Hotel

The geology , of the old Greek γη- (Ge, “ground”) and λογος ( logos , “word”, “reason”), is the Science which treats composition, structure, history and evolution of the internal and external layers of the Ground, and processes which work it. Geology is an important discipline among the Sciences of the Earth. Associated with radiochronologic methods of dating and studies of Meteorite S, it made it possible to determine the age of the Earth, which one currently estimates at 4,57 billion years. It intervenes, at the same time as the Géophysique applied, in the research and/or the exploitation of the natural resources in particular the Pétrole, the coal, the Minerai S, the invaluable and semi-precious stones and the Eau. In its current meaning, the term geology was used for the first French time in 1751 by Diderot and creates in Italian in 1603 by Aldrovandi. The word geologist is used in 1798 by Jean-Andre Deluc; it was fixed the following year by Horace-Bénédict de Saussure.

History

See also: History of geology

• History of volcanology
• History of mineralogy
• History of paleontology

Various related disciplines

Geology has many fasteners with other sciences, among which it is advisable to quote:

• the Geochemistry of the earth's crust, which studies the chemistry of the surface layers of the Earth; the geochemistry of the deeper layers relates to more the Géophysique intern, or Physique of the sphere, that geology;

• the Geophysical , organized with the international scales in the geodetic Union and international geophysics (U.G.G.I.), which studies the structure and the internal composition of the Earth with tools borrowed from physics and mathematics; contrary to geological and mineral sciences, which are primarily descriptive and qualitative sciences, sciences geophysics are arranged among the exact sciences and quantitative; the geologists often hear under the “geophysical” term only the geophysical applied (including/understanding methods seismic, gravimetric, magnetic, electric, electromagnetic,… applied to the oil and mining prospection, archeology, the environmental studies, etc); the Hydrogéophysique belongs to the latter;

• the seismic Genius which deals with macroseismic studies on the ground following an earthquake of some importance; it is also occupied to evaluate the seismic Risque and to fix paraseismic Normes for a given country or an area; it also takes part in the monitoring of areas at the risk and, if possible, tries to envisage future earthquakes, either by statistical methods, or by deterministic methods when it is possible;

• the Paléosismologie is a branch of the Sismologie directly dependant on geology; its goal is to find in trenches or geological cuts of the indices of old seisms, to date them so that they can be useful in the statistical forecast of the seisms, and to provide to the geophysicists information possibly making it possible to quantify (mechanism with the hearth, magnitude, seismic moment,…) these old earthquakes;

• the Hydrogeology, which studies the flows of subterranean water, knowing that the nature of the basement crossed by water directly influences the quantity and water quality emerging with the source or exhaurée of drilling;

• the Geomorphology, which studies the forms of the terrestrial relief; it is considered that it concerns more the geographer than the geologist, and one generally arranges it among the branches of the physical Géographie;

• the Mineralogy, which studies nature, the composition and the physical properties of the minerals which compose the rocks;

• the Paleontology, which studies the organizations passed thanks to the description and to the analysis of the fossilized remainders;

• the Morphotectonique, which studies the morphological consequences of the tectonic processes and erosion.

• the Micropaléontologie, which studies the microscopic fossils contained in the sediments;

• the Petrology, which studies the nature of the rocks and the mechanisms which govern the genesis and the transformation of the rocks;

• the Sedimentology which studies the sedimentary rocks and formations; in this case one also speaks about Stratigraphie which studies the succession of the various geological layers or layers;

• the Seismology, which studies the earthquakes and the propagation natural or caused seismic waves (one speaks then about seismic); this discipline is an important branch of the Géophysique, and only some of its results interest the geologist;

• the Volcanology, which analyzes and tries to envisage the volcanic phenomena, which studies the mineralogical chemical composition and the processes of installation of the volcanic products;

• the structural Geology which is the study of the deformations of the rocks and the mechanisms governing the deformation of these rocks on all the scales; with large scales, one speaks about Tectonique;

• the Metallogeny, which studies the mechanisms of formation of the metalliferous layers and proposes to define methodological tools and guides of prospection usable by the mining explorers and prospectors;

• the Géoarchéologie, which studies the archaeological sediments and the deposits of quaternary age;

• the Exogéologie or astrogeology which, thanks to methods of teledetection, with the Experimentation in situ or in laboratory and with the sampling, studies the Composition, the Structure and the history of the surface of the Planets of the Solar system and their Natural satellite S, the Aréologie deals more particularly with the planet Mars;

• the Geotechnical , which works on and the Rock mechanics ground upstream of civil engineering;

• the Geodesy, which studies the shape and dimensions of the Earth; this one is an exact science, sister-binocular of the Astronomie, which by its part Gravimétrie belongs to the disciplines of the Géophysique.

• the Speleology, relates to the study of the natural Cavité S, generally in ic zone Karst; this study includes the geological knowledge of the country rock.