historical geology
Because of the fact that we mentioned that changes in the Earth's relief are not perceptible to humans, we must always refer to geological time. That is, a century is too short a time to observe notable differences in the change in the Earth's relief. To be able to observe notable changes such as, for example, the course of a river or the retreat of a cliff, we must wait approximately 20 centuries. Another change that can be made to the relief is the movement of a glacier tongue or the formation of an external lake.
For all this that we have mentioned, there is a greater difficulty in the studies of the sciences of historical geology since space and time scales must be used from magnitudes that go from very small values to values on a gigantic scale. The unit of time in geology could be said to be one million years. This is a sufficient period of time for important changes to be observed, such as the fact that a river deepens its valley, the coasts can push back cliffs or the mountains destroy the eroded peaks.
Using the scale that geologists use and comparing it with the 24 hours that a day has, it can be determined that more or less one hour would correspond to approximately 200 million years. We compare the geological periods that have taken place throughout the history of our planet, and we can say that the Precambrian eon would correspond to at least 9 hours, and the Archean eon to about 12 hours. The remainder, known as the Primary Era, begins after 21 p.m., and the Secondary Era at 22.48:37 p.m. The Quaternary Era, which is when the first human beings appeared, lasts only about XNUMX seconds.
All this leaves us perplexed when we see that the 2.000 years of maximum human history would only last a tenth of a second, making it clear that for the age of our planet and the times in which geological processes occur, 2.000 years are very short periods of time.
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