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Geology (from Greek γη- (ge-, "the earth") and λογος (logos, "word", "reason")) is the science and study of the Earth, its composition, structure, physical properties, history, and the processes that shape it. Geologists have helped establish the age of the Earth at about 4.5 billion (4.5x109) years, and have determined that the Earth's crust is fragmented into tectonic plates that move over a semi-molten upper mantle ( asthenosphere) via processes that are collectively referred to as plate tectonics. Geologists help locate and manage the earth's natural resources, such as oil and coal, as well as metals such as iron, copperCopper is a chemical element in the periodic table that has the symbol Cu and atomic number 29. Notable characteristics Copper is a reddish-coloured metal, with a high electrical and thermal conductivity (among pure metals at room temperature, only silver, and uraniumUranium is a chemical element in the periodic table that has the symbol U and atomic number 92. A heavy, silvery-white, toxic, metallic , and naturally- radioactive element, uranium belongs to the actinide series and its isotope uranium-235 is used as the. Additional economic interests include minerals such as asbestosThis page is about the group of minerals, for the Regional County Municipality in Quebec, see Asbestos Regional County Municipality, Quebec Asbestos (Greek a-, "not"; sbestos, "extinguishable") is a group of fibrous metamorphic minerals. The name is deriv, perlitePerlite is an amorphous glass mineral of volcanic origin. Typical analysis: 70-75% SiO, 12-15% AlO, Na O 3-4%, K O 3-5%, Fe O 0,5-2%, Mg O 0,2-0,7%, CaO 0,5-1,5% Loss On Ignition 3-5% Properties: When it reaches temperatures of 850-900°C, perlite softens, micaThe mica group of minerals includes several closely related materials having highly perfect basal cleavage. All are monoclinic with a tendency towards pseudo-hexagonal crystals and are similar in chemical composition. The highly perfect cleavage, which is, phosphates, zeolites, clayFor the town in the United States, see Clay, New York. Clay is a generic term for an aggregate of hydrous silicate particles less than 4 micrometers in diameter. It consists of small crystals of the minerals silica (SiO) and alumina (AlO). These elements,, pumice, quartz, and silica, as well as elements such as sulfur, chlorine, and helium.
Astrogeology refers to the application of geologic principles to other bodies of the solar system. However, specialised terms such as selenology (studies of the Moon), areology (of Mars), etc., are also in use.
The word "geology" was first used by Jean-André Deluc in the year 1778 and introduced as a fixed term by Horace-Bénédict de Saussure in the year 1779. An older meaning of the word was first used by Richard de Bury. He used it to distinguish between earthly and theological jurisprudence.
1 History
Georg Agricola (1494-1555) wrote the first systematic treatise about mining and smelting works, De re metallica libri XII, with an appendix Buch von den Lebewesen unter Tage (book of the creatures beneath the earth). He covered subjects like wind energy, hydrodynamic power, melting cookers, transport of ores, extraction of soda, sulfur and alum, and administrative issues. The book was published in 1556.
James Hutton is often viewed as the first modern geologist. In 1785 he presented a paper entitled Theory of the Earth to the Royal Society of Edinburgh. In his paper, he explained his theory that the Earth must be much older than had previously been supposed in order to allow enough time for mountains to be eroded and for sediment to form new rocks at the bottom of the sea, which in turn were raised up to become dry land.
Followers of Hutton were known as Plutonists because they believed that some rocks were formed by vulcanism which is the deposition of lava from volcanoes, as opposed to the Neptunists, who believed that all rocks had settled out of a large ocean whose level gradually dropped over time.
William Smith (1769-1839) drew some of the first geological maps and began the process of ordering rock strata (layers) by examining the fossils contained in them.
Sir Charles Lyell first published his famous book, Principles of Geology, in 1830 and continued to publish new revisions until he died in 1875. He successfully promoted the doctrine of uniformitarianism. This theory states that slow geological processes have occurred throughout the Earth's history and are still occurring today. In contrast, catastrophism is the theory that Earth's features formed in single, catastrophic events and remained unchanged thereafter. Though Hutton believed in uniformitarianism, the idea was not widely accepted at the time.
The theory of continental drift was proposed by Alfred Wegener in 1912 and by Arthur Holmes, but wasn't broadly accepted until the 1960s when the theory of plate tectonics was developed.
