Geology ("to speak about the Earth") is a scintific discipline that focuses on the structure, composition, topology, history and changes the Earth has gone and is going through. Geology overlaps with chemistry when it comes to analyzing things such as buried organic remains. It overlaps with physics when it comes to understanding terrestrial properties such as the magnetic field. Paleontology is an example of how biology and geology come together. Together with meteorology and oceanography, it is a component of geoscience (also known as Earth science.)
Although geology as we know it today did not exist until after the renaissance (the word itself did not exist until the 18th century), some of its basic principles such as mineralogy have been observed and researched since immemorable times. For example, many metals such as gold, iron and copper were extracted from their ores through a process known as "smelting" during ancient times. This process proved to be crucial since it allowed for the manufacture of ornaments as well as armour and weapons. Indeed, the field of mining, which suplements humanity with much needed materials, owes its existence to geology. Interestingly, fossils were often used as decoration as well and would later be recognized as the remnants of once living beings.
The Greeks recognized erosion of materials and also described fossils fish found in moutains. Aristotle believed that earthquakes and volcanic eruptions were the result of winds escaping from the Earth's interior. In 200 BC, Eratosthenes, a librarian in Alexandria, measured the Earth's diameter very accurately.
It was during the Medieval Period that early compasses were born. They were created thanks to the understanding of the magnetic properties of magnetite. Isidore of Seville, Vincent de Beauvais and Bartholomew the Englishman were interested in geology.
Mineralogy: Information about minerals and their applications Petrology: The chemical and physical properties of rocks as well as their classification and mode of formation. Geodesy: Basic properties of Earth such as its circumference and gravity. Geohysics: Examining the physical poperties of Earth such as the mechanism behind that fuels the movement of tectonic plates. Geochemistry: The chemical composition of the Earth, be it organic or inorganic. Geohydrology: The study of groundwater, that is, water that is trapped under the surface.