HISTORICAL GEOLOGY: HISTORY, OBJECT OF STUDY, METHODOLOGY - GEOGRAFÍA - 2025

The geological history is a branch of geology that is dedicated to the study of Earth history, ranging from the origin of the planet to its current situation. Historical geology uses knowledge contributed by other scientific branches, such as physics, chemistry, stratigraphy, and paleontology.

Likewise, historical geology is based on the comprehensive analysis of biological and geological events that have been recorded in the rocky material of the earth's crust. Consequently, it is a discipline that studies the evolution of the lithosphere and its relationship with the biosphere, the hydrosphere and the atmosphere.

Historical geology performs a comprehensive analysis of geological events found in rocky material. Source: Pixabay.com

Edison Navarrete, in his text Notes on Historical Geology (2017), established that this scientific branch is developed taking into account the plate tectonic theory, which explains the origin of oceans and continents; this relationship allowed the discipline to enrich itself as a historical science.

In turn, this branch takes the concept of "faunal stages" -proven from paleontology-, which consists of a division system based on the changes recorded in the set of fossils.

Among the contributions of historical geology is the use of the words Inferior, Medio, or Superior to catalog the ages of rock groups.

History

Origins in relative dating

Historical geology was created from the use of the method of relative dating, which consists of a type of dating based on the comparison of two elements that are chronologically distant.

For example, this discipline considers that the lower levels of the earth's crust - known as strata - are older, since they were formed before the levels located above.

Similarly, relative dating allows establishing chronological affinities using the “guide fossils” (a term coined by Josep Fullola in his text Introduction to prehistory, from 2005). Thanks to these fossils, a temporal order can be defined in the objects or phenomena found.

Geological Studies in Classical Antiquity

According to Santiago Fernández, in his work Concept and historical development of geology (1987), historical geology can be classified as a modern science, since it is a discipline strongly dependent on other classical sciences.

However, historical-geological studies were found from Ancient Greece. For example, Aristotle (384-322 BC) established the slowness of geological processes, a notion that was not recognized until the 19th century.

Another Greek author who ventured into this scientific trend was the historian Strabo (63-20 BC), who is considered one of the first geographers to carry out geological principles and hypotheses.

Influence of mineralogy

Mineralogy is considered as one of the first geological sciences to separate from geology. This is because mineralogy has been related to industry since its inception, which is why it evolved from the industrial development of man, which required fuels and minerals.

The founder of the mineralogy is considered to be Georg Bauer (1494-1555), as he was the first to systematically describe minerals.

Similarly, both mineralogy and historical geology were nourished by the studies of Leonardo da Vinci (1542-1592), who is credited with creating the first geological profile. In addition, da Vinci himself was in charge of correctly interpreting the origin of the fossils, along with that of the evaporative rocks.

What is studying (object of study)

Geology - the science that underpins historical geology - is in charge of studying the Earth together with all the phenomena that act on it. In addition, geology documents the materials that make up the earth's crust, along with its structure and characteristics.

Consequently, historical geology has as its object of study the transformations of the Earth from its origin (approximately 4,570 million years ago) to the present, taking into account the dates on which these transformations occurred.

This means that historical geology records the phenomena and elements of the earth's crust through a chronological order that is structured in geological periods or ages.

Methodology

Chronostratigraphic Units

In order to establish the temporal periods of the Earth, geologists arranged the rocks through a sequence of chronostratigraphic units - units of time and ground levels-, which are defined as divisions of rocky bodies that seek to represent terrestrial soils through through their training time.

The limits of the chronostratigraphic units are established according to the characteristics of the real geological events that were recorded in the rocks.

Likewise, these limits are also created taking into account the predominant organisms, along with the climatic changes and the mass extinctions that the terrestrial fields experienced.

Stratigraphy

Historical geology uses stratigraphy as a method of study, which consists of a branch of geology in charge of interpreting metamorphic, volcanic and sedimentary rocks. The objective of all this was to be able to identify and describe them.

Stratigraphy bases its research on a series of principles, among which the principle of uniformitarianism stands out, which establishes that the geological laws have been the same since the beginning of the Earth and produce the same effects from its beginnings to the present.

Another fundamental principle of stratigraphy used by historical geology is the principle of faunal succession, which proposes that the strata that were deposited at different geological ages contain different fossils, thanks to the biological evolution of the species.

Strata of different geological ages contain different fossils. Source: pixabay.com

Faunal stages and other methods of division

Historical geology uses the concept of “faunal stages” as a research method, which consists of a division system established by paleontologists based on the characteristics of the fossils that have been recorded.

Therefore, the faunal stages are constituted by the changes that fossils present as a consequence of biological evolution; This makes it possible to determine the different chronological moments in which the modifications were experienced.

Likewise, geologists use other nomenclatures to express units of time, such as the "Middle Cambrian" or the "Upper Jurassic", which determine a specific period of the earth's crust.

References

1. Aceñolaza, G. (sf) Historical geology. Retrieved on September 29, 2019 from INSUGEO: insugeo.org.ar
2. Fernández, S. (1987) Concept and historical development of geology. Retrieved on September 28, 2019 from Dialnet: Dialnet.net
3. Frodeman, R. (1995) Geological reasoning: geology as an interpretive and historical science. Retrieved on July 29, 2019 from Geoscience World: pubs.geoscienceworld.org
4. Mejía, T. (sf) What does geology study? Retrieved on September 29, 2019 from Lifeder: lifeder.com
5. Moore, R. (1933) Historical geology. Retrieved on September 29, 2019 from Science: sciencemag.org
6. Navarrete, E. (2017) Notes on historical geology. Retrieved on September 28, 2019 from ResearchGate: researchgate.net
7. Oldroyd, D. (1979) Historicism and the Rise of Historical Geology. Retrieved on September 29, 2019 from Journals: journals.sagepub.com
8. SA (sf) Historical geology. Retrieved on September 29, 2019 from Wikipedia: es.wikipedia.org