May 22, 2022

Geology (from the Greek γῆ /guê/, 'Earth', and -λογία /-loguía/, 'treatise')[1][2]​ is the natural science that studies the composition and structure, both internal and superficial, of the planet Earth, and the processes by which it has evolved over geological time.[3] It comprises a set of geosciences, well known today from the point of view of its pedagogy, development and professional application. It offers essential testimonies to understand plate tectonics, the history of life through paleontology, and how it evolved, as well as the climates of the past. Today, geology is of fundamental importance in the exploration of mineral deposits (mining) and hydrocarbons (oil and natural gas), and the evaluation of underground water resources (hydrogeology). It is also of fundamental importance in the prevention and understanding of natural phenomena such as mass removal, in general earthquakes, tsunamis, volcanic eruptions, among others. It provides key knowledge in solving environmental pollution problems, and provides information on past climate changes. It also plays an important role in geotechnics and civil engineering. Geology includes branches such as geophysics, tectonics, structural geology, stratigraphy, historical geology, hydrogeology, geomorphology, petrology, and soil science. Although mining and precious stones have been the subject of human interest throughout the history of civilization, their scientific development within the science of geology did not occur until the eighteenth century. The study of the Earth, especially paleontology, flourished in the 19th century, and the growth of other disciplines, such as geophysics with the theory of plate tectonics in the 1960s, had a similar impact on Earth sciences. to the theory of evolution over biology. By extension, it is applied to the study of the rest of the bodies and matter of the solar system (astrogeology or planetary geology).


Geological time

Important milestones

4.6 billion years: Formation of the Solar System.[7] 4.54 Ga: Formation of the Earth. c. 4 Ga: End of Late Heavy Bombardment, first evidence of life.[8] c. 3.5 Ga: Start of Photosynthesis. c. 2.3 Ga: Oxygenated atmosphere, first global glaciation[8]* 730–635 Ma: second global glaciation.[9] 542± 0.3 Ma: Cambrian explosion – Great multiplication of living organisms; first abundant fossil record; beginning of the Paleozoic.[10] c. 380 Ma: First terrestrial vertebrates.[11] 250 Ma: Permian-Triassic mass extinction[12]​– At least 90% of all animals on land die; end of the Paleozoic and beginning of the Mesozoic. 65 Ma: Cretaceous-Tertiary mass extinction – Dinosaurs disappear; end of the Mesozoic and beginning of the Cenozoic.[13] c. 7 Ma: Appearance of the hominids.[14] 3.9 Ma: Appearance of Australopithecus, direct ancestor of Homo sapiens.[15] 200 ka: Appearance of the first modern Homo sapiens in East Africa.[16]

Dating Methods

Relative dates

Methods for relative dating were developed when geology first emerged as a natural science. Geologists still use the following principles today as a means of providing information about geologic history and the timing of geologic events. The principle of uniformitarianism states that the geological processes observed at work that modify the earth's crust today have worked in much the same way throughout geological time.[17] A fundamental principle of geology proposed by the Scottish physician and geologist 18th century James Hutton is q