1.
Lithosphere
–
A lithosphere is the rigid, outermost shell of a terrestrial-type planet or natural satellite that is defined by its rigid mechanical properties. On Earth, it is composed of the crust and the portion of the mantle that behaves elastically on time scales of thousands of years or greater. The outermost shell of a planet, the crust, is defined on the basis of its chemistry. Earths lithosphere includes the crust and the uppermost mantle, which constitute the hard, the lithosphere is subdivided into tectonic plates. The uppermost part of the lithosphere that chemically reacts to the atmosphere, hydrosphere and biosphere through the forming process is called the pedosphere. The lithosphere is underlain by the asthenosphere which is the weaker, hotter, the study of past and current formations of landscapes is called geomorphology. The concept of the lithosphere as Earth’s strong outer layer was described by A. E. H, love in his 1911 monograph Some problems of Geodynamics and further developed by Joseph Barrell, who wrote a series of papers about the concept and introduced the term lithosphere. The concept was based on the presence of significant gravity anomalies over continental crust and these ideas were expanded by Reginald Aldworth Daly in 1940 with his seminal work Strength and Structure of the Earth and have been broadly accepted by geologists and geophysicists. The temperature at which olivine begins to deform viscously is often used to set this isotherm because olivine is generally the weakest mineral in the upper mantle, the mantle part of the lithosphere consists largely of peridotite. The crust is distinguished from the mantle by the change in chemical composition that takes place at the Moho discontinuity. Oceanic lithosphere consists mainly of mafic crust and ultramafic mantle and is denser than continental lithosphere, oceanic lithosphere thickens as it ages and moves away from the mid-ocean ridge. This thickening occurs by conductive cooling, which converts hot asthenosphere into lithospheric mantle and causes the oceanic lithosphere to become increasingly thick, the thickness of the mantle part of the oceanic lithosphere can be approximated as a thermal boundary layer that thickens as the square root of time. H ∼2 κ t Here, h is the thickness of the mantle lithosphere, κ is the thermal diffusivity for silicate rocks. The age is equal to L/V, where L is the distance from the spreading centre of mid-oceanic ridge. Oceanic lithosphere is less dense than asthenosphere for a few tens of millions of years and this is because the chemically differentiated oceanic crust is lighter than asthenosphere, but thermal contraction of the mantle lithosphere makes it more dense than the asthenosphere. New oceanic lithosphere is constantly being produced at mid-ocean ridges and is recycled back to the mantle at subduction zones, geoscientists can directly study the nature of the subcontinental mantle by examining mantle xenoliths brought up in kimberlite, lamproite, and other volcanic pipes. The histories of these xenoliths have been investigated by many methods, such studies have confirmed that mantle lithospheres below some cratons have persisted for periods in excess of 3 billion years, despite the mantle flow that accompanies plate tectonics. Cryosphere Geosphere Kola Superdeep Borehole Plate tectonics Solid Earth Chernicoff, Stanley, Whitney, earths Crust, Lithosphere and Asthenosphere Crust and Lithosphere
2.
Fault (geology)
–
In geology, a fault is a planar fracture or discontinuity in a volume of rock, across which there has been significant displacement as a result of rock-mass movement. Large faults within the Earths crust result from the action of tectonic forces. Energy release associated with movement on active faults is the cause of most earthquakes. A fault plane is the plane that represents the surface of a fault. A fault trace or fault line is the intersection of a plane with the ground surface. A fault trace is also the line commonly plotted on maps to represent a fault. Since faults do not usually consist of a single, clean fracture, the two sides of a non-vertical fault are known as the hanging wall and footwall. By definition, the wall occurs above the fault plane. This terminology comes from mining, when working a tabular ore body, because of friction and the rigidity of rocks, they cannot glide or flow past each other easily, and occasionally all movement stops. A fault in ductile rocks can also release instantaneously when the rate is too great. The energy released by instantaneous strain-release causes earthquakes, a common phenomenon along transform boundaries, slip is defined as the relative movement of geological features present on either side of a fault plane, and is a displacement vector. A faults sense of slip is defined as the motion of the rock on each side of the fault with respect to the other side. In practice, it is only possible to find the slip direction of faults. Based on direction of slip, faults can be categorized as, strike-slip. Dip-slip, offset is predominantly vertical and/or perpendicular to the fault trace, oblique-slip, combining significant strike and dip slip. The fault surface is usually vertical and the footwall moves either left or right or laterally with very little vertical motion. Strike-slip faults with left-lateral motion are known as sinistral faults. Those with right-lateral motion are known as dextral faults
3.
Motion (physics)
–
In physics, motion is a change in position of an object over time. Motion is described in terms of displacement, distance, velocity, acceleration, time, motion of a body is observed by attaching a frame of reference to an observer and measuring the change in position of the body relative to that frame. If the position of a body is not changing with respect to a frame of reference. An objects motion cannot change unless it is acted upon by a force, momentum is a quantity which is used for measuring motion of an object. As there is no frame of reference, absolute motion cannot be determined. Thus, everything in the universe can be considered to be moving, more generally, motion is a concept that applies to objects, bodies, and matter particles, to radiation, radiation fields and radiation particles, and to space, its curvature and space-time. One can also speak of motion of shapes and boundaries, so, the term motion in general signifies a continuous change in the configuration of a physical system. For example, one can talk about motion of a wave or about motion of a quantum particle, in physics, motion is described through two sets of apparently contradictory laws of mechanics. Motions of all large scale and familiar objects in the universe are described by classical mechanics, whereas the motion of very small atomic and sub-atomic objects is described by quantum mechanics. It produces very accurate results within these domains, and is one of the oldest and largest in science, engineering, classical mechanics is fundamentally based on Newtons laws of motion. These laws describe the relationship between the acting on a body and the motion of that body. They were first compiled by Sir Isaac Newton in his work Philosophiæ Naturalis Principia Mathematica and his three laws are, A body either is at rest or moves with constant velocity, until and unless an outer force is applied to it. An object will travel in one direction only until an outer force changes its direction, whenever one body exerts a force F onto a second body, the second body exerts the force −F on the first body. F and −F are equal in magnitude and opposite in sense, so, the body which exerts F will go backwards. Newtons three laws of motion, along with his Newtons law of motion, which were the first to provide a mathematical model for understanding orbiting bodies in outer space. This explanation unified the motion of bodies and motion of objects on earth. Classical mechanics was later enhanced by Albert Einsteins special relativity. Motion of objects with a velocity, approaching the speed of light
4.
Horizontal plane
–
Alternatively, a spirit level, which exploits the buoyancy of a bubble, can be used to determine if the plane is horizontal. In radio science, horizontal plane is used to plot an antennas relative field strength in relation to the ground on a polar graph. Normally the maximum of 1.000 or 0 dB is at the top, other field strengths are expressed as a decimal less than 1.000, a percentage less than 100%, or decibels less than 0 dB. If the graph is of an actual or proposed installation, rotation is applied so that the top is 0o true north, see also the perpendicular vertical plane. In general, something that is horizontal can be drawn from left to right, although the word horizontal is commonly used in daily life and language, it is subject to many misconceptions. The concept of horizontality only makes sense in the context of a clearly measurable gravity field, i. e. in the neighborhood of a planet, star, when the gravity field becomes very weak, the notion of being horizontal loses its meaning. A plane is only at the chosen point. Horizontal planes at two points are not parallel, they intersect. Thus both horizontality and verticality are strictly speaking local concepts, and it is necessary to state to which location the direction or the plane refers to. In reality, the gravity field of a planet such as Earth is deformed due to the inhomogeneous spatial distribution of materials with different densities. Actual horizontal planes are not even parallel even if their reference points are along the same vertical line. At any given location, the gravitational force is not quite constant over time. For instance, on Earth the horizontal plane at a given point changes with the position of the Moon. On a rotating planet such as Earth, the gravitational pull of the planet is different from the apparent net force that can be measured in the laboratory or in the field. This difference is the force associated with the planets rotation. This is a force, it only arises when calculations or experiments are conducted in non-inertial frames of reference. Hence, the world appears to be flat locally, and horizontal planes in nearby locations appear to be parallel, such statements are nevertheless approximations, whether they are acceptable in any particular context or application depends on the applicable requirements, in particular in terms of accuracy. In this case, the direction is typically from the left side of the paper to the right side
5.
Sinistral and dextral
–
Sinistral and dextral, in some scientific fields, are the two types of chirality or relative direction. The terms are derived from the Latin words for left and right, other disciplines have different terms or simply use left and right. Relative direction and chirality are distinct concepts, relative direction is from the point of view of the observer. A completely symmetrical object has a left and a side, from the observers point of view, if the top and bottom. Chirality, however, is observer-independent, no matter how one looks at a screw thread. In geology the terms sinistral and dextral refer to the component of movement of blocks on either side of a fault or the sense of movement within a shear zone. These are terms of direction, as the movement of the blocks are described relative to each other when viewed from above. Movement is sinistral if the block on the side of the fault moves to the left. Movement is dextral if the block on the side of the fault moves to the right. Because the coiled shells of gastropods are asymmetrical, they possess a quality called chirality, over 90% of gastropod species have dextral shells in their coiling. A small minority of species and genera are almost always sinistral, a very few species show an even mixture of dextral and sinistral individuals. The most obvious characteristic of flatfish, other than their flatness, is asymmetry because both eyes are on the side of the head in the adult fish. In some families of flatfish, the eyes are always on the side of the body. Primitive spiny turbots include equal numbers of right- and left-sided individuals, and are generally more symmetrical than other families
6.
Subduction zones
–
Subduction is a geological process that takes place at convergent boundaries of tectonic plates where one plate moves under another and is forced or sinks due to gravity into the mantle. Regions where this occurs are known as subduction zones. Rates of subduction are typically in centimeters per year, with the rate of convergence being approximately two to eight centimeters per year along most plate boundaries. Plates include both oceanic crust and continental crust, stable subduction zones involve the oceanic lithosphere of one plate sliding beneath the continental or oceanic lithosphere of another plate due to the higher density of the oceanic lithosphere. That is, the lithosphere is always oceanic while the overriding lithosphere may or may not be oceanic. Subduction zones are sites that have a rate of volcanism, earthquakes. Subduction zones are sites of convective downwelling of Earths lithosphere, subduction zones exist at convergent plate boundaries where one plate of oceanic lithosphere converges with another plate. The descending slab, the plate, is over-ridden by the leading edge of the other plate. The slab sinks at an angle of approximately twenty-five to forty-five degrees to Earths surface and this sinking is driven by the temperature difference between the subducting oceanic lithosphere and the surrounding mantle asthenosphere, as the colder oceanic lithosphere is, on average, denser. At a depth of approximately 80–120 kilometers, the basalt of the oceanic crust is converted to a rock called eclogite. At that point, the density of the oceanic crust increases and provides additional negative buoyancy and it is at subduction zones that Earths lithosphere, oceanic crust, sedimentary layers and some trapped water are recycled into the deep mantle. Earth is so far the only planet where subduction is known to occur, subduction is the driving force behind plate tectonics, and without it, plate tectonics could not occur. Subduction zones dive down into the mantle beneath 55,000 kilometers of convergent plate margins, subduction zones burrow deeply but are imperfectly camouflaged, and geophysics and geochemistry can be used to study them. Not surprisingly, the shallowest portions of subduction zones are known best, subduction zones are strongly asymmetric for the first several hundred kilometers of their descent. They start to go down at oceanic trenches and their descents are marked by inclined zones of earthquakes that dip away from the trench beneath the volcanoes and extend down to the 660-kilometer discontinuity. Subduction zones are defined by the array of earthquakes known as the Wadati–Benioff zone after the two scientists who first identified this distinctive aspect. Subduction zone earthquakes occur at greater depths than elsewhere on Earth, such deep earthquakes may be driven by deep phase transformations, thermal runaway, the subducting basalt and sediment are normally rich in hydrous minerals and clays. Additionally, large quantities of water are introduced into cracks and fractures created as the slab bends downward
7.
Divergent boundary
–
In plate tectonics, a divergent boundary or divergent plate boundary is a linear feature that exists between two tectonic plates that are moving away from each other. Divergent boundaries within continents initially produce rifts which eventually become rift valleys, most active divergent plate boundaries occur between oceanic plates and exist as mid-oceanic ridges. Divergent boundaries also form volcanic islands which occur when the plates apart to produce gaps which molten lava rises to fill. Current research indicates that complex convection within the Earths mantle allows material to rise to the base of the lithosphere beneath each divergent plate boundary. This supplies the area with vast amounts of heat and a reduction in pressure that melts rock from the asthenosphere beneath the area forming large flood basalt or lava flows. Each eruption occurs in only a part of the boundary at any one time. Over millions of years, tectonic plates may move many hundreds of kilometers away from both sides of a divergent plate boundary, because of this, rocks closest to a boundary are younger than rocks further away on the same plate. At divergent boundaries, two plates move apart from other and the space that this creates is filled with new crustal material sourced from molten magma that forms below. The origin of new divergent boundaries at triple junctions is thought to be associated with the phenomenon known as hotspots. Here, exceedingly large convective cells bring very large quantities of hot asthenospheric material near the surface, the hot spot which may have initiated the Mid-Atlantic Ridge system currently underlies Iceland which is widening at a rate of a few centimeters per year. Divergent boundaries can create massive fault zones in the ridge system. Spreading is generally not uniform, so where spreading rates of adjacent ridge blocks are different and these are the fracture zones, many bearing names, that are a major source of submarine earthquakes. A sea floor map will show a strange pattern of blocky structures that are separated by linear features perpendicular to the ridge axis. If one views the sea floor between the zones as conveyor belts carrying the ridge on each side of the rift away from the spreading center the action becomes clear. Crest depths of the old ridges, parallel to the current spreading center and it is at mid-ocean ridges that one of the key pieces of evidence forcing acceptance of the seafloor spreading hypothesis was found. Airborne geomagnetic surveys showed a pattern of symmetrical magnetic reversals on opposite sides of ridge centers. The pattern was far too regular to be coincidental as the widths of the bands were too closely matched. Scientists had been studying polar reversals and the link was made by Lawrence W. Morley, Frederick John Vine, the magnetic banding directly corresponds with the Earths polar reversals
8.
Zigzag
–
In the Groove was a series of music video games that used a four-panel dance pad. The series was first distributed by Roxor Games during a time when four-panel dance games in the market were on the decline. As of October 18,2006, Konami has acquired the property rights to the series. The name In the Groove refers to three different things, the version of the game In the Groove, the PlayStation 2 and PC version of the game. In the Groove 2 is the game in this franchise. An In the Groove 3 was planned but canceled, due to a lawsuit with Konami. The gameplay mechanics of In the Groove are very similar to Konamis Dance Dance Revolution series, during normal gameplay, color arrows scroll upwards from the bottom of the screen and pass over a set of gray, stationary arrows near the top. When the scrolling arrows overlap the stationary ones, the player must step on the arrow on the dance platform. Longer arrows referred to as Holds must be held down for their length for them to count. Rolls, which appear to be spiky, green and yellow holds, mines deduct score and health if a players foot is on an arrow when they pass by the corresponding target arrow on-screen. On the players far side of the screen is a life bar and this is affected by the accuracy judgements the player receives for hitting arrows. Most machines have the Auto-Fail feature turned off - that is, any player whose life bar empties during a song can still finish playing that song, all machines will immediately fail any player who stops hitting arrows long enough to accrue 30 misses in a row. Similar to other dancing games, the player is judged for how accurately they step relative to when they were supposed to step. From best to worst, possible judgements are Fantastic, Excellent, Great, Decent, for holds and rolls, if the player finishes the hold or roll successfully, they receive a Yeah judgement. If not, the player receives a Bad, in the middle of the screen, the game keeps track of a players current combo, which is the length of the players most recent chain of good timing judgements. A players combo carries over one song to the next. However, if the player utilizes a USB card to track of their scores. The game has safety nets for players on easy difficulties that allows them to all of the songs on their credit without failing out
9.
Seafloor spreading
–
Seafloor spreading is a process that occurs at mid-ocean ridges, where new oceanic crust is formed through volcanic activity and then gradually moves away from the ridge. Seafloor spreading helps explain continental drift in the theory of plate tectonics, basaltic magma rises up the fractures and cools on the ocean floor to form new seabed. Older rocks will be farther away from the spreading zone while younger rocks will be found nearer to the spreading zone. Additionally spreading rates determine if the ridge is a fast, intermediate, as a general rule, fast ridges see spreading rate of more than 9 cm/year. Intermediate ridges have a rate of 4-9 cm/year while slow spreading ridges have a rate less than 4 cm/year. Earlier theories of continental drift were that continents ploughed through the sea, the idea that the seafloor itself moves as it expands from a central axis was proposed by Harry Hess from Princeton University in the 1960s. The theory is accepted now, and the phenomenon is known to be caused by convection currents in the asthenosphere, which is ductile, or plastic. In the general case, sea floor spreading starts as a rift in a land mass. The process starts with heating at the base of the continental crust which causes it to become more plastic, because less dense objects rise in relation to denser objects, the area being heated becomes a broad dome. As the crust bows upward, fractures occur that gradually grow into rifts, the typical rift system consists of three rift arms at approximately 120 degree angles. These areas are named triple junctions and can be found in places across the world today. The separated margins of the continents evolve to form passive margins, Hess theory was that new seafloor is formed when magma is forced upward toward the surface at a mid-ocean ridge. If spreading continues past the incipient stage described above, two of the arms will open while the third arm stops opening and becomes a failed rift. As the two active rifts continue to open, eventually the continental crust is attenuated as far as it will stretch, at this point basaltic oceanic crust begins to form between the separating continental fragments. When one of the rifts opens into the ocean, the rift system is flooded with seawater. The Red Sea is an example of a new arm of the sea, during this period of initial flooding the new sea is sensitive to changes in climate and eustasy. As a result, the new sea will evaporate several times before the elevation of the valley has been lowered to the point that the sea becomes stable. During this period of evaporation large evaporite deposits will be made in the rift valley, later these deposits have the potential to become hydrocarbon seals and are of particular interest to petroleum geologists
10.
Plate tectonics
–
The theoretical model builds on the concept of continental drift developed during the first few decades of the 20th century. The geoscientific community accepted plate-tectonic theory after seafloor spreading was validated in the late 1950s, the lithosphere, which is the rigid outermost shell of a planet, is broken up into tectonic plates. The Earths lithosphere is composed of seven or eight major plates, where the plates meet, their relative motion determines the type of boundary, convergent, divergent, or transform. Earthquakes, volcanic activity, mountain-building, and oceanic trench formation occur along plate boundaries. The relative movement of the plates typically ranges from zero to 100 mm annually, tectonic plates are composed of oceanic lithosphere and thicker continental lithosphere, each topped by its own kind of crust. Along convergent boundaries, subduction carries plates into the mantle, the material lost is balanced by the formation of new crust along divergent margins by seafloor spreading. In this way, the surface of the lithosphere remains the same. This prediction of plate tectonics is also referred to as the conveyor belt principle, earlier theories, since disproven, proposed gradual shrinking or gradual expansion of the globe. Tectonic plates are able to move because the Earths lithosphere has greater strength than the underlying asthenosphere. Lateral density variations in the result in convection. Plate movement is thought to be driven by a combination of the motion of the seafloor away from the ridge and drag, with downward suction. Another explanation lies in the different forces generated by forces of the Sun. The relative importance of each of these factors and their relationship to other is unclear. The outer layers of the Earth are divided into the lithosphere and asthenosphere and this is based on differences in mechanical properties and in the method for the transfer of heat. Mechanically, the lithosphere is cooler and more rigid, while the asthenosphere is hotter, in terms of heat transfer, the lithosphere loses heat by conduction, whereas the asthenosphere also transfers heat by convection and has a nearly adiabatic temperature gradient. The key principle of plate tectonics is that the lithosphere exists as separate and distinct tectonic plates, Plate motions range up to a typical 10–40 mm/year, to about 160 mm/year. The driving mechanism behind this movement is described below, tectonic lithosphere plates consist of lithospheric mantle overlain by either or both of two types of crustal material, oceanic crust and continental crust. Average oceanic lithosphere is typically 100 km thick, its thickness is a function of its age, as passes, it conductively cools
11.
John Tuzo Wilson
–
John Tuzo Wilson, CC, OBE, FRS, FRSC, FRSE was a Canadian geophysicist and geologist who achieved worldwide acclaim for his contributions to the theory of plate tectonics. Plate tectonics is the idea that the outer layers of the Earth. Wilson maintained that the Hawaiian Islands were created as a tectonic plate shifted to the northwest over a fixed hotspot and he also conceived of the transform fault, a major plate boundary where two plates move past each other horizontally. His name was given to two young Canadian submarine volcanoes called the Tuzo Wilson Seamounts, the Wilson cycle of seabed expansion and contraction bears his name. Wilsons father was of Scottish descent and his mother was a third-generation Canadian of French descent and he was born in Ottawa, Ontario. He became one of the first people in Canada to receive a degree in geophysics and he obtained various other related degrees from St. Johns College, Cambridge. His academic years culminated in his obtaining a doctorate in geology in 1936 from Princeton University, after completing his studies, Wilson enlisted in the Canadian Army and served in World War II. He retired from the army with the rank of Colonel, John Tuzo Wilson was President of the International Union of Geodesy and Geophysics. In 1969, he was made an Officer of the Order of Canada and was promoted to the rank of Companion of that order in 1974, Wilson was awarded the John J. Carty Award from the National Academy of Sciences in 1975. In 1978, he was awarded the Wollaston Medal of the Geological Society of London and he was a Fellow of the Royal Society of Canada, of the Royal Society of London and of the Royal Society of Edinburgh. He was the Principal of Erindale College at the University of Toronto and was the host of the television series The Planet of Man and he was elected President-elect and President of the American Geophysical Union. He also served as the Director General of the Ontario Science Centre from 1974 to 1985 and he and his plate tectonic theory are commemorated on the grounds outside by the Centre by a giant immovable spike indicating the amount of continental drift since Wilsons birth. The John Tuzo Wilson Medal of the Canadian Geophysical Union recognizes achievements in geophysics and he is also commemorated by a named memorial professorship and an eponymous annual public lecture delivered at the University of Toronto. He is one of the 2016 inductees into Legends Row, Mississauga Walk of Fame, cabot Fault, An Appalachian Equivalent of the San Andreas and Great Glen Faults and some Implications for Continental Displacement. Evidence from Islands on the Spreading of Ocean Floors, a Possible Origin of the Hawaiian Islands. A new Class of Faults and their Bearing on Continental Drift, vine, F. J. Wilson, J. Tuzo. Magnetic Anomalies over a Young Oceanic Ridge off Vancouver Island, did the Atlantic close and then re-open. Are the structures of the Caribbean and Scotia arc regions analogous to ice rafting, list of geophysicists Science and technology in Canada Supercontinent cycle J. Tuzo Wilson
12.
Oceanic ridges
–
A mid-ocean ridge is an underwater mountain system formed by plate tectonics. It consists of various mountains linked in chains, typically having a known as a rift running along its spine. This type of mountain ridge is characteristic of what is known as an oceanic spreading center. The production of new results from mantle upwelling in response to plate spreading. The buoyant melt rises as magma at a linear weakness in the oceanic crust, a mid-ocean ridge demarcates the boundary between two tectonic plates, and consequently is termed a divergent plate boundary. Mid-ocean ridges are geologically active, with new magma constantly emerging onto the floor and into the crust at. The crystallized magma forms new crust of basalt and gabbro and they are formed by two oceanic plates moving away from each other. The rocks making up the crust below the seafloor are youngest along the axis of the ridge and age with increasing distance from that axis, new magma of basalt composition emerges at and near the axis because of decompression melting in the underlying Earths mantle. The oceanic crust is made up of much younger than the Earth itself. Most oceanic crust in the basins is less than 200 million years old. The crust is in a constant state of renewal at the ocean ridges, moving away from the mid-ocean ridge, ocean depth progressively increases, the greatest depths are in ocean trenches. As the oceanic crust moves away from the axis, the peridotite in the underlying mantle cools. The crust and the relatively rigid peridotite below it make up the oceanic lithosphere, by contrast, fast spreading ridges like the East Pacific Rise are narrow, sharp incisions surrounded by generally flat topography that slopes away from the ridge over many hundreds of miles. The overall shape of ridges results from Pratt isostacy, close to the ridge there is hot. As the oceanic plates cool, away from the axes, the oceanic mantle lithosphere thickens. Thus older seafloor is underlain by denser material and sits lower, there are two processes, ridge-push and slab pull, thought to be responsible for the spreading seen at mid-ocean ridges, and there is some uncertainty as to which is dominant. Ridge-push occurs when the bulk of the ridge pushes the rest of the tectonic plate away from the ridge. At the subduction zone, slab-pull comes into effect and this is simply the weight of the tectonic plate being subducted below the overlying plate dragging the rest of the plate along behind it
13.
Harry Fielding Reid
–
Harry Fielding Reid was an American geophysicist. He was notable for his contributions to seismology, particularly his theory of elastic rebound that related faults to earthquakes, Harry Fielding Reid was the fourth child of seven born to Andrew Reid and Fanny Brooke Gwathmey Reid. HF Reids mother was a descendant of Betty Washington Lewis, sister of the first US President, the younger Reids early education took him for at least one year to Switzerland, he is also known to have attended and graduated from the Pennsylvania Military Academy. In 1877 Reid enrolled at the newly founded Johns Hopkins University, during the following year, he entered the Hopkins Ph. D. program, which was then revolutionizing American scientific and intellectual life. Reid studied under physicist Henry Rowland and mathematician J. J. Sylvester, while in graduate school Reid married Edith Gittings. Her father, James Gittings, was descended from a long-standing Baltimore County family with connections to the legal and medical communities of Maryland. Her mother was Mary Elizabeth MacGill, whose father was a physician in Hagerstown, together, Reid and his wife would have two children, Francis Fielding Reid, born in 1892, and Doris Fielding Reid, born in 1895. Through the Gittings line the two Reid children were distant cousins to Wallis Warfield, later Duchess of Windsor, through his mother, Harry Fielding Reid was a great-great-grandnephew of George Washington. From the autumn of 1884 through the summer of 1886. During the fall of ‘84 and winter of ‘85, he may have worked at the laboratory of Hermann von Helmholtz in Berlin and his wife was with him throughout his stay, and they were joined for most of their travels by her mother, Mary Elizabeth MacGill Gittings. Among her observations was that her daughter regarded the German language as one of “sneezes and splutters. ”Gittings found the climate of Berlin to be “foggy and dismal, ” noted that the locals still ate dinner in mid-afternoon. During the autumn of 1885, Reid, his wife and mother-in-law settled into a house in Cambridge, UK. Reid was soon introduced to J. J. Thomson, a young physicist who had recently appointed to a professorship at Trinity College. This friendship, both professional and personal, was to continue within the Reid and Thomson families up to the present time, J. J. Thomson was 29 at the time they first met, Harry Fielding Reid was 26. Letters exchanged among the family members reflect an intimacy that was born of their very early years together. Both J. J. Thomson and his son George Paget would go on to win Nobel Prizes for their work in subatomic physics. J. J. still holds a place in the history of physics for his work in making the Cavendish Laboratory perhaps the finest-ever school for training research physicists. In the fall of 1886 Reid accepted an appointment at the Case School of Applied Science in Cleveland and he taught physics and mathematics there for eight years before being appointed an Associate at Johns Hopkins, a rank that was the equivalent of today’s Assistant Professor
14.
Elastic-rebound theory
–
The elastic rebound theory is an explanation for how energy is spread during earthquakes. As rocks on opposite sides of a fault are subjected to force and shift, they accumulate energy, at that time, a sudden movement occurs along the fault, releasing the accumulated energy, and the rocks snap back to their original undeformed shape. In geology, the elastic rebound theory was the first theory to explain earthquakes. Previously it was thought that ruptures of the surface were the result of ground shaking rather than the converse suggested by this theory. Ancient cultural explanations of earthquakes were often along the lines of the mythical Japanese Namazu, a demigod, or daimyojin, holds a heavy stone over his head to keep him from moving. Once in a while the daimyojin is distracted so Namazu moves, following the great 1906 San Francisco earthquake, Harry Fielding Reid examined the displacement of the ground surface around the San Andreas Fault. From his observations he concluded that the earthquake must have been the result of the rebound of previously stored elastic strain energy in the rocks on either side of the fault. In an seismic period, the Earths plates move relative to each other except at most plate boundaries where they are locked. Thus, if a road is built across the fault as in the figure panel Time 1, it is perpendicular to the trace at the point E. The far field plate motions cause the rocks in the region of the fault to accrue elastic deformation. The deformation builds at the rate of a few centimeters per year, when the accumulated strain is great enough to overcome the strength of the rocks, an earthquake occurs. The time period between Time 1 and Time 2 could be months to hundreds of years, while the change from Time 2 to Time 3 is seconds. Like an elastic band, the more the rocks are strained the more energy is stored. The stored energy is released during the rupture partly as heat, partly in damaging the rock, modern measurements using GPS largely support Reid’s theory as the basis of seismic movement, though actual events are often more complicated
15.
Earthquakes
–
An earthquake is the shaking of the surface of the Earth, resulting from the sudden release of energy in the Earths lithosphere that creates seismic waves. Earthquakes can range in size from those that are so weak that they cannot be felt to those violent enough to people around. The seismicity or seismic activity of an area refers to the frequency, type, Earthquakes are measured using measurements from seismometers. The moment magnitude is the most common scale on which earthquakes larger than approximately 5 are reported for the entire globe and these two scales are numerically similar over their range of validity. Magnitude 3 or lower earthquakes are mostly imperceptible or weak and magnitude 7 and over potentially cause damage over larger areas. The largest earthquakes in historic times have been of magnitude slightly over 9, intensity of shaking is measured on the modified Mercalli scale. The shallower an earthquake, the damage to structures it causes. At the Earths surface, earthquakes manifest themselves by shaking and sometimes displacement of the ground, when the epicenter of a large earthquake is located offshore, the seabed may be displaced sufficiently to cause a tsunami. Earthquakes can also trigger landslides, and occasionally volcanic activity, in its most general sense, the word earthquake is used to describe any seismic event — whether natural or caused by humans — that generates seismic waves. Earthquakes are caused mostly by rupture of faults, but also by other events such as volcanic activity, landslides, mine blasts. An earthquakes point of rupture is called its focus or hypocenter. The epicenter is the point at ground level directly above the hypocenter, tectonic earthquakes occur anywhere in the earth where there is sufficient stored elastic strain energy to drive fracture propagation along a fault plane. The sides of a fault move past each other smoothly and aseismically only if there are no irregularities or asperities along the surface that increase the frictional resistance. Most fault surfaces do have such asperities and this leads to a form of stick-slip behavior, once the fault has locked, continued relative motion between the plates leads to increasing stress and therefore, stored strain energy in the volume around the fault surface. This continues until the stress has risen sufficiently to break through the asperity, suddenly allowing sliding over the portion of the fault. This energy is released as a combination of radiated elastic strain seismic waves, frictional heating of the fault surface and this process of gradual build-up of strain and stress punctuated by occasional sudden earthquake failure is referred to as the elastic-rebound theory. It is estimated that only 10 percent or less of a total energy is radiated as seismic energy. Most of the energy is used to power the earthquake fracture growth or is converted into heat generated by friction
16.
Hypothesis
–
A hypothesis is a proposed explanation for a phenomenon. For a hypothesis to be a scientific hypothesis, the method requires that one can test it. Scientists generally base scientific hypotheses on previous observations that cannot satisfactorily be explained with the scientific theories. Even though the hypothesis and theory are often used synonymously. A working hypothesis is a provisionally accepted hypothesis proposed for further research, P is the assumption in a What If question. Remember, the way that you prove an implication is by assuming the hypothesis, --Philip Wadler In its ancient usage, hypothesis referred to a summary of the plot of a classical drama. The English word hypothesis comes from the ancient Greek ὑπόθεσις word hupothesis, in Platos Meno, Socrates dissects virtue with a method used by mathematicians, that of investigating from a hypothesis. In this sense, hypothesis refers to an idea or to a convenient mathematical approach that simplifies cumbersome calculations. In common usage in the 21st century, a hypothesis refers to an idea whose merit requires evaluation. For proper evaluation, the framer of a hypothesis needs to define specifics in operational terms, a hypothesis requires more work by the researcher in order to either confirm or disprove it. In due course, a hypothesis may become part of a theory or occasionally may grow to become a theory itself. Normally, scientific hypotheses have the form of a mathematical model, in entrepreneurial science, a hypothesis is used to formulate provisional ideas within a business setting. The formulated hypothesis is then evaluated where either the hypothesis is proven to be true or false through a verifiability- or falsifiability-oriented Experiment, any useful hypothesis will enable predictions by reasoning. It might predict the outcome of an experiment in a setting or the observation of a phenomenon in nature. The prediction may also invoke statistics and only talk about probabilities, other philosophers of science have rejected the criterion of falsifiability or supplemented it with other criteria, such as verifiability or coherence. The scientific method involves experimentation, to test the ability of some hypothesis to adequately answer the question under investigation. In contrast, unfettered observation is not as likely to raise unexplained issues or open questions in science, a thought experiment might also be used to test the hypothesis as well. In framing a hypothesis, the investigator must not currently know the outcome of a test or that it remains reasonably under continuing investigation, only in such cases does the experiment, test or study potentially increase the probability of showing the truth of a hypothesis
17.
Deformation (mechanics)
–
Deformation in continuum mechanics is the transformation of a body from a reference configuration to a current configuration. A configuration is a set containing the positions of all particles of the body, a deformation may be caused by external loads, body forces, or changes in temperature, moisture content, or chemical reactions, etc. Strain is a description of deformation in terms of displacement of particles in the body that excludes rigid-body motions. In a continuous body, a deformation field results from a field induced by applied forces or is due to changes in the temperature field inside the body. The relation between stresses and induced strains is expressed by constitutive equations, e. g. Hookes law for linear elastic materials, deformations which are recovered after the stress field has been removed are called elastic deformations. In this case, the continuum completely recovers its original configuration, on the other hand, irreversible deformations remain even after stresses have been removed. Another type of deformation is viscous deformation, which is the irreversible part of viscoelastic deformation. In the case of elastic deformations, the response function linking strain to the stress is the compliance tensor of the material. Strain is a measure of deformation representing the displacement between particles in the relative to a reference length. A general deformation of a body can be expressed in the form x = F where X is the position of material points in the body. Such a measure does not distinguish between rigid body motions and changes in shape of the body, a deformation has units of length. We could, for example, define strain to be ε ≐ ∂ ∂ X = F ′ − I, hence strains are dimensionless and are usually expressed as a decimal fraction, a percentage or in parts-per notation. Strains measure how much a given deformation differs locally from a rigid-body deformation, a strain is in general a tensor quantity. Physical insight into strains can be gained by observing that a given strain can be decomposed into normal and this could be applied by elongation, shortening, or volume changes, or angular distortion. However, it is sufficient to know the normal and shear components of strain on a set of three perpendicular directions. In this case, the undeformed and deformed configurations of the continuum are significantly different and this is commonly the case with elastomers, plastically-deforming materials and other fluids and biological soft tissue. Infinitesimal strain theory, also called small strain theory, small deformation theory, small displacement theory, in this case, the undeformed and deformed configurations of the body can be assumed identical. Large-displacement or large-rotation theory, which assumes small strains but large rotations, in each of these theories the strain is then defined differently
18.
Compression (physics)
–
It is contrasted with tension or traction, the application of balanced outward forces, and with shearing forces, directed so as to displace layers of the material parallel to each other. The compressive strength of materials and structures is an important engineering consideration, in uniaxial compression the forces are directed along one direction only, so that they act towards decreasing the objects length along that direction. If the stress vector itself is opposite to x, the material is said to be under compression or pure compressive stress along x. In a solid, the amount of compression depends on the direction x. If the stress vector is purely compressive and has the same magnitude for all directions and this is the only type of static compression that liquids and gases can bear. In a mechanical longitudinal wave, or compression wave, the medium is displaced in the waves direction, when put under compression, every material will suffer some deformation, even if imperceptible, that causes the average relative positions of its atoms and molecules to change. The deformation may be permanent, or may be reversed when the compression forces disappear, in the latter case, the deformation gives rise to reaction forces that oppose the compression forces, and may eventually balance them. Liquids and gases cannot bear steady uniaxial or biaxial compression, they will deform promptly and permanently, however they can bear isotropic compression, and may be compressed in other ways momentarily, for instance in a sound wave. The deformation may not be uniform and may not be aligned with the compression forces, what happens in the directions where there is no compression depends on the material. Most materials will expand in those directions, but some special materials will remain unchanged or even contract, by inducing compression, mechanical properties such as compressive strength or modulus of elasticity, can be measured. Compression machines range from small table top systems to ones with over 53 MN capacity. Gases are often stored and shipped in highly compressed form, to save space, slightly compressed air or other gases are also used to fill balloons, rubber boats, and other inflatable structures. Compressed liquids are used in equipment and in fracking. In internal combustion engines the explosive mixture gets compressed before it is ignited, in the Otto cycle, for instance, the second stroke of the piston effects the compression of the charge which has been drawn into the cylinder by the first forward stroke. This compression, moreover, obviates the shock which would otherwise be caused by the admission of the steam for the return stroke. Buckling Container compression test Compression member Compressive strength Longitudinal wave P-wave Rarefaction Strength of materials
19.
Rift zone
–
For example, in the currently ongoing eruption of Kilauea in Hawaii, lava is emitted continuously from the Puʻu ʻŌʻō vent located in Kilaueas East Rift Zone roughly 15 km east of Kilauea Crater. Rift zones tend to extend for tens of kilometers radially outward from the volcanic summit, the accumulated lava of repeated eruptions from rift zones causes these volcanoes to have an elongated shape. Perhaps the best example of this is Mauna Loa, which in Hawaiian means long mountain, the origin of the fractures that comprise the rift zones is the spreading of the volcano. The more material a shield volcano accumulates, the heavier it gets and these systems of fissures that make up a rift zone allow this to happen more easily. Hawaii, Most Hawaiian volcanoes have two or sometimes three rift zones
20.
Mid-oceanic ridge
–
A mid-ocean ridge is an underwater mountain system formed by plate tectonics. It consists of various mountains linked in chains, typically having a known as a rift running along its spine. This type of mountain ridge is characteristic of what is known as an oceanic spreading center. The production of new results from mantle upwelling in response to plate spreading. The buoyant melt rises as magma at a linear weakness in the oceanic crust, a mid-ocean ridge demarcates the boundary between two tectonic plates, and consequently is termed a divergent plate boundary. Mid-ocean ridges are geologically active, with new magma constantly emerging onto the floor and into the crust at. The crystallized magma forms new crust of basalt and gabbro and they are formed by two oceanic plates moving away from each other. The rocks making up the crust below the seafloor are youngest along the axis of the ridge and age with increasing distance from that axis, new magma of basalt composition emerges at and near the axis because of decompression melting in the underlying Earths mantle. The oceanic crust is made up of much younger than the Earth itself. Most oceanic crust in the basins is less than 200 million years old. The crust is in a constant state of renewal at the ocean ridges, moving away from the mid-ocean ridge, ocean depth progressively increases, the greatest depths are in ocean trenches. As the oceanic crust moves away from the axis, the peridotite in the underlying mantle cools. The crust and the relatively rigid peridotite below it make up the oceanic lithosphere, by contrast, fast spreading ridges like the East Pacific Rise are narrow, sharp incisions surrounded by generally flat topography that slopes away from the ridge over many hundreds of miles. The overall shape of ridges results from Pratt isostacy, close to the ridge there is hot. As the oceanic plates cool, away from the axes, the oceanic mantle lithosphere thickens. Thus older seafloor is underlain by denser material and sits lower, there are two processes, ridge-push and slab pull, thought to be responsible for the spreading seen at mid-ocean ridges, and there is some uncertainty as to which is dominant. Ridge-push occurs when the bulk of the ridge pushes the rest of the tectonic plate away from the ridge. At the subduction zone, slab-pull comes into effect and this is simply the weight of the tectonic plate being subducted below the overlying plate dragging the rest of the plate along behind it
21.
Upwelling
–
The nutrient-rich upwelled water stimulates the growth and reproduction of primary producers such as phytoplankton. Due to the biomass of phytoplankton and presence of water in these regions, upwelling zones can be identified by cool sea surface temperatures. The increased availability in upwelling regions results in levels of primary productivity. Approximately 25% of the global marine fish catches come from five upwellings that occupy only 5% of the total ocean area. Upwellings that are driven by coastal currents or diverging open ocean have the greatest impact on nutrient-enriched waters, the three main drivers that work together to cause upwelling are wind, Coriolis effects, and Ekman transport. They operate differently for different types of upwelling, but the effects are the same. In the overall process of upwelling, winds blow across the sea surface at a particular direction, as a result of the wind, the water is transported a net of 90 degrees from the direction of the wind due to Coriolis forces and Ekman transport. This results in a spiral of water movement down the water column, then, it is the Coriolis forces that dictate which way the water will move, in the Northern hemisphere, the water is transported to the right of the direction of the wind. In the Southern Hemisphere, the water is transported to the left of the wind, if this net movement of water is divergent, then upwelling of deep water occurs to replace the water that was lost. The major upwellings in the ocean are associated with the divergence of currents that bring deeper, colder, coastal upwelling is the best known type of upwelling, and the most closely related to human activities as it supports some of the most productive fisheries in the world. Wind-driven currents are diverted to the right of the winds in the Northern Hemisphere, the result is a net movement of surface water at right angles to the direction of the wind, known as the Ekman transport. When Ekman transport is occurring away from the coast, surface waters moving away are replaced by deeper, colder, and denser water. Normally, this process occurs at a rate of about 5–10 meters per day. Deep waters are rich in nutrients, including nitrate, phosphate and silicic acid, Upwelling regions therefore result in very high levels of primary production in comparison to other areas of the ocean. They account for about 50% of global marine productivity, high primary production propagates up the food chain because phytoplankton are at the base of the oceanic food chain. All of these currents support major fisheries, the four major eastern boundary currents in which coastal upwelling primarily occurs are the Canary Current, Benguela Current, California Current, and Humboldt Current. The Benguela Current is the boundary of the South Atlantic subtropical gyre. The subsystems are divided by an area of permanent upwelling off of Luderitz, the California Current System is an eastern boundary current of the North Pacific that is also characterized by a north and south split
22.
Basaltic
–
Basalt is a common extrusive igneous rock formed from the rapid cooling of basaltic lava exposed at or very near the surface of a planet or moon. Flood basalt describes the formation in a series of basalt flows. By definition, basalt is an igneous rock with generally 45-55% silica and less than 10% feldspathoid by volume. Basalt commonly features a very fine-grained or glassy matrix interspersed with visible mineral grains, the average density is 3.0 gm/cm3. Basalt is defined by its content and texture, and physical descriptions without mineralogical context may be unreliable in some circumstances. Basalt is usually grey to black in colour, but rapidly weathers to brown or rust-red due to oxidation of its mafic minerals into hematite, although usually characterized as dark, basaltic rocks exhibit a wide range of shading due to regional geochemical processes. Due to weathering or high concentrations of plagioclase, some basalts can be quite light-coloured and these phenocrysts usually are of olivine or a calcium-rich plagioclase, which have the highest melting temperatures of the typical minerals that can crystallize from the melt. Basalt with a texture is called vesicular basalt, when the bulk of the rock is mostly solid. Gabbro is often marketed commercially as black granite and these ultramafic volcanic rocks, with silica contents below 45% are usually classified as komatiites. Agricola applied basalt to the black rock of the Schloßberg at Stolpen. Tholeiitic basalt is relatively rich in silica and poor in sodium, included in this category are most basalts of the ocean floor, most large oceanic islands, and continental flood basalts such as the Columbia River Plateau. Basalt rocks are in some cases classified after their content in High-Ti and Low-Ti varieties. High-Ti and Low-Ti basalts have been distinguished in the Paraná and Etendeka traps and it has greater than 17% alumina and is intermediate in composition between tholeiite and alkali basalt, the relatively alumina-rich composition is based on rocks without phenocrysts of plagioclase. Alkali basalt is relatively poor in silica and rich in sodium and it is silica-undersaturated and may contain feldspathoids, alkali feldspar and phlogopite. Boninite is a form of basalt that is erupted generally in back-arc basins. Ocean island basalt Lunar basalt On Earth, most basalt magmas have formed by melting of the mantle. Basalt commonly erupts on Io, the third largest moon of Jupiter, and has formed on the Moon, Mars, Venus. The crustal portions of oceanic tectonic plates are composed predominantly of basalt, produced from upwelling mantle below, the mineralogy of basalt is characterized by a preponderance of calcic plagioclase feldspar and pyroxene
23.
Magma
–
Besides molten rock, magma may also contain suspended crystals, dissolved gas and sometimes gas bubbles. Magma often collects in magma chambers that may feed a volcano or solidify underground to form an intrusion, magma is capable of intruding into adjacent rocks, extrusion onto the surface as lava, and explosive ejection as tephra to form pyroclastic rock. Magma is a complex high-temperature fluid substance, temperatures of most magmas are in the range 700 °C to 1300 °C, but very rare carbonatite magmas may be as cool as 600 °C, and komatiite magmas may have been as hot as 1600 °C. Environments of magma formation and compositions are commonly correlated, environments include subduction zones, continental rift zones, mid-ocean ridges and hotspots. Despite being found in such locales, the bulk of the Earths crust. Except for the outer core, most of the Earth takes the form of a rheid. Magma, as liquid, preferentially forms in high temperature, low pressure environments within several kilometers of the Earths surface, magma compositions may evolve after formation by fractional crystallization, contamination, and magma mixing. By definition rock formed of solidified magma is called igneous rock, melting of solid rocks to form magma is controlled by three physical parameters, temperature, pressure, and composition. Mechanisms are discussed in the entry for igneous rock, as a rock melts, its volume changes. When enough rock is melted, the small globules of melt link up, under pressure within the earth, as little as a fraction of a percent partial melting may be sufficient to cause melt to be squeezed from its source. The degree of melting is critical for determining what type of magma is produced. The degree of partial melting required to form a melt can be estimated by considering the relative enrichment of incompatible elements versus compatible elements, incompatible elements commonly include potassium, barium, cesium, and rubidium. Rock types produced by small degrees of melting in the Earths mantle are typically alkaline. Typically, primitive melts of this composition form lamprophyre, lamproite, kimberlite and sometimes nepheline-bearing mafic rocks such as alkali basalts, pegmatite may be produced by low degrees of partial melting of the crust. Some granite-composition magmas are eutectic melts, and they may be produced by low to high degrees of melting of the crust. At high degrees of melting of the crust, granitoids such as tonalite, granodiorite and monzonite can be produced. Being only the time in recorded history that magma had been reached, IDDP decided to invest in the hole. A cemented steel case was constructed in the hole with a perforation at the close to the magma
24.
Peridotite
–
Peridotite is a dense, coarse-grained igneous rock consisting mostly of the minerals olivine and pyroxene. Peridotite is ultramafic, as the rock contains less than 45% silica and it is high in magnesium, reflecting the high proportions of magnesium-rich olivine, with appreciable iron. Peridotite is derived from the Earths mantle, either as solid blocks and fragments, the compositions of peridotites from these layered igneous complexes vary widely, reflecting the relative proportions of pyroxenes, chromite, plagioclase, and amphibole. Peridotite is the dominant rock of the part of the Earths mantle. The word peridotite comes from the gemstone peridot, which consists of pale green olivine, classic peridotite is bright green with some specks of black, although most hand samples tend to be darker green. Peridotitic outcrops typically range from bright yellow to dark green in color. While green and yellow are the most common colors, peridotitic rocks may exhibit a range of colors such as blue, brown. Dunite, more than 90% olivine, typically with Mg/Fe ratio of about 9,1, wehrlite, mostly composed of olivine plus clinopyroxene. Harzburgite, mostly composed of olivine plus orthopyroxene, and relatively low proportions of basaltic ingredients, lherzolite, most common form of peridotite, mostly composed of olivine, orthopyroxene, and clinopyroxene, and have relatively high proportions of basaltic ingredients. Partial fusion of lherzolite and extraction of the melt fraction can leave a residue of harzburgite. Magnesium-rich olivine forms a proportion of peridotite, and so magnesium content is high. Layered igneous complexes have more varied compositions, depending on the fractions of pyroxenes, chromite, plagioclase. Minor minerals and mineral groups in peridotite include plagioclase, spinel, garnet, amphibole, in peridotite, plagioclase is stable at relatively low pressures, aluminous spinel at higher pressures, and garnet at yet higher pressures. Peridotite is the dominant rock of the Earths mantle above a depth of about 400 km, below that depth, olivine is converted to the higher-pressure mineral wadsleyite. Oceanic plates consist of up to about 100 km of peridotite covered by a thin crust, the crust, commonly about 6 km thick, consists of basalt, gabbro, and minor sediments. The peridotite below the ocean crust, abyssal peridotite, is found on the walls of rifts in the sea floor. Oceanic plates are usually subducted back into the mantle in subduction zones, peridotites also occur as fragments carried up by magmas from the mantle. Among the rocks that commonly include peridotite xenoliths are basalt and kimberlite, certain volcanic rocks, sometimes called komatiites, are so rich in olivine and pyroxene that they also can be termed peridotite
25.
Gabbro
–
Gabbro refers to a large group of dark, often phaneritic, mafic intrusive igneous rocks chemically equivalent to basalt. It forms when magma is trapped beneath the Earths surface. Much of the Earths oceanic crust is made of gabbro, formed at mid-ocean ridges, Gabbro is also found as plutons associated with continental volcanism. Due to its variant nature, the term gabbro may be applied loosely to a range of intrusive rocks. The term gabbro was used in the 1760s to name a set of types that were found in the ophiolites of the Apennine Mountains in Italy. Then, in 1809, the German geologist Christian Leopold von Buch used the term more restrictively in his description of these Italian ophiolitic rocks and he assigned the name gabbro to rocks that geologists nowadays would more strictly call metagabbro. Von Buch named gabbro after Gabbro, a village in Rosignano Marittimo municipality of Tuscany, Gabbro is dense, greenish or dark-colored and contains pyroxene, plagioclase, and minor amounts of amphibole and olivine. The pyroxene content is mostly clinopyroxene, generally augite, but small amounts of orthopyroxene may also be present, if the amount of orthopyroxene is more than 95% of the total pyroxene content, then the rock is termed norite. On the other hand, gabbro has more than 95% of its pyroxenes in the form of the monoclinic clinopyroxene/s, the calcium rich plagioclase feldspar and pyroxene content vary between 10% - 90% in gabbro. If more than 90% plagioclase is present, then the rock is an anorthosite, if on the other hand, the rock contains more than 90% pyroxenes, it is termed pyroxenite. Gabbro may also contain amounts of olivine, amphibole and biotite. The quartz content in gabbro is less than 5% of total volume, quartz gabbros or monzogabbros are also known to occur, for example the cizlakite at Pohorje in northeastern Slovenia, and are probably derived from magma that was over-saturated with silica. Gabbros contain minor amounts, typically a few percent, of iron-titanium oxides such as magnetite, ilmenite, Gabbro is generally coarse grained, with crystals in the size range of 1 mm or greater. Finer grained equivalents of gabbro are called diabase, although the term microgabbro is often used when extra descriptiveness is desired, Gabbro may be extremely coarse grained to pegmatitic, and some pyroxene-plagioclase cumulates are essentially coarse grained gabbro, some may exhibit acicular crystal habits. Gabbro is usually equigranular in texture, although it may be porphyritic at times, cumulate gabbros are more properly termed pyroxene-plagioclase adcumulate. Gabbro is an part of the oceanic crust, and can be found in many ophiolite complexes as parts of zones III. Long belts of gabbroic intrusions are typically formed at proto-rift zones and around ancient rift zone margins, mantle plume hypotheses may rely on identifying mafic and ultramafic intrusions and coeval basalt volcanism. It is better to base a rock definition on descriptive characteristics of the rather than how or where it was formed
26.
Fracture zone
–
A fracture zone is a linear oceanic feature—often hundreds, even thousands of kilometers long—resulting from the action of offset mid-ocean ridge axis segments. They are a consequence of plate tectonics, lithospheric plates on either side of an active transform fault move in opposite directions, here, strike-slip activity occurs. In actual usage, many transform faults aligned with fracture zones are often referred to as fracture zones although technically. Mid-ocean ridges are divergent boundaries that push apart two plates, as the plates on either side of a mid-ocean ridge move, transform faults are created due to variances in plate motion. As the plates continue to move over time, these faults offset the mid-ocean ridge and these offsets cause fractures in the ocean floor that can extend for hundreds of kilometers out from a mid-ocean ridge. Fracture zones and the faults that form them are separate features. Transform faults are plate boundaries, meaning that on side of the fault is a different plate. In contrast, on side of a fracture zone, the crust belongs to the same plate. As many areas of the floor, particularly the Atlantic Ocean, are currently inactive. However, by observing the fracture zones, one can determine both the direction and rate of past plate motion and this is found by observing the patterns of magnetic striping on the ocean floor. By measuring the offset in the striping, one can then determine the rate of past plate motions. In a similar method, one can use the relative ages of the seafloor on either side of a zone to determine the rate of past plate motions. By comparing how offset similarly aged seafloor is, one can determine how quickly the plate has moved, the Blanco Fracture Zone is a fracture zone running between the Juan de Fuca Ridge and the Gorda Ridge. The dominating feature of the zone is the 150 km long Blanco Ridge. The Charlie-Gibbs Fracture Zone consists of two zones in the North Atlantic that extend for over 2000 km. These fracture zones displace the Mid-Atlantic Ridge a total of 350 km to the west, the section of the Mid-Atlantic Ridge between the two fracture zones is seismically active. The Mendocino Fracture Zone extends for over 4,000 km off the coast of California and separates the Pacific Plate and Gorda Plate. The bathymetric depths on the side of the fracture zone are 800 to 1,200 m shallower than to the south
27.
Atlantic Ocean
–
The Atlantic Ocean is the second largest of the worlds oceans with a total area of about 106,460,000 square kilometres. It covers approximately 20 percent of the Earths surface and about 29 percent of its surface area. It separates the Old World from the New World, the Atlantic Ocean occupies an elongated, S-shaped basin extending longitudinally between Eurasia and Africa to the east, and the Americas to the west. The Equatorial Counter Current subdivides it into the North Atlantic Ocean, in contrast, the term Atlantic originally referred specifically to the Atlas Mountains in Morocco and the sea off the Strait of Gibraltar and the North African coast. The Greek word thalassa has been reused by scientists for the huge Panthalassa ocean that surrounded the supercontinent Pangaea hundreds of years ago. The term Aethiopian Ocean, derived from Ancient Ethiopia, was applied to the Southern Atlantic as late as the mid-19th century, many Irish or British people refer to the United States and Canada as across the pond, and vice versa. The Black Atlantic refers to the role of ocean in shaping black peoples history. Irish migration to the US is meant when the term The Green Atlantic is used, the term Red Atlantic has been used in reference to the Marxian concept of an Atlantic working class, as well as to the Atlantic experience of indigenous Americans. Correspondingly, the extent and number of oceans and seas varies, the Atlantic Ocean is bounded on the west by North and South America. It connects to the Arctic Ocean through the Denmark Strait, Greenland Sea, Norwegian Sea, to the east, the boundaries of the ocean proper are Europe, the Strait of Gibraltar and Africa. In the southeast, the Atlantic merges into the Indian Ocean, the 20° East meridian, running south from Cape Agulhas to Antarctica defines its border. In the 1953 definition it extends south to Antarctica, while in later maps it is bounded at the 60° parallel by the Southern Ocean, the Atlantic has irregular coasts indented by numerous bays, gulfs, and seas. Including these marginal seas the coast line of the Atlantic measures 111,866 km compared to 135,663 km for the Pacific. Including its marginal seas, the Atlantic covers an area of 106,460,000 km2 or 23. 5% of the ocean and has a volume of 310,410,900 km3 or 23. 3%. Excluding its marginal seas, the Atlantic covers 81,760,000 km2 and has a volume of 305,811,900 km3, the North Atlantic covers 41,490,000 km2 and the South Atlantic 40,270,000 km2. The average depth is 3,646 m and the maximum depth, the bathymetry of the Atlantic is dominated by a submarine mountain range called the Mid-Atlantic Ridge. It runs from 87°N or 300 km south of the North Pole to the subantarctic Bouvet Island at 42°S, the MAR divides the Atlantic longitudinally into two halves, in each of which a series of basins are delimited by secondary, transverse ridges. The MAR reaches above 2000 m along most of its length, the MAR is a barrier for bottom water, but at these two transform faults deep water currents can pass from one side to the other
28.
South America
–
South America is a continent located in the western hemisphere, mostly in the southern hemisphere, with a relatively small portion in the northern hemisphere. It may also be considered a subcontinent of the Americas, which is the used in nations that speak Romance languages. The reference to South America instead of other regions has increased in the last decades due to changing geopolitical dynamics. It is bordered on the west by the Pacific Ocean and on the north and east by the Atlantic Ocean, North America and it includes twelve sovereign states, a part of France, and a non-sovereign area. In addition to this, the ABC islands of the Kingdom of the Netherlands, Trinidad and Tobago, South America has an area of 17,840,000 square kilometers. Its population as of 2005 has been estimated at more than 371,090,000, South America ranks fourth in area and fifth in population. Brazil is by far the most populous South American country, with more than half of the population, followed by Colombia, Argentina, Venezuela. In recent decades Brazil has also concentrated half of the regions GDP and has become a first regional power, most of the population lives near the continents western or eastern coasts while the interior and the far south are sparsely populated. Most of the continent lies in the tropics, the continents cultural and ethnic outlook has its origin with the interaction of indigenous peoples with European conquerors and immigrants and, more locally, with African slaves. Given a long history of colonialism, the majority of South Americans speak Portuguese or Spanish. South America occupies the portion of the Americas. The continent is delimited on the northwest by the Darién watershed along the Colombia–Panama border. Almost all of mainland South America sits on the South American Plate, South Americas major mineral resources are gold, silver, copper, iron ore, tin, and petroleum. These resources found in South America have brought high income to its countries especially in times of war or of rapid growth by industrialized countries elsewhere. However, the concentration in producing one major export commodity often has hindered the development of diversified economies and this is leading to efforts to diversify production to drive away from staying as economies dedicated to one major export. South America is one of the most biodiverse continents on earth, South America is home to many interesting and unique species of animals including the llama, anaconda, piranha, jaguar, vicuña, and tapir. The Amazon rainforests possess high biodiversity, containing a proportion of the Earths species. Brazil is the largest country in South America, encompassing around half of the land area
29.
Africa
–
Africa is the worlds second-largest and second-most-populous continent. At about 30.3 million km² including adjacent islands, it covers 6% of Earths total surface area and 20.4 % of its land area. With 1.2 billion people as of 2016, it accounts for about 16% of the human population. The continent includes Madagascar and various archipelagos and it contains 54 fully recognized sovereign states, nine territories and two de facto independent states with limited or no recognition. Africas population is the youngest amongst all the continents, the age in 2012 was 19.7. Algeria is Africas largest country by area, and Nigeria by population, afarensis, Homo erectus, H. habilis and H. ergaster – with the earliest Homo sapiens found in Ethiopia being dated to circa 200,000 years ago. Africa straddles the equator and encompasses numerous climate areas, it is the continent to stretch from the northern temperate to southern temperate zones. Africa hosts a diversity of ethnicities, cultures and languages. In the late 19th century European countries colonized most of Africa, Africa also varies greatly with regard to environments, economics, historical ties and government systems. However, most present states in Africa originate from a process of decolonization in the 20th century, afri was a Latin name used to refer to the inhabitants of Africa, which in its widest sense referred to all lands south of the Mediterranean. This name seems to have referred to a native Libyan tribe. The name is connected with Hebrew or Phoenician ʿafar dust. The same word may be found in the name of the Banu Ifran from Algeria and Tripolitania, under Roman rule, Carthage became the capital of the province of Africa Proconsularis, which also included the coastal part of modern Libya. The Latin suffix -ica can sometimes be used to denote a land, the later Muslim kingdom of Ifriqiya, modern-day Tunisia, also preserved a form of the name. According to the Romans, Africa lay to the west of Egypt, while Asia was used to refer to Anatolia, as Europeans came to understand the real extent of the continent, the idea of Africa expanded with their knowledge. 25,4, whose descendants, he claimed, had invaded Libya, isidore of Seville in Etymologiae XIV.5.2. Suggests Africa comes from the Latin aprica, meaning sunny, massey, in 1881, stated that Africa is derived from the Egyptian af-rui-ka, meaning to turn toward the opening of the Ka. The Ka is the double of every person and the opening of the Ka refers to a womb or birthplace
30.
Romanche Trench
–
The Romanche Trench, also called the Romanche Furrow or Romanche Gap, is the third deepest of the major trenches of the Atlantic Ocean, after the Puerto Rico Trench and the South Sandwich Trench. It bisects the Mid-Atlantic Ridge just north of the equator at the narrowest part of the Atlantic between Brazil and West Africa, extending from 2°N to 2°S and from 16°W to 20°W. The trench has been formed by the actions of the Romanche Fracture Zone, a portion of which is an active transform boundary offsetting sections of the Mid-Atlantic Ridge. The trench has a depth of 7,761 m, is 300 km long and has a width of 19 km. Deep water flow through the trench is from west to east with a rate of 3.6 Sverdrups of 1.57 °C water, antarctic Bottom Water flows below the LNADW and reaches down to the seafloor. Formed around Antarctica, the AABW is cold, has low salinity, as it flows north, it is constrained by numerous obstacles on the seafloor. In the basin on the side of the MAR the Walvis Ridge blocks the northward passage. For LNADW and AABW, the Romanche and Chain Fracture Zones are the only deep passages in the MAR where interbasin exchange is possible, as AABW flows through the Romanche Fracture Zone, salinity and temperature increase significantly. The Romanche Fracture Zone offsets the Mid-Atlantic ridge by 900 km, according to the normal scenario for the opening of the South Atlantic, it is spreading at a rate of 1.75 cm/year and began forming about 50 Ma. North of and parallel to the zone is a transverse ridge which is particularly prominent over hundreds of kilometres east and west of the MAB of the South Atlantic. The western part of the ridge consists of fragments of uplifted oceanic crust. The summit of the ridge is capped by Miocene shallow water limestones that reached above sea level 20 Ma before subsiding abnormally fast. The eastern part of the ridge, however, consists of a thick sequence of stratified material called the Romanche Sedimentary Sequence. The transverse ridge separates the present trench from an 800 km -long aseismic valley where the Romanche transform was located until about 10–8 Ma, the hydrothermal vents of the MAR support many life forms. The Romanche and Chain Fracture Zones creates a gap in the MAR. Swarms of hydrothermal shrimps reminiscent of those found from northern MAR vent-sites have been found on the part of the southern MAR. Bivalve communities have been reported around vents further south and these species await a formal description and it is not known whether or not they represent communities distinct from those on the northern MAR. The flow of NADW through the Romanche and Chain Fracture Zones may serve as a conduit for larval transport from the western North Atlantic to the eastern South Atlantic
31.
Pacific Ocean
–
The Pacific Ocean is the largest and deepest of the Earths oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean in the south and is bounded by Asia and Australia in the west, the Mariana Trench in the western North Pacific is the deepest point in the world, reaching a depth of 10,911 metres. Both the center of the Water Hemisphere and the Western Hemisphere are in the Pacific Ocean, the oceans current name was coined by Portuguese explorer Ferdinand Magellan during the Spanish circumnavigation of the world in 1521, as he encountered favourable winds on reaching the ocean. He called it Mar Pacífico, which in both Portuguese and Spanish means peaceful sea, important human migrations occurred in the Pacific in prehistoric times. Long-distance trade developed all along the coast from Mozambique to Japan, trade, and therefore knowledge, extended to the Indonesian islands but apparently not Australia. By at least 878 when there was a significant Islamic settlement in Canton much of trade was controlled by Arabs or Muslims. In 219 BC Xu Fu sailed out into the Pacific searching for the elixir of immortality, from 1404 to 1433 Zheng He led expeditions into the Indian Ocean. The east side of the ocean was discovered by Spanish explorer Vasco Núñez de Balboa in 1513 after his expedition crossed the Isthmus of Panama and he named it Mar del Sur because the ocean was to the south of the coast of the isthmus where he first observed the Pacific. Later, Portuguese explorer Ferdinand Magellan sailed the Pacific East to West on a Castilian expedition of world circumnavigation starting in 1519, Magellan called the ocean Pacífico because, after sailing through the stormy seas off Cape Horn, the expedition found calm waters. The ocean was often called the Sea of Magellan in his honor until the eighteenth century, sailing around and east of the Moluccas, between 1525 and 1527, Portuguese expeditions discovered the Caroline Islands, the Aru Islands, and Papua New Guinea. In 1542–43 the Portuguese also reached Japan, in 1564, five Spanish ships consisting of 379 explorers crossed the ocean from Mexico led by Miguel López de Legazpi and sailed to the Philippines and Mariana Islands. The Manila galleons operated for two and a half centuries linking Manila and Acapulco, in one of the longest trade routes in history, Spanish expeditions also discovered Tuvalu, the Marquesas, the Cook Islands, the Solomon Islands, and the Admiralty Islands in the South Pacific. In the 16th and 17th century Spain considered the Pacific Ocean a Mare clausum—a sea closed to other naval powers, as the only known entrance from the Atlantic the Strait of Magellan was at times patrolled by fleets sent to prevent entrance of non-Spanish ships. On the western end of the Pacific Ocean the Dutch threatened the Spanish Philippines, Spain also sent expeditions to the Pacific Northwest reaching Vancouver Island in southern Canada, and Alaska. The French explored and settled Polynesia, and the British made three voyages with James Cook to the South Pacific and Australia, Hawaii, and the North American Pacific Northwest, one of the earliest voyages of scientific exploration was organized by Spain in the Malaspina Expedition of 1789–1794. It sailed vast areas of the Pacific, from Cape Horn to Alaska, Guam and the Philippines, New Zealand, Australia, and the South Pacific. Growing imperialism during the 19th century resulted in the occupation of much of Oceania by other European powers, and later, Japan, in Oceania, France got a leading position as imperial power after making Tahiti and New Caledonia protectorates in 1842 and 1853 respectively. After navy visits to Easter Island in 1875 and 1887, Chilean navy officer Policarpo Toro managed to negotiate an incorporation of the island into Chile with native Rapanui in 1888, by occupying Easter Island, Chile joined the imperial nations
32.
San Andreas Fault
–
The San Andreas Fault is a continental transform fault that extends roughly 800 miles through California. It forms the boundary between the Pacific Plate and the North American Plate, and its motion is right-lateral strike-slip. The fault was first identified in 1895 by Professor Andrew Lawson of UC Berkeley and it is often described as having been named after San Andreas Lake, a small body of water that was formed in a valley between the two plates. However, according to some of his reports from 1895 and 1908, following the 1906 San Francisco earthquake, Lawson concluded that the fault extended all the way into southern California. In 1953, geologist Thomas Dibblee astounded the scientific establishment with his conclusion that hundreds of miles of lateral movement could occur along the fault. A project called the San Andreas Fault Observatory at Depth near Parkfield, Monterey County, is drilling into the fault to improve prediction and this is the approximate location of the epicenter of the 1906 San Francisco earthquake. The fault returns onshore at Bolinas Lagoon just north of Stinson Beach in Marin County, from Fort Ross the northern segment continues overland, forming in part a linear valley through which the Gualala River flows. It goes back offshore at Point Arena, after that, it runs underwater along the coast until it nears Cape Mendocino, where it begins to bend to the west, terminating at the Mendocino Triple Junction. The central segment of the San Andreas fault runs in a direction from Parkfield to Hollister. The southern segment begins near Bombay Beach, California, box Canyon, near the Salton Sea, contains upturned strata associated with that section of the fault. The fault then runs along the base of the San Bernardino Mountains, crosses through the Cajon Pass. These mountains are a result of movement along the San Andreas Fault and are called the Transverse Range. In Palmdale, a portion of the fault is easily examined at a roadcut for the Antelope Valley Freeway, the fault continues northwest alongside the Elizabeth Lake Road to the town of Elizabeth Lake. As it passes the towns of Gorman, Tejon Pass and Frazier Park and this restraining bend is thought to be where the fault locks up in Southern California, with an earthquake-recurrence interval of roughly 140–160 years. Northwest of Frazier Park, the runs through the Carrizo Plain. The Elkhorn Scarp defines the fault trace along much of its length within the plain, the southern segment, which stretches from Parkfield in Monterey County all the way to the Salton Sea, is capable of an 8. 1-magnitude earthquake. At its closest, this fault passes about 35 miles to the northeast of Los Angeles. Such a large earthquake on this segment would kill thousands of people in Los Angeles, San Bernardino, Riverside, and surrounding areas
33.
Continental margin
–
The continental margin is the zone of the ocean floor that separates the thin oceanic crust from thick continental crust. Together, the shelf, continental slope, and continental rise are called the continental margin. Continental margins constitute about 28% of the oceanic area, the transition from continental to oceanic crust commonly occurs within the outer part of the margin, called the continental rise. Oceanwards, beyond the edge of the rise, lies the abyssal plain, the underwater part of the continental crust is the continental shelf, which usually abruptly terminates at the continental slope, which in turn terminates at the foot of the slope. The underwater part constitutes about 20% of the continental crust, the continental shelf is an expansive, shallow area of land extending outward from a continent. At the edge of that is the slope, a steep incline where several habitats exist. Earthquakes and volcanic eruptions are common on the west coast of North America, but there are no active volcanoes on the east coast, geologists refer to the west coast as a active continental margin, and the east coast as a passive continental margin. These differences can be found on several continents, most passive continental margins have broad continental shelves, whereas active continental margins typically have narrow continental shelves. In addition, active continental margins are near plate boundaries, whereas passive continental margins tend to be away from an active plate boundary
34.
East Pacific Rise
–
The East Pacific Rise is a mid-oceanic ridge, a divergent tectonic plate boundary located along the floor of the Pacific Ocean. It separates the Pacific Plate to the west from the North American Plate, the Rivera Plate, the Cocos Plate, the Nazca Plate, and the Antarctic Plate. Much of the lies about 3200 km off the South American coast and rises about 1. The oceanic crust is moving away from the East Pacific Rise to either side, near Easter Island the rate is over 15 cm per year which is the fastest in the world but it is lower at about 6 cm at the north end. On the eastern side of the rise the eastward moving Cocos and Nazca plates meet the westward moving South American Plate, the belt of volcanoes along the Andes and the arc of volcanoes through Central America and Mexico are the direct results of this collision. Due east of the Baja California Peninsula, the Rise is sometimes referred to as the Gulf of California Rift Zone, in this area, newly formed oceanic crust is intermingled with rifted continental crust originating from the North American Plate. The southern extension of the East Pacific Rise merges with the Southeast Indian Ridge at the Macquarie Triple Junction south of New Zealand, along the East Pacific Rise the hydrothermal vents called black smokers were first discovered and have been extensively studied. These vents are forming volcanogenic massive sulfide ore deposits on the ocean floor, many strange deep-water creatures have been found here. The southern stretch of the East Pacific Rise is one of the sections of the Earths mid-ocean ridge system. East Pacific Rise 2004 – Scripps Institution of Oceanography Columbia University Researchers Find Key to the Formation of New Seafloor Spreading Centers – Columbia University
35.
Mendocino Triple Junction
–
The Mendocino Triple Junction is the point where the Gorda plate, the North American plate, and the Pacific plate meet, in the Pacific Ocean near Cape Mendocino in northern California. The accommodation of this configuration results in a transform boundary along the Mendocino Fracture Zone. At this point, removal of the subducting Gorda lithosphere from beneath North America causes asthenospheric upwelling and this instigates different tectonic processes, which include surficial uplift, crustal deformation, intense seismic activity, high heat flow, and even the extrusion of volcanic rocks. This activity is centred on the current triple junction position, but evidence for its migration is found in the geology all along the California coast, the passage of the MTJ causes mantle material to flow into the region vacated by the Gorda plate. Lower crust-upper mantle viscous coupling plays a dominant role in converting accretionary margin materials into continent-like crust, in this way, as the MTJ migrates, there is production of a basal conveyor belt beneath North America that transports material from the south to the north. This is consistent with a pattern of anomalous crustal structure determined by local-earthquake crustal tomography in the region. The region is dominated by Mesozoic-to-Cretaceous aged rocks which make up an uplifted subduction zone accretionary wedge called the Franciscan Complex. This unit is made up of sandstones, shales, cherts, metagraywackes, melanges, as well as mafic volcanics, the spatial distribution of heat flow in the vicinity of the MTJ is similar to what would be expected in a subduction environment. That is, heat flow is low above the subducting Gorda slab, south of the MTJ, heat flow through the California coast is higher, around 90 mW/m². The distance south of the MTJ over which heat flow increases gives an indication of the timing of development of the heat flow anomaly, the observed surface heat flow doubles over a distance of ~200 km, corresponding to a timeframe of migration of 4–5 Ma. It is also consistent with a source for the anomaly, thought to be asthenospheric mantle material, emplaced at depths of 15–25 km. This rise of the heat flow anomaly time implies that there is only a thin crustal lid above the slab window. The presence of hot asthenospheric mantle at shallow levels beneath the western margin of North America is likely to generate melt and cause magmatism. Accordingly, a sequence of volcanoes in the wake of the MTJ passing were activated, an example of volcanic bodies that formed by magma upwelling and solidification are the Nine Sisters, located between Morro Bay and San Luis Obispo in California. The source of the material flows into the slab window is a matter of debate, specifically whether it is derived directly from the underlying mantle. In general, mantle wedge-derived melts are relatively more hydrous, have lower viscosity, most of the seismicity near the MTJ is offshore, concentrated along the Mendocino Transform Fault. That having been said, seismicity is also distributed within the Gorda plate itself, owing to its size, young age. Motion along the Mendocino Transform Fault is right-lateral on E-W oriented, within the portion of North American crust overlying the Gorda slab, motion on faults is reverse, and in April 1992, a M =7.1 earthquake ruptured the southern portion of the Cascadia subduction zone
36.
Juan de Fuca plate
–
It is named after the explorer of the same name. One of the smallest of Earths tectonic plates, the Juan de Fuca Plate is a remnant part of the once-vast Farallon Plate, the Juan de Fuca plate system has its origins with Panthalassas oceanic basin and crust. This oceanic crust has primarily been subducted under the North American plate, Panthalassas oceanic plate remnants are understood to be the Juan de Fuca, Gorda, Cocos and the Nazca plates, all four of which were part of the Farallon Plate. The Juan de Fuca plate is bounded on the south by the Blanco Fracture Zone, on the north by the Nootka Fault and along the west by the Pacific Plate. The Juan de Fuca plate itself has since fractured into three pieces, and the name is applied to the plate in some references. The three fragments are differentiated as such, the piece to the south is known as the Gorda Plate, the separate pieces are demarcated by the large offsets of the undersea spreading zone. These in turn are part of the Pacific Ring of Fire, the last megathrust earthquake at the Cascadia subduction zone was the 1700 Cascadia earthquake, estimated to have a moment magnitude of 8.7 to 9.2. Based on carbon dating of tsunami deposits, it occurred around 1700. As reported in National Geographic on 8 December 2003, Japanese records indicate the quake caused a tsunami in Japan, in 2008, small earthquakes were observed within the plate. The unusual quakes were described as more than 600 quakes over the past 10 days in a basin 150 miles southwest of Newport. The quakes were unlike most quakes in that they did not follow the pattern of a quake, followed by smaller aftershocks, rather. Furthermore, they did not occur on the plate boundary. The subterranean quakes were heard on hydrophones, and scientists described the sounds as similar to thunder, the basaltic formations of this plate could potentially be suitable for long-term CO2 sequestration as part of a carbon capture and storage system. Injection of CO2 would lead to the formation of stable carbonates and it is estimated that 100 years of US carbon emissions could be stored securely, without risk of leakage back into the atmosphere. Geology of the Pacific Northwest Plate tectonics National Geographic on Japanese records verifying an American earthquake Cascadia tectonic history with map
37.
Oligocene
–
The Oligocene is a geologic epoch of the Paleogene Period and extends from about 33.9 million to 23 million years before the present. As with other geologic periods, the rock beds that define the epoch are well identified but the exact dates of the start. The name Oligocene comes from the Ancient Greek ὀλίγος and καινός, the Oligocene is preceded by the Eocene Epoch and is followed by the Miocene Epoch. The Oligocene is the third and final epoch of the Paleogene Period, the Oligocene is often considered an important time of transition, a link between the archaic world of the tropical Eocene and the more modern ecosystems of the Miocene. Major changes during the Oligocene included an expansion of grasslands. By contrast, the Oligocene–Miocene boundary is not set at an easily identified worldwide event, Oligocene faunal stages from youngest to oldest are, The Paleogene Period general temperature decline is interrupted by an Oligocene 7-million-year stepwise climate change. A deeper 8.2 °C,400, 000-year temperature depression leads the 2 °C, the stepwise climate change began 32.5 Ma and lasted through to 25.5 Ma, as depicted in the PaleoTemps chart. The Oligocene climate change was a increase in ice volume. The 7-million-year depression abruptly terminated within 1–2 million years of the La Garita Caldera eruption at 28–26 Ma, a deep 400, 000-year glaciated Oligocene Miocene boundary event is recorded at McMurdo Sound and King George Island. During this epoch, the continued to drift toward their present positions. Antarctica became more isolated and finally developed an ice cap, a brief marine incursion marks the early Oligocene in Europe. Marine fossils from the Oligocene are rare in North America, there appears to have been a land bridge in the early Oligocene between North America and Europe, since the faunas of the two regions are very similar. Sometime during the Oligocene, South America was finally detached from Antarctica and it also allowed the Antarctic Circumpolar Current to flow, rapidly cooling the Antarctic continent. Angiosperms continued their expansion throughout the world as tropical and sub-tropical forests were replaced by deciduous forests. Open plains and deserts became more common and grasses expanded from their habitat in the Eocene moving out into open tracts. However, even at the end of the period, grass was not quite enough for modern savannas. In North America, subtropical species dominated with cashews and lychee trees present, and temperate trees such as roses, beeches, the legumes spread, while sedges, bulrushes, and ferns continued their ascent. Even more open landscapes allowed animals to grow to larger sizes than they had earlier in the Paleocene epoch 30 million years earlier, marine faunas became fairly modern, as did terrestrial vertebrate fauna on the northern continents
38.
Farallon plate
–
The Farallon Plate was an ancient oceanic plate that began subducting under the west coast of the North American Plate—then located in modern Utah—as Pangaea broke apart during the Jurassic period. It is named for the Farallon Islands, which are located just west of San Francisco, over time, the central part of the Farallon Plate was completely subducted under the southwestern part of the North American Plate. These fragments from elsewhere are called terranes, much of western North America is composed of these accreted terranes. The understanding of the Farallon Plate is rapidly evolving as details from seismic tomography provide improved details of the submerged remnants, since the North American west coast shows a convoluted structure, significant work has been required to resolve the complexity. In 2013 a new and more nuanced explanation emerged, proposing two additional now-subducted plates which would account for some of the complexity. As data accumulated, a view developed that one large oceanic plate, the Farallon plate, acted as a conveyor belt, conveying terranes to North Americas west coast. As the continent overran the subducting Farallon plate, the plate became subducted into the mantle below the continent. When the plates converged, the oceanic plate sank into the mantle to form a slab below the lighter continent. However this simple model was unable to explain many terrane complexities, one such large slab wall runs from north-west Canada to the eastern U. S. and extends to Central America, this slab wall had traditionally been associated with the subducting Farallon plate. Sigloch and Mihalynuk proposed that the Farallon should be partitioned into Northern Farallon, Angayucham, Mezcalera, the overridden segment is replaced by an incipient South Farallon trench. 160–155 Myr ago the Rocky Mountain deformation begins, recorded by a synorogenic clastic wedge, the Franciscan subduction complex on the South Farallon plate begins. 125 Myr ago the collision of the North America margin with an archipelago of terranes begins and this broad expanse causes strong deformations and creates the Sevier Mountains and the Canadian Rocky Mountains. 124–90 Myr ago the Omenica magmatic belts are formed in the Pacific Northwest along with a gradual override of the Mezcalera promontory by the Pacific Northwest,85 Myr ago the South Farallon trench moves westward after accretion of the Shatsky Rise Conjugate plateau. Sonora volcanism results from the slab sinking, the Tarahumara ignimbrite province is formed. 85–55 Myr ago Strong transpressive coupling of Farallon plate to terranes produces the buoyant Shatsky Rise, the Laramide orogeny results from basement uplift more than 1,000 km inland. 72–69 Myr ago the Angayucham arc, is overridden by North America, northward shuffle of Insular terrane, Intermontane terrane, and Angayucham terranes along margin. 55–50 Myr ago saw the override of the Cascadia Root arc by the Pacific Northwest along with accretion of the Siletzia and Pacific Rim terranes
39.
North American plate
–
The North American Plate is a tectonic plate covering most of North America, Greenland, Cuba, the Bahamas, extreme northeastern Russia, and parts of Iceland and the Azores. It extends eastward to the Mid-Atlantic Ridge and westward to the Chersky Range in eastern Siberia, the plate includes both continental and oceanic crust. The interior of the continental landmass includes an extensive granitic core called a craton. Along most of the edges of this craton are fragments of material called terranes. It is thought that much of North America west of the Rocky Mountains is composed of such terranes, the parallel Septentrional and Enriquillo-Plantain Garden faults, which run through the island of Hispaniola and bound the Gonâve Microplate, are also a part of the boundary. On the northerly boundary is a continuation of the Mid-Atlantic ridge called the Gakkel Ridge, the rest of the boundary in the far northwestern part of the plate extends into Siberia. On its western edge, the Farallon Plate has been subducting under the North American Plate since the Jurassic Period, the Juan de Fuca, Explorer, Gorda, Rivera, Cocos and Nazca plates are remnants of the Farallon Plate. The boundary along the Gulf of California is complex and it is generally accepted that a piece of the North American Plate was broken off and transported north as the East Pacific Rise propagated northward, creating the Gulf of California. A few hotspots are thought to exist below the North American Plate, the most notable hotspots are the Yellowstone, Raton, and Anahim hotspots. The Yellowstone and Anahim hotspots are thought to have first arrived during the Miocene period and are still geologically active, for the most part, the North American Plate moves in roughly a southwest direction away from the Mid-Atlantic Ridge. One recent study suggests that a convective current is propelling the plate. Geologic timeline of Western North America New Madrid Seismic Zone - an ancient intraplate fault zone within the North American Plate, notable as early as 1699 Notes
40.
Southern Alps (New Zealand)
–
The Southern Alps are a mountain range extending along much of the length of New Zealands South Island, reaching its greatest elevations near the islands western side. The term Southern Alps generally refers to the range, although separate names are given to many of the smaller ranges that form part of it. The range includes the South Islands Main Divide, which separates the water catchments of the heavily populated eastern side of the island from those on the west coast. Politically, the Main Divide forms the boundary between the Canterbury and West Coast Regions, the Southern Alps run 500 km north to south. Their tallest peak is Aoraki / Mount Cook, the highest point in New Zealand at 3,724 metres, the mountains are cut through with glacial valleys and lakes. A chain of lakes are found on the eastern side of the ridge from Lake Coleridge in the north to Lake Wakatipu in Otago in the south. Settlements include Maruia Springs, a spa near Lewis Pass, the town of Arthurs Pass, the Southern Alps were named by Captain Cook on 23 March 1770, who described their prodigious height. They had previously noted by Abel Tasman in 1642, whose description of the South Islands west coast is often translated as a land uplifted high. The climate is cold with snow and ice year-round at the highest points, because of its orientation perpendicular to the prevailing westerly winds, the range creates excellent wave soaring conditions for glider pilots. The town of Omarama, in the lee of the mountains, has gained a reputation for its gliding conditions. The prevailing westerlies also create a pattern known as the Norwest arch, in which moist air is pushed up over the mountains. This weather pattern is visible in summer across Canterbury and North Otago. Over the last 45 million years, the collision has pushed up a 20 km thickness of rocks on the Pacific Plate to form the Alps, although much of this has been eroded away. Uplift has been most rapid during the last 5 million years, despite the substantial uplift, most of the relative motion along the Alpine Fault is transverse, not vertical. However, significant dip-slip occurs on the boundary to the north and east of the North Island, in the Hikurangi Trench. The mountains are rich in flora with about 25% of the plant species being found above the treeline in alpine plant habitats. The cold windswept slopes above the treeline are covered with areas of fellfield, to the east, the Alps descend to the high grasslands of Canterbury and Otago. Plants adapted to the alpine conditions include woody shrubs like Hebe, Dracophyllum, and Coprosma, wildlife of the mountains includes the endemic rock wren and the kea, a large parrot that was once hunted as a pest
41.
Alpine Fault
–
The Alpine Fault is a geological fault, specifically a right-lateral strike-slip fault, that runs almost the entire length of New Zealands South Island. It forms a boundary between the Pacific Plate and the Indo-Australian Plate. Earthquakes along the fault, and the earth movements, have formed the Southern Alps. The uplift to the southeast of the fault is due to an element of convergence between the plates, meaning that the fault has a significant high-angle reverse oblique component to its displacement. The Alpine Fault is believed to align with the Macquarie Fault Zone in the Puysegur Trench off the corner of the South Island. The Hope fault is thought to represent the continuation of the Alpine fault. Average slip rates in the central region are about 30mm a year. Over the last thousand years, there have four major ruptures along the Alpine Fault causing earthquakes of about magnitude 8. These had previously been determined to have occurred in approximately 1100,1430,1620 and 1717 CE, the 1717 quake appears to have involved a rupture along nearly 400 kilometres of the southern two thirds of the fault. Scientists say that an earthquake could happen at any time as the interval since 1717 is longer than between the earlier events. In addition, an earthquake was identified to have occurred between 887 and 965. GNS Science researchers have compiled an 8000-year timeline of 24 major quakes on the fault from sediments at Hokuri Creek, in earthquake terms, the 850 kilometres long fault is remarkably consistent, rupturing on average each 330 years, at intervals ranging from 140 years to 510 years. Large ruptures can also trigger earthquakes on the faults continuing north from the Alpine Fault, there is paleotsunami evidence of near-simultaneous ruptures of the Alpine fault and Wellington faults to the North having occurred at least twice in the past 1,000 years. – GNS Science Earthquakes and Tectonics in New Zealand – Nature & Company Limited The Next Alpine Fault Earthquake in New Zealand – GNS Science
42.
New Zealand
–
New Zealand /njuːˈziːlənd/ is an island nation in the southwestern Pacific Ocean. The country geographically comprises two main landmasses—the North Island, or Te Ika-a-Māui, and the South Island, or Te Waipounamu—and around 600 smaller islands. New Zealand is situated some 1,500 kilometres east of Australia across the Tasman Sea and roughly 1,000 kilometres south of the Pacific island areas of New Caledonia, Fiji, because of its remoteness, it was one of the last lands to be settled by humans. During its long period of isolation, New Zealand developed a distinct biodiversity of animal, fungal, the countrys varied topography and its sharp mountain peaks, such as the Southern Alps, owe much to the tectonic uplift of land and volcanic eruptions. New Zealands capital city is Wellington, while its most populous city is Auckland, sometime between 1250 and 1300 CE, Polynesians settled in the islands that later were named New Zealand and developed a distinctive Māori culture. In 1642, Dutch explorer Abel Tasman became the first European to sight New Zealand, in 1840, representatives of Britain and Māori chiefs signed the Treaty of Waitangi, which declared British sovereignty over the islands. In 1841, New Zealand became a colony within the British Empire, today, the majority of New Zealands population of 4.7 million is of European descent, the indigenous Māori are the largest minority, followed by Asians and Pacific Islanders. Reflecting this, New Zealands culture is derived from Māori and early British settlers. The official languages are English, Māori and New Zealand Sign Language, New Zealand is a developed country and ranks highly in international comparisons of national performance, such as health, education, economic freedom and quality of life. Since the 1980s, New Zealand has transformed from an agrarian, Queen Elizabeth II is the countrys head of state and is represented by a governor-general. In addition, New Zealand is organised into 11 regional councils and 67 territorial authorities for local government purposes, the Realm of New Zealand also includes Tokelau, the Cook Islands and Niue, and the Ross Dependency, which is New Zealands territorial claim in Antarctica. New Zealand is a member of the United Nations, Commonwealth of Nations, ANZUS, Organisation for Economic Co-operation and Development, Pacific Islands Forum, and Asia-Pacific Economic Cooperation. Dutch explorer Abel Tasman sighted New Zealand in 1642 and called it Staten Landt, in 1645, Dutch cartographers renamed the land Nova Zeelandia after the Dutch province of Zeeland. British explorer James Cook subsequently anglicised the name to New Zealand, Aotearoa is the current Māori name for New Zealand. It is unknown whether Māori had a name for the country before the arrival of Europeans. Māori had several names for the two main islands, including Te Ika-a-Māui for the North Island and Te Waipounamu or Te Waka o Aoraki for the South Island. Early European maps labelled the islands North, Middle and South, in 1830, maps began to use North and South to distinguish the two largest islands and by 1907, this was the accepted norm. The New Zealand Geographic Board discovered in 2009 that the names of the North Island and South Island had never been formalised and this set the names as North Island or Te Ika-a-Māui, and South Island or Te Waipounamu
43.
West Coast, New Zealand
–
The West Coast is a region of New Zealand on the west coast of the South Island, one of the more remote and most sparsely populated areas of the country. It is administered by the West Coast Regional Council, at the territorial authority level, the region comprises Buller District, Grey District and Westland District. The principal towns are Westport, Greymouth, and Hokitika, fiordland is on the west coast, but is in the Southland Region rather than the West Coast Region. Inhabitants of the West Coast are colloquially known as Coasters, the region reaches from Kahurangi Point in the north to Awarua Point in the south, a distance of 600 km. To the west is the Tasman Sea, and to the east are the Southern Alps, much of the land is rugged, with a coastal plain where much of the population resides. The land is very scenic, with wild coastlines, mountains, scenic areas include the Haast Pass, Fox and Franz Josef Glaciers, the Pancake Rocks at Punakaiki and the Heaphy Track. The region has a high rainfall due to the prevailing northwesterly wind pattern and the location of the Southern Alps. The rain shadow effect is responsible for the arid climate of the Canterbury Plains on the other side of the Southern Alps. The regions area is 23,276 km2 and it is divided into the three districts of Buller, Grey and Westland. Industries on the West Coast include mining for coal and alluvial gold, forestry and wood processing, dairy farming has grown strongly - the local dairy co-operatives Westland Milk Products remained independent when most others merged to form Fonterra in 2001. Other industries are the manufacturing and sales of greenstone jewellery, sphagnum moss gathering, the sub-national GDP of the region was estimated at US$779 million in 2003, 1% of national GDP. The region is home to Māori, who valued it for the greenstone found there in abundance, the region was only occasionally visited by Europeans until the discovery of gold near the Taramakau River in 1864 by two Māori, Ihaia Tainui and Haimona Taukau. By the end of the year there were an estimated 1800 prospectors, many of them around the Hokitika area, after that time, the population dwindled, but the main towns that still exist had become established. Following greenstone and gold, the valuable mineral was coal. Discovered near the Buller River in the mid-1840s, mining began in earnest during the 1860s, by the 1880s coal had become the region’s main industry, with mines throughout the northern half of the region, especially around Westport. Many of these continued in operation until the mid-20th century, timber has also long been a major industry, although in recent years there has been an uneasy balance between forestry for wood and forestry for conservation. Much of the region is public land administered by the Department of Conservation, ecotourism is now an important industry, and this goes hand in hand with the conservation efforts. The region is populated, especially in the south, with the 2006 census recording 31,326 inhabitants, up from 30,303 in 2001
44.
Middle East
–
The Middle East is a transcontinental region centered on Western Asia and Egypt. The corresponding adjective is Middle-Eastern and the noun is Middle-Easterner. The term has come into usage as a replacement of the term Near East beginning in the early 20th century. Arabs, Turks, Persians, Kurds, and Azeris constitute the largest ethnic groups in the region by population. Indigenous minorities of the Middle East include Jews, Assyrians and other Arameans, Baloch, Berbers, Copts, Druze, Lurs, Mandaeans, Samaritans, Shabaks, Tats, in the Middle East, there is also a Romani community. European ethnic groups form a diaspora in the region include Albanians, Bosniaks, Circassians, Crimean Tatars, Franco-Levantines. Among other migrant populations are Bengalis as well as other Indians, Chinese, Filipinos, Indonesians, Pakistanis, the history of the Middle East dates back to ancient times, with the importance of the region being recognized for millennia. Most of the countries border the Persian Gulf have vast reserves of crude oil. The term Middle East may have originated in the 1850s in the British India Office, however, it became more widely known when American naval strategist Alfred Thayer Mahan used the term in 1902 to designate the area between Arabia and India. During this time the British and Russian Empires were vying for influence in Central Asia, Mahan realized not only the strategic importance of the region, but also of its center, the Persian Gulf. Mahan first used the term in his article The Persian Gulf and International Relations, published in September 1902 in the National Review, a British journal. The Middle East, if I may adopt a term which I have not seen, will some day need its Malta, as well as its Gibraltar, it does not follow that either will be in the Persian Gulf. The British Navy should have the facility to concentrate in force if occasion arise, about Aden, India, mahans article was reprinted in The Times and followed in October by a 20-article series entitled The Middle Eastern Question, written by Sir Ignatius Valentine Chirol. During this series, Sir Ignatius expanded the definition of Middle East to include regions of Asia which extend to the borders of India or command the approaches to India. After the series ended in 1903, The Times removed quotation marks from subsequent uses of the term, in the late 1930s, the British established the Middle East Command, which was based in Cairo, for its military forces in the region. After that time, the term Middle East gained broader usage in Europe, the description Middle has also led to some confusion over changing definitions. Before the First World War, Near East was used in English to refer to the Balkans and the Ottoman Empire, while Middle East referred to Iran, the Caucasus, Afghanistan, Central Asia, and Turkestan. The first official use of the term Middle East by the United States government was in the 1957 Eisenhower Doctrine, the Associated Press Stylebook says that Near East formerly referred to the farther west countries while Middle East referred to the eastern ones, but that now they are synonymous
45.
Dead Sea Transform
–
The Dead Sea Transform fault system, also sometimes referred to as the Dead Sea Rift, is a series of faults that run from the Maras Triple Junction to the northern end of the Red Sea Rift. The fault system forms the boundary between the African Plate to the west and the Arabian Plate to the east. It is a zone of left lateral displacement, signifying the relative motions of the two plates, both plates are moving in a general north-northeast direction, but the Arabian Plate is moving faster, resulting in the observed left lateral motions along the fault of approximately 107 km. The DST fault system is considered to be a transform fault that has accommodated a 105 km northwards displacement of the Arabian Plate. GPS data give similar rates of movement of the Arabian Plate relative to the Africa Plate. It has also proposed that the fault zone is a rift system that is an incipient oceanic spreading center. The Dead Sea Transform began to form during the early to mid-Miocene, a total displacement of 64 km has been estimated for this early phase of motion. In the Pliocene the DST propagated northwards once more through Lebanon into northwestern Syria before reaching the East Anatolian Fault. The southern section of the DST is about 400 km long, extending from the center in the Red Sea at southern end of the Gulf of Aqaba to just north of the Hula basin in southernmost Lebanon. The Gulf of Aqaba was created by movement on four left-stepping strike-slip fault segments in a diagonal stepwise sequence known as echelon formation. In the areas where these segments overlap, pull-apart basins have developed, parts of three of these faults ruptured during the 1995 Gulf of Aqaba earthquake. The Wadi Arabah segment of the DST extends for about 160 km from the Gulf of Aqaba to the end of the Dead Sea. Some researchers have further broken down this segment, recognising two separate segments, Avrona and Arava, the Avrona fault extends from the northern part of the Gulf of Aqaba for about 50 km along the Arava Valley. The Arava fault runs from just north of the Avrona fault segment for about 100 km, a slip rate of 4 ±2 mm per year has been estimated from the offset of gullies across the fault. Four major earthquakes are thought to have occurred due to movement on this fault in the last 1,000 years, the Dead Sea is formed in a pull-apart basin due to the left-stepping offset between the Wadi Arabah and Jordan Valley segments. The part of the basin with a fill of more than 2 km is 150 km long. In the north, the fill reaches its maximum thickness of about 10 km. The Jordan valley segment of the DST, the Jordan Rift Valley, a slip rate of between 4.7 and 5.1 mm per year has been estimated over the last 47,500 years
46.
Turkey
–
Turkey, officially the Republic of Turkey, is a transcontinental country in Eurasia, mainly in Anatolia in Western Asia, with a smaller portion on the Balkan peninsula in Southeast Europe. Turkey is a democratic, secular, unitary, parliamentary republic with a cultural heritage. The country is encircled by seas on three sides, the Aegean Sea is to the west, the Black Sea to the north, and the Mediterranean Sea to the south. The Bosphorus, the Sea of Marmara, and the Dardanelles, Ankara is the capital while Istanbul is the countrys largest city and main cultural and commercial centre. Approximately 70-80% of the countrys citizens identify themselves as ethnic Turks, other ethnic groups include legally recognised and unrecognised minorities. Kurds are the largest ethnic minority group, making up approximately 20% of the population, the area of Turkey has been inhabited since the Paleolithic by various ancient Anatolian civilisations, as well as Assyrians, Greeks, Thracians, Phrygians, Urartians and Armenians. After Alexander the Greats conquest, the area was Hellenized, a process continued under the Roman Empire. The Seljuk Sultanate of Rûm ruled Anatolia until the Mongol invasion in 1243, the empire reached the peak of its power in the 16th century, especially during the reign of Suleiman the Magnificent. During the war, the Ottoman government committed genocides against its Armenian, Assyrian, following the war, the conglomeration of territories and peoples that formerly comprised the Ottoman Empire was partitioned into several new states. Turkey is a member of the UN, an early member of NATO. Turkeys growing economy and diplomatic initiatives have led to its recognition as a regional power while her location has given it geopolitical, the name of Turkey is based on the ethnonym Türk. The first recorded use of the term Türk or Türük as an autonym is contained in the Old Turkic inscriptions of the Göktürks of Central Asia, the English name Turkey first appeared in the late 14th century and is derived from Medieval Latin Turchia. Similarly, the medieval Khazar Empire, a Turkic state on the shores of the Black. The medieval Arabs referred to the Mamluk Sultanate as al-Dawla al-Turkiyya, the Ottoman Empire was sometimes referred to as Turkey or the Turkish Empire among its European contemporaries. The Anatolian peninsula, comprising most of modern Turkey, is one of the oldest permanently settled regions in the world, various ancient Anatolian populations have lived in Anatolia, from at least the Neolithic period until the Hellenistic period. Many of these peoples spoke the Anatolian languages, a branch of the larger Indo-European language family, in fact, given the antiquity of the Indo-European Hittite and Luwian languages, some scholars have proposed Anatolia as the hypothetical centre from which the Indo-European languages radiated. The European part of Turkey, called Eastern Thrace, has also been inhabited since at least forty years ago. It is the largest and best-preserved Neolithic site found to date, the settlement of Troy started in the Neolithic Age and continued into the Iron Age
47.
North Anatolian Fault
–
The North Anatolian Fault is an active right-lateral strike-slip fault in northern Anatolia which runs along the transform boundary between the Eurasian Plate and the Anatolian Plate. It runs about 20 km south of Istanbul, the North Anatolian Fault is similar in many ways to the San Andreas Fault in California. Both are continental transforms with similar lengths and slip rates, the Sea of Marmara near Istanbul is an extensional basin similar to the Salton Trough in California, where a releasing bend in the strike-slip system creates a pull-apart basin. Since the disastrous 1939 Erzincan earthquake, there have been seven earthquakes measuring over 7.0 in magnitude, seismologists studying this pattern believe that each earthquake may trigger the next. By analyzing the stresses along the fault caused by each large earthquake and it is thought that the chain is not complete, and that an earthquake will soon strike further west along the fault – perhaps near the heavily populated city of Istanbul
