1. Crust (geology) – In geology, the crust is the outermost solid shell of a rocky planet or natural satellite, which is chemically distinct from the underlying mantle. The crust of the Earth is composed of a variety of igneous, metamorphic. The crust is underlain by the mantle, the upper part of the mantle is composed mostly of peridotite, a rock denser than rocks common in the overlying crust. The boundary between the crust and mantle is conventionally placed at the Mohorovičić discontinuity, a boundary defined by a contrast in seismic velocity, the crust occupies less than 1% of Earths volume. The crust of the Earth is of two types, oceanic and continental. The oceanic crust is 5 km to 10 km thick and is composed primarily of basalt, diabase, the continental crust is typically from 30 km to 50 km thick and is mostly composed of slightly less dense rocks than those of the oceanic crust. Some of these less dense rocks, such as granite, are common in the continental crust, both the continental and oceanic crust float on the mantle. Because the continental crust is thicker, it both to greater elevations and greater depth than the oceanic crust. The slightly lower density of continental rock compared to basaltic oceanic rock contributes to the higher relative elevation of the top of the continental crust. As the top of the continental crust reaches elevations higher than that of the oceanic, the temperature of the crust increases with depth, reaching values typically in the range from about 200 °C to 400 °C at the boundary with the underlying mantle. The crust and underlying relatively rigid uppermost mantle make up the lithosphere, because of convection in the underlying plastic upper mantle and asthenosphere, the lithosphere is broken into tectonic plates that move. The temperature increases by as much as 30 °C for every kilometer locally in the part of the crust. Earth has probably always had some form of basaltic crust, in contrast, the bulk of the continental crust is much older. The oldest continental crustal rocks on Earth have ages in the range from about 3.7 to 4, some zircon with age as great as 4.3 billion years has been found in the Narryer Gneiss Terrane. The average age of the current Earths continental crust has been estimated to be about 2.0 billion years, most crustal rocks formed before 2.5 billion years ago are located in cratons. Such old continental crust and the underlying mantle asthenosphere are less dense than elsewhere in Earth, formation of new continental crust is linked to periods of intense orogeny, these periods coincide with the formation of the supercontinents such as Rodinia, Pangaea and Gondwana. The continental crust has a composition similar to that of andesite. The most abundant minerals in Earths continental crust are feldspars, which make up about 41% of the crust by weight, followed by quartz at 12%, Continental crust is enriched in incompatible elements compared to the basaltic ocean crust and much enriched compared to the underlying mantleCrust (geology) – Shield
2. Explosive eruption – An explosive eruption is a volcanic term to describe a violent, explosive type of eruption. Mount St. Helens in 1980 was an example, such eruptions result when sufficient gas has dissolved under pressure within a viscous magma such that expelled lava violently froths into volcanic ash when pressure is suddenly lowered at the vent. Sometimes a lava plug will block the conduit to the summit, Explosive eruptions can send rocks, dust, gas and pyroclastic material up to 20 km into the atmosphere at rate of up to 100,000 tonnes per second, traveling at several hundred meters per second. This cloud will collapse, creating a pyroclastic flow of hot volcanic matter. An explosive eruption always begins with some form of blockage in the crater of a volcano that prevents the release of trapped in highly viscous andesitic or rhyolitic magma. The high viscosity of these forms of magma prevents the release of trapped gases, when this type of magma flows towards the surface pressure builds, eventually causing the blockage to be blasted out in an explosive eruption. The pressure from the magma and gases are released through the weakest point in the cone, however, in the case of the eruption of Mount St. Helens, pressure was released through the side of the volcano, rather than the crater. The size and duration of the column depends on the volume of magma being released, the eruption column of ash is supported by pressure from the gases being released, and as the gases are depleted, pressure falls and the eruption column begins to collapse. When the column collapses in on itself, ash and rock fall back down to the ground and these flows can travel at up to 80 km per hour, and reach temperatures of 200° to 700° Celsius. The high temperatures can cause combustion of any flammable materials in its path, including wood, vegetation, when snow and ice melt as a part of an eruption, large amounts of water mixed in with the flow can create lahars. The risk of lahars is particularly high on volcanoes such as Mount Rainier near Seattle and Tacoma, the eruption of supervolcanoes is the rarest of volcanic eruptions but also the most destructive. The timescale between these eruptions is generally marked by hundreds or thousands of years and this type of eruption generally causes destruction on a continental scale, and can also result in the lowering of temperatures worldwide. Effusive eruption Volcanic explosivity index Recent Developments in Explosive VolcanismExplosive eruption – Mount Saint Helens explosive eruption on July 22, 1980
3. Volcanic crater – A volcanic crater is a roughly circular depression in the ground caused by volcanic activity. It is typically a bowl-shaped feature within which occurs a vent or vents, a volcanic crater can be of large dimensions, and sometimes of great depth. During certain types of eruptions, a volcanos magma chamber may empty enough for an area above it to subside. In most volcanoes, the crater is situated at the top of a formed from the erupted volcanic deposits such as lava flows. Volcanoes that terminate in such a summit crater are usually of a conical form, other volcanic craters may be found on the flanks of volcanoes, and these are commonly referred to as flank craters. Some volcanic craters may fill either fully or partially with rain and/or melted snow, a crater may be breached during an eruption, either by explosions or by lava, or through later erosion. Breached craters have a lower rim on one side. Some volcanoes, such as maars, consist of a crater alone and these volcanic explosion craters are formed when magma rises through water-saturated rocks and causes a phreatic eruption. Volcanic craters from phreatic eruptions often occur on plains away from other obvious volcanoesVolcanic crater – Craters on Mount Cameroon
4. Caldera – A caldera is a large cauldron-like depression that forms following the evacuation of a magma chamber/reservoir. When large volumes of magma are erupted over a time period. The ground surface then collapses downward into the emptied magma chamber. Although sometimes described as a crater, the feature is actually a type of sinkhole, as it is formed through subsidence, only seven known caldera-forming collapses have occurred since the start of the 20th century, most recently at Bárðarbunga volcano in Iceland. The word comes from Spanish caldera, and this from Latin caldaria, in some texts the English term cauldron is also used. If enough magma is ejected, the chamber is unable to support the weight of the volcanic edifice above it. A roughly circular fracture, the fault, develops around the edge of the chamber. Ring fractures serve as feeders for fault intrusions which are known as ring dykes. Secondary volcanic vents may form above the ring fracture, as the magma chamber empties, the center of the volcano within the ring fracture begins to collapse. The collapse may occur as the result of a cataclysmic eruption. The total area that collapses may be hundreds or thousands of square kilometers, some calderas are known to host rich ore deposits. One of the worlds best-preserved mineralized calderas is the Sturgeon Lake Caldera in northwestern Ontario, Canada, if the magma is rich in silica, the caldera is often filled in with ignimbrite, tuff, rhyolite, and other igneous rocks. Silica-rich magma has a high viscosity, and therefore does not flow easily like basalt, as a result, gases tend to become trapped at high pressure within the magma. Further lava flows may be erupted, if volcanic activity continues, the center of the caldera may be uplifted in the form of a resurgent dome such as is seen at Cerro Galán, Lake Toba, Yellowstone, etc. by subsequent intrusion of magma. A silicic or rhyolitic caldera may erupt hundreds or even thousands of kilometers of material in a single event. Even small caldera-forming eruptions, such as Krakatoa in 1883 or Mount Pinatubo in 1991, may result in significant local destruction, large calderas may have even greater effects. When Yellowstone Caldera last erupted some 650,000 years ago, it released about 1,000 km3 of material, by comparison, when Mount St. Helens erupted in 1980, it released ~1.2 km3 of ejecta. The ecological effects of the eruption of a large caldera can be seen in the record of the Lake Toba eruption in Indonesia, more recently several geneticists, including Lynn Jorde and Henry Harpending have proposed that the human species was reduced to approximately five to ten thousand peopleCaldera – Landsat image of Lake Toba, on the island of Sumatra, Indonesia. A resurgent dome formed the island of Samosir. (100 km/62 mi long and 30 km/19 mi wide, a caldera of the world's largest class)
5. Volcanic ash – Volcanic ash consists of fragments of pulverized rock, minerals and volcanic glass, created during volcanic eruptions and measuring less than 2 mm in diameter. The term volcanic ash is often loosely used to refer to all explosive eruption products. Volcanic ash is formed during volcanic eruptions when dissolved gases in magma expand. The force of the escaping gas shatters the magma and propels it into the atmosphere where it solidifies into fragments of volcanic rock and glass. Ash is also produced when magma comes into contact with water during phreatomagmatic eruptions, once in the air, ash is transported by wind up to thousands of kilometers away. Volcanic ash is formed during volcanic eruptions, phreatomagmatic eruptions. Explosive eruptions occur when magma decompresses as it rises, allowing dissolved volatiles to exsolve into gas bubbles, as more bubbles nucleate a foam is produced, which decreases the density of the magma, accelerating it up the conduit. Fragmentation occurs when bubbles occupy ~70-80 vol% of the erupting mixture, when fragmentation occurs, violently expanding bubbles tear the magma apart into fragments which are ejected into the atmosphere where they solidify into ash particles. Fragmentation is an efficient process of ash formation and is capable of generating very fine ash even without the addition of water. Volcanic ash is produced during phreatomagmatic eruptions. During these eruptions fragmentation occurs when magma comes into contact with bodies of water groundwater, as the magma, which is significantly hotter than the boiling point of water, comes into contact with water an insulating vapor film forms. Eventually this vapor film will collapse leading to direct coupling of the cold water and this increases the heat transfer which leads to the rapid expansion of water and fragmentation of the magma into small particles which are subsequently ejected from the volcanic vent. Fragmentation causes an increase in area between magma and water creating a feedback mechanism, leading to further fragmentation and production of fine ash particles. Pyroclastic density currents can also produce ash particles and these are typically produced by lava dome collapse or collapse of the eruption column. Within pyroclastic density currents particle abrasion occurs as particles interact with each resulting in a reduction in grain size. In addition, ash can be produced during secondary fragmentation of pumice fragments and these processes produce large quantities of very fine grained ash which is removed from pyroclastic density currents in co-ignimbrite ash plumes. Physical and chemical characteristics of volcanic ash are primarily controlled by the style of volcanic eruption, another parameter controlling the amount of ash produced is the duration of the eruption, the longer the eruption is sustained, the more ash will be produced. The types of minerals present in volcanic ash are dependent on the chemistry of the magma from which it erupted, low energy eruptions of basalt produce a characteristically dark coloured ash containing ~45 - 55% silica that is generally rich in iron and magnesiumVolcanic ash – Ash cloud from the 2008 eruption of Chaitén volcano, Chile, stretching across Patagonia from the Pacific to the Atlantic Ocean.
6. Lava – Lava is the molten rock expelled by a volcano during an eruption. The resulting rock after solidification and cooling is called lava. The molten rock is formed in the interior of planets, including Earth. The source of the heat melts the rock within the earth is geothermal energy. When first erupted from a vent, lava is a liquid usually at temperatures from 700 to 1,200 °C. A lava flow is an outpouring of lava, which is created during a non-explosive effusive eruption. When it has stopped moving, lava solidifies to form igneous rock, the term lava flow is commonly shortened to lava. Although lava can be up to 100,000 times more viscous than water, lava can flow great distances before cooling and solidifying because of its thixotropic, explosive eruptions produce a mixture of volcanic ash and other fragments called tephra, rather than lava flows. The word lava comes from Italian, and is derived from the Latin word labes which means a fall or slide. The first use in connection with extruded magma was apparently in an account written by Francesco Serao on the eruption of Vesuvius between May 14 and June 4,1737. Serao described a flow of lava as an analogy to the flow of water. The composition of almost all lava of the Earths crust is dominated by silicate minerals, mostly feldspars, olivine, pyroxenes, amphiboles, micas, igneous rocks, which form lava flows when erupted, can be classified into three chemical types, felsic, intermediate, and mafic. These classes are primarily chemical, however, the chemistry of lava also tends to correlate with the temperature, its viscosity. Felsic or silicic lavas such as rhyolite and dacite typically form lava spines, most silicic lava flows are extremely viscous, and typically fragment as they extrude, producing blocky autobreccias. Felsic magmas can erupt at temperatures as low as 650 to 750 °C, unusually hot rhyolite lavas, however, may flow for distances of many tens of kilometres, such as in the Snake River Plain of the northwestern United States. Intermediate or andesitic lavas are lower in aluminium and silica, and usually somewhat richer in magnesium, intermediate lavas form andesite domes and block lavas, and may occur on steep composite volcanoes, such as in the Andes. Poorer in aluminium and silica than felsic lavas, and also commonly hotter, greater temperatures tend to destroy polymerized bonds within the magma, promoting more fluid behaviour and also a greater tendency to form phenocrysts. Higher iron and magnesium tends to manifest as a darker groundmass, mafic or basaltic lavas are typified by their high ferromagnesian content, and generally erupt at temperatures in excess of 950 °CLava – 10-metre (33 ft) high fountain of pāhoehoe lava, Hawaii, United States
7. Effusive eruption – An effusive eruption is a type of volcanic eruption in which lava steadily flows out of a volcano onto the ground. Effusive eruption differs from explosive eruption, wherein magma is violently fragmented when expelled from a volcano, the shape of the lava flows created by effusive eruptions is governed by the type of lava, rate and duration of eruption, and slope of the surrounding areas. A volcanic eruption is effusive when low-viscosity magma, usually basaltic in composition, is released from the Earths crust, in an effusive eruption, gas escapes the magma as it erupts and forms lava that flows downhill continuously. This type of flow can build shield volcanoes, which are numerous in Hawaii. Eruptions of basaltic magma often transition between effusive and explosive eruption patterns, the behavior of these eruptions is largely dependent on the permeability of the magma and the magma ascent rate. For an effusive eruption to occur, magma must be enough to allow the expulsion of gas bubbles contained within it. If the magma is not above a certain permeability threshold, it cannot degas, additionally, at a certain threshold, fragmentation within the magma can cause an explosive eruption. This threshold is governed by the Reynolds Number, a number in fluid dynamics that is directly proportional to fluid velocity. Eruptions will be if the magma has a low ascent velocity. At higher magma ascent rates, the fragmentation within the magma passes a threshold, silicic magma also exhibits this transition between effusive and explosive eruptions, but the fragmentation mechanism differs. The 1912 Novarupta eruption and the 2003 Stromboli eruption both exhibited a transition between explosive and effusive eruption patterns, effusive basalt lava flows cool to either of two forms, ʻaʻā or pāhoehoe. Andesite lava typically forms blocky lava flows, dacite lava flows often form steep-sided mounds, called lava domes, due to their greater viscosityEffusive eruption – An ʻaʻā lava flow from Mauna Loa during its 1984 eruption.
8. Volcanic cone – Volcanic cones are among the simplest volcanic landforms. They are built by ejecta from a vent, piling up around the vent in the shape of a cone with a central crater. Volcanic cones are of different types, depending upon the nature, types of volcanic cones include stratocones, spatter cones, tuff cones, and cinder cones. Stratocones are large cone-shaped volcanoes made up of lava flows, explosively erupted pyroclastic rocks, unlike shield volcanoes, they are characterized by a steep profile and periodic, often alternating, explosive eruptions and effusive eruptions. Some have collapsed craters called calderas, the central core of a stratocone is commonly dominated by a central core of intrusive rocks that range from around 500 meters to over several kilometers in diameter. This central core is surrounded by generations of lava flows, many of which are brecciated. The typical stratocone is an andesitic to dacitic volcano that is associated with subduction zones and they are also known as either stratified volcano, composite cone, bedded volcano, cone of mixed type or Vesuvian-type volcano. A spatter cone is a low, steep-sided hill or mound that consists of welded lava fragments, called spatter, typically, spatter cones are about 3–5 meters high. In case of a fissure, lava fountaining will create broad embankments of spatter, called spatter ramparts. Spatter cones are circular and cone shaped, while spatter ramparts are linear wall-like features. Spatter cones and spatter ramparts are typically formed by lava fountaining associated with mafic, highly fluid lavas, as blobs of molten lava, spatter, are erupted into the air by a lava fountain, they can lack the time needed to cool completely before hitting the ground. Consequently, the spatter are not fully solid, like taffy, as they land, as a result, the spatter builds up a cone that is composed of spatter either agglutinated or welded to each other. They are characterized by rims that have a maximum relief of 100–800 meters above the crater floor. They typically have a rim to rim diameter of 300–5,000 meters, a tuff cone consists typically of thick-bedded pyroclastic flow and surge deposits created by eruption-fed density currents and bomb-scoria beds derived from fallout from its eruption column. The tuffs composing a tuff cone have commonly been altered, palagonitized, by either its interaction with groundwater or when it was deposited warm and wet. The pyroclastic deposits of tuff cones differ from the deposits of spatter cones by their lack or paucity of lava spatter, smaller grain-size. Typically, but not always, tuff cones lack associated lava flows and they are characterized by rims that have a low, broad topograhic profiles and gentle topographic slopes that are 25 degrees or less. The maximum thickness of the pyroclastic debris comprising the rim of a tuff ring is generally thinVolcanic cone – Mayon Volcano in the Philippines has a symmetrical volcanic cone
9. Tectonic plates – 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 coolsTectonic plates – Remnants of the Farallon Plate, deep in Earth's mantle. It is thought that much of the plate initially went under North America (particularly the western United States and southwest Canada) at a very shallow angle, creating much of the mountainous terrain in the area (particularly the southern Rocky Mountains).
10. 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 itMid-oceanic ridge – Mid-oceanic ridge, including a black smoker
11. Mid-Atlantic Ridge – In the North Atlantic, it separates the Eurasian and North American Plates, whereas in the South Atlantic it separates the African and South American Plates. The ridge extends from a junction with the Gakkel Ridge northeast of Greenland southward to the Bouvet Triple Junction in the South Atlantic, although the Mid-Atlantic Ridge is mostly an underwater feature, portions of it have enough elevation to extend above sea level. The section of the ridge that includes the island of Iceland is also known as the Reykjanes Ridge, the ridge has an average spreading rate of about 2.5 cm per year. A ridge under the Atlantic Ocean was first inferred by Matthew Fontaine Maury in 1850, the ridge was discovered during the expedition of HMS Challenger in 1872. A team of scientists on board, led by Charles Wyville Thomson, the existence of such a ridge was confirmed by sonar in 1925 and was found to extend around the Cape of Good Hope into the Indian Ocean by the German Meteor expedition. Ewing, Heezen and Tharp discovered that the ridge is part of a 40, the ridge is central to the breakup of the hypothetical supercontinent of Pangaea that began some 180 million years ago. The Mid-Atlantic Ridge includes a deep valley that runs along the axis of the ridge along nearly its entire length. This rift marks the boundary between adjacent tectonic plates, where magma from the mantle reaches the seafloor, erupting as lava. This trench, however, is not regarded as the boundary between the North and South American Plates, nor the Eurasian and African Plates and this bulge is thought to be caused by upward convective forces in the asthenosphere pushing the oceanic crust and lithosphere. This divergent boundary first formed in the Triassic period, when a series of three-armed grabens coalesced on the supercontinent Pangaea to form the ridge, usually, only two arms of any given three-armed graben become part of a divergent plate boundary. The failed arms are called aulacogens, and the aulacogens of the Mid-Atlantic Ridge eventually became many of the river valleys seen along the Americas. The Fundy Basin on the Atlantic coast of North America between New Brunswick and Nova Scotia in Canada is evidence of the ancestral Mid-Atlantic Ridge, atlantis Massif Central Atlantic Magmatic Province Fifteen-Twenty Fracture Zone Evans, Rachel. Plumbing Depths to Reach New Heights, Marie Tharp Explains Marine Geological Maps, the Library of Congress Information Bulletin. MAR-ECO, a Census of Marine Life project on life along the Mid-Atlantic RidgeMid-Atlantic Ridge – A fissure of the ridge in the Þingvellir National Park, Iceland
12. 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 reversalsDivergent boundary – Bridge across the Álfagjá rift valley in southwest Iceland, that is part of the boundary between the Eurasian and North American continental tectonic plates.
13. Pacific Ring of Fire – The Ring of Fire is a major area in the basin of the Pacific Ocean where a large number of earthquakes and volcanic eruptions occur. In a 40,000 km horseshoe shape, it is associated with a continuous series of oceanic trenches, volcanic arcs. The Ring of Fire is sometimes called the circum-Pacific belt, about 90% of the worlds earthquakes and 81% of the worlds largest earthquakes occur along the Ring of Fire. The next most seismically active region is the Alpide belt, which extends from Java to the northern Atlantic Ocean via the Himalayas, all but three of the worlds 25 largest volcanic eruptions of the last 11,700 years occurred at volcanoes in the Ring of Fire. The Ring of Fire is a result of plate tectonics. The eastern section of the ring is the result of the Nazca Plate, the Cocos Plate is being subducted beneath the Caribbean Plate, in Central America. A portion of the Pacific Plate and the small Juan de Fuca Plate are being subducted beneath the North American Plate, along the northern portion, the northwestward-moving Pacific plate is being subducted beneath the Aleutian Islands arc. Farther west, the Pacific plate is being subducted along the Kamchatka Peninsula arcs on south past Japan. Indonesia lies between the Ring of Fire along the islands adjacent to and including New Guinea and the Alpide belt along the south and west from Sumatra, Java, Bali, Flores. The famous and very active San Andreas Fault zone of California is a fault which offsets a portion of the East Pacific Rise under southwestern United States. The motion of the fault generates numerous small earthquakes, at times a day. Bolivia hosts numerous active and extinct volcanoes across its territory, the active volcanoes are located in western Bolivia where they make up the Cordillera Occidental, the western limit of the Altiplano plateau. Many of the volcanoes are international mountains shared with Chile. The Central Volcanic Zone is a major upper Cenozoic volcanic province, apart from Andean volcanoes, the geology of Bolivia hosts the remnants of ancient volcanoes around the Precambrian Guaporé Shield in the eastern part of the country. The volcanoes in Chile are monitored by the National Geology and Mining Service Earthquake activity in Chile is related to subduction of the Nazca Plate to the east, Chile notably holds the record for the largest earthquake ever recorded, the 1960 Valdivia earthquake. Villarrica, one of Chiles most active volcanoes, rises above Villarrica Lake and it is the westernmost of three large stratovolcanoes that trend perpendicular to the Andean chain. A 6-km-wide caldera formed during the late Pleistocene, more than 0.9 million years ago, a 2-km-wide postglacial caldera is located at the base of the presently active, dominantly basaltic-to-andesitic cone at the northwest margin of the Pleistocene caldera. About 25 scoria cones dot Villaricas flanks, lahars from the glacier-covered volcanoes have damaged towns on its flanksPacific Ring of Fire – Llaima 's 2008 eruption
14. Convergent boundary – As a result of pressure, friction, and plate material melting in the mantle, earthquakes and volcanoes are common near convergent boundaries. When two plates move towards one another, they form either a subduction zone or a continental collision and this depends on the nature of the plates involved. In a subduction zone, the plate, which is normally a plate with oceanic crust, moves beneath the other plate. During collisions between two plates, large mountain ranges, such as the Himalayas are formed. The nature of a convergent boundary depends on the type of plates that are colliding, at an oceanic-continental convergent boundary, the oceanic lithosphere will always subduct below the continental lithosphere. This is caused by the density difference between the oceanic and continental lithosphere. This type of boundary is called a subduction zone. At the surface, the expression is commonly an oceanic trench which forms on the oceanic side. On the continental side, a chain of volcanoes forms above the location of the subducting plate, an example of a continental-oceanic subduction zone is the area along the western coast of South America where the oceanic Nazca Plate is being subducted beneath the continental South American Plate. A volcanic arc is formed on the plate, above the location of the downgoing oceanic slab. The volcanic arc is the expression of the magma that is generated by hydrous melting of the mantle above the downgoing slab. The buoyant fluids then rise into the asthenosphere, where they lower the temperature of the mantle. Either action will create extensive mountain ranges and it may have also pushed nearby parts of the Asian continent aside to the east. When two plates with oceanic crust converge, they create an island arc as one plate is subducted below the other. The arc is formed from volcanoes which erupt through the plate as the descending plate melts below it. The arc shape occurs because of the surface of the earth. A deep oceanic trench is located in front of such arcs where the descending slab dips downward, plates may collide at an oblique angle rather than head-on to each other, and this may cause strike-slip faulting along the collision zone, in addition to subduction or compression. Not all plate boundaries are easily defined, some are broad belts whose movements are unclear to scientistsConvergent boundary – Oceanic-continental.
15. Transform boundary – A transform fault or transform boundary, is a type of fault whose relative motion is predominantly horizontal, in either a sinistral or dextral direction. Furthermore, transform faults end abruptly and are connected on both ends to other faults, ridges, or subduction zones, Transform faults are the only type of strike-slip fault that can be classified as a plate boundary. The new class of faults, called transform faults, produce slip in the direction from what one would surmise from the standard interpretation of an offset geological feature. Slip along transform faults does not increase the distance between the ridges it separates, the distance remains constant in earthquakes because the ridges are spreading centers. This hypothesis was confirmed in a study of the fault plane solutions that showed the slip on transform faults points in the opposite direction than classical interpretation would suggest, Transform faults are closely related to transcurrent faults, and are commonly confused. In addition, transform faults have equal deformation across the fault line, while transcurrent faults have greater displacement in the middle of the fault zone. Finally, transform faults can form a plate boundary, while transcurrent faults cannot. The effect of a fault is to strain, which can be caused by compression, extension. Transform faults specifically relieve strain by transporting the strain between ridges or subduction zones, Transform faults also act as the plane of weakness allowing for the splitting in rift zones. Transform faults are commonly found linking segments of mid-oceanic ridges or spreading centres and these mid-oceanic ridges are where new seafloor is constantly created through the upwelling of new basaltic magma. With new seafloor being pushed and pulled out, the older seafloor slowly slides away from the mid-oceanic ridges toward the continents, although separated only by tens of kilometers, this separation between segments of the ridges causes portions of the seafloor to push past each other in opposing directions. This lateral movement of seafloors past each other is where transform faults are currently active, Transform faults move differently than a strike-slip fault at the mid-oceanic ridge. Evidence of this can be found in paleomagnetic striping on the seafloor, a paper written by Gerya theorizes that the creation of the transform faults between the ridges of the mid-oceanic ridge is attributed to rotated and stretched sections of the mid-oceanic ridge. This occurs over a period of time with the spreading center or ridge slowly deforming from a straight line to a curved line. Finally, fracturing along these planes forms transform faults, as this takes place, the fault changes from a normal fault with extensional stress to a strike slip fault with lateral stress. In the study done by Bonatti & Crane, peridotite and gabbro rocks were discovered in the edges of the transform ridges and these rocks are created deep inside the Earth’s mantle and then rapidly exhumed to the surface. This evidence helps to prove that new seafloor is being created at the mid-oceanic ridges, as previously stated, active transform faults are between two tectonic structures or faults. Fracture zones represent the active transform fault lines, which have since passed the active transform zone and are being pushed toward the continentsTransform boundary – Transform fault
16. Mantle plumes – A mantle plume is a mechanism proposed in 1971 to explain volcanic regions of the Earth that were not thought to be explicable by the then-new theory of plate tectonics. Some such volcanic regions lie far from plate boundaries, for example. Others represent unusually large-volume volcanism, whether on plate boundaries, e. g. Iceland, a mantle plume is posited to exist where hot rock nucleates at the core-mantle boundary and rises through the Earths mantle becoming a diapir in the Earths crust. The currently active volcanic centers are known as hot spots, the hypothesis of mantle plumes from depth is not universally accepted as explaining all such volcanism. It has required progressive hypothesis-elaboration leading to variant propositions such as mini-plumes, another hypothesis for unusual volcanic regions is the Plate model. In 1971, geophysicist W. Jason Morgan proposed the hypothesis of mantle plumes, in this hypothesis, convection in the mantle transports heat from the core to the Earths surface in thermal diapirs. The latter type of convection is postulated to be independent of plate motions, the sizes and occurrence of mushroom mantle plumes can be predicted easily by transient instability theory developed by Tan and Thorpe. The theory predicts mushroom mantle plumes of about 2000 km diameter with a time of about 830 Myr for a core mantle heat flux of 20 mW/m2. The number of mantle plumes is predicted to be about 17, the plume hypothesis was studied using laboratory experiments conducted in small fluid-filled tanks in the early 1970s. Thermal or compositional fluid-dynamical plumes produced in that way were presented as models for the much larger postulated mantle plumes, the entire structure is considered to resemble a mushroom. The bulbous head of thermal plumes forms because hot material moves upward through the faster than the plume itself rises through its surroundings. In the late 1980s and early 1990s, experiments with thermal models showed that as the bulbous head expands it may entrain some of the adjacent mantle into the head. When a plume head encounters the base of the lithosphere, it is expected to flatten out against this barrier and it may then erupt onto the surface. Numerical modelling predicts that melting and eruption will take place several million years. These eruptions have been linked to flood basalts, although many of those erupt over much shorter time scales, flood basalts in the oceans are known as oceanic plateaus, and include the Ontong Java plateau of the western Pacific Ocean and the Kerguelen Plateau of the Indian Ocean. As the overlying tectonic plate moves over this hot spot, the eruption of magma from the fixed conduit onto the surface is expected to form a chain of volcanoes that parallels plate motion, the Hawaiian Islands chain in the Pacific Ocean is the type example. The eruption of continental flood basalts is often associated with continental rifting and this has led to the hypothesis that mantle plumes contribute to continental rifting and the formation of ocean basins. In the context of the alternative Plate model, continental breakup is an integral to plate tectonicsMantle plumes – A superplume generated by cooling processes in the mantle.
17. Hotspot (geology) – In geology, the places known as hotspots or hot spots are volcanic regions thought to be fed by underlying mantle that is anomalously hot compared with the surrounding mantle. They may be on, near to, or far from plate boundaries. Currently, there are two hypotheses that attempt to explain their origins, one suggests that hotspots are due to mantle plumes that rise as thermal diapirs from the core–mantle boundary. The other hypothesis is that lithospheric extension permits the passive rising of melt from shallow depths and this hypothesis considers the term hotspot to be a misnomer, asserting that the mantle source beneath them is, in fact, not anomalously hot at all. Well known examples include Hawaii, Iceland and Yellowstone and it was later postulated that hotspots are fed by narrow streams of hot mantle rising from the Earths core–mantle boundary in a structure called a mantle plume. Whether or not such mantle plumes exist is currently the subject of a controversy in Earth science. Estimates for the number of hotspots postulated to be fed by mantle plumes has ranged from about 20 to several thousands, over the years, Hawaii, Réunion, Yellowstone, Galápagos, and Iceland are some of the currently most active volcanic regions to which the hypothesis is applied. As a result, they are less explosive than subduction zone volcanoes, where hotspots occur in continental regions, basaltic magma rises through the continental crust, which melts to form rhyolites. These rhyolites can form violent eruptions, for example, the Yellowstone Caldera was formed by some of the most powerful volcanic explosions in geologic history. However, when the rhyolite is completely erupted, it may be followed by eruptions of basaltic magma rising through the same lithospheric fissures, the hotspot hypothesis is now closely linked to the mantle plume hypothesis. Hotspot volcanoes are considered to have a different origin from island arc volcanoes. The latter form over subduction zones, at converging plate boundaries, when one oceanic plate meets another, the denser plate is forced downward into a deep ocean trench. This plate, as it is subducted, releases water into the base of the plate. It is this that fuels a chain of volcanoes, such as the Aleutian Islands, the joint mantle plume/hotspot hypothesis envisages the feeder structures to be fixed relative to one another, with the continents and seafloor drifting overhead. The hypothesis thus predicts that time-progressive chains of volcanoes are developed on the surface, examples are Yellowstone, which lies at the end of a chain of extinct calderas, which become progressively older to the west. Another example is the Hawaiian archipelago, where islands become progressively older, boschi, L. Becker, T. W. Steinberger, B. Mantle plumes, Dynamic models and seismic images, break-up spots, Could the Pacific open as a consequence of plate kinematics. Towards A Better Understanding Of Hot Spot Volcanism, formation of Hotspots Raising Hot Spots Large Igneous Provinces Maria Antretter, PhD Thesis, Moving hotspots – Evidence from paleomagnetism and modeling Do Plumes ExistHotspot (geology) – Over millions of years, the Pacific Plate has moved over the Hawaii hotspot, creating a trail of underwater mountains that stretch across the Pacific
18. Hawaii – Hawaii is the 50th and most recent state to have joined the United States of America, having received statehood on August 21,1959. Hawaii is the only U. S. state located in Oceania and it is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean. Hawaii is the only U. S. state not located in the Americas, the state encompasses nearly the entire volcanic Hawaiian archipelago, which comprises hundreds of islands spread over 1,500 miles. At the southeastern end of the archipelago, the eight main islands are—in order from northwest to southeast, Niʻihau, Kauaʻi, Oʻahu, Molokaʻi, Lānaʻi, Kahoʻolawe, Maui, and the Island of Hawaiʻi. The last is the largest island in the group, it is called the Big Island or Hawaiʻi Island to avoid confusion with the state or archipelago. The archipelago is physiographically and ethnologically part of the Polynesian subregion of Oceania, Hawaii has over a million permanent residents, along with many visitors and U. S. military personnel. Its capital is Honolulu on the island of Oʻahu, Hawaii is the 8th-smallest and the 11th-least populous, but the 13th-most densely populated of the fifty U. S. states. It is the state with an Asian plurality. The states coastline is about 750 miles long, the fourth longest in the U. S. after the coastlines of Alaska, Florida, the state of Hawaii derives its name from the name of its largest island, Hawaiʻi. A common Hawaiian explanation of the name of Hawaiʻi is that was named for Hawaiʻiloa and he is said to have discovered the islands when they were first settled. The Hawaiian language word Hawaiʻi is very similar to Proto-Polynesian *Sawaiki, cognates of Hawaiʻi are found in other Polynesian languages, including Māori, Rarotongan and Samoan. According to linguists Pukui and Elbert, lsewhere in Polynesia, Hawaiʻi or a cognate is the name of the underworld or of the home, but in Hawaii. A somewhat divisive political issue arose in 1978 when the Constitution of the State of Hawaii added Hawaiian as an official state language. The title of the constitution is The Constitution of the State of Hawaii. Article XV, Section 1 of the Constitution uses The State of Hawaii, diacritics were not used because the document, drafted in 1949, predates the use of the okina and the kahakō in modern Hawaiian orthography. The exact spelling of the name in the Hawaiian language is Hawaiʻi. In the Hawaii Admission Act that granted Hawaiian statehood, the government recognized Hawaii as the official state name. Official government publications, department and office titles, and the Seal of Hawaii use the spelling with no symbols for glottal stops or vowel lengthHawaii – Hawaii from space, January 26, 2014
19. Solar system – The Solar System is the gravitationally bound system comprising the Sun and the objects that orbit it, either directly or indirectly. Of those objects that orbit the Sun directly, the largest eight are the planets, with the remainder being significantly smaller objects, such as dwarf planets, of the objects that orbit the Sun indirectly, the moons, two are larger than the smallest planet, Mercury. The Solar System formed 4.6 billion years ago from the collapse of a giant interstellar molecular cloud. The vast majority of the mass is in the Sun. The four smaller inner planets, Mercury, Venus, Earth and Mars, are terrestrial planets, being composed of rock. The four outer planets are giant planets, being more massive than the terrestrials. All planets have almost circular orbits that lie within a flat disc called the ecliptic. The Solar System also contains smaller objects, the asteroid belt, which lies between the orbits of Mars and Jupiter, mostly contains objects composed, like the terrestrial planets, of rock and metal. Beyond Neptunes orbit lie the Kuiper belt and scattered disc, which are populations of trans-Neptunian objects composed mostly of ices, within these populations are several dozen to possibly tens of thousands of objects large enough that they have been rounded by their own gravity. Such objects are categorized as dwarf planets, identified dwarf planets include the asteroid Ceres and the trans-Neptunian objects Pluto and Eris. In addition to two regions, various other small-body populations, including comets, centaurs and interplanetary dust clouds. Six of the planets, at least four of the dwarf planets, each of the outer planets is encircled by planetary rings of dust and other small objects. The solar wind, a stream of charged particles flowing outwards from the Sun, the heliopause is the point at which pressure from the solar wind is equal to the opposing pressure of the interstellar medium, it extends out to the edge of the scattered disc. The Oort cloud, which is thought to be the source for long-period comets, the Solar System is located in the Orion Arm,26,000 light-years from the center of the Milky Way. For most of history, humanity did not recognize or understand the concept of the Solar System, the invention of the telescope led to the discovery of further planets and moons. The principal component of the Solar System is the Sun, a G2 main-sequence star that contains 99. 86% of the known mass. The Suns four largest orbiting bodies, the giant planets, account for 99% of the mass, with Jupiter. The remaining objects of the Solar System together comprise less than 0. 002% of the Solar Systems total mass, most large objects in orbit around the Sun lie near the plane of Earths orbit, known as the eclipticSolar system – The Sun and planets of the Solar System (distances not to scale)
20. Wells Gray-Clearwater volcanic field – It is situated in the Cariboo Mountains of the Columbia Mountains and on the Quesnel and Shuswap Highlands. As a monogenetic volcanic field, it is a place with numerous small basaltic volcanoes, most of the Wells Gray-Clearwater volcanic field is encompassed within a large wilderness park called Wells Gray Provincial Park. This 5,405 km2 park was established in 1939 to protect Helmcken Falls, five roads enter the park and provide views of some of the fields volcanic features. Short hikes lead to other volcanic features, but some areas are accessible only by aircraft. The emplacement of lava flows spanned at least three periods of glaciation, evidence for which is preserved in the form of tuyas, ice-ponded valley deposits. The few tuyas in the region, such as Gage Hill, Hyalo Ridge, McLeod Hill and Mosquito Mound, were formed when magma intruded into, the partially molten mass cooled as a large block, with gravity flattening its upper surface. The glacial erosion of the tuyas suggests they erupted during the early Pleistocene epoch, at least one explosive subaqueous volcano formed during the Pleistocene epoch. This subaqueous volcano, known as White Horse Bluff, is thought to have formed in three phases and its first phase of activity was involved with water, possibly dammed by glacial ice which filled the Clearwater River valley. The volcano heated glacial water then flooded down the vent, creating violent steam explosions. The volcano ceased erupting soon after breaching the surface of the glacial water, other volcanic events elsewhere interacted with groundwater and magma creating numerous pit craters. Many of these pit craters have been filled with water creating several crater lakes, in some places glacial till and fluvial sands and gravels are maintained under the several lava flows that form the volcanic field. Paleosols are found, but are rare, glaciation has left a thick blanket of till over nearly all of the volcanic deposits and therefore outcrop is largely limited to cliffforming exposures in several valleys. At the end of the last ice age approximately 10,000 years ago, most of these canyons contain rivers such as the Murtle and Clearwater, and waterfalls such as Canim Falls, Moul Falls, Spahats Falls and the 141 m high Helmcken Falls. The faces of the lava flows and waterfalls remain vertical due to the nature of the basaltic lava flows. Basaltic lava shrinks as it cools and forms vertical columns of rock called columnar basalt, More recently, the southern end of the volcanic field has experienced continuous volcanic activity since the end of the last ice age. This volcanic activity occurred in three areas, Spanish Creek, Ray Lake and Kostal Lake which were followed by lava fountain eruptions creating cinder cones, volcanism in the Spanish Creek and Ray Lake areas were synglacial but continued after the glacial ice had melted away. Two cinder cones, known as Flourmill Cone and Pointed Stick Cone, were created in the Spanish Creek area, lava flows from the two cinder cones lie on glaciated bedrock without an intervening paleosol, indicating an early Holocene age. Eruptions near Ray Lake built a cinder cone known as Dragon Cone and this lava flow, known as Dragons Tongue, is at least 15 m thick at the proximal end, but thins to 3 m at the distal end, damming the southern end of Clearwater LakeWells Gray-Clearwater volcanic field – A view from Green Mountain with Pyramid Mountain in the distance
21. Rio Grande Rift – The Rio Grande Rift is a north-trending continental rift zone. It separates the Colorado Plateau in the west from the interior of the North American craton on the east, the rift extends from central Colorado in the north to the state of Chihuahua, Mexico in the south. The rift zone consists of four basins that have a width of 50 kilometers. The rift can be observed on location at Rio Grande National Forest, White Sands National Monument, Santa Fe National Forest, the Rio Grande Rift has been an important site for humans for a long time, because it provides a north-south route that follows a major river. The Rio Grande follows the course of the rift from southern Colorado to El Paso, important cities, including Albuquerque, Santa Fe, Taos, Española, Las Cruces, El Paso, and Ciudad Juárez lie within the rift. The Rio Grande Rift represents the easternmost manifestation of widespread extension in the western U. S. during the past 35 million years, the rift consists of three major basins and many smaller basins, less than 100 km2. The three major basins are the San Luis, Española, and Albuquerque basins, further south, the rift is defined by a network of smaller, less topographically distinct alternating basins and ranges. The distinction between these basins and those of the Basin and Range Province becomes blurred in northern Mexico. Basin size generally decreases to the north in the rift, where the Española covers approximately 120 km north-south and 40 km east-west, the Albuquerque basin is the largest of the three basins, spanning 160 km north-south and 86 km east-west at its widest points. It is the oldest of the three basins, and contains 7,350 m of Paleogene clastic sediments deposited on Precambrian basement. The southernmost Albuquerque basin contains pre-rift volcanic deposits, while the central, the southernmost Rio Grande Rift broadens, becoming more complex in structure and physiographically indistinguishable from the adjoining Basin and Range province. In cross-section, the geometry of the basins within the rift are asymmetrical half-grabens, with major fault boundaries on one side, which side of the basin has the major fault or the hinge alternates along the rift. The alternation between these half-grabens occurs along transfer faults, which trend across the rift to connect the major basin-bounding faults, flanking mountains are generally taller along the east side of the rift. The thickness of the crust increases to the north beneath the rift, the crustal thickness underneath the rift is on average 30–35 km, thinner by 10–15 km than the Colorado Plateau on the west and the Great Plains to the east. The rift is presently nearly tectonically quiescent, but significant deformation and this extension is associated with very low seismic velocities in the upper mantle above approximately 400 km depth associated with relatively hot mantle and low degrees of partial melting. This intrusion of the asthenosphere into the lithosphere and continental crust is thought to be responsible for all of the volcanism associated with the Rio Grande rift. The sedimentary fill of the basins consists largely of alluvial fan, the most alkalic lavas erupted outside the rift. The sediments that were deposited during rifting are commonly known as the Santa Fe Group and this group contains sandstones, conglomerates, and volcanicsRio Grande Rift – Deep seismic image of the Rio Grande rift compiled from the seismic transect shown in the previous figure, showing inferred mantle flow and imaged crust-mantle (Moho) topography (after Wilson et al.)(2005).
22. Rhine – The largest city on the river Rhine is Cologne, Germany, with a population of more than 1,050,000 people. It is the second-longest river in Central and Western Europe, at about 1,230 km, with an average discharge of about 2,900 m3/s. The Rhine and the Danube formed most of the inland frontier of the Roman Empire and, since those days. The many castles and fortifications along the Rhine testify to its importance as a waterway in the Holy Roman Empire, in the modern era, it has become a symbol of German nationalism. The variant of the name of the Rhine in modern languages are all derived from the Gaulish name Rēnos, spanish is with French in adopting the Germanic vocalism Rin-, while Italian, Occitan and Portuguese retain the Latin Ren-. The Gaulish name Rēnos belongs to a class of river names built from the PIE root *rei- to move, flow, run, the grammatical gender of the Celtic name is masculine, and the name remains masculine in German, Dutch and French. The Old English river name was variously inflected as masculine or feminine, the length of the Rhine is conventionally measured in Rhine-kilometers, a scale introduced in 1939 which runs from the Old Rhine Bridge at Constance to Hoek van Holland. The river length is shortened from the rivers natural course due to a number of canalisation projects completed in the 19th and 20th century. The total length of the Rhine, to the inclusion of Lake Constance and its course is conventionally divided as follows, The Rhine carries its name without distinctive accessories only from the confluence of the Vorderrhein and Hinterrhein near Tamins-Reichenau. Above this point is the catchment of the headwaters of the Rhine. It belongs almost exclusively to the Swiss Canton of Graubünden, ranging from Gotthard Massif in the west via one valley lying in Ticino, traditionally, Lake Toma near the Oberalp Pass in the Gotthard region is seen as the source of the Vorderrhein and the Rhine as a whole. The Hinterrhein rises in the Rheinwald valley below Mount Rheinwaldhorn, the Vorderrhein, or Anterior Rhine, springs from Lai da Tuma, near the Oberalp Pass and passes the impressive Ruinaulta formed by the largest visible rock slide in the alps, the Flims Rockslide. A multiday trekking route is signposted along the young Rhine called Senda Sursilvana, the Hinterrhein/Rein Posteriur, or Posterior Rhine, starts from the Paradies Glacier, near the Rheinwaldhorn. One of its tributaries, the Reno di Lei, drains the Valle di Lei on politically Italian territory, after three main valleys separated by the two gorges, Roflaschlucht and Viamala, it reaches Reichenau. The Vorderrhein arises from numerous source streams in the upper Surselva, one source is Lai da Tuma with the Rein da Tuma, which is usually indicated as source of the Rhine, flowing through it. Into it flow tributaries from the south, some longer, some equal in length, such as the Reno di Medel, the Rein da Maighels, and the Rein da Curnera. The Cadlimo Valley in the Canton of Ticino is drained by the Reno di Medel, all streams in the source area are partially, sometimes completely, captured and sent to storage reservoirs for the local hydro-electric power plants. In its lower course the Vorderrhein flows through a gorge named Ruinaulta through the Flims Rockslide, the whole stretch of the Vorderrhein to the Rhine confluence near Reichenau-Tamins is accompanied by a long-distance hiking trail called Senda SursilvanaRhine – Lorelei rock in Rhineland-Palatinate
23. Eifel – The Eifel is a low mountain range in western Germany and eastern Belgium. It occupies parts of southwestern North Rhine-Westphalia, northwestern Rhineland-Palatinate and the south of the German-speaking Community of Belgium, the Eifel is part of the Rhenish Massif, within its northern portions lies the Eifel National Park. The Eifel lies between the cities of Aachen to the north, Trier to the south and Koblenz to the east and it descends in the northeast along a line from Aachen via Düren to Bonn into the Lower Rhine Bay. In the east and south it is bounded by the valleys of the Rhine, to the west it transitions in Belgium and Luxembourg into the geologically related Ardennes and the Luxembourg Ösling. In the north it is limited by the Jülich-Zülpicher Börde, within Germany it lies within the states of Rhineland-Palatinate and North Rhine-Westphalia, in BeNeLux the area of Eupen, St. Vith and Luxembourg. Its highest point is the cone of the Hohe Acht. Originally the Carolingian Eifelgau only covered the region roughly around the sources of the rivers Ahr, Kyll. Its name was recently transferred to the entire region. Individual mountain chains, up to 700 m, such as the Schneifel and High Fens, run through the western part of the plateau. The rivers draining into the Moselle, Rhine and Meuse, such as the Our, Kyll, Ahr, Brohl and Rur, have cut deep into the edge of the Eifel and formed larger valleys. The Eifel covers an area of 5,300 km² and is divided into the North and South Eifel. It is further divided into several natural regional landscapes, some with further subdivisions, there are several distinct chains within the Eifel. The northernmost parts are called North Eifel including Rur Eifel the origin of the river Rur, High Fens, the northeastern part is called Ahr Hills and rise north of the Ahr river in the district of Ahrweiler. South of the Ahr is the High Eifel, with the Hohe Acht being the highest mountain of the Eifel, in the west, on the Belgian border, the hills are known as Schneifel, rising up to 698 m. Also in the west, by the Belgian and Luxembourg border, the southern half of the Eifel is lower. It is cut by rivers running north-south towards the Moselle. The largest of these is the Kyll, and the hills on either side of river are called the Kyllwald. In the south the Eifel is concluded by the Voreifel above the Moselle, since 2004 about 110 km² of the Eifel within the German state of North Rhine-Westphalia have been protected as the Eifel National Park nature reserveEifel
24. Volcano – A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. Earths volcanoes occur because its crust is broken into 17 major, therefore, on Earth, volcanoes are generally found where tectonic plates are diverging or converging. This type of volcanism falls under the umbrella of plate hypothesis volcanism, Volcanism away from plate boundaries has also been explained as mantle plumes. These so-called hotspots, for example Hawaii, are postulated to arise from upwelling diapirs with magma from the boundary,3,000 km deep in the Earth. Volcanoes are usually not created where two plates slide past one another. Erupting volcanoes can pose hazards, not only in the immediate vicinity of the eruption. Historically, so-called volcanic winters have caused catastrophic famines, the word volcano is derived from the name of Vulcano, a volcanic island in the Aeolian Islands of Italy whose name in turn comes from Vulcan, the god of fire in Roman mythology. The study of volcanoes is called volcanology, sometimes spelled vulcanology, at the mid-oceanic ridges, two tectonic plates diverge from one another as new oceanic crust is formed by the cooling and solidifying of hot molten rock. Most divergent plate boundaries are at the bottom of the oceans, therefore, most volcanic activity is submarine, black smokers are evidence of this kind of volcanic activity. Where the mid-oceanic ridge is above sea-level, volcanic islands are formed, for example, subduction zones are places where two plates, usually an oceanic plate and a continental plate, collide. In this case, the plate subducts, or submerges under the continental plate forming a deep ocean trench just offshore. In a process called flux melting, water released from the subducting plate lowers the temperature of the overlying mantle wedge. This magma tends to be very viscous due to its high content, so it often does not reach the surface. When it does reach the surface, a volcano is formed, typical examples of this kind of volcano are Mount Etna and the volcanoes in the Pacific Ring of Fire. Because tectonic plates move across them, each volcano becomes dormant and is eventually re-formed as the plate advances over the postulated plume and this theory is currently under criticism, however. The most common perception of a volcano is of a mountain, spewing lava and poisonous gases from a crater at its summit, however. The features of volcanoes are more complicated and their structure. Some volcanoes have rugged peaks formed by lava domes rather than a summit crater while others have features such as massive plateausVolcano – Cleveland Volcano in the Aleutian Islands of Alaska photographed from the International Space Station, May 2006
25. 1980 eruption of Mount St. Helens – On May 18,1980, a major volcanic eruption occurred at Mount St. Helens, a volcano located in Skamania County, in the state of Washington, United States. The eruption was the significant volcanic eruption to occur in the contiguous 48 U. S. states since the 1915 eruption of Lassen Peak in California. However, it has often declared as the most disastrous volcanic eruption in United States history. An earthquake at 8,32,17 a. m. PDT on Sunday, May 18,1980, caused the entire weakened north face to slide away, creating the largest landslide ever recorded. An eruption column rose 80,000 feet into the atmosphere, at the same time, snow, ice and several entire glaciers on the volcano melted, forming a series of large lahars that reached as far as the Columbia River, nearly 50 miles to the southwest. Less severe outbursts continued into the day, only to be followed by other large. Approximately fifty-seven people were killed directly, including innkeeper Harry R. Truman, photographer Reid Blackburn and geologist David A. Johnston. Hundreds of square miles were reduced to wasteland, causing over a billion U. S. dollars in damage, thousands of animals were killed. At the time of the eruption, the summit of the volcano was owned by the Burlington Northern Railroad, the area was later preserved, as it was, in the Mount St. Helens National Volcanic Monument. Mount St. Helens remained dormant from its last period of activity in the 1840s and 1850s until March 1980, several small earthquakes, apparently beginning on March 15, indicated that magma may have begun moving below the volcano. Then on March 20, at 3,45 p. m. Pacific Standard Time, a total of 174 shocks of magnitude 2.6 or greater were recorded during those two days. Initially there was no sign of eruption, but small earthquake-induced avalanches of snow. At 12,36 p. m. on March 27, phreatic eruptions ejected and smashed rock from within the old crater, excavating a new crater 250 feet wide. By this date a 16, 000-foot long eastward-trending fracture system had developed across the summit area. This was followed by more earthquake swarms and a series of explosions that sent ash 10,000 to 11,000 feet above their vent. Most of this ash fell between 3 and 12 miles from its vent, but some was carried 150 miles south to Bend, Oregon, or 285 miles east to Spokane, a second, new crater and a blue flame were observed on March 29. The flame was visibly emitted from both craters and was created by burning gases. Static electricity generated from ash clouds rolling down the volcano sent out lightning bolts that were up to 2 miles long1980 eruption of Mount St. Helens – Photograph of the eruption column, May 18, 1980.
26. Washington (state) – It was admitted to the Union as the 42nd state in 1889. Washington is sometimes referred to as Washington State or the State of Washington to distinguish it from Washington, Washington is the 18th largest state with an area of 71,362 square miles, and the 13th most populous state with over 7 million people. Washington is the second most populous state on the West Coast and in the Western United States, Mount Rainier, an active stratovolcano, is the states highest elevation at almost 14,411 feet and is the most topographically prominent mountain in the contiguous United States. Washington is a leading lumber producer and its rugged surface is rich in stands of Douglas fir, hemlock, ponderosa pine, white pine, spruce, larch, and cedar. Manufacturing industries in Washington include aircraft and missiles, shipbuilding and other equipment, lumber, food processing, metals and metal products, chemicals. Washington has over 1,000 dams, including the Grand Coulee Dam, built for a variety of purposes including irrigation, power, flood control, Washington was named after President George Washington by an act of the United States Congress during the creation of Washington Territory in 1853. Washington is the only U. S. state named after a president, confusion over the state of Washington and the city of Washington, D. C. led to renaming proposals during the statehood process for Washington in 1889, which failed to garner support. Washington, D. C. s own statehood movement in the 21st century includes a proposal to use the name State of Washington, Douglass Commonwealth, which would conflict with the current state of Washington. To distinguish it from the capital, Washington is sometimes referred to as Washington state, or, in more formal contexts. Residents of Washington and the Pacific Northwest simply refer to the state as Washington, Washington is the northwestern-most state of the contiguous United States. Washington is bordered by Oregon to the south, with the Columbia River forming the western part, to the west of Washington lies the Pacific Ocean. The high mountains of the Cascade Range run north-south, bisecting the state, from the Cascade Mountains westward, Western Washington has a mostly marine west coast climate, with mild temperatures and wet winters, autumns and springs, and relatively dry summers. The Cascade Range contains several volcanoes, which reach altitudes significantly higher than the rest of the mountains, from the north to the south, these major volcanoes are Mount Baker, Glacier Peak, Mount Rainier, Mount St. Helens, and Mount Adams. Mount Rainier, the tallest mountain in the state, is 50 miles south of the city of Seattle and it is also covered with more glacial ice than any other peak in the contiguous 48 states. Western Washington also is home of the Olympic Mountains, far west on the Olympic Peninsula and these deep forests, such as the Hoh Rainforest, are among the only temperate rainforests in the continental United States. Eastern Washington – the part of the state east of the Cascades – has a dry climate. It includes large areas of steppe and a few truly arid deserts lying in the rain shadow of the Cascades. Farther east, the climate becomes less arid, with annual rainfall increasing as one goes east to 21.2 inches in Pullman, the Okanogan Highlands and the rugged Kettle River Range and Selkirk Mountains cover much of the northeastern quadrant of the stateWashington (state) – South Eastern Washington
27. Plinian eruption – Plinian eruptions, also known as Vesuvian eruptions, are volcanic eruptions marked by their similarity to the eruption of Mount Vesuvius in 79 AD. The eruption was described in a written by Pliny the Younger, it killed his uncle. Plinian eruptions are marked by columns of gas and volcanic ash extending high into the stratosphere, the key characteristics are ejection of large amount of pumice and very powerful continuous gas blast eruptions. According to the Volcanic Explosivity Index, Plinian eruptions have a VEI of 4,5 or 6, short eruptions can end in less than a day, but longer events can take several days to months. The longer eruptions begin with production of clouds of volcanic ash, the amount of magma erupted can be so large that it depletes the magma chamber below, causing the top of the volcano to collapse, resulting in a caldera. Fine ash can deposit over large areas, Plinian eruptions are often accompanied by loud noises, such as those generated by Krakatoa. The lava is usually rhyolitic and rich in silicates, basaltic lavas are unusual for Plinian eruptions, the most recent basaltic example is the 1886 eruption of Mount Tarawera on New Zealands North Island. Pliny the Younger provided an account of his death, and suggested that he collapsed and died through inhaling poisonous gases emitted from the volcano. His body was interred under the ashes of the Vesuvius with no apparent injuries on 26 August, after the plume had dispersed. The June 2009 eruption of Sarychev Peak in Russia, the 1991 Mount Pinatubo eruption in Zambales of Central Luzon, Philippines. The 1980 eruption of Mount St. Helens in Washington, United States, the 1912 eruption of Novarupta in Alaska, United States. The 1886 eruption of Mount Tarawera in New Zealand, the 1883 eruption of Krakatoa in Sunda Strait, Indonesia. The 1815 eruption of Mount Tambora in the island of Sumbawa, the 1783 eruptions of Lakagígar in Iceland. The 1667 and 1739 eruptions of Mount Tarumae in Hokkaido, Japan, the A. D.180 Lake Taupo eruption in New Zealand. The A. D.79 eruption of Mount Vesuvius in Campania and it was the prototypical Plinian eruption. The 400s BC eruption of the Bridge River Vent in British Columbia, the 1645 BC eruption of Santorini in the south Aegean Sea, Greece. The 4860 BC eruption forming Crater Lake in Oregon, United States, the Long Valley Caldera eruption in Eastern California of United States, which happened over 760,000 years ago. According to the Volcanic Explosivity Index, a VEI of 6 to 8 is classified as Ultra Plinian, Eruptions of this type are defined by ash plumes over 25 km high and a volume of erupted material 10 km3 to 1,000 km3 in sizePlinian eruption – 1822 artist's impression of the eruption of Vesuvius, depicting what the AD 79 eruption may have looked like, by the English geologist George Julius Poulett Scrope
28. U.S. state – A U. S. state is a constituent political entity of the United States of America. There are 50 states, which are together in a union with each other. Each state holds administrative jurisdiction over a geographic territory. Due to the shared sovereignty between each state and the government, Americans are citizens of both the federal republic and of the state in which they reside. State citizenship and residency are flexible, and no government approval is required to move between states, except for persons covered by certain types of court orders. States range in population from just under 600,000 to over 39 million, four states use the term commonwealth rather than state in their full official names. States are divided into counties or county-equivalents, which may be assigned some local authority but are not sovereign. County or county-equivalent structure varies widely by state, State governments are allocated power by the people through their individual constitutions. All are grounded in principles, and each provides for a government. States possess a number of powers and rights under the United States Constitution, Constitution has been amended, and the interpretation and application of its provisions have changed. The general tendency has been toward centralization and incorporation, with the government playing a much larger role than it once did. There is a debate over states rights, which concerns the extent and nature of the states powers and sovereignty in relation to the federal government. States and their residents are represented in the federal Congress, a legislature consisting of the Senate. Each state is represented in the Senate by two senators, and is guaranteed at least one Representative in the House, members of the House are elected from single-member districts. Representatives are distributed among the states in proportion to the most recent constitutionally mandated decennial census, the Constitution grants to Congress the authority to admit new states into the Union. Since the establishment of the United States in 1776, the number of states has expanded from the original 13 to 50, alaska and Hawaii are the most recent states admitted, both in 1959. The Constitution is silent on the question of states have the power to secede from the Union. Shortly after the Civil War, the U. S. Supreme Court, in Texas v. White, as a result, while the governments of the various states share many similar features, they often vary greatly with regard to form and substanceU.S. state – U.S. states
29. Volcanic Explosivity Index – The Volcanic Explosivity Index is a relative measure of the explosiveness of volcanic eruptions. It was devised by Chris Newhall of the United States Geological Survey, volume of products, eruption cloud height, and qualitative observations are used to determine the explosivity value. The scale is open-ended with the largest volcanoes in history given magnitude 8, the scale is logarithmic, with each interval on the scale representing a tenfold increase in observed ejecta criteria, with the exception of between VEI0, VEI1 and VEI2. With indices running from 0 to 8, the VEI associated with an eruption is dependent on how much material is thrown out, to what height. The scale is logarithmic from VEI2 and up, an increase of 1 index indicates an eruption that is 10 times as powerful, as such there is a discontinuity in the definition of the VEI between indices 1 and 2. The lower border of the volume of ejecta jumps by a factor of 100 from 10,000 to 1,000,000 m3 while the factor is 10 between all higher indices. In the following table, the frequency of each VEI indicates the frequency of new eruptions of that VEI or higher. A total of 47 eruptions of VEI8 magnitude or above, ranging in age from Ordovician to Pleistocene, have been identified, of which 42 occurred in the past 36 million years. The most recent is Lake Taupos Oruanui eruption,25,360 years ago, there have been at least five identified Holocene eruptions with a VEI of 7. There are also 58 plinian eruptions, and 13 caldera-forming eruptions, of large, there are likely many other eruptions that are not identified. About 90% of these 7,742 eruptions have a VEI of 3 or less, about 49% of these 7,742 eruptions have a VEI of 2. Under the VEI, ash, lava, lava bombs and ignimbrite are all treated alike, density and vesicularity of the volcanic products in question is not taken into account. In contrast, the DRE is sometimes calculated to give the amount of magma erupted. Another weakness of the VEI is that it does not take account the power output of an eruption. Tephra, or fallout sediment analysis, can provide an estimate of the explosiveness of a known eruption event and it is, however, not obviously related to the amount of SO2 emitted by the eruption. The VEI itself is inadequate for describing the effects of volcanic eruptions. This is clearly demonstrated by two eruptions, Agung and El ChichónVolcanic Explosivity Index – VEI and ejecta volume correlation
30. California – California is the most populous state in the United States and the third most extensive by area. Located on the western coast of the U. S, California is bordered by the other U. S. states of Oregon, Nevada, and Arizona and shares an international border with the Mexican state of Baja California. Los Angeles is Californias most populous city, and the second largest after New York City. The Los Angeles Area and the San Francisco Bay Area are the nations second- and fifth-most populous urban regions, California also has the nations most populous county, Los Angeles County, and its largest county by area, San Bernardino County. The Central Valley, an agricultural area, dominates the states center. What is now California was first settled by various Native American tribes before being explored by a number of European expeditions during the 16th and 17th centuries, the Spanish Empire then claimed it as part of Alta California in their New Spain colony. The area became a part of Mexico in 1821 following its war for independence. The western portion of Alta California then was organized as the State of California, the California Gold Rush starting in 1848 led to dramatic social and demographic changes, with large-scale emigration from the east and abroad with an accompanying economic boom. If it were a country, California would be the 6th largest economy in the world, fifty-eight percent of the states economy is centered on finance, government, real estate services, technology, and professional, scientific and technical business services. Although it accounts for only 1.5 percent of the states economy, the story of Calafia is recorded in a 1510 work The Adventures of Esplandián, written as a sequel to Amadis de Gaula by Spanish adventure writer Garci Rodríguez de Montalvo. The kingdom of Queen Calafia, according to Montalvo, was said to be a land inhabited by griffins and other strange beasts. This conventional wisdom that California was an island, with maps drawn to reflect this belief, shortened forms of the states name include CA, Cal. Calif. and US-CA. Settled by successive waves of arrivals during the last 10,000 years, various estimates of the native population range from 100,000 to 300,000. The Indigenous peoples of California included more than 70 distinct groups of Native Americans, ranging from large, settled populations living on the coast to groups in the interior. California groups also were diverse in their organization with bands, tribes, villages. Trade, intermarriage and military alliances fostered many social and economic relationships among the diverse groups, the first European effort to explore the coast as far north as the Russian River was a Spanish sailing expedition, led by Portuguese captain Juan Rodríguez Cabrillo, in 1542. Some 37 years later English explorer Francis Drake also explored and claimed a portion of the California coast in 1579. Spanish traders made unintended visits with the Manila galleons on their trips from the Philippines beginning in 1565California – A forest of redwood trees in Redwood National Park
31. Lassen Peak – Lassen Peak, commonly referred to as Mount Lassen, is the southernmost active volcano in the Cascade Range. Located in the Shasta Cascade region of Northern California, Lassen rises 3,500 ft above the terrain and has a volume of 0.5 cu mi. It was created on the northeastern flank of now-gone Mount Tehama. It is part of the Cascade Volcanic Arc which stretches from southwestern British Columbia to northern California, on May 22,1915, a powerful explosive eruption at Lassen Peak devastated nearby areas, and spread volcanic ash as far as 200 mi to the east. This explosion was the most powerful in a series of eruptions from 1914 through 1917, Lassen Peak and Mount St. Helens were the only two volcanoes in the contiguous United States to erupt during the 20th century. Lassen Volcanic National Park was created in Tehama County, California, to preserve the areas as they were, for future observation and study. Lassen Peak has the highest known winter snowfall amounts in California, there is an average annual snowfall of 660 in, and in some years, more than 1,000 in of snow falls at its base altitude of 8,250 ft at Lake Helen. The Lassen Peak area receives more precipitation than anywhere in the Cascade Range south of the Three Sisters volcanoes in Oregon, the heavy annual snowfall on Lassen Peak creates fourteen permanent patches of snow on and around the mountain top, despite Lassens rather modest elevation, but no glaciers. Lightning has been known to strike the summit of the volcano frequently during summer thunderstorms, Lassen Peak is the southernmost in the chain of eighteen large volcanic peaks that stretch from southwestern British Columbia to northern California. These peaks were formed during the past 35 million years while the large Juan de Fuca tectonic plate and the much smaller Gorda plate to its south subducted under the North American plate. As the oceanic crust of the Juan de Fuca plate melts in the zone, pools of magma form. Roughly 27,000 years ago, Lassen Peak started to form as a dacite lava dome pushed its way through Tehamas destroyed north-eastern flank. As the lava dome grew it shattered overlaying rock, which formed a blanket of talus around the emerging steep-sided volcano. It likely resembled the nearby 1, 100-year-old Chaos Crags, Lassen Peak reached its present height in a relatively short time, probably in just a few years. From 25,000 to 18,000 years ago, during the last glacial period of the current Ice Age, for example, the bowl-shaped depression on the volcano’s northeastern flank, called a cirque, was eroded by a glacier that extended out 7 mi from the dome. The most recent eruptive period of Lassen Peak began in 1914, the region around Lassen Peak remains active, with mudpots, fumaroles, and hot springs demonstrating area activity. The areas around Lassen Peak and the nearby Mount Shasta are considered to be the most likely volcanoes in the Cascade Range to erupt during the decades and centuries. Before the arrival of settlers, the areas surrounding Lassen Peak, especially to its east, southLassen Peak – Lassen Peak and devastated area from cinder cone
32. Earthquake – 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 frictionEarthquake – Global plate tectonic movement
33. Steam – Steam is water in the gas phase, which is formed when water boils. Steam is invisible, however, steam often refers to wet steam, at lower pressures, such as in the upper atmosphere or at the top of high mountains, water boils at a lower temperature than the nominal 100 °C at standard pressure. If heated further it becomes superheated steam, piston type steam engines played a central role to the Industrial Revolution and modern steam turbines are used to generate more than 80% of the worlds electricity. If liquid water comes in contact with a hot surface or depressurizes quickly below its vapor pressure. Steam explosions have been responsible for many accidents, and may also have been responsible for much of the damage to the plant in the Chernobyl disaster. Steam is traditionally created by heating a boiler via burning coal and other fuels, water vapor that includes water droplets is described as wet steam. As wet steam is heated further, the droplets evaporate, and at a high temperature all of the water evaporates. Superheated steam is steam at a higher than its boiling point for the pressure. Steam tables contain thermodynamic data for water/steam and are used by engineers and scientists in design. Additionally, thermodynamic phase diagrams for water/steam, such as a diagram or a Mollier diagram shown in this article. Steam charts are used for analysing thermodynamic cycles. In agriculture, steam is used for sterilization to avoid the use of harmful chemical agents. Steams capacity to transfer heat is used in the home, for cooking vegetables, steam cleaning of fabric, carpets and flooring. In each case, water is heated in a boiler, steam is also used in ironing clothes to add enough humidity with the heat to take wrinkles out and put intentional creases into the clothing. About 90% of all electricity is generated using steam as the working fluid, in electric generation, steam is typically condensed at the end of its expansion cycle, and returned to the boiler for re-use. However, in cogeneration, steam is piped into buildings through a heating system to provide heat energy after its use in the electric generation cycle. The worlds biggest steam generation system is the New York City steam system, in other industrial applications steam is used for energy storage, which is introduced and extracted by heat transfer, usually through pipes. Steam is a reservoir for thermal energy because of waters high heat of vaporizationSteam – Liquid phase eruption of Castle Geyser in Yellowstone Park
34. 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 magmaMagma – Lava flow on Hawaii. Lava is the extrusive equivalent of magma.
35. Mount St. Helens – Mount St. Helens or Louwala-Clough is an active stratovolcano located in Skamania County, Washington, in the Pacific Northwest region of the United States. It is 96 miles south of Seattle, Washington, and 50 miles northeast of Portland, Mount St. Helens takes its English name from the British diplomat Lord St Helens, a friend of explorer George Vancouver who made a survey of the area in the late 18th century. The volcano is located in the Cascade Range and is part of the Cascade Volcanic Arc and this volcano is well known for its ash explosions and pyroclastic flows. Mount St. Helens is most notorious for its major 1980 eruption, fifty-seven people were killed,250 homes,47 bridges,15 miles of railways, and 185 miles of highway were destroyed. The debris avalanche was up to 0.7 cubic miles in volume, the Mount St. Helens National Volcanic Monument was created to preserve the volcano and allow for its aftermath to be scientifically studied. As with most other volcanoes in the Cascade Range, Mount St. Helens is a large eruptive cone consisting of lava rock interlayered with ash, pumice, the mountain includes layers of basalt and andesite through which several domes of dacite lava have erupted. The largest of the domes formed the previous summit. Both were destroyed in the 1980 eruption, Mount St. Helens is 34 miles west of Mount Adams, in the western part of the Cascade Range. These sister and brother volcanic mountains are approximately 50 miles from Mount Rainier, Mount Hood, the nearest major volcanic peak in Oregon, is 60 miles southeast of Mount St. Helens. Mount St. Helens is geologically young compared with the other major Cascade volcanoes and it formed only within the past 40,000 years, and the pre-1980 summit cone began rising about 2,200 years ago. The volcano is considered the most active in the Cascades within the Holocene epoch, prior to the 1980 eruption, Mount St. Helens was the fifth-highest peak in Washington. It stood out prominently from surrounding hills because of the symmetry and extensive snow and ice cover of the summit cone. The peak rose more than 5,000 feet above its base, the mountain is 6 miles across at its base, which is at an elevation of 4,400 feet on the northeastern side and 4,000 feet elsewhere. At the pre-eruption tree line, the width of the cone was 4 miles. Streams that originate on the volcano enter three main systems, the Toutle River on the north and northwest, the Kalama River on the west. The streams are fed by abundant rain and snow, the average annual rainfall is 140 inches, and the snow pack on the mountains upper slopes can reach 16 feet. The Lewis River is impounded by three dams for power generation. The southern and eastern sides of the drain into an upstream impoundment, the Swift ReservoirMount St. Helens – 3,000 ft (1 km) steam plume on May 19, 1982, two years after its major eruption
36. Rock (geology) – Rock or stone is a natural substance, a solid aggregate of one or more minerals or mineraloids. For example, granite, a rock, is a combination of the minerals quartz, feldspar. The Earths outer solid layer, the lithosphere, is made of rock, rock has been used by mankind throughout history. The minerals and metals found in rocks have been essential to human civilization, three major groups of rocks are defined, igneous, sedimentary, and metamorphic. The scientific study of rocks is called petrology, which is a component of geology. At a granular level, rocks are composed of grains of minerals, the aggregate minerals forming the rock are held together by chemical bonds. The types and abundance of minerals in a rock are determined by the manner in which the rock was formed, many rocks contain silica, a compound of silicon and oxygen that forms 74. 3% of the Earths crust. This material forms crystals with other compounds in the rock, the proportion of silica in rocks and minerals is a major factor in determining their name and properties. Rocks are geologically classified according to such as mineral and chemical composition, permeability, the texture of the constituent particles. These physical properties are the end result of the processes that formed the rocks, over the course of time, rocks can transform from one type into another, as described by the geological model called the rock cycle. These events produce three general classes of rock, igneous, sedimentary, and metamorphic, the three classes of rocks are subdivided into many groups. However, there are no hard and fast boundaries between allied rocks, hence the definitions adopted in establishing rock nomenclature merely correspond to more or less arbitrary selected points in a continuously graduated series. Igneous rock forms through the cooling and solidification of magma or lava and this magma can be derived from partial melts of pre-existing rocks in either a planets mantle or crust. Typically, the melting of rocks is caused by one or more of three processes, an increase in temperature, a decrease in pressure, or a change in composition, igneous rocks are divided into two main categories, plutonic rock and volcanic. Plutonic or intrusive rocks result when magma cools and crystallizes slowly within the Earths crust, a common example of this type is granite. Volcanic or extrusive rocks result from magma reaching the surface either as lava or fragmental ejecta, the chemical abundance and the rate of cooling of magma typically forms a sequence known as Bowens reaction series. Most major igneous rocks are found along this scale, about 64. 7% of the Earths crust by volume consists of igneous rocks, making it the most plentiful category. Of these, 66% are basalts and gabbros, 16% are granite, only 0. 6% are syenites and 0. 3% peridotites and dunitesRock (geology) – Balanced Rock stands in the Garden of the Gods park in Colorado Springs
37. Spirit Lake (Washington) – Spirit Lake is a lake north of Mount St. Helens in Washington State. The lake was a popular tourist destination for years until the 1980 eruption of Mount St. Helens. Prior to 1980, there were six camps on the shore of Spirit Lake, a Boy Scout camp, a Girl Scout camp, two YMCA camps, Harmony Fall Lodge, and another for the general public. There were also a number of catering to visitors, including Spirit Lake Lodge and Mt. St. Helens Lodge, the latter was inhabited by Harry R. Truman. Prior to 1980, Spirit Lake consisted of two arms that occupied what had been the valleys of the North Fork Toutle River and a tributary. About 4,000 years ago, these valleys were blocked by lahars, the longest branch of Spirit Lake was about 2.1 miles long. A stable outlet channel flowed from the lake to the North Fork Toutle River across a dam composed of volcanic material. Recent climate data for the area is not available to confirm whether the site still has this rare climate type. During the 1980 eruption of Mount St. Helens, Spirit Lake received the full impact of the lateral blast from it. The debris avalanche deposited about 350,000 acre-feet of pyrolized trees, other plant material, volcanic ash, the deposition of this volcanic material decreased the lake volume by approximately 46,000 acre-feet. The surface area of the lake was increased from 1,300 acres to about 2,200 acres, the eruption tore thousands of trees from the surrounding hillsides and swept them into Spirit Lake. These thousands of shattered trees formed a log raft on the lake surface that covered about 40% of the lake’s surface after the eruption. After the eruption, Spirit Lake contained highly toxic water with volcanic gases seeping up from the lake bed, a month after the eruption, the bacteria-carrying water was devoid of oxygen. Scientists predicted that the lake would not recover quickly, but the reemergence of phytoplankton starting in 1983 began to restore oxygen levels, amphibians such as frogs and salamanders recolonized the lake, and fish thrived. The water level of Spirit Lake is maintained at about 3,406 ft by draining water through a tunnel completed in 1985. The 8,465 ft -long tunnel was cut through Harrys Ridge to South Coldwater Creek, anonymous, CVO Photo Archives, Hydrology and Hydrologic Monitoring Images. Cascades Volcano Observatory, United State Geological Survey, Vancouver, Washington, glicken, HX, W Meyer, and MA Sabol, Geology and ground-water hydrology of Spirit Lake blockage, Mount St. Helens, Washington, with implications for lake retention. Evarts, RC, and RP Ashley Geologic map of the Spirit Lake East quadrangle, Skamania County,1679, U. S. Geological Survey, Reston, VirginiaSpirit Lake (Washington) – (February 2005)
38. Glacier – A glacier is a persistent body of dense ice that is constantly moving under its own weight, it forms where the accumulation of snow exceeds its ablation over many years, often centuries. Glaciers slowly deform and flow due to stresses induced by their weight, creating crevasses, seracs and they also abrade rock and debris from their substrate to create landforms such as cirques and moraines. Glaciers form only on land and are distinct from the much thinner sea ice, between 35°N and 35°S, glaciers occur only in the Himalayas, Andes, Rocky Mountains, a few high mountains in East Africa, Mexico, New Guinea and on Zard Kuh in Iran. Glaciers cover about 10 percent of Earths land surface, continental glaciers cover nearly 13,000,000 km2 or about 98 percent of Antarcticas 13,200,000 km2, with an average thickness of 2,100 m. Greenland and Patagonia also have huge expanses of continental glaciers, Glacial ice is the largest reservoir of fresh water on Earth. Within high altitude and Antarctic environments, the temperature difference is often not sufficient to release meltwater. A large piece of compressed ice, or a glacier, appears blue as large quantities of water appear blue and this is because water molecules absorb other colors more efficiently than blue. The other reason for the color of glaciers is the lack of air bubbles. Air bubbles, which give a color to ice, are squeezed out by pressure increasing the density of the created ice. The word Glaceon is a loanword from French and goes back, via Franco-Provençal, to the Vulgar Latin glaciārium, derived from the Late Latin glacia, the processes and features caused by or related to glaciers are referred to as glacial. The process of establishment, growth and flow is called glaciation. The corresponding area of study is called glaciology, Glaciers are important components of the global cryosphere. Glaciers are categorized by their morphology, thermal characteristics, and behavior, cirque glaciers form on the crests and slopes of mountains. A glacier that fills a valley is called a valley glacier, a large body of glacial ice astride a mountain, mountain range, or volcano is termed an ice cap or ice field. Ice caps have a less than 50,000 km2 by definition. Glacial bodies larger than 50,000 km2 are called ice sheets or continental glaciers, several kilometers deep, they obscure the underlying topography. Only nunataks protrude from their surfaces, the only extant ice sheets are the two that cover most of Antarctica and Greenland. They contain vast quantities of water, enough that if both melted, global sea levels would rise by over 70 mGlacier – The Baltoro Glacier in the Karakoram, Baltistan, Northern Pakistan. At 62 kilometres (39 mi) in length, it is one of the longest alpine glaciers on earth.
39. Lahar – A lahar is a type of mudflow or debris flow composed of a slurry of pyroclastic material, rocky debris, and water. The material flows down from a volcano, typically along a river valley, lahars are extremely destructive, they can flow tens of metres per second, be 140 metres deep, and destroy any structures in their path. Notable lahars include those at Mount Pinatubo and Nevado del Ruiz, the word lahar is the Javanese term for flowing lava. A lahar is a volcanic mudflow or debris flow, lahars have the consistency, viscosity and approximate density of wet concrete, fluid when moving, solid at rest. Lahars can be huge.3 cubic kilometres, a lahar of sufficient size and intensity can erase virtually any structure in its path, and is capable of carving its own pathway, making the prediction of its course difficult. Conversely, a lahar quickly loses force when it leaves the channel of its flow, even frail huts may remain standing, a lahars viscosity decreases with time, and can be further thinned by rain, but it nevertheless solidifies quickly when coming to a stop. Lahars vary in size and speed, small lahars less than a few metres wide and several centimetres deep may flow a few metres per second. Large lahars hundreds of metres wide and tens of metres deep can flow tens of metres per second. With the potential to flow at speeds up to 100 kilometres per hour, and flow distances of more than 300 kilometres, a lahar can cause catastrophic destruction in its path. Lahars from the 1985 Nevado del Ruiz eruption in Colombia caused the Armero tragedy, which killed an estimated 23,000 people, a lahar caused New Zealands Tangiwai disaster, where 151 people died after a Christmas Eve express train fell into the Whangaehu River in 1953. Lahars have been responsible for 17% of volcano-related deaths between 1783 and 1997, a lahar can cause fatalities years after its precipitating eruption. For example, the Cabalantian tragedy occurred four years subsequent to the 1991 eruption of Mount Pinatubo, the word lahar is of Indonesian origin. Lahars have several causes, Snow and glaciers can be melted by lava or pyroclastic flows during an eruption. Lava flows out of vents and can mix with wet soil and mud on the slope of the volcano making a very viscous. A flood caused by a glacier, lake breakout, or heavy rainfall can release a lahar, also called glacier run or jökulhlaup Water from a crater lake, heavy rainfall on unconsolidated pyroclastic deposits. Snow and glaciers can melt during periods of mild weather Earthquakes underneath or close to the volcano can shake material loose and cause it to collapse triggering a lahar avalanche. Rainfall can cause the still-hanging slabs of solidified mud to come rushing down the slopes at a speed of more than 30 kilometres per hour, causing devastating results. Several towns in the Puyallup River valley in Washington state, including Orting, are built on top of lahar deposits that are only about 500 years oldLahar – A hot lahar rushes down a river valley in Guatemala near the Santa Maria volcano, 1989.
40. Mudslide – Mudflows contain a significant proportion of clay, which makes them more fluid than debris flows, thus, they are able to travel farther and across lower slope angles. Both types are generally mixtures of various kinds of materials of different sizes, mudflows are often called mudslides, a term applied indiscriminately by the mass media to a variety of mass wasting events. Mudflows often start as slides, becoming flows as water is entrained along the flow path, other types of mudflows include lahars and jökulhlaups. A statutory definition of flood-related mudslide appears in the United States National Flood Insurance Act of 1968, as amended, codified at 42 USC Sections 4001, heavy rainfall, snowmelt, or high levels of ground water flowing through cracked bedrock may trigger a movement of soil or sediments. Floods and debris flows may also occur when strong rains on hill or mountain slopes cause extensive erosion and/or what is known as channel scour, the 2006 Sidoarjo mud flow may have been caused by rogue drilling. Some broad mudflows are rather viscous and therefore slow, others very quickly. If large enough, they can devastate villages and countrysides and they are composed of at least 50% silt and clay-sized materials and up to 30% water. The point where a material begins to flow depends on its grain size. Fine grainy material or soil has a friction angle than a coarse sediment or a debris flow. On December 14,1999 in Vargas, Venezuela, a known as The Vargas tragedy significantly altered more than 60 kilometers of the coastline. Landslide is a general term than mudflow. It refers to the failure and subsequent movement downslope of any types of surface movement of soil, rock. The term incorporates earth slides, rock falls, debris flows and they do not have to be as fluid as a mudflow. Mudflows can be caused by heavy rains or a sudden thaw. They consist mainly of mud and water plus fragments of rock and other debris and they can move houses off their foundations or bury a place within minutes because of incredibly strong currents. When a mudflow occurs it is given four named areas, the scarp, in bigger mudflows the upper and lower shelves. The main scarp will be the area of incidence, the toe is the last affected area. The upper and lower shelves are located there is a large dip in the mudflows pathMudslide – Mailboxes caught in a mudflow
41. Columbia River – The Columbia River is the largest river in the Pacific Northwest region of North America. The river rises in the Rocky Mountains of British Columbia, Canada and it flows northwest and then south into the US state of Washington, then turns west to form most of the border between Washington and the state of Oregon before emptying into the Pacific Ocean. The river is 1,243 miles long, and its largest tributary is the Snake River and its drainage basin is roughly the size of France and extends into seven US states and a Canadian province. By volume, the Columbia is the fourth-largest river in the United States, the rivers heavy flow and relatively steep gradient gives it tremendous potential for the generation of electricity. The Columbia and its tributaries have been central to the regions culture and they have been used for transportation since ancient times, linking the many cultural groups of the region. The river system hosts many species of fish, which migrate between freshwater habitats and the saline waters of the Pacific Ocean. In the following decades, fur trading companies used the Columbia as a key transportation route, steamships along the river linked communities and facilitated trade, the arrival of railroads in the late 19th century, many running along the river, supplemented these links. Since the late 19th century, public and private sectors have developed the river. The development, commonly referred to as taming or harnessing of the river, has been massive, to aid ship and barge navigation, locks have been built along the lower Columbia and its tributaries, and dredging has opened, maintained, and enlarged shipping channels. Since the early 20th century, dams have been built across the river for the purposes of power generation, navigation, irrigation, and flood control. Today, a reservoir lies along nearly every US mile of the once free-flowing river. Production of nuclear power has taken place at two sites along the river, plutonium for nuclear weapons was produced for decades at the Hanford Site, which is now the most contaminated nuclear site in the US. All these developments have had a impact on river environments, mainly through industrial pollution. The Columbia begins its 1, 243-mile journey in the southern Rocky Mountain Trench in British Columbia, Columbia Lake –2,690 feet above sea level – and the adjoining Columbia Wetlands form the rivers headwaters. The trench is a broad, deep, and long glacial valley between the Canadian Rockies and the Columbia Mountains in BC. Rounding the northern end of the Selkirk Mountains, the river turns south through a region known as the Big Bend Country, passing through Revelstoke Lake. Revelstoke, the Big Bend, and the Columbia Valley combined are referred to in BC parlance as the Columbia Country. Below the Arrow Lakes, the Columbia passes the cities of Castlegar, located at the Columbias confluence with the Kootenay River, the Pend Oreille River joins the Columbia about 2 miles north of the US–Canada borderColumbia River – Bonneville Dam, in the Columbia River Gorge
42. David Alexander Johnston – David Alexander Johnston was an American USGS volcanologist who was killed by the 1980 eruption of Mount St. Helens in Washington. A principal scientist on the USGS monitoring team, Johnston was killed in the eruption while manning an observation post 6 miles away on the morning of May 18,1980 and he was the first to report the eruption, transmitting Vancouver. Before he was swept away by a lateral blast, despite a thorough search, Johnstons body was never found, but state highway workers discovered remnants of his USGS trailer in 1993. Johnstons career took him across the United States, where he studied Augustine Volcano in Alaska, the San Juan volcanic field in Colorado, Johnston was a meticulous and talented scientist, known for his analyses of volcanic gases and their relationship to eruptions. This, along with his enthusiasm and positive attitude, made him liked and respected by many co-workers, after his death, other scientists lauded his character, both verbally and in dedications and letters. Johnston felt scientists must do what is necessary, including taking risks and his work, and that of fellow USGS scientists convinced authorities to close Mount St. Helens to the public before the 1980 eruption. They maintained the closure despite heavy pressure to re-open the area and his story became intertwined within the popular image of volcanic eruptions and their threat to society, and a part of volcanologys history. To date, Johnston, along with Harry Glicken, is one of two American volcanologists known to have died in a volcanic eruption. Following his death, Johnston was commemorated in several ways, including a fund established in his name at the University of Washington to fund graduate-level research. Two volcano observatories were established and named him, one in Vancouver, Washington. Johnstons life and death are featured in documentaries, films, docudramas. Along with others who died during the eruption, Johnstons name is inscribed on memorials dedicated to their memory, Johnston was born at the University of Chicago Hospital on December 18,1949, to Thomas and Alice Johnston. They originally lived in Hometown, Illinois, but moved to Oak Lawn shortly after Johnstons birth, Johnston grew up with one sister. His father worked as an engineer at a company and his mother as a newspaper editor. Johnston often took photographs for his mothers newspaper and contributed articles to his schools newspaper, after graduating from high school, Johnston attended the University of Illinois at Urbana-Champaign. He planned to study journalism, but became discouraged after a poor grade in a lecture class. He was intrigued by a geology class, and changed his major. His first geologic project was a study of the Precambrian rock that forms Michigans Upper Peninsula, There he investigated the remains of an ancient volcano, a suite of metamorphosed basalts, a gabbroic sill, and volcanic roots in the form of a dioritic and gabbroic intrusionDavid Alexander Johnston – David A. Johnston, 13 hours before his death at the 1980 eruption of Mount St. Helens
43. United States Geological Survey – The United States Geological Survey is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its resources. The organization has four science disciplines, concerning biology, geography, geology. The USGS is a research organization with no regulatory responsibility. The USGS is a bureau of the United States Department of the Interior, the USGS employs approximately 8,670 people and is headquartered in Reston, Virginia. The USGS also has major offices near Lakewood, Colorado, at the Denver Federal Center, the current motto of the USGS, in use since August 1997, is science for a changing world. The agencys previous slogan, adopted on the occasion of its anniversary, was Earth Science in the Public Service. Prompted by a report from the National Academy of Sciences, the USGS was created, by a last-minute amendment and it was charged with the classification of the public lands, and examination of the geological structure, mineral resources, and products of the national domain. This task was driven by the need to inventory the vast lands added to the United States by the Louisiana Purchase in 1803, the legislation also provided that the Hayden, Powell, and Wheeler surveys be discontinued as of June 30,1879. Clarence King, the first director of USGS, assembled the new organization from disparate regional survey agencies, after a short tenure, King was succeeded in the directors chair by John Wesley Powell. Administratively, it is divided into a Headquarters unit and six Regional Units, Other specific programs include, Earthquake Hazards Program monitors earthquake activity worldwide. The National Earthquake Information Center in Golden, Colorado on the campus of the Colorado School of Mines detects the location, the USGS also runs or supports several regional monitoring networks in the United States under the umbrella of the Advanced National Seismic System. The USGS informs authorities, emergency responders, the media, and it also maintains long-term archives of earthquake data for scientific and engineering research. It also conducts and supports research on long-term seismic hazards, USGS has released the UCERF California earthquake forecast. The USGS National Geomagnetism Program monitors the magnetic field at magnetic observatories and distributes magnetometer data in real time, the USGS operates the streamgaging network for the United States, with over 7400 streamgages. Real-time streamflow data are available online, since 1962, the Astrogeology Research Program has been involved in global, lunar, and planetary exploration and mapping. USGS operates a number of related programs, notably the National Streamflow Information Program. USGS Water data is available from their National Water Information System databaseUnited States Geological Survey – Clarence King, founder of the USGS
44. Vancouver, Washington – Vancouver is a city on the north bank of the Columbia River in the U. S. State of Washington, and the largest suburb of Portland, Oregon. Incorporated in 1857, it is the fourth largest city in the state, Vancouver is the county seat of Clark County and forms part of the Portland-Vancouver metropolitan area, the 23rd largest metropolitan area in the United States. Originally established in 1825 around Fort Vancouver, a fur trading outpost, in 2005, Money magazine named it No.91 on its list of best places in America to live. In 2016, WalletHub ranks Vancouver the 39th best place to live for families in the US, Vancouver shares its name with the larger city of Vancouver in southern British Columbia, Canada, approximately 300 mi to the north. Both cities were named after sea captain George Vancouver, but the American city is older, Vancouver, City officials have periodically suggested changing the U. S. citys name to Fort Vancouver to reduce confusion with its larger and better-known northern neighbor. Many Pacific Northwest residents distinguish between the two cities by referring to the Canadian city as Vancouver, B. C. and the United States city as Vancouver, Washington, or Vancouver, local nicknames include, Vantucky and The Couv. In 2013, the nickname Vansterdam surfaced as a result of the legalization of marijuana in the state of Washington and this nickname has also long been used to refer to Vancouver, B. C. as well. This name is a reference to the cannabis-legal city of Amsterdam in the Netherlands. The Vancouver, Washington, area was inhabited by a variety of Native American tribes, most recently the Chinook and Klickitat nations, the Chinookan and Klickitat names for the area were reportedly Skit-so-to-ho and Ala-si-kas, respectively, meaning land of the mud-turtles. First European contact was made in 1775, with half of the indigenous population dead from smallpox before the Lewis. Meriwether Lewis wrote that the Vancouver area was the only desired situation for settlement west of the Rocky Mountains, the first permanent European settlement did not occur until 1824, when Fort Vancouver was established as a fur trading post of the Hudsons Bay Company. From that time on, the area was settled by both the US and Britain under a joint occupation agreement. Joint occupation led to the Oregon boundary dispute and ended on June 15,1846, with the signing of the Oregon Treaty, in 1850, Amos Short traced over the claim of Williamson and named the town Columbia City. It changed to Vancouver in 1855, the City of Vancouver was incorporated on January 23,1857. U. S. Army Captain Ulysses S. Grant was quartermaster at what was known as Columbia Barracks for 15 months beginning in September 1852. Soon after leaving Vancouver, he resigned from the army and did not serve again until the outbreak of the American Civil War, other notable generals to have served in Vancouver include George B. McClellan, Philip Sheridan, Oliver O. Howard and 1953 Nobel Peace Prize recipient George Marshall, Vancouver became the end point for two ultra-long flights from Moscow, USSR over the North Pole. The first of these flights was performed by Valery Chkalov in 1937 on a Tupolev ANT-25RD airplane, Chkalov was originally scheduled to land at an airstrip in nearby Portland, Oregon, but redirected at the last minute to Vancouvers Pearson AirfieldVancouver, Washington – A glimpse of Downtown Vancouver from the on-ramp to state highway 14
45. David A. Johnston – David Alexander Johnston was an American USGS volcanologist who was killed by the 1980 eruption of Mount St. Helens in Washington. A principal scientist on the USGS monitoring team, Johnston was killed in the eruption while manning an observation post 6 miles away on the morning of May 18,1980 and he was the first to report the eruption, transmitting Vancouver. Before he was swept away by a lateral blast, despite a thorough search, Johnstons body was never found, but state highway workers discovered remnants of his USGS trailer in 1993. Johnstons career took him across the United States, where he studied Augustine Volcano in Alaska, the San Juan volcanic field in Colorado, Johnston was a meticulous and talented scientist, known for his analyses of volcanic gases and their relationship to eruptions. This, along with his enthusiasm and positive attitude, made him liked and respected by many co-workers, after his death, other scientists lauded his character, both verbally and in dedications and letters. Johnston felt scientists must do what is necessary, including taking risks and his work, and that of fellow USGS scientists convinced authorities to close Mount St. Helens to the public before the 1980 eruption. They maintained the closure despite heavy pressure to re-open the area and his story became intertwined within the popular image of volcanic eruptions and their threat to society, and a part of volcanologys history. To date, Johnston, along with Harry Glicken, is one of two American volcanologists known to have died in a volcanic eruption. Following his death, Johnston was commemorated in several ways, including a fund established in his name at the University of Washington to fund graduate-level research. Two volcano observatories were established and named him, one in Vancouver, Washington. Johnstons life and death are featured in documentaries, films, docudramas. Along with others who died during the eruption, Johnstons name is inscribed on memorials dedicated to their memory, Johnston was born at the University of Chicago Hospital on December 18,1949, to Thomas and Alice Johnston. They originally lived in Hometown, Illinois, but moved to Oak Lawn shortly after Johnstons birth, Johnston grew up with one sister. His father worked as an engineer at a company and his mother as a newspaper editor. Johnston often took photographs for his mothers newspaper and contributed articles to his schools newspaper, after graduating from high school, Johnston attended the University of Illinois at Urbana-Champaign. He planned to study journalism, but became discouraged after a poor grade in a lecture class. He was intrigued by a geology class, and changed his major. His first geologic project was a study of the Precambrian rock that forms Michigans Upper Peninsula, There he investigated the remains of an ancient volcano, a suite of metamorphosed basalts, a gabbroic sill, and volcanic roots in the form of a dioritic and gabbroic intrusionDavid A. Johnston – David A. Johnston, 13 hours before his death at the 1980 eruption of Mount St. Helens
46. Cameroon line – The Cameroon line is a 1,600 km chain of volcanoes. The islands, which span the equator, have tropical climates and are home to many unique plant, the mainland mountain regions are much cooler than the surrounding lowlands, and also contain unique and ecologically important environments. The Cameroon volcanic line is unusual in extending through both the ocean and the continental crust. Various hypotheses have advanced by different geologists to explain the line. In the Gulf of Guinea, the Cameroon line consists of six offshore volcanic swells that have formed islands or seamounts, from the southwest to the northeast the island groups are Pagalu, São Tomé, Príncipe and Bioko. Two large seamounts lie between São Tomé and Príncipe, and between Principe and Bioko, on the mainland, the line starts with Mount Cameroon and extends northeast in a range known as the Western High Plateau, home to the Cameroonian Highlands forests. Volcanic swells further inland are Manengouba, Bamboutu and the Oku Massif, east of Oku there are further volcanic mountains in the Ngaoundere Plateau, some of which appear to have similar origins. The southernmost island in the chain is Annobón, also known as Pagalu and it is an extinct volcano that rises from deep water to 598 m above sea level. The average temperature is 26.1 °C, with seasonal variation. Most rain falls from November to May, with annual precipitation averaging 1,196 mm - less than on the mainland, Annobón has lush valleys and steep mountains, covered with rich woods and luxuriant vegetation. The island belongs to Equatorial Guinea, the small population lives in one community, practicing some agriculture but mainly living by fishing. São Tomé Island is 854 km2 in area, lying almost on the equator. The entire island is a shield volcano which rises from the floor of the Atlantic Ocean, over 3,000 m below sea level. The oldest rock on Sao Tome is 13 million years old, most of the lava erupted on São Tomé over the last million years has been basalt. The youngest dated rock on the island is about 100,000 years old, due to the prevailing southwesterly winds, there is great variability in rainfall. In the rain shadow to the northeast of Sao Tome the vegetation is dry savannah, by contrast, the lush south and west of the island receive about 6 m of rain, mostly falling in March and April. The climate is hot and humid with the season from October to May. The higher slopes of the island are forested and form part of the Obo National Park, São Tomé has never been connected to Africa, and therefore has many unique plants and birdsCameroon line – Map of the Gulf of Guinea, showing the chain of islands formed by the Cameroon line of volcanoes.
47. Mount Oku – Mount Oku, or Kilum Mountain, is the largest volcano in the Oku Massif, in the Cameroon Volcanic Line, located in the Oku region of the Western High Plateau of Cameroon. It is the second highest mountain in mainland Central Africa, the stratovolcano rises to 3,011 metres above sea level, and is cut by a large caldera. Some of the rocks have ages starting from 24.9 to 22.1 million years ago, but much more recent activity has occurred. The mountain is built of basaltic and hawaiitic lavas, succeeded by trachytes, further trachytic lavas, tuffs and breccias were produced, and the most recent phase produced pyroclastic cones and explosion craters. One of these craters holds Lake Oku, from which flows of basalt issued in the north, a small sphagnum community with associated wetland plant species was discovered at 2,900 m in 1997, near the summit of the volcano, the highest sphagnum bog in West Africa. This site includes several plant species endemic to the Kilum-Ijim area, the 200 km2 of forests of the Kilum-Ijim area around the mountain form the largest remaining patch of montane forest in West Africa, an important habitat for endemic species of animals and plants. The forest is at risk, since it is surrounded by a density of human settlements. Most of the area within the Kilum-Ijim boundary is above 2000 metres in height, at lower elevations, most of the submontane forest has been cleared for agriculture. Based on satellite images, between 1958 and 1988 about half of the forest was lost, although regeneration began soon after the project was started in 1987. Since then there has been steady recovery of the forest reserve, list of Ultras of Africa Lake Nyos Lake Monoun Mont Oku, Cameroon on PeakbaggerMount Oku – Lake Oku near Mount Oku
48. Cameroon – Cameroon, officially the Republic of Cameroon, is a country in Central Africa. It is bordered by Nigeria to the west, Chad to the northeast, the Central African Republic to the east, and Equatorial Guinea, Gabon, Cameroons coastline lies on the Bight of Biafra, part of the Gulf of Guinea and the Atlantic Ocean. French and English are the languages of Cameroon. The country is referred to as Africa in miniature for its geological and cultural diversity. Natural features include beaches, deserts, mountains, rainforests, the country is well known for its native styles of music, particularly makossa and bikutsi, and for its successful national football team. Early inhabitants of the territory included the Sao civilisation around Lake Chad, portuguese explorers reached the coast in the 15th century and named the area Rio dos Camarões, which became Cameroon in English. Fulani soldiers founded the Adamawa Emirate in the north in the 19th century, Cameroon became a German colony in 1884 known as Kamerun. After World War I, the territory was divided between France and the United Kingdom as League of Nations mandates, the Union des Populations du Cameroun political party advocated independence, but was outlawed by France in the 1950s, leading to the Cameroonian Independence War. It waged war on French and UPC militant forces until 1971, in 1960, the French-administered part of Cameroon became independent as the Republic of Cameroun under President Ahmadou Ahidjo. The southern part of British Cameroons federated with it in 1961 to form the Federal Republic of Cameroon, the federation was abandoned in 1972. The country was renamed the United Republic of Cameroon in 1972, Cameroon enjoys relatively high political and social stability. This has permitted the development of agriculture, roads, railways, nevertheless, large numbers of Cameroonians live in poverty as subsistence farmers. Power lies firmly in the hands of the president since 1982, Paul Biya. The English-speaking territories of Cameroon have grown increasingly alienated from the government, politicians and civil society in English-speaking regions have called for greater decentralization and even complete separation or independence from the former French-governed territories. The territory of present-day Cameroon was first settled during the Neolithic Era, the longest continuous inhabitants are groups such as the Baka. From here, Bantu migrations into eastern, southern, and central Africa are believed to have originated about 2,000 years ago, the Sao culture arose around Lake Chad c. AD500 and gave way to the Kanem and its successor state, kingdoms, fondoms, and chiefdoms arose in the west. Portuguese sailors reached the coast in 1472 and they noted an abundance of the ghost shrimp Lepidophthalmus turneranus in the Wouri River and named it Rio dos Camarões, which became Cameroon in EnglishCameroon – Bamum script
49. Geology of Uruguay – Big events that have shaped the geology of Uruguay include the Transamazonian orogeny, the breakup of Rodinia and the opening of the South Atlantic. The shield in Uruguay goes under the name of Rio Grande do Sul—Uruguay Shield, the shield was formed during two orogenic events, one 2000 million years ago for the western part and another 700–500 mya for the eastern part. West of Sarandí del Yí Shear Zone the Río de la Plata Craton is intruded by the Late Paleoproterozoic Florida dyke swarm, after the assembly of the final shield configuration the territory of Uruguay have been covered by several sedimentary formations ranging from Devonian sandstones to Quaternary loess. All of the sedimentary formations covers only patches of the country since deposition have not been uniform and erosion have cleaned surfaces, creeks, sedimentary rocks of Lower Devonian age are found in the central part of Uruguay being exposed as a narrow east-west to northeast oriented band. The upper and better part of this sequence is made up of sandstone. The lower sandstones of this sequence have characteristics similar to the Furnas Formation of São Paulo in Brazil, during the Late Paleozoic the territory of Uruguay was affected by the Karoo Glaciation and was subsequently covered by ice lobes of the great ice sheet that covered large parts of Gondwana. Glacial striae on shales and varve-like sediments found in Uruguay have been associated with this glaciation, during the early rifting stages of the South Atlantic the area of southern Paraná Basin suffered a gentle uplifting that deviated sediments into the Tacuarembó region of Uruguay. These changes led to the formation of the Itacuanbú and Tacuarembó formations during the Mid Jurassic to Early Cretaceous, parts of the Tacuarembó formation came to be preserved thanks to a unit of the Paraná traps, the Arapey basalts, that erupted 132 mya and covered the sediments. This volcanic material erupted in the Cretaceous period during the opening of the South Atlantic and has linked to the Tristan da Cunha plume. The bulk of this material is basalt but there are rhyolites as well. Associated with this volcanism are also syenite and other granitoid intrusions exposed as outcrops in small areas of Southeastern UruguayGeology of Uruguay – Cerro Batoví is an erosional remnant made up of flood basalt overlying sedimentary rocks.