Geology (from Ancient Greek ??, g? , ie "earth" and -? o ", -logia , ie" study of, discourse ") is an earth science related to solid Earth, composed rocks, and the process by which they change over time. Geology may also refer to studies of solid features of terrestrial planets or any natural satellites (such as Mars or the Moon).
Geology describes the Earth's structure beneath its surface, and the processes that have shaped the structure. It also provides a tool for determining the relative and absolute ages of rocks found in certain locations, and also to illustrate the history of these rocks. By combining these tools, geologists are able to record the geological history of the Earth as a whole, and also to show the age of the Earth. Geology provides key evidence for tectonic plates, the evolutionary history of life, and Earth's past climate.
Geologists use various methods to understand the structure and evolution of the Earth, including fieldwork, rock descriptions, geophysical techniques, chemical analysis, physical experiments, and numerical modeling. In practical terms, geology is essential for the exploration and exploitation of minerals and hydrocarbons, evaluating water resources, understanding natural hazards, remediation of environmental problems, and providing insights into past climate change. Geology, the main academic discipline, also plays a role in geotechnical engineering.
Video Geology
Geological material
The majority of geological data comes from research on solid Earth material. It usually falls into one of two categories: rock and unconsolidated material.
Rock
The majority of research in geology is associated with the study of rocks, since the rock provides a central record of the majority of Earth's geological history. There are three main types of rock: frozen, sediment, and metamorphic. The rock cycle illustrates the relationship between them (see diagram).
When the stone crystallizes from melt (magma or lava), it is igneous rock. These rocks can be decayed and eroded, then prescribed and mined into sedimentary rocks. It can then be converted into metamorphic rock by heat and pressure that changes its mineral content, producing a distinctive fabric. These three types can melt again, and when this happens, a new magma is formed, from which igneous rocks may once again crystallize.
Testing
To study the three types of rocks, geologists evaluated the composite minerals. Each mineral has different physical properties, and there are many tests to determine each. Specimens can be tested for:
- Luster: Measurement of the amount of light reflected from the surface. Luster is broken down into metal and not metal.
- Colors: Minerals are grouped by color. Most of the diagnostics but the dirt can change the color of minerals.
- Streak: Done by scraping the sample on a porcelain plate. Consecutive colors can help name the minerals.
- Hardness: Mineral resistance to scratches.
- The breaking pattern: Minerals can show fractures or hemispheres, the first is the uneven surface damage and the last of the damage along the parallel plane of close proximity.
- Specific gravity: mineral specific volume weight.
- Aperture: Involves dripping hydrochloric acid in minerals for testing to hiss.
- Magnet: Involves using magnets to test magnets.
- Flavor: Minerals can have a distinctive flavor, like halit (which tastes like table salt).
- Odor: Minerals can have a distinctive odor. For example, the smell of sulfur is like a rotten egg.
Unconsolidated material
Geologists also study non-preserved materials (referred to as drift ), which usually come from newer savings. These materials are shallow deposits located above the bedrock. This study is often known as Quaternary geology, after a period of Quaternary geological history.
Maps Geology
Structure of All Earth
Plate tectonics
In the 1960s, it was discovered that the Earth's lithosphere, which includes the crust and the uppermost rigid part of the upper mantle, is separated into a tectonic plate that travels across the deforming mantle, the plastic top layer, called the asthenosphere. This theory is supported by several types of observations, including seabed deployment and global distribution of mountain terrain and seismicity.
There is an intimate coupling between the movement of the plates on the surface and the convection of the mantle (ie heat transfer caused by mass movement of molecules in the liquid). Thus, oceanic plates and adjacent coat convection currents always move in the same direction - because the lithosphere of the ocean is actually a rigid upper thermal overhead layer of a convincing mantle. The coupling between the rigid plates moving on the Earth's surface and the convincing coat is called the tectonic plate.
The development of plate tectonics has provided a physical basis for many solid Earth observations. The long linear geological features are described as plate boundaries. As an example:
- The mountains in the middle of the sea, the high seabed area where hydrothermal and volcanic holes exist, are seen as distinct borders, where two plates are separated.
- The statues of volcanoes and earthquakes theorize as convergent boundaries, in which one plate channels, or moves, under another.
Changing boundaries, such as the San Andreas Fault system, resulted in a powerful earthquake that stretched. The tectonic plates have also provided a mechanism for Alfred Wegener's theory of continental drift, in which continents move across the Earth's surface over geologic time. They also provide a driving force for deformation of the crust, and new arrangements for structural geological observation. The strength of plate tectonic theory lies in its ability to combine all these observations into a theory of how the lithosphere moves above a convincing mantle.
Earth Structure
Advances in seismology, computer modeling, and mineralogy and crystallography at high temperatures and pressures provide insights into the internal composition and structure of the Earth.
Seismologists can use the time of arrival of seismic waves in reverse to describe the interior of the Earth. Initial progress in this area indicates the presence of a liquid outer core (where shear waves can not propagate) and solid solid core. This progress leads to the development of the Earth's layer model, with the above crust and lithosphere, the mantle below (separated by seismic discontinuities at 410 and 660 kilometers), and the outer core and the inner core below. Recently, seismologists have been able to create detailed images of the wave velocity inside the earth in the same way that the doctor's picture in CT scans. These images have led to a much more detailed view of the interior of the Earth, and have replaced the simplified layered model with a much more dynamic model.
Mineralogy has been able to use pressure and temperature data from seismic studies and modeling together knowledge of the composition of Earth elements to reproduce these conditions in experimental settings and measure changes in crystal structure. These studies explain the chemical changes associated with major seismic discontinuities in the mantle and show the expected crystallographic structure in the core of the Earth's core.
Geological time
The geological time scale covers the Earth's history. This is parenthesized by the date of the first Solar System material at 4,567 Ga (or 4.567 billion years ago) and the formation of Earth at 4.54 Ga (4.54 billion years), which is the beginning of an informally recognized Hadean eon - geological time division. At the end of the scale, it is characterized by today (in the Holocene period).
Time scale
The following four timelines show the geological time scale. The first shows the entire time of the Earth formation to date, but this gives little room for the newest eons. Therefore, the second timeline shows an expanded view of the most recent eon. In the same way, the most recent era expanded in the third timeline, and the most recent period was extended to the fourth timeline.
Important milestones
- 4.567 Ga: The formation of the solar system
- 4.54 Ga: Accretion, or formation, Earth
- c. 4 Ga: End of Late Heavy Bombardment, first life
- c. 3.5 Ga: Start photosynthesis
- c. 2.3 Ga: Oxygenated atmosphere, Earth's first snowball
- 730-635 Ma (megaannum: million years ago): Second snowball earth
- 542 Ã, Â ± 0.3 Ma: The Cambrian Explosion - a great multiplication of hard life; the first abundant fossils; starting from Paleozoikum
- c. 380 Ma: The first vertebrate land animal
- 250 Ma: Permian-Triassic Extinction - 90% of all land animals die; end of Paleozoic and early Mesozoic
- 66 Ma: Cretaceous-Paleogene Extinction - Dinosaurs die; end Mesozoic and early Cenozoikum
- c. 7 Ma: Hominins first appeared
- 3.9 Ma: Australopithecus First, the direct ancestor of modern Homo sapiens, appears
- 200 ka (kiloannum: a thousand years ago): The first modern Homo sapiens appeared in East Africa
Dating method
Relative date
The method for relative dating was developed when geology first emerged as a natural science. Geologists still use the following principles today as a means of providing information about geological history and timing of geological events.
The principle of uniformitarianism states that the geological processes observed in today's modified crust operations have worked in the same way from geologic time. A basic geological principle put forward by the 18th-century Scottish physicist and geologist, James Hutton, is that "now is the key of the past." In Hutton's words: "Our world's past history must be explained by what can be seen happening now."
The principle of intrusive relationships involves cross-border intrusion. In geology, when the intrusion of igneous rocks cuts off sedimentary rock formations, it can be determined that the intrusion of igneous rocks is younger than sedimentary rocks. Different types of intrusions include stock, laccolith, batholith, sills and embankments.
The principle of cross-sectoral relations is related to the formation of the fracture and the age of the circuit in its path. The damage is younger than the rocks they cut; therefore, if a fault is found that pierces some formation but not the one above it, the cut formation is older than the fault, and the uncut must be younger than the fault. Finding the master bed in this situation can help determine whether the error is a normal error or a push error.
The inclusion principle and the components state that, with sedimentary rocks, if inclusions (or clasts ) are found in formation, then inclusions must be older than the formations containing them. For example, in sedimentary rocks, it is common for gravels from older formations to be shredded and inserted into newer layers. A similar situation with igneous rocks occurs when xenolith is found. This foreign body is taken as a magma or lava flow, and is combined, then cooled into the matrix. As a result, xenoliths are older than the stones that contain them.
The principle of the original horizontality states that sediment deposition occurs as a base of horizontal beds. The observation of modern marine and non-marine sediments in various environments supports this generalization (although cross-bedding tends, the overall orientation of the cross-bedded units is horizontal).
The principle of superposition states that layers of sedimentary rock in an undisturbed tectonic order are younger than those below and older than those above. The logic of the younger layers can not slip beneath the previously stored layer. This principle allows the sediment layer to be seen as a vertical line form, a partial or complete record of the elapsed time from the deposition of the lowest layer to the highest bed settlement.
The principle of fauna succession is based on the appearance of fossils in sedimentary rocks. When organisms exist at the same time period around the world, their presence or (sometimes) absences can be used to provide the relative age of the formation in which they are found. Based on the principles composed by William Smith nearly a hundred years before the publication of Charles Darwin's theory of evolution, the principles of succession developed independently of evolutionary thought. The principle becomes very complex, however, given the uncertainty of fossilization, the localization of fossil species due to lateral changes in the habitat (changes in facies in the sediment layer), and that not all fossils can be found globally at the same time.
Absolute dating
Geologists also use methods to determine the absolute age of rock samples and geological events. These dates are useful on their own and may also be used in conjunction with relative dating methods or to calibrate relative methods.
At the beginning of the 20th century, advances in geology were facilitated by the ability to obtain an accurate absolute date for geological events using radioactive isotopes and other methods. This changes the understanding of geological time. Previously, geologists could only use fossils and stratigraphic correlations to the current rock parts relative to each other. With an isotope date, it becomes possible to assign absolute ages to rock units, and this absolute date can be applied to fossil sequences where there is distortable material, changing the relative old age to a new absolute age.
For many geological applications, the isotopic ratio of radioactive elements is measured in minerals that provide the amount of time that has elapsed since the rock passes through the closing temperature in particular, the point at which different radiometric isotopes stop spreading in and out of the crystal lattice. It is used in geochronological and thermocronological studies. Common methods include uranium-lead dating, potassium-argon dating, argon-argon dating and uranium-thorium dating. These methods are used for various applications. Dating layers of lava and volcanic ash found in stratigraphic sequences can provide absolute age data for sedimentary rock units that do not contain radioactive isotopes and calibrate relative dating techniques. This method can also be used to determine the age of pluton mining. The thermochemical technique can be used to determine the temperature profile within the crust, elevated mountains, and paleotopography.
The lanthanide series element fractionation is used to calculate the age since the stone is removed from the mantle.
Another method is used for newer events. Optically stimulated luminescence and cosmogenic radionuclide brushing are used for surface and/or current erosion rates. Dendrochronology can also be used for landscape dating. Radiocarbon dating is used for young materials that are geologically organic carbon.
Geological development of an area
The geology of an area changes over time when rock units are stored and inserted, and the deformation process changes its shape and location.
The rock units were first conquered by sediment to the surface or intrusion to the rocks above it. Deposition can occur when the sediment settles into the Earth's surface and then lithify into sedimentary rock, or when as volcanic material such as volcanic ash or lava flows envelop the surface. Igneous intrusions such as batholiths, laccoliths, embankments, and sills, push up onto the rocks above it, and crystallize as they interrupt.
Once the initial sequence of rocks has been stored, the rock units may be deformed and/or morphed. Deformation usually occurs as a result of horizontal shortening, horizontal extension, or side-to-side (strike-slip) movement. This structural regime is broadly related to convergent boundaries, different boundaries, and changing the boundaries, respectively, between tectonic plates.
When rock units are placed under horizontal compression, they shorten and become thicker. Because rock units, in addition to mud, do not significantly alter the volume, this is achieved in two main ways: through fractures and folding. In shallow crust, where brittle deformation may occur, a thrust fault shape, which causes deeper stones to move over shallow rocks. Because deeper stones are often older, as noted by the principle of superposition, this can cause older rocks to move above the younger ones. Movements along the fracture may result in folding, either because the fault is not planar or because the rock layer is dragged, forming a dragging lip because slippage occurs along the fault. Deeper on Earth, rocks behave plastic and fold rather than damage. These folds can be the place where the material in the middle of the fold buckles upwards, creating an "antiform", or where it buckles downwards, creating "synforms". If the top of the rock units in the fold remains pointing upwards, they are called anticlines and synclines, respectively. If some units are folded down, structures are called inverted anticlines or syncliners, and if all units of reversed rock or correct rising directions are unknown, they are only called by the most common terms, antiforms and synforms.
Even higher pressures and temperatures during horizontal shortening can lead to folding and rock metamorphism. This metamorphism causes changes in the mineral composition of rocks; creating a surface foliation, or planar, associated with mineral growth under pressure. It can remove the original texture of rocks, such as beds in sedimentary rocks, features lava flows, and crystalline patterns in the crystal stones.
The extension causes the rock units as a whole to become longer and thinner. This is primarily done through a normal cesarean and through vibrating stretching and thinning. Normal errors dropping rock units higher below those lower. This usually results in a younger unit placed under an older unit. Stretching units can cause their depletion; in fact, there is a location within the Maria Fold and Thrust Belt where the entire series of Grand Canyon sediments can be seen over a meter. The rocks at depth to be stretched with ductile are often also metamorphosed. This unfolded rock can also clamp the lens, known as boudin, after the French word for "sausage", because of its visual similarity.
As stone units shift past each other, a horizontal fault develops in shallow areas, and becomes a sliding zone at deeper depths where rocks change shape.
The addition of new rock units, either by precipitation or intrusively, often occurs during deformation. Damage and other deformation processes result in the creation of topographic gradients, causing material in rock units to rise in altitude to be eroded by hillsides and canals. These sediments are deposited on rock units that will descend. Continuous motion along the fault maintains a topographic gradient regardless of the sediment movement, and continues to create an accommodation space for materials to store. The incidence of deformation is often associated with volcanic and fire activity. Volcanic ash and lava accumulate on the surface, and frozen intrusion enters from below. The embankment, the length, the intrusion of the planar igneous rocks, come together with cracks, and therefore often form in large numbers in areas that are actively changing shape. It can produce emplacement of a dyke embankment, as can be observed in Canadian shields, or embankment rings around volcanic lava tubes.
All of these processes do not always occur in one environment, and do not always happen in one sequence. The Hawaiian Islands, for example, are almost entirely composed of layered basalt lava flows. The sediment sequences of the middle-continental United States and the Grand Canyon in the southwestern United States contain a pile of undeveloped sedimentary rock that still existed since the Cambrian era. Other areas are much more geologically complex. In the southwest United States, sedimentary, volcanic, and intrusive rocks have metamorphosed, damaged, polluted, and folded. Even older rocks, such as the Acasta gneiss of the slave craton in northwest Canada, the world's oldest known rocks have metamorphosed to the point where their origin can not be distinguished without laboratory analysis. In addition, this process can occur gradually. In many places, the Grand Canyon in the southwest United States becomes a very visible example, lower rock units are metamorphosed and altered, and then the deformation ends and the upper unit, which has no effect to be deposited. Although any number of stone emplacements and rock deformations may occur, and they can occur several times, these concepts provide guidance for understanding the geological history of a region.
Geological method
Geologists use a number of field, laboratory, and numerical modeling methods to describe Earth's history and understand the processes that occur on and within the Earth. In typical geological investigations, geologists use primary information related to petrology (study of rocks), stratigraphy (the study of sediment layers), and structural geology (the study of the position of rock units and their deformation). In many cases, geologists also study modern soils, rivers, landscapes, and glaciers; investigate past and present life paths and biogeochemical pathways, and use geophysical methods to investigate subsurface. The geological sub-specialization may distinguish exogenous endogenous and exogen .
Field method
The geological fieldwork varies depending on the task at hand. Public field work may consist of:
- Geological mapping
- Structural mapping: identify the location of major rock units as well as errors and folds leading to its placement there.
- Stratigraphic mapping: determination of the location of sedimentary facies (lithofacies and biofasies) or isopach mapping with the same sedimentary sedimentary rock thickness
- Surfing mapping: recording land locations and surficial deposits
- Topographic feature surveys
- compilation of topographic maps
- Attempt to understand changes across the landscape, including:
- Erosion and deposition patterns
- Stream flow changes through migration and avulsion
- the Hillslope process
- Subsurface mapping via geophysical method
- This method includes:
- Shallow seismic survey
- Groundbreaking radar
- Aerodynamic survey
- Electrical resistance tomography
- They help in:
- Hydrocarbon exploration
- Looking for groundwater
- Find buried archaeological artifacts
- This method includes:
- High resolution Stratigraphy
- Measure and describe the stratigraphic portion on the surface
- Drilled and recorded well
- Biogeochemistry and geomycrobiology
- Collect samples to:
- define the biochemical path
- identify new species of organism
- identification of new chemical compounds
- and use these findings to:
- understand the early life on Earth and how it functions and is metabolized
- find important compounds for use in medicines
- Collect samples to:
- Paleontology: extracting fossil material
- For research on life and evolution of the past
- For museums and education
- Sample collection for geocronology and thermocronology
- Glaciology: measuring the characteristics of the glacier and its movements
Petrology
In addition to identifying rocks in the field (lithology), petrology identifies rock samples in the laboratory. The two main methods for identifying rocks in a laboratory are through an optical microscope and by using an electron microprobe. In optical mineralogy analysis, petrologists analyze the thin part of rock samples using a petrographic microscope, in which minerals can be identified through different properties in polarized and polarized light across planes, including birefringence, pleochroism, twinning, and interference with conoscopic lenses. In electron microprobe, individual locations are analyzed for precise chemical composition and variation of composition in individual crystals. The study of stable and radioactive isotopes provides insight into the geochemical evolution of rock units.
Petrologists can also use fluid inclusion data and conduct high temperature physical experiments and pressure to understand the temperature and pressure at which different mineral phases appear, and how they are changed through frozen and metamorphic processes. This study can be extrapolated to the field to understand the metamorphic process and the crystallization conditions of igneous rocks. This work can also help explain the processes occurring on Earth, such as subduction and evolution of the magma space.
Geology structure
Structural geologists use microscopic analysis of thin sections of geologically oriented samples to observe fabrics in rocks that provide information about strains in the structure of rock crystals. They also plan and combine measurements of geological structures to better understand the fault and fold orientation to reconstruct the history of rock deformations in the area. In addition, they performed analog and numerical experiments of rock deformation in large and small settings.
Structural analysis is often done by plotting the orientation of various features into the stereonet. Strononet is a projection of ball stereography into the plane, where the plane is projected as a line and a line projected as a point. This can be used to find the location of the folding ax, the relationship between cesarean, and the relationship between other geological structures.
Among the most famous experiments in structural geology are those involving orogenic wedges, which are the zones where mounts are built along the boundaries of tectonic convergent plates. In the analogue version of this experiment, the horizontal layer of sand is drawn along the lower surface into the back stop, resulting in a realistic fault pattern and tapered orogenic tapered growth (all angles remain the same). Numerical models work in the same way as these analog models, although they are often more sophisticated and may include erosion and rapture patterns in mountain belts. This helps to show the relationship between erosion and the shape of the mountains. These studies may also provide useful information about pathways for metamorphosis through pressure, temperature, space, and time.
Stratigraphy
In the laboratory, stratigraphy analyzes samples of recoverable stratigraphic sections from the field, such as from drill core. Stratigraphers also analyzed data from geophysical surveys showing the location of substrate stratigraphic units. Geophysical and well log data can be combined to produce a better view from below the surface, and stratigraphy often uses computer programs to do this in three dimensions. Stratigraphers can then use this data to reconstruct ancient processes occurring on the surface of the Earth, interpret the past environment, and find areas for extraction of water, coal, and hydrocarbons.
In the laboratory, biostratigraphers analyzed rock samples from the outcrop and drill core for the fossils found in them. These fossils help scientists to determine the nucleus and understand the deposition environment in which rock units are formed. The geochemist precisely marks the rocks in the stratigraphic section to provide a better absolute limit on time and deposition levels. Magnetic Stratigraphy looks for signs of magnetic reversal in the igneous rock units inside the drill core. Other scientists are studying stable isotopes on rocks to gain insight into the past climate.
Planetary Geology
With the advent of space exploration in the twentieth century, geologists have begun to see other planetary bodies in the same way that has been developed to study Earth. This new field of study is called planetary geology (sometimes known as astrogeology) and relies on a known geological principle to study other bodies of the solar system.
Although the Greek prefix geo refers to Earth, "geology" is often used together with the names of other planetary bodies when describing their compositions and internal processes: for example "Martian geology" and "Lunar geology". Special terms such as selenology (study of the Moon), isology (Mars), etc., are also used.
Although planetary geologists are interested in studying all aspects of other planets, a significant focus is to look for evidence of past or present life in another world. This has led to many missions whose primary purpose or addition is to examine the planet's body for proof of life. One of them is the Phoenix lander, who analyzes the Martian soil for the water, chemical, and mineralogical elements associated with biological processes.
Applied geology
Economic geology
Economic geology is an important geological branch that deals with various aspects of the mineral economy that humans use to meet their various needs. An economic mineral is a mineral that can be extracted advantageously. Economic geologists help discover and manage the Earth's natural resources, such as petroleum and coal, and mineral resources, including metals such as iron, copper, and uranium.
Mining geology
Mining geology consists of the extraction of mineral resources from Earth. Some resources of economic interest include gems, metals such as gold and copper, and many minerals such as asbestos, perlites, mica, phosphates, zeolites, clays, pumice, quartz, and silica, as well as elements such as sulfur, chlorine, and helium.
Petroleum geology
Petroleum geologists study the locations of the Earth's surface that can contain extractable hydrocarbons, especially petroleum and natural gas. Since many of these reservoirs are found in sedimentary basins, they study the formation of these basins, as well as the evolution of sediment and tectonics and the current position of the rock units.
Geological engineering
Geological engineering is the application of geological principles to engineering practices for the purpose of ensuring that geological factors affecting the location, design, construction, operation, and maintenance of engineering work are properly addressed.
In the field of civil engineering, the principles of geology and analysis are used to ensure the mechanical principles of structured materials. This allows tunnels to be built without collapsing, bridges and skyscrapers built on a solid foundation, and buildings to be built will not settle in clay and mud.
Hydrology and environmental issues
Geological and geological principles can be applied to a variety of environmental issues such as river restoration, brownfields recovery, and understanding of interactions between natural habitats and geological environments. Groundwater hydro- logy, or hydrogeology, is used to find ground water, which can often provide uncontaminated and especially important water supply in dry areas, and to monitor the spread of contaminants in groundwater wells.
Geologists also obtained data through stratigraphy, drill holes, core samples, and ice cores. Ice cores and sedimentary cores are used for paleoclimate reconstruction, which tells geologists about past and present temperatures and precipitation around the world. This dataset is our primary source of information on global climate change beyond instrumental data.
Natural hazards
Geologists and geophysicists learn the danger of nature to enforce safe building codes and warning systems used to prevent the loss of property and life. Examples of important natural hazards related to geology (as compared with those primarily or merely related to meteorology) are:
Geological history
The study of the Earth's physical matter dates back at least to the ancient Greeks when Theophrastus (372-287 BC) wrote the work of the Lithium Fairy ( On Stones ). During the Roman period, Pliny the Elder wrote in detail about many minerals and metals later in practical use - even jotting down the origin of yellows correctly.
Some modern scholars, such as Fielding H. Garrison, argue that the origin of geological sciences can be traced back to Persia after the Muslim conquest ended. Abu al-Rayhan al-Biruni (973-1048 CE) was one of the earliest Persian geologists, whose work includes the earliest writings on Indian geology, hypothesized that the Indian subcontinent had once been a sea. Drawing from the Greek and Indian scientific literature not destroyed by Muslim conquests, the Persian scholar Ibn Sina (Avicenna, 981-1037) proposed a detailed explanation for the formation of mountains, the origins of earthquakes, and other topics that became the center of modern geology, important for the development of science in the future. In China, the Shen Kuo polymath (1031-1095) formulated a hypothesis for the process of soil formation: based on observations of fossilized animal shells in a geological layer on a mountain hundreds of miles away from the ocean, it concluded that the land was formed by erosion of the mountains and with sediment mud.
Nicolas Steno (1638-1686) is credited with the law of superposition, the principle of original horizontality, and the principle of lateral continuity: the three principles that define stratigraphy.
The word geology was first used by Ulisse Aldrovandi in 1603, then by Jean-AndrÃÆ' © Deluc in 1778 and was introduced as a fixed term by Horace-BÃÆ' © nÃÆ'Â © dict de Saussure in 1779. The word it comes from the Greek?, gÃÆ'ª , which means "earth" and ?????, logo , meaning "speech". But according to another source, the word "geology" comes from a Norwegian, Mikkel PedersÃÆ'¸n Escholt (1600-1699), who is a priest and scholar. Escholt first used the definition in his book entitled, Geologia Norvegica (1657).
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 therein.
James Hutton is often seen 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 explains his theory that the Earth must be much older than before which should allow enough time for the mountains to be eroded and for sediments to form new rocks on the seafloor, which in turn is elevated to dry land. Hutton published a two-volume version of his ideas in 1795 (Vol 1, Vol 2).
Hutton followers are known as Plutonists because they believe that some rocks are formed by volcanism, which is the deposition of lava from a volcano, as opposed to Neptunis, by Abraham Werner, who believed that all the rocks had come out of the vast ocean that gradually declined with time.
The first US geological map was produced in 1809 by William Maclure. In 1807, Maclure began a self-imposed task to create a geological survey in the United States. Almost every state in the Union is traversed and mapped by it, the Alleghenya Mountains are crossed and crossed about 50 times. His unlicensed work was submitted to the American Philosophical Society in a memoir entitled Observations on United States Geology that explains the Geological Map , and published in Society Transactions >, along with the country's first geological map. It started the British geological map of William Smith for six years, although it was built using a different rock classification.
Sir Charles Lyell first published his famous book, Principles of Geology, in 1830. This book, which influenced Charles Darwin's ideas, succeeded in promoting the doctrine of uniformitarianism. This theory states that a slow geological process has occurred throughout Earth's history and still occurs today. By contrast, catastrophism is the theory that Earth's features are formed in single, catastrophic events and remain unchanged thereafter. Although Hutton believed in uniformitarianism, the idea was not widely accepted at the time.
Much of the geology of the 19th century revolves around the question of the exact age of the Earth. Estimates vary from several hundred thousand to billions of years. At the beginning of the 20th century, radiometric dating allowed Earth's age to be estimated at two billion years. This vast awareness of time opens the door for new theories about the processes that make up the planet.
Some of the most significant advances in 20th-century geology were the development of tectonic plate theory in the 1960s and the improvement of the planet's approximate age. The theory of plate tectonics arises from two separate geological observations: the spread of seabed and continental drift. The theory of revolutionizing Earth science. Today Earth is known to be about 4.5 billion years old.
Regional geology
See also
References
External links
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