1.
Summit
–
A summit is a point on a surface that is higher in elevation than all points immediately adjacent to it. Mathematically, a summit is a maximum in elevation. The topographic terms acme, apex, peak, and zenith are synonymous, the UIAA definition is that a summit is independent if it has a prominence of 30 metres or more, it is a mountain if it has a prominence of at least 300 metres. This can be summarised as follows, A pyramidal peak is an exaggerated form produced by ice erosion of a mountain top, Summit may also refer to the highest point along a line, trail, or route. In many parts of the western United States, the term refers to the highest point along a road, highway. For example, the highest point along Interstate 80 in California is referred to as Donner Summit while the highest point on Interstate 5 is Siskiyou Mountain Summit, geoid Hill List of highest mountains Maxima and minima Nadir Summit accordance Peak finder
Summit
–
The highest elevation summit, Mount Everest, shown with a climber at the summit wearing an oxygen mask. The summit is 8850 m (29,035 ft) elevation. (While the cruising altitude of jetliners is roughly 10,000 m (32,808 feet), they are pressurized.)
Summit
–
View from the summit of Switzerland's highest,
Monte Rosa
Summit
–
The summit of
Mount Damavand,
Iran, in winter
Summit
–
Jeff Davis Peak, one of the highest peaks entirely within
Nevada
2.
Geographic coordinate system
–
A geographic coordinate system is a coordinate system used in geography that enables every location on Earth to be specified by a set of numbers, letters or symbols. The coordinates are chosen such that one of the numbers represents a vertical position. A common choice of coordinates is latitude, longitude and elevation, to specify a location on a two-dimensional map requires a map projection. The invention of a coordinate system is generally credited to Eratosthenes of Cyrene. Ptolemy credited him with the adoption of longitude and latitude. Ptolemys 2nd-century Geography used the prime meridian but measured latitude from the equator instead. Mathematical cartography resumed in Europe following Maximus Planudes recovery of Ptolemys text a little before 1300, in 1884, the United States hosted the International Meridian Conference, attended by representatives from twenty-five nations. Twenty-two of them agreed to adopt the longitude of the Royal Observatory in Greenwich, the Dominican Republic voted against the motion, while France and Brazil abstained. France adopted Greenwich Mean Time in place of local determinations by the Paris Observatory in 1911, the latitude of a point on Earths surface is the angle between the equatorial plane and the straight line that passes through that point and through the center of the Earth. Lines joining points of the same latitude trace circles on the surface of Earth called parallels, as they are parallel to the equator, the north pole is 90° N, the south pole is 90° S. The 0° parallel of latitude is designated the equator, the plane of all geographic coordinate systems. The equator divides the globe into Northern and Southern Hemispheres, the longitude of a point on Earths surface is the angle east or west of a reference meridian to another meridian that passes through that point. All meridians are halves of great ellipses, which converge at the north and south poles, the prime meridian determines the proper Eastern and Western Hemispheres, although maps often divide these hemispheres further west in order to keep the Old World on a single side. The antipodal meridian of Greenwich is both 180°W and 180°E, the combination of these two components specifies the position of any location on the surface of Earth, without consideration of altitude or depth. The grid formed by lines of latitude and longitude is known as a graticule, the origin/zero point of this system is located in the Gulf of Guinea about 625 km south of Tema, Ghana. To completely specify a location of a feature on, in, or above Earth. Earth is not a sphere, but a shape approximating a biaxial ellipsoid. It is nearly spherical, but has an equatorial bulge making the radius at the equator about 0. 3% larger than the radius measured through the poles, the shorter axis approximately coincides with the axis of rotation
Geographic coordinate system
–
Longitude lines are perpendicular and latitude lines are parallel to the equator.
3.
Moquegua Region
–
Moquegua is a department in southern Peru that extends from the coast to the highlands. The regions volcanoes and its geomorphology make its geography remarkable and these are veritable oasis enclaved in the rocks, arid hillsides and some terraces where horticulture is possible. High quality alfalfa as well as fruits, especially grapes, are produced here, due to a good climate, the second sector is the valley of Omate, one of the most populated and fertile soils of the department. The Ubinas Volcano, Perus most active volcano, is located nearby, in the hillsides, the land is fertile in contrast with the desolation and sterility of its highlands. In the southern part of the Tambo River is located the town of Carumas, the Moquegua River is a short run one and is formed by its tributaries, the Torata, Huaracane and Tumilaca rivers. After passing through the capital, it digs deep into a canyon called the Osmare. The Moquegua Region is bordered by the Arequipa Region in the north, the Puno Region in the east, the Tacna Region in the south, the region is divided into 3 provinces, which are composed of 20 districts. As of 2002, the Instituto Nacional de Estadística e Informática estimates the population to be 156,750. According to the last census in Peru in 2007, the languages learnt first by the residents were Spanish, Aymara, Quechua, other indigenous languages were learnt first by 0. 19% and foreign languages by 0. 04%. The Quechua variety spoken in Moquegua is Cusco–Collao Quechua, the largest immigrant groups come from the Puno Region and the Arequipa Region. The population is out with 43. 3% under the age of 20,9. 9% from 20 to 24,28. 6% from 25 to 44,13. 4% from 45 to 64. Secondary education has been attended by 33. 3% of the population and 5. 5% also have graduated from non-university higher education,37. 9% only have attended primary education and 7. 1% have not had any education. The illiteracy rate in the region is 10%, according to chronicler Garcilaso de la Vega, it was Inca Mayta Cápac who organized the military expedition to expand the domains of the Cusco monarchs along this part of the coast. Since these were fertile lands, capable of supporting a larger population, in doing so, they were also protecting the Inca domain over the conquered lands. C. There is no data on the Spanish conquest or the founding of the city of Moquegua by its army. Presumably, it was founded on 25 November 1541 by Pedro Cansino and his wife, during the War of the Pacific, Moquegua suffered the invasion of Chilean troops. This army looted all buildings —including churches—, tortured women, Contisuyo Museum is also located in the city of Moquegua. The museum exhibits a variety of remains of the Uros
Moquegua Region
–
Moquegua valley
Moquegua Region
–
Plaza de Armas in the city of Moquegua, the background shows the city's cathedral.
4.
Peru
–
Peru, officially the Republic of Peru, is a country in western South America. It is bordered in the north by Ecuador and Colombia, in the east by Brazil, in the southeast by Bolivia, in the south by Chile, and in the west by the Pacific Ocean. Peruvian territory was home to ancient cultures spanning from the Norte Chico civilization in Caral, one of the oldest in the world, to the Inca Empire, the largest state in Pre-Columbian America. The Spanish Empire conquered the region in the 16th century and established a Viceroyalty with its capital in Lima, ideas of political autonomy later spread throughout Spanish America and Peru gained its independence, which was formally proclaimed in 1821. After the battle of Ayacucho, three years after proclamation, Peru ensured its independence, subsequently, the country has undergone changes in government from oligarchic to democratic systems. Peru has gone through periods of political unrest and internal conflict as well as periods of stability, Peru is a representative democratic republic divided into 25 regions. It is a country with a high Human Development Index score. Its main economic activities include mining, manufacturing, agriculture and fishing, the Peruvian population, estimated at 31.2 million in 2015, is multiethnic, including Amerindians, Europeans, Africans and Asians. The main spoken language is Spanish, although a significant number of Peruvians speak Quechua or other native languages and this mixture of cultural traditions has resulted in a wide diversity of expressions in fields such as art, cuisine, literature, and music. The name of the country may be derived from Birú, the name of a ruler who lived near the Bay of San Miguel, Panama. When his possessions were visited by Spanish explorers in 1522, they were the southernmost part of the New World yet known to Europeans, thus, when Francisco Pizarro explored the regions farther south, they came to be designated Birú or Perú. An alternative history is provided by the contemporary writer Inca Garcilasco de la Vega, son of an Inca princess, the Spanish Crown gave the name legal status with the 1529 Capitulación de Toledo, which designated the newly encountered Inca Empire as the province of Peru. Under Spanish rule, the country adopted the denomination Viceroyalty of Peru, the earliest evidences of human presence in Peruvian territory have been dated to approximately 9,000 BC. Andean societies were based on agriculture, using such as irrigation and terracing, camelid husbandry. Organization relied on reciprocity and redistribution because these societies had no notion of market or money, the oldest known complex society in Peru, the Norte Chico civilization, flourished along the coast of the Pacific Ocean between 3,000 and 1,800 BC. These early developments were followed by archaeological cultures that developed mostly around the coastal, the Cupisnique culture which flourished from around 1000 to 200 BC along what is now Perus Pacific Coast was an example of early pre-Incan culture. The Chavín culture that developed from 1500 to 300 BC was probably more of a religious than a political phenomenon, on the coast, these included the civilizations of the Paracas, Nazca, Wari, and the more outstanding Chimu and Mochica. Their capital was at Chan Chan outside of modern-day Trujillo, in the 15th century, the Incas emerged as a powerful state which, in the span of a century, formed the largest empire in pre-Columbian America with their capital in Cusco
Peru
–
Sculpted
Chavin head embedded in one of the walls of the temple of
Chavín de Huantar
Peru
Peru
–
A
Moche ceramic vessel from the 5th century depicting a man's head
Peru
–
The citadel of
Machu Picchu, an iconic symbol of pre-Columbian Peru
5.
Mountain range
–
A mountain range is a geographic area containing numerous geologically related mountains. A mountain system or system of ranges, sometimes is used to combine several geological features that are geographically related. Mountain ranges are usually segmented by highlands or mountain passes and valleys, individual mountains within the same mountain range do not necessarily have the same geologic structure or petrology. They may be a mix of different orogenic expressions and terranes, for example thrust sheets, uplifted blocks, fold mountains, most geologically young mountain ranges on the Earths land surface are associated with either the Pacific Ring of Fire or the Alpide Belt. The Andes is 7,000 kilometres long and is considered the worlds longest mountain system. The Alpide belt includes Indonesia and southeast Asia, through the Himalaya, the belt also includes other European and Asian mountain ranges. The Himalayas contain the highest mountains in the world, including Mount Everest, mountain ranges outside of these two systems include the Arctic Cordillera, the Urals, the Appalachians, the Scandinavian Mountains, the Altai Mountains and the Hijaz Mountains. If the definition of a range is stretched to include underwater mountains. The mountain systems of the earth are characterized by a tree structure, the sub-range relationship is often expressed as a parent-child relationship. For example, the White Mountains of New Hampshire and the Blue Ridge Mountains are sub-ranges of the Appalachian Mountains, equivalently, the Appalachians are the parent of the White Mountains and Blue Ridge Mountains, and the White Mountains and the Blue Ridge Mountains are children of the Appalachians. The position of mountains influences climate, such as rain or snow, when air masses move up and over mountains, the air cools producing orographic precipitation. As the air descends on the side, it warms again and is drier. Often, a shadow will affect the leeward side of a range. Mountain ranges are constantly subjected to forces which work to tear them down. Erosion is at work while the mountains are being uplifted and long after until the mountains are reduced to low hills, rivers are traditionally believed to be the principle erosive factor on mountain ranges, with their ability of bedrock incision and sediment transport. The rugged topography of a range is the product of erosion. The basins adjacent to a mountain range are filled with sediments which are buried and turned into sedimentary rock. The early Cenozoic uplift of the Rocky Mountains of Colorado provides an example and this mass of rock was removed as the range was actively undergoing uplift
Mountain range
–
The
Himalayas, the highest mountain range on Earth, seen from space
Mountain range
–
Mountain range of
High Tatras in
Slovakia in 1865
Mountain range
–
The
Andes, the world's longest mountain range on the surface of a continent, seen from the air
Mountain range
–
Hillary and Norgay Montes on Pluto (14 July 2015)
6.
Central Volcanic Zone
–
The Andean Volcanic Belt is a major volcanic belt along the Andean cordillera in Argentina, Bolivia, Chile, Colombia, Ecuador and Peru. It formed as a result of subduction of the Nazca Plate, the belt is subdivided into four main volcanic zones that are separated from each other by volcanic gaps. The volcanoes of the belt are diverse in terms of activity style, products, while some differences can be explained by which volcanic zone a volcano belongs to, there are significant differences within volcanic zones and even between neighboring volcanoes. Romeral in Colombia is the northernmost member of the Andean Volcanic Belt, South of latitude 49° S within the Austral Volcanic Zone volcanic activity decreases with the southernmost volcano Fueguino in Tierra del Fuego archipelago. The Andean Volcanic Belt is segmented into four areas of active volcanism. The Northern Volcanic Zone extends from Colombia to Ecuador and includes all volcanoes on the mainland of these countries. Of the zones volcanoes,55 are located in Ecuador while 19 are in Colombia, in Ecuador the volcanoes are located in the Cordillera Occidental and Cordillera Real while in Colombia they are located in Cordillera Central. The volcanic arc has formed due to subduction of the Nazca Plate under western South America, some volcanoes of the Northern Volcanic Zone, such as Galeras and Nevado del Ruiz that lie in densely populated highland areas, are major sources of hazards. It has been estimated that crustal thickness beneath this region varies from around 40 to perhaps more than 55 km, sangay is the southernmost volcano of the Northern Volcanic Zone. The Central Volcanic Zone is an arc in western South America. It is one of the four zones of the Andes. The Central Volcanic Zone extends from Peru to Chile and forms the boundary of the Altiplano plateau. The volcanic arc has formed due to subduction of the Nazca Plate under western South America along the Peru–Chile Trench, the CVZ is characterized by a continental crust that reaches a thickness of approximately 70 km. Within this zone there are 44 major and 18 minor volcanic centers that are considered to be active, other silicic systems are Los Frailes ignimbrite plateau in Bolivia, and the caldera complexes of Incapillo and Cerro Galán in Argentina. The South Volcanic Zone extends roughly from Central Chiles Andes at the latitude of Santiago, 33°S, to Cerro Arenales in Aysén Region at ca. 46°S, a distance of well over 870 mi, the arc has formed due to subduction of the Nazca Plate under the South American Plate along the Peru–Chile Trench. The southern end of the SVZ is marked by the Chile Triple Junction where the Chile Rise subducts under South America at the Taitao Peninsula giving origin to the Patagonian Volcanic Gap, further south lies the Austral Volcanic Zone. During the Pliocene the SVZ south of 38°S consisted of a volcanic arc
Central Volcanic Zone
–
Map of the volcanic arcs in the
Andes, and
subducted structures affecting volcanism
Central Volcanic Zone
–
Nevados de Chillán (2003)
7.
Andes
–
The Andes or Andean Mountains are the longest continental mountain range in the world. They are a range of highlands along the western edge of South America. This range is about 7,000 km long, about 200 to 700 km wide, the Andes extend from north to south through seven South American countries, Venezuela, Colombia, Ecuador, Peru, Bolivia, Argentina and Chile. Along their length, the Andes are split into several ranges, the Andes are the location of several high plateaus – some of which host major cities, such as Quito, Bogotá, Arequipa, Medellín, Sucre, Mérida and La Paz. The Altiplano plateau is the worlds second-highest after the Tibetan plateau and these ranges are in turn grouped into three major divisions based on climate, the Tropical Andes, the Dry Andes, and the Wet Andes. The Andes are the worlds highest mountain range outside of Asia, the highest mountain outside Asia, Mount Aconcagua, rises to an elevation of about 6,961 m above sea level. The peak of Chimborazo in the Ecuadorean Andes is farther from the Earths center than any other location on the Earths surface, the worlds highest volcanoes are in the Andes, including Ojos del Salado on the Chile-Argentina border, which rises to 6,893 m. The etymology of the word Andes has been debated, the majority consensus is that it derives from the Quechua word anti, which means east as in Antisuyu, one of the four regions of the Inca Empire. In the northern part of the Andes, the isolated Sierra Nevada de Santa Marta range is considered to be part of the Andes. The term cordillera comes from the Spanish word cordel, meaning rope, the Andes range is about 200 km wide throughout its length, except in the Bolivian flexure where it is about 640 kilometres wide. The Andes are the result of plate tectonics processes, caused by the subduction of oceanic crust beneath the South American plate. The main cause of the rise of the Andes is the compression of the rim of the South American Plate due to the subduction of the Nazca Plate. In the south, the Andes share a boundary with the former Patagonia Terrane. To the west, the Andes end at the Pacific Ocean, from a geographical approach, the Andes are considered to have their western boundaries marked by the appearance of coastal lowlands and a less rugged topography. The Andes Mountains also contain large quantities of iron ore located in mountains within the range. The Andean orogen has a series of bends or oroclines, the Bolivian Orocline is a seaward concave bending in the coast of South America and the Andes Mountains at about 18° S. At this point the orientation of the Andes turns from Northwest in Peru to South in Chile, the Andean segment north and south of the orocline have been rotated 15° to 20° counter clockwise and clockwise respectively. The Bolivian Orocline area overlaps with the area of maximum width of the Altiplano Plateau, the specific point at 18° S where the coastline bends is known as the Arica Elbow
Andes
–
Aerial photo of a portion of the Andes between
Argentina and
Chile
Andes
Andes
–
"
Cono de Arita " in the
Puna de Atacama,
Salta (
Argentina).
Andes
–
Aerial view of Aconcagua.
8.
Stratovolcano
–
A stratovolcano, also known as a composite volcano, is a conical volcano built up by many layers of hardened lava, tephra, pumice, and volcanic ash. Unlike shield volcanoes, stratovolcanoes are characterized by a profile and periodic explosive eruptions and effusive eruptions. The lava flowing from stratovolcanoes typically cools and hardens before spreading far due to high viscosity, the magma forming this lava is often felsic, having high-to-intermediate levels of silica, with lesser amounts of less-viscous mafic magma. Extensive felsic lava flows are uncommon, but have travelled as far as 15 km, stratovolcanoes are sometimes called composite volcanoes because of their composite layered structure built up from sequential outpourings of eruptive materials. They are among the most common types of volcanoes, in contrast to the less common shield volcanoes, two famous stratovolcanoes are Krakatoa, best known for its catastrophic eruption in 1883 and Vesuvius, famous for its destruction of the towns Pompeii and Herculaneum in 79 CE. Both eruptions claimed thousands of lives, in modern times, Mount Saint Helens and Mount Pinatubo have erupted catastrophically. Existence of stratovolcanoes has not been proved on other bodies of the solar system with one exception. Their existence was suggested for some isolated massifs on Mars, e. g. Zephyria Tholus, stratovolcanoes are common at subduction zones, forming chains along plate tectonic boundaries where oceanic crust is drawn under continental crust or another oceanic plate. The release of water from hydrated minerals is termed dewatering, and occurs at pressures and temperatures for each mineral. The magma then rises through the crust, incorporating silica-rich crustal rock, when the magma nears the top surface, it pools in a magma chamber under or within the volcano. There, the low pressure allows water and other volatiles dissolved in the magma to escape from solution, as occurs when a bottle of carbonated water is opened. Once a critical volume of magma and gas accumulates, the obstacle of the cone is overcome. In recorded history, explosive eruptions at subduction zone volcanoes have posed the greatest hazard to civilizations. Subduction-zone stratovolcanoes, such as Mount St. Helens, Mount Etna and Mount Pinatubo, typically erupt with explosive force, as a consequence, the tremendous internal pressures of the trapped volcanic gases remain in the pasty magma. Following the breaching of the chamber, the magma degasses explosively. The gases and water out with speed and force. Since 1600 CE, nearly 300,000 people have killed by volcanic eruptions. Most deaths were caused by flows and mudflows, deadly hazards that often accompany explosive eruptions of subduction-zone stratovolcanoes
Stratovolcano
–
Mount Vesuvius near Naples, Italy, erupted in AD 79. The last eruption of this stratovolcano occurred in March 1944. It has been essentially dormant since then.
Stratovolcano
–
Mount Etna on the Island of
Sicily
Stratovolcano
–
Mount Unzen in southwestern Japan
Stratovolcano
–
Mayon Volcano erupted on December 29, 2009, producing lava flows.
9.
Types of volcanic eruptions
–
Several types of volcanic eruptions—during which lava, tephra, and assorted gases are expelled from a volcanic vent or fissure—have been distinguished by volcanologists. These are often named after famous volcanoes where that type of behavior has been observed, some volcanoes may exhibit only one characteristic type of eruption during a period of activity, while others may display an entire sequence of types all in one eruptive series. There are three different types of eruptions, the most well-observed are magmatic eruptions, which involve the decompression of gas within magma that propels it forward. Phreatomagmatic eruptions are another type of eruption, driven by the compression of gas within magma. Within these wide-defining eruptive types are several subtypes, the weakest are Hawaiian and submarine, then Strombolian, followed by Vulcanian and Surtseyan. The stronger eruptive types are Pelean eruptions, followed by Plinian eruptions, subglacial and phreatic eruptions are defined by their eruptive mechanism, and vary in strength. An important measure of strength is Volcanic Explosivity Index, an order of magnitude scale ranging from 0 to 8 that often correlates to eruptive types. Explosive eruptions are characterized by gas-driven explosions that propels magma and tephra, effusive eruptions, meanwhile, are characterized by the outpouring of lava without significant explosive eruption. Volcanic eruptions vary widely in strength, on the one extreme there are effusive Hawaiian eruptions, which are characterized by lava fountains and fluid lava flows, which are typically not very dangerous. On the other extreme, Plinian eruptions are large, violent, volcanoes are not bound to one eruptive style, and frequently display many different types, both passive and explosive, even the span of a single eruptive cycle. Volcanoes do not always erupt vertically from a crater near their peak. Some volcanoes exhibit lateral and fissure eruptions, notably, many Hawaiian eruptions start from rift zones, and some of the strongest Surtseyan eruptions develop along fracture zones. Scientists believed that pulses of magma mixed together in the chamber before climbing upward—a process estimated to several thousands of years. But Columbia University volcanologists found that the eruption of Costa Rica’s Irazú Volcano in 1963 was likely triggered by magma that took a route from the mantle over just a few months. The volcanic explosivity index is a scale, from 0 to 8 and it is used by the Smithsonian Institutions Global Volcanism Program in assessing the impact of historic and prehistoric lava flows. It operates in a way similar to the Richter scale for earthquakes, the vast majority of volcanic eruptions are of VEIs between 0 and 2. Volcanic eruptions by VEI index Magmatic eruptions produce juvenile clasts during explosive decompression from gas release, Hawaiian eruptions are a type of volcanic eruption, named after the Hawaiian volcanoes with which this eruptive type is hallmark. Hawaiian eruptions are the calmest types of events, characterized by the effusive eruption of very fluid basalt-type lavas with low gaseous content
Types of volcanic eruptions
–
Some of the eruptive structures formed during volcanic activity: a
Plinian eruption column,
Hawaiian pahoehoe flows, and a lava arc from a
Strombolian eruption.
Types of volcanic eruptions
–
Ropey
pahoehoe lava from
Kilauea,
Hawaiʻi.
Types of volcanic eruptions
–
An example of the lava arcs formed during Strombolian activity. This image is of
Stromboli itself.
Types of volcanic eruptions
–
Tavurvur in
Papua New Guinea erupting.
10.
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 plateaus
Volcano
–
Cleveland Volcano in the
Aleutian Islands of
Alaska photographed from the
International Space Station, May 2006
Volcano
–
Ash plumes reached a height of 19 kilometres (12 mi) during the climactic
explosive eruption at
Mount Pinatubo, Philippines in 1991.
Volcano
–
A 2007 eruptive column at
Mount Etna producing volcanic ash, pumice and lava bombs
Volcano
–
Ubinas Volcano
11.
Pleistocene
–
The Pleistocene is the geological epoch which lasted from about 2,588,000 to 11,700 years ago, spanning the worlds most recent period of repeated glaciations. The end of the Pleistocene corresponds with the end of the last glacial period, the Pleistocene is the first epoch of the Quaternary Period or sixth epoch of the Cenozoic Era. In the ICS timescale, the Pleistocene is divided into four stages or ages, all of these stages were defined in southern Europe. In addition to this subdivision, various regional subdivisions are often used. Charles Lyell introduced the term pleistocene in 1839 to describe strata in Sicily that had at least 70% of their molluscan fauna still living today and this distinguished it from the older Pliocene Epoch, which Lyell had originally thought to be the youngest fossil rock layer. The Pleistocene has been dated from 2.588 million to 11,700 years before present and it covers most of the latest period of repeated glaciation, up to and including the Younger Dryas cold spell. The end of the Younger Dryas has been dated to about 9640 BC, the IUGS has yet to approve a type section, Global Boundary Stratotype Section and Point, for the upper Pleistocene/Holocene boundary. The proposed section is the North Greenland Ice Core Project ice core 75°06 N 42°18 W, the lower boundary of the Pleistocene Series is formally defined magnetostratigraphically as the base of the Matuyama chronozone, isotopic stage 103. Above this point there are notable extinctions of the calcareous nanofossils, Discoaster pentaradiatus, the Pleistocene covers the recent period of repeated glaciations. The name Plio-Pleistocene has, in the past, been used to mean the last ice age. The revised definition of the Quaternary, by pushing back the date of the Pleistocene to 2.58 Ma. Pleistocene climate was marked by repeated glacial cycles in which continental glaciers pushed to the 40th parallel in some places and it is estimated that, at maximum glacial extent, 30% of the Earths surface was covered by ice. In addition, a zone of permafrost stretched southward from the edge of the sheet, a few hundred kilometres in North America. The mean annual temperature at the edge of the ice was −6 °C, during interglacial times, such as at present, drowned coastlines were common, mitigated by isostatic or other emergent motion of some regions. The effects of glaciation were global, antarctica was ice-bound throughout the Pleistocene as well as the preceding Pliocene. The Andes were covered in the south by the Patagonian ice cap, there were glaciers in New Zealand and Tasmania. The current decaying glaciers of Mount Kenya, Mount Kilimanjaro, glaciers existed in the mountains of Ethiopia and to the west in the Atlas mountains. In the northern hemisphere, many glaciers fused into one, the Cordilleran ice sheet covered the North American northwest, the east was covered by the Laurentide
Pleistocene
–
The maximum extent of
glacial ice in the north polar area during the Pleistocene period.
Pleistocene
–
Ice ages as reflected in atmospheric CO 2, stored in bubbles from glacial ice of
Antarctica.
Pleistocene
–
Pleistocene of
Northern Spain showing
woolly mammoth,
cave lions eating a
reindeer,
tarpans, and
woolly rhinoceros.
Pleistocene
–
Pleistocene of
South America showing
Megatherium and two
Glyptodon.
12.
Lava flows
–
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 °C
Lava flows
–
10-metre (33 ft) high
fountain of pāhoehoe lava,
Hawaii, United States
Lava flows
–
Lava flow during a rift eruption at
Krafla,
Iceland in 1984.
Lava flows
–
Pāhoehoe and
ʻaʻā lava flows side by side at the
Big Island of Hawaii in September, 2007
Lava flows
–
Toes of a pāhoehoe advance across a road in
Kalapana on the east rift zone of
Kīlauea Volcano in
Hawaii, United States.
13.
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 people
Caldera
–
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)
Caldera
–
Animation of analogue experiment showing origin of volcanic caldera in box filled with flour.
Caldera
–
Satellite photograph of the summit caldera on
Fernandina Island in the
Galapagos archipelago.
Caldera
–
Oblique aerial photo of Nemrut Caldera, Van Lake, Eastern Turkey
14.
Oligocene
–
The Oligocene is a geologic epoch of the Paleogene Period and extends from about 33.9 million to 23 million years before the present. As with other geologic periods, the rock beds that define the epoch are well identified but the exact dates of the start. The name Oligocene comes from the Ancient Greek ὀλίγος and καινός, the Oligocene is preceded by the Eocene Epoch and is followed by the Miocene Epoch. The Oligocene is the third and final epoch of the Paleogene Period, the Oligocene is often considered an important time of transition, a link between the archaic world of the tropical Eocene and the more modern ecosystems of the Miocene. Major changes during the Oligocene included an expansion of grasslands. By contrast, the Oligocene–Miocene boundary is not set at an easily identified worldwide event, Oligocene faunal stages from youngest to oldest are, The Paleogene Period general temperature decline is interrupted by an Oligocene 7-million-year stepwise climate change. A deeper 8.2 °C,400, 000-year temperature depression leads the 2 °C, the stepwise climate change began 32.5 Ma and lasted through to 25.5 Ma, as depicted in the PaleoTemps chart. The Oligocene climate change was a increase in ice volume. The 7-million-year depression abruptly terminated within 1–2 million years of the La Garita Caldera eruption at 28–26 Ma, a deep 400, 000-year glaciated Oligocene Miocene boundary event is recorded at McMurdo Sound and King George Island. During this epoch, the continued to drift toward their present positions. Antarctica became more isolated and finally developed an ice cap, a brief marine incursion marks the early Oligocene in Europe. Marine fossils from the Oligocene are rare in North America, there appears to have been a land bridge in the early Oligocene between North America and Europe, since the faunas of the two regions are very similar. Sometime during the Oligocene, South America was finally detached from Antarctica and it also allowed the Antarctic Circumpolar Current to flow, rapidly cooling the Antarctic continent. Angiosperms continued their expansion throughout the world as tropical and sub-tropical forests were replaced by deciduous forests. Open plains and deserts became more common and grasses expanded from their habitat in the Eocene moving out into open tracts. However, even at the end of the period, grass was not quite enough for modern savannas. In North America, subtropical species dominated with cashews and lychee trees present, and temperate trees such as roses, beeches, the legumes spread, while sedges, bulrushes, and ferns continued their ascent. Even more open landscapes allowed animals to grow to larger sizes than they had earlier in the Paleocene epoch 30 million years earlier, marine faunas became fairly modern, as did terrestrial vertebrate fauna on the northern continents
Oligocene
–
Restoration of Oligocene fauna of North America
15.
Miocene
–
The Miocene is the first geological epoch of the Neogene Period and extends from about 23.03 to 5.333 million years ago. The Miocene was named by Sir Charles Lyell and its name comes from the Greek words μείων and καινός and means less recent because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene Epoch and is followed by the Pliocene Epoch, the earth went from the Oligocene through the Miocene and into the Pliocene, with the climate slowly cooling towards a series of ice ages. The Miocene boundaries are not marked by a single distinct global event, the apes arose and diversified during the Miocene, becoming widespread in the Old World. By the end of this epoch, the ancestors of humans had split away from the ancestors of the chimpanzees to follow their own evolutionary path, as in the Oligocene before it, grasslands continued to expand and forests to dwindle in extent. In the Miocene seas, kelp forests made their first appearance, the plants and animals of the Miocene were fairly modern. The Miocene faunal stages from youngest to oldest are typically named according to the International Commission on Stratigraphy, Two subdivisions each form the lower, middle, continents continued to drift toward their present positions. Mountain building took place in western North America, Europe, both continental and marine Miocene deposits are common worldwide with marine outcrops common near modern shorelines. Well studied continental exposures occur in the North American Great Plains, India continued to collide with Asia, creating dramatic new mountain ranges. The Tethys Seaway continued to shrink and then disappeared as Africa collided with Eurasia in the Turkish–Arabian region between 19 and 12 Ma. The subsequent uplift of mountains in the western Mediterranean region and a fall in sea levels combined to cause a temporary drying up of the Mediterranean Sea near the end of the Miocene. The global trend was towards increasing aridity caused primarily by global cooling reducing the ability of the atmosphere to absorb moisture, climates remained moderately warm, although the slow global cooling that eventually led to the Pleistocene glaciations continued. Although a long-term cooling trend was well underway, there is evidence of a period during the Miocene when the global climate rivalled that of the Oligocene. The Miocene warming began 21 million years ago and continued until 14 million years ago, by 8 million years ago, temperatures dropped sharply once again, and the Antarctic ice sheet was already approaching its present-day size and thickness. Greenland may have begun to have large glaciers as early as 7 to 8 million years ago, life during the Miocene Epoch was mostly supported by the two newly formed biomes, kelp forests and grasslands. This allows for more grazers, such as horses, rhinoceroses, ninety five percent of modern plants existed by the end of this epoch. The higher organic content and water retention of the deeper and richer grassland soils, with long term burial of carbon in sediments, produced a carbon and this, combined with higher surface albedo and lower evapotranspiration of grassland, contributed to a cooler, drier climate. The expansion of grasslands and radiations among terrestrial herbivores correlates to fluctuations in CO2
Miocene
–
The
dragon blood tree is considered a remnant of the Mio-Pliocene Laurasian subtropical forests that are now almost extinct in North Africa.
Miocene
–
Cameloid footprint (Lamaichnum alfi Sarjeant and Reynolds, 1999; convex hyporelief) from the
Barstow Formation (Miocene) of Rainbow Basin, California.
Miocene
–
Miocene fauna of North America
Miocene
–
A Miocene crab (Tumidocarcinus giganteus) from the collection of the
Children's Museum of Indianapolis
16.
Neogene
–
The Neogene is a geologic period and system that spans 20.45 million years from the end of the Paleogene Period 23.03 million years ago to the beginning of the present Quaternary Period 2.58 Mya. The Neogene is sub-divided into two epochs, the earlier Miocene and the later Pliocene, some geologists assert that the Neogene cannot be clearly delineated from the modern geological period, the Quaternary. During this period, mammals and birds continued to evolve into modern forms. Early hominids, the ancestors of humans, appeared in Africa near the end of the period, some continental movement took place, the most significant event being the connection of North and South America at the Isthmus of Panama, late in the Pliocene. This cut off the ocean currents from the Pacific to the Atlantic ocean. The global climate cooled considerably over the course of the Neogene, the terms Neogene System and upper Tertiary System describe the rocks deposited during the Neogene Period. The continents in the Neogene were very close to their current positions, the Isthmus of Panama formed, connecting North and South America. The Indian subcontinent continued to collide with Asia, forming the Himalayas, sea levels fell, creating land bridges between Africa and Eurasia and between Eurasia and North America. The global climate became seasonal and continued an overall drying and cooling trend which began at the start of the Paleogene. The ice caps on both poles began to grow and thicken, and by the end of the period the first of a series of glaciations of the current Ice Age began, marine and continental flora and fauna have a modern appearance. The reptile group Choristodera became extinct in the part of the period. Mammals and birds continued to be the dominant terrestrial vertebrates, the first hominids, the ancestors of humans, appeared in Africa and spread into Eurasia. In response to the cooler, seasonal climate, tropical plant species gave way to deciduous ones, grasses therefore greatly diversified, and herbivorous mammals evolved alongside it, creating the many grazing animals of today such as horses, antelope, and bison. The Neogene traditionally ended at the end of the Pliocene Epoch, just before the definition of the beginning of the Quaternary Period. However, there was a movement amongst geologists to also include ongoing geological time in the Neogene, by dividing the Cenozoic Era into three periods instead of seven epochs, the periods are more closely comparable to the duration of periods in the Mesozoic and Paleozoic eras. The International Commission on Stratigraphy once proposed that the Quaternary be considered a sub-era of the Neogene, with a date of 2.58 Ma. In the 2004 proposal of the ICS, the Neogene would have consisted of the Miocene and Pliocene epochs, thus the Neogene Period ends bounding the succeeding Quaternary Period at 2.58 Mya. Digital Atlas of Neogene Life for the Southeastern United States — by San Jose State University via Web Archive
Neogene
–
Scene featuring Miocene (Early Neogene) fauna
17.
Ignimbrite
–
Ignimbrites are made of a very poorly sorted mixture of volcanic ash and pumice lapilli, commonly with scattered lithic fragments. The ash is composed of shards and crystal fragments. Ignimbrites may be loose and unconsolidated, or lithified rock called lapilli-tuff, near the volcanic source, ignimbrites commonly contain thick accumulations of lithic blocks, and distally, many show meter-thick accumulations of rounded cobbles of pumice. Ignimbrites may be white, grey, pink, beige, brown or black depending on their composition, many pale ignimbrites are dacitic or rhyolitic. Darker coloured ignimbrites may be densely welded volcanic glass or, less commonly, there are two main models that have been proposed to explain the deposition of ignimbrites from a pyroclastic density current, the en masse deposition and the progressive aggradation models. The en masse model was proposed by volcanologist Robert Stephen John Sparks in 1976, Sparks attributed the poor sorting in ignimbrites to laminar flows of very high particle concentration. Pyroclastic flows were envisioned as being similar to flows, with a body undergoing laminar flow. The flow would travel as a flow, with an essentially non-deforming mass travelling on a thin shear zone. This would produce a unit with an inversely graded base. There are several problems with the en masse model, since ignimbrite is a deposit, its characteristics cannot completely represent the flow, and the deposit may only record the depositional process. It has been posited that the changes are recording progressive aggradation at the base of the flow from an eruption whose composition changes with time. For this to be so, the base of the flow cannot be turbulent, the instantaneous deposition of an entire body of material is not possible because displacement of the fluid is not possible instantaneously. Any displacement of the fluid would mobilize the upper part of the flow, rheomorphic structures are only observed in high grade ignimbrites. There are two types of flow, post-depositional re-mobilization, and late stage viscous flow. While there is debate in the field of the relative importance of either mechanism. A change from particulate flow to a fluid could cause the rapid en masse cooling in the last few meters. It is also theorized that transformation occurs at a layer at the base of the flow. Another model proposed is that the density current became stationary before the structures form
Ignimbrite
–
Rocks from the
Bishop tuff from California, United States, uncompressed with
pumice on left; compressed with
fiamme on right.
Ignimbrite
–
Rheomorphic flow structures in a welded ignimbrite, Isle of Lipari, Italy
Ignimbrite
–
A block of Ignimbrite
Ignimbrite
–
Light microscope image of a welded ignimbrite, composed of eutaxitic lapilli-tuff as seen in thin section (Long dimension is several mm). The glass shards (mostly brown) sometimes become welded together when the deposit is still hot, and can be deformed by flow and compaction about crystal fragments (clear).
18.
Intrusive rock
–
Intrusive rock is formed when magma crystallizes and solidifies underground to form intrusions, for example plutons, batholiths, dikes, sills, laccoliths, and volcanic necks. Intrusive rock forms within Earths crust from the crystallization of magma, magma slowly pushes up from deep within the earth into any cracks or spaces it can find, sometimes pushing existing country rock out of the way, a process that can take millions of years. As the magma slowly cools into a solid, the different parts of the magma crystallize into rocks, many mountain ranges, such as the Sierra Nevada in California, are formed mostly from large granite intrusions, see Sierra Nevada Batholith. Intrusions are one of the two ways igneous rock can form, the other is extrusive rock, that is, an eruption or similar event. Technically speaking, an intrusion is any formation of igneous rock, rock formed from magma that cools. In contrast, an extrusion consists of rock, rock formed above the surface of the crust. Large bodies of magma that solidify underground before they reach the surface of the crust are called plutons, plutonic rocks form 7% of the Earths current land surface. Coarse-grained intrusive igneous rocks form at depth within the earth are called abyssal while those that form near the surface are called subvolcanic or hypabyssal. The term intrusive suite seems near synonymous, there is, however, a modest difference, An intrusive suite is a group of plutons related in time and space. Intrusions vary widely, from mountain-range-sized batholiths to thin veinlike fracture fillings of aplite or pegmatite, when exposed by erosion, such batholiths may occupy large areas. A well-known example of an intrusion is Devils Tower, another is Shiprock, New Mexico, USA. Be the pluton is large, it may be called a batholith or a stock, Intrusive rocks are characterized by large crystal sizes, and as the individual crystals are visible, the rock is called phaneritic. This is as the magma cools underground, and while cooling may be fast or slow, cooling is slower than on the surface, if it runs parallel to rock layers, it is called a sill. If an intrusion makes rocks above rise to form a dome, as heat dissipation is slow, and as the rock is under pressure, crystals form, and no vitreous rapidly chilled matter is present. The intrusions did not flow while solidifying, hence do not show lines, contained gases could not escape through the thick strata, thus form cavities, which can often be observed. Because their crystals are of the rough equal size, these rocks are said to be equigranular, there is typically no distinction between a first generation of large well-shaped crystals and a fine-grained ground-mass. Earlier crystals originated at a time when most of the rock was still liquid and are more or less perfect, later crystals are less regular in shape because they were compelled to occupy the spaces left between the already-formed crystals. The former case is said to be idiomorphic, the latter is xenomorphic, there are also many other characteristics that serve to distinguish the members of these two groups
Intrusive rock
–
Devils Tower, an igneous intrusion exposed when the surrounding softer rock eroded away.
Intrusive rock
–
A dike intrudes into the
country rock,
Baranof Island,
Alaska,
USA.
Intrusive rock
–
An intrusion (pink
Notch Peak monzonite) inter-fingers (partly as a
dike) with highly metamorphosed black-and-white-striped host rock (
Cambrian carbonate rocks). Near Notch Peak,
House Range,
Utah.
19.
Pumice
–
Pumice, called pumicite in its powdered or dust form, is a volcanic rock that consists of highly vesicular rough textured volcanic glass, which may or may not contain crystals. Scoria is another vesicular volcanic rock that differs from pumice in having larger vesicles, thicker walls and being dark colored. Pumice is created when super-heated, highly pressurized rock is violently ejected from a volcano, the unusual foamy configuration of pumice happens because of simultaneous rapid cooling and rapid depressurization. The depressurization creates bubbles by lowering the solubility of gases that are dissolved in the lava, the simultaneous cooling and depressurization freezes the bubbles in a matrix. Eruptions under water are cooled and the large volume of pumice created can be a shipping hazard for cargo ships. Pumice is composed of highly microvesicular glass pyroclastic with very thin and it is commonly, but not exclusively of silicic or felsic to intermediate in composition, but basaltic and other compositions are known. Pumice is commonly pale in color, ranging from white, cream, blue or grey and it forms when volcanic gases exsolving from viscous magma form bubbles that remain within the viscous magma as it cools to glass. Pumice is a product of explosive eruptions and commonly forms zones in upper parts of silicic lavas. Pumice has a porosity of 90%, and initially floats on water. Scoria differs from pumice in being denser, with larger vesicles and thicker vesicle walls, it sinks rapidly. The difference is the result of the viscosity of the magma that forms scoria. When larger amounts of gas are present, the result is a variety of pumice known as pumicite. Pumice is considered a glass because it has no crystal structure, pumice varies in density according to the thickness of the solid material between the bubbles, many samples float in water. After the explosion of Krakatoa, rafts of pumice drifted through the Pacific Ocean for up to 20 years, in fact, pumice rafts disperse and support several marine species. In 1979,1984 and 2006, underwater volcanic eruptions near Tonga created large pumice rafts, there are two main forms of vesicles. Most pumice contains tubular microvesicles that can impart a silky or fibrous fabric, the elongation of the microvesicles occurs due to ductile elongation in the volcanic conduit or, in the case of pumiceous lavas, during flow. The other form of vesicles are subspherical to spherical and result from high pressure during eruption. Pumice is widely used to make concrete or insulative low-density cinder blocks
Pumice
–
Specimen of highly porous pumice from
Teide volcano on
Tenerife,
Canary Islands.
Density of specimen approximately 0.25 g/cm 3; scale in
centimeters.
Pumice
–
Illustrates the porous nature in detail.
Pumice
–
Rocks from the
Bishop tuff, uncompressed with pumice on left; compressed with
fiamme on right.
Pumice
–
A 15 centimeter (6 inch) piece of pumice supported by a rolled-up U.S. 20-dollar bill demonstrates its very low density.
20.
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 °C
Lava
–
10-metre (33 ft) high
fountain of pāhoehoe lava,
Hawaii, United States
Lava
–
Lava flow during a rift eruption at
Krafla,
Iceland in 1984.
Lava
–
Pāhoehoe and
ʻaʻā lava flows side by side at the
Big Island of Hawaii in September, 2007
Lava
–
Toes of a pāhoehoe advance across a road in
Kalapana on the east rift zone of
Kīlauea Volcano in
Hawaii, United States.
21.
Lapilli
–
Lapilli is a size classification term for tephra, which is material that falls out of the air during a volcanic eruption or during some meteorite impacts. Lapilli means little stones in Latin, by definition lapilli range from 2 to 64 mm in diameter. A pyroclastic particle greater than 64 mm in diameter is known as a bomb when molten. Pyroclastic material with less than 2 mm in diameter is referred to as volcanic ash. Lapilli are spheroid-, teardrop-, dumbbell- or button-shaped droplets of molten or semi-molten lava ejected from an eruption that fall to earth while still at least partially molten. These granules are not accretionary, but instead the result of liquid rock cooling as it travels through the air. Lapilli tuffs are a common form of volcanic rock typical of rhyolite, andesite and dacite pyroclastic eruptions. Most lapilli tuffs which remain in ancient terrains are formed by the accumulation, the heat of the newly deposited volcanic pile tends to cause the semi-molten material to flatten out as it they becomes welded. Welded tuff textures are distinctive, with flattened lapilli, fiamme, blocks and these rocks are quite indurated and tough, as opposed to non-welded lapilli tuffs, which are unconsolidated and easily eroded. Rounded tephra balls are called accretionary lapilli if they consist of volcanic ash particles, accretionary lapilli are like volcanic hailstones that form by the addition of concentric layers of moist ash around a central nucleus. This texture can be confused with spherulitic and axiolitic texture and these lapilli are a variety of accretionary lapilli, though they contain lithic or crystal cores coated by rinds of coarse to fine ash. Armoured lapilli only form in hydroclastic eruptions, where significant moisture is present, the vapour column contains cohesive ash which sticks to particles within it. Tuff Tephra Cinder Lava Rock microstructure of volcanic rocks Volcanic Materials Identification Tephra fall from Mt St. Helens
Lapilli
–
Lapilli on
Kilauea
Lapilli
–
Lapilli on
Fuerteventura
Lapilli
–
Accretionary lapilli in the
Mesoproterozoic Stac Fada Member of the
Torridonian, of probable impact origin
22.
Geomorphology
–
Geomorphology is the scientific study of the origin and evolution of topographic and bathymetric features created by physical, chemical or biological processes operating at or near the Earths surface. Geomorphologists work within disciplines such as geography, geology, geodesy, engineering geology, archaeology. This broad base of interests contributes to many styles and interests within the field. Earths surface is modified by a combination of processes that sculpt landscapes, and geologic processes that cause tectonic uplift and subsidence. Many of these factors are strongly mediated by climate, the broad-scale topographies of the Earth illustrate this intersection of surface and subsurface action. Mountain belts are uplifted due to geologic processes, denudation of these high uplifted regions produces sediment that is transported and deposited elsewhere within the landscape or off the coast. On progressively smaller scales, similar ideas apply, where individual landforms evolve in response to the balance of additive processes, often, these processes directly affect each other, ice sheets, water, and sediment are all loads that change topography through flexural isostasy. Topography can modify the climate, for example through orographic precipitation. Many geomorphologists are particularly interested in the potential for feedbacks between climate and tectonics, mediated by geomorphic processes, in addition to these broad-scale questions, geomorphologists address issues that are more specific and/or more local. Fluvial geomorphologists focus on rivers, how they transport sediment, migrate across the landscape, cut into bedrock, respond to environmental and tectonic changes, and interact with humans. Soils geomorphologists investigate soil profiles and chemistry to learn about the history of a landscape and understand how climate, biota. Other geomorphologists study how hillslopes form and change, still others investigate the relationships between ecology and geomorphology. Because geomorphology is defined to comprise everything related to the surface of the Earth and its modification, geomorphologists use a wide range of techniques in their work. These may include fieldwork and field data collection, the interpretation of remotely sensed data, geochemical analyses, geomorphologists may rely on geochronology, using dating methods to measure the rate of changes to the surface. Practical applications of geomorphology include hazard assessment, river control and stream restoration, planetary geomorphology studies landforms on other terrestrial planets such as Mars. Indications of effects of wind, fluvial, glacial, mass wasting, meteor impact, tectonics and this effort not only helps better understand the geologic and atmospheric history of those planets but also extends geomorphological study of the Earth. Planetary geomorphologists often use Earth analogues to aid in their study of surfaces of other planets, other than some notable exceptions in antiquity, geomorphology is a relatively young science, growing along with interest in other aspects of the earth sciences in the mid-19th century. This section provides a brief outline of some of the major figures
Geomorphology
–
Badlands incised into shale at the foot of the North Caineville Plateau, Utah, within the pass carved by the
Fremont River known as the Blue Gate.
GK Gilbert studied the landscapes of this area in great detail, forming the observational foundation for many of his studies on geomorphology.
Geomorphology
–
Surface of the Earth, showing higher elevations in red color.
Geomorphology
–
Wave action and water chemistry lead to structural failure in exposed rocks
Geomorphology
–
"Cono de Arita" at the dry lake
Salar de Arizaro on the
Atacama Plateau,
Los Andes Department,
Salta Province, in north-western
Argentina.
23.
Holocene
–
The Holocene is the geological epoch that began after the Pleistocene at approximately 11,700 years before present. The term Recent has often used as an exact synonym of Holocene. The Holocene is part of the Quaternary period and its name comes from the Ancient Greek words ὅλος and καινός, meaning entirely recent. It has been identified with the current warm period, known as MIS1, given these, a new term, Anthropocene, is specifically proposed and used informally only for the very latest part of modern history involving significant human impact. It is accepted by the International Commission on Stratigraphy that the Holocene started approximately 11,700 years ago, the epoch follows the Pleistocene and the last glacial period. The Holocene can be subdivided into five time intervals, or chronozones, based on climatic fluctuations, Preboreal, Boreal, Atlantic, Subboreal and they find a general correspondence across Eurasia and North America, though the method was once thought to be of no interest. The scheme was defined for Northern Europe, but the changes were claimed to occur more widely. The periods of the include a few of the final pre-Holocene oscillations of the last glacial period. Paleontologists have not defined any faunal stages for the Holocene, if subdivision is necessary, periods of human technological development, such as the Mesolithic, Neolithic, and Bronze Age, are usually used. However, the time periods referenced by these terms vary with the emergence of those technologies in different parts of the world, climatically, the Holocene may be divided evenly into the Hypsithermal and Neoglacial periods, the boundary coincides with the start of the Bronze Age in Europe. According to some scholars, a division, the Anthropocene, has now begun. Continental motions due to plate tectonics are less than a kilometre over a span of only 10,000 years, however, ice melt caused world sea levels to rise about 35 m in the early part of the Holocene. The sea level rise and temporary land depression allowed temporary marine incursions into areas that are now far from the sea, Holocene marine fossils are known, for example, from Vermont and Michigan. Other than higher-latitude temporary marine incursions associated with depression, Holocene fossils are found primarily in lakebed, floodplain. Holocene marine deposits along low-latitude coastlines are rare because the rise in sea levels during the period exceeds any likely tectonic uplift of non-glacial origin, post-glacial rebound in the Scandinavia region resulted in the formation of the Baltic Sea. The region continues to rise, still causing weak earthquakes across Northern Europe, the equivalent event in North America was the rebound of Hudson Bay, as it shrank from its larger, immediate post-glacial Tyrrell Sea phase, to near its present boundaries. Climate has been stable over the Holocene. It appears that this was influenced by the glacial ice remaining in the Northern Hemisphere until the later date
Holocene
–
Holocene cinder cone volcano on State Highway 18 near
Veyo, Utah
Holocene
–
Bronze bead necklace,
Muséum de Toulouse
24.
International Space Station
–
The International Space Station is a space station, or a habitable artificial satellite, in low Earth orbit. Its first component launched into orbit in 1998, and the ISS is now the largest man-made body in space, the ISS consists of pressurised modules, external trusses, solar arrays, and other components. ISS components have been launched by Russian Proton and Soyuz rockets, the ISS serves as a microgravity and space environment research laboratory in which crew members conduct experiments in biology, human biology, physics, astronomy, meteorology, and other fields. The station is suited for the testing of systems and equipment required for missions to the Moon. The ISS maintains an orbit with an altitude of between 330 and 435 km by means of reboost manoeuvres using the engines of the Zvezda module or visiting spacecraft and it completes 15.54 orbits per day. The ISS is the space station to be inhabited by crews, following the Soviet and later Russian Salyut, Almaz. The station has continuously occupied for 16 years and 156 days since the arrival of Expedition 1 on 2 November 2000. This is the longest continuous presence in low Earth orbit. It has been visited by astronauts, cosmonauts and space tourists from 17 different nations, Soyuz has very limited downmass capability. The ISS programme is a joint project among five participating space agencies, NASA, Roscosmos, JAXA, ESA, the ownership and use of the space station is established by intergovernmental treaties and agreements. The station is divided two sections, the Russian Orbital Segment and the United States Orbital Segment, which is shared by many nations. As of January 2014, the American portion of ISS is being funded until 2024, Roscosmos has endorsed the continued operation of ISS through 2024 but has proposed using elements of the Russian Orbital Segment to construct a new Russian space station called OPSEK. On 28 March 2015, Russian sources announced that Roscosmos and NASA had agreed to collaborate on the development of a replacement for the current ISS. NASA later issued a statement expressing thanks for Russias interest in future co-operation in space exploration. According to the original Memorandum of Understanding between NASA and Rosaviakosmos, the International Space Station was intended to be a laboratory, observatory and factory in low Earth orbit. It was also planned to provide transportation, maintenance, and act as a base for possible future missions to the Moon, Mars. In the 2010 United States National Space Policy, the ISS was given roles of serving commercial, diplomatic. The ISS provides a platform to conduct scientific research, the ISS simplifies individual experiments by eliminating the need for separate rocket launches and research staff
International Space Station
–
International Space Station
International Space Station
–
Sunrise at Zvezda
International Space Station
–
Fisheye view of several labs
International Space Station
–
CubeSats are deployed by the
NanoRacks CubeSat Deployer attached to the end of the Japanese robotic arm
25.
Misti
–
Misti, also known as Putina or Wawa Putina, is a stratovolcano of andesite, dacite and rhyolite located in southern Peru near the city of Arequipa. With its seasonally snow-capped, symmetrical cone, Misti stands at 5,822 metres above sea level and its last eruption was in 1985,198 years after its previous documented eruption. In the inner crater fumarole activity can be seen, near the inner crater six Inca mummies and rare Inca artifacts were found in 1998 during a month-long excavation directed by archaeologists Johan Reinhard and Jose Antonio Chavez. These findings are currently stored at the Museo de Santuarios Andinos in Arequipa, there are two main climbing routes on the volcano. The Pastores route starts at 3,300 metres, usually a camp is made at 4,500 metres at Nido de Aguilas. The Aguada Blanca route starts at 4,000 metres near the Aguada Blanca reservoir, neither climbing routes presents technical difficulties, but both are considered strenuous because of the steep loose sand slopes. List of volcanoes in Peru Reinhard, Johan, the Ice Maiden, Inca Mummies, Mountain Gods, and Sacred Sites in the Andes. El Misti Volcano and Arequipa, Peru, el Misti Volcano and the City of Arequipa, Peru
Misti
–
Misti
Misti
–
This
mosaic of two astronaut photographs illustrates the proximity of
Arequipa to Misti.
Misti
–
Misti, as seen from Arequipa´s horse racecourse.
26.
Subduction
–
Subduction is a geological process that takes place at convergent boundaries of tectonic plates where one plate moves under another and is forced or sinks due to gravity into the mantle. Regions where this occurs are known as subduction zones. Rates of subduction are typically in centimeters per year, with the rate of convergence being approximately two to eight centimeters per year along most plate boundaries. Plates include both oceanic crust and continental crust, stable subduction zones involve the oceanic lithosphere of one plate sliding beneath the continental or oceanic lithosphere of another plate due to the higher density of the oceanic lithosphere. That is, the lithosphere is always oceanic while the overriding lithosphere may or may not be oceanic. Subduction zones are sites that have a rate of volcanism, earthquakes. Subduction zones are sites of convective downwelling of Earths lithosphere, subduction zones exist at convergent plate boundaries where one plate of oceanic lithosphere converges with another plate. The descending slab, the plate, is over-ridden by the leading edge of the other plate. The slab sinks at an angle of approximately twenty-five to forty-five degrees to Earths surface and this sinking is driven by the temperature difference between the subducting oceanic lithosphere and the surrounding mantle asthenosphere, as the colder oceanic lithosphere is, on average, denser. At a depth of approximately 80–120 kilometers, the basalt of the oceanic crust is converted to a rock called eclogite. At that point, the density of the oceanic crust increases and provides additional negative buoyancy and it is at subduction zones that Earths lithosphere, oceanic crust, sedimentary layers and some trapped water are recycled into the deep mantle. Earth is so far the only planet where subduction is known to occur, subduction is the driving force behind plate tectonics, and without it, plate tectonics could not occur. Subduction zones dive down into the mantle beneath 55,000 kilometers of convergent plate margins, subduction zones burrow deeply but are imperfectly camouflaged, and geophysics and geochemistry can be used to study them. Not surprisingly, the shallowest portions of subduction zones are known best, subduction zones are strongly asymmetric for the first several hundred kilometers of their descent. They start to go down at oceanic trenches and their descents are marked by inclined zones of earthquakes that dip away from the trench beneath the volcanoes and extend down to the 660-kilometer discontinuity. Subduction zones are defined by the array of earthquakes known as the Wadati–Benioff zone after the two scientists who first identified this distinctive aspect. Subduction zone earthquakes occur at greater depths than elsewhere on Earth, such deep earthquakes may be driven by deep phase transformations, thermal runaway, the subducting basalt and sediment are normally rich in hydrous minerals and clays. Additionally, large quantities of water are introduced into cracks and fractures created as the slab bends downward
Subduction
Subduction
–
Geometry of a subduction zone - insets to show
accretionary prism and partial melting of hydrated
asthenosphere
27.
Asthenosphere
–
The asthenosphere is the highly viscous, mechanically weak and ductilely deforming region of the upper mantle of the Earth. It lies below the lithosphere, at depths between approximately 80 and 200 km below the surface, the Lithosphere-Asthenosphere boundary is usually referred to as LAB. The asthenosphere is generally solid, although some of its regions could be melted, the lower boundary of the asthenosphere is not well defined. The thickness of the asthenosphere depends mainly on the temperature, in some regions the asthenosphere could extend as deep as 700 km. It is considered the region of mid-ocean ridge basalt. The asthenosphere is a part of the mantle just below the lithosphere that is involved in plate tectonic movement. The lithosphere-asthenosphere boundary is taken at the 1300 °C isotherm, above which the mantle behaves in a rigid fashion. Seismic waves pass relatively slowly through the asthenosphere compared to the lithospheric mantle, thus it has been called the low-velocity zone. This decreasing in seismic waves velocity from lithosphere to asthenosphere could be caused by the presence of a small percentage of melt in the asthenosphere. The lower boundary of the LVZ lies at a depth of 180–220 km, in the old oceanic mantle the transition from the lithosphere to the asthenosphere, the so-called lithosphere-asthenosphere boundary is shallow with a sharp and large velocity drop. At the mid-ocean ridges the LAB rises to within a few kilometers of the ocean floor, the upper part of the asthenosphere is believed to be the zone upon which the great rigid and brittle lithospheric plates of the Earths crust move about. In this way, it flows like a current, radiating heat outward from the Earths interior. Above the asthenosphere, at the rate of deformation, rock behaves elastically and, being brittle, can break. The rigid lithosphere is thought to float or move about on the slowly flowing asthenosphere, an Introduction to the Solar System. San Diego State University, The Earths internal heat energy and interior structure
Asthenosphere
–
Earth cutaway from
core to
crust, the asthenosphere lying between the upper mantle and the lithospheric mantle (detail not to scale)
28.
Mantle (geology)
–
The mantle is a layer inside a terrestrial planet and some other rocky planetary bodies. For a mantle to form, the body must be large enough to have undergone the process of planetary differentiation by density. The mantle surrounds the planetary core, the mantle is surrounded by the crust. The terrestrial planets, the Moon, two of Jupiters moons and the asteroid Vesta each have a made of silicate rock. Interpretation of spacecraft data suggests that at least two moons of Jupiter, as well as Titan and Triton each have a mantle made of ice or other solid volatile substances. The interior of Earth, similar to the terrestrial planets, is divided into layers of different composition. The mantle is a layer between the crust and the outer core, Earths mantle is a silicate rocky shell with an average thickness of 2,886 kilometres. The mantle makes up about 84% of Earths volume and it is predominantly solid but in geological time it behaves as a very viscous fluid. The mantle encloses the hot core rich in iron and nickel, past episodes of melting and volcanism at the shallower levels of the mantle have produced a thin crust of crystallized melt products near the surface. A thin crust, the part of the lithosphere, surrounds the mantle and is about 5 to 75 km thick. In some places under the ocean the mantle is exposed on the surface of Earth. The mantle is divided into sections which are based upon results from seismology and these layers are the following, the upper mantle, the transition zone, the lower mantle, and anomalous core–mantle boundary with a variable thickness. The uppermost mantle plus overlying crust are relatively rigid and form the lithosphere, below the lithosphere the upper mantle becomes notably more plastic. In some regions below the lithosphere, the shear velocity is reduced. Inge Lehmann discovered a seismic discontinuity at about 220 km depth, although this discontinuity has been found in other studies, the transition zone is an area of great complexity, it physically separates the upper and lower mantle. Very little is known about the lower mantle apart from that it appears to be relatively seismically homogeneous, the D layer at the core–mantle boundary separates the mantle from the core. A principal source of the heat that drives plate tectonics is the decay of uranium, thorium. The mantle differs substantially from the crust in its properties as the direct consequence of the difference in composition
Mantle (geology)
–
The internal structure of Earth
29.
Nazca Lines
–
The Nazca Lines /ˈnæzkɑː/ are a series of large ancient geoglyphs in the Nazca Desert, in southern Peru. The largest figures are up to 1,200 ft long and they were designated as a UNESCO World Heritage Site in 1994. The high, arid plateau stretches more than 80 km between the towns of Nazca and Palpa on the Pampas de Jumana, about 400 km south of Lima. Although some local geoglyphs resemble Paracas motifs, scholars believe the Nazca Lines were created by the Nazca culture between 500 BCE and 500 CE The figures vary in complexity. Hundreds are simple lines and geometric shapes, more than 70 are zoomorphic designs of animals, such as birds, fish, llamas, jaguars, other designs include phytomorphic shapes, such as trees and flowers. The designs are shallow lines made in the ground by removing the reddish pebbles, scholars differ in interpreting the purpose of the designs but, in general, they ascribe religious significance to them. Because of its isolation and the dry, windless, stable climate of the plateau, extremely rare changes in weather may temporarily alter the general designs. As of 2012, the lines are said to have been deteriorating because of an influx of squatters inhabiting the lands, contrary to the popular belief that the lines and figures can be seen only with the aid of flight, they are visible from the surrounding foothills. The first mention of the Nazca Lines in print was by Pedro Cieza de León in his book of 1553, although partially visible from the nearby hills, the first to distinguish them were Peruvian military and civilian pilots. In 1927 the Peruvian archaeologist Toribio Mejía Xesspe spotted them while he was hiking through the foothills and he discussed them at a conference in Lima in 1939. Paul Kosok, a historian from Long Island University, is credited as the first scholar to study the Nazca Lines. In the country in 1940–41 to study ancient irrigation systems, he flew over the lines, another chance helped him see how lines converged at the winter solstice in the Southern Hemisphere. He began to study how the lines might have been created and he was joined by Maria Reiche, a German mathematician and archaeologist, to help figure out the purpose of the Nazca Lines. They proposed one of the earliest reasons for the existence of the figures, to be markers on the horizon to show where the sun, archaeologists, historians, and mathematicians have all tried to determine the purpose of the lines. Determining how they were made has been easier than figuring why they were made, scholars have theorized the Nazca people could have used simple tools and surveying equipment to construct the lines. Archaeological surveys have found wooden stakes in the ground at the end of some lines, one such stake was carbon-dated and was the basis for establishing the age of the design complex. Prominent skeptic Joe Nickell has reproduced the figures using tools and technology available to the Nazca people, scientific American called his work remarkable in its exactness when compared to the actual lines. With careful planning and simple technologies, a team of people could recreate even the largest figures within days
Nazca Lines
–
UNESCO World Heritage Site
Nazca Lines
–
Nazca Lines seen from
SPOT Satellite
Nazca Lines
–
Satellite picture of an area containing lines: North is to the right. (Coordinates: 14°43′S 75°08′W / 14.717°S 75.133°W / -14.717; -75.133)
Nazca Lines
30.
Ticsani
–
Ticsani or Tixani is a volcano in the Andes of Peru, about 5,408 metres high. It is situated in the Moquegua Region, Mariscal Nieto Province, in the districts of Cuchumbaya, the volcano is of dacitic composition and has been K-Ar dated to be 190000 years old. The volcano was constructed in steps, starting from lava flows. This system collapsed westward leaving a 3 km long NW-SE ridge, in the middle Holocene, three andesitic lava domes formed with explosive eruptions. These were later overlaid with brown pumice and bombs from a later phreatomagmatic eruption, the activity of this system ended with the emplacement of the Ticsani lava dome. One dacitic pumice fall of 0,4 km3 has been dated ca 11600 yr BP, Ticsani was one of the volcanoes ascended in summer 1902 by Francisco Alayza Paz Soldan
Ticsani
–
The Tixani lava dome complex (center)
31.
Huaynaputina
–
Huaynaputina is a stratovolcano in a volcanic upland in southern Peru. The volcano does not have a mountain profile, but instead is a large volcanic crater. It has produced andesite and dacite. On 19 February 1600, it exploded catastrophically, in the largest volcanic explosion in South America in historic times, the eruption continued with a series of events into March. Huaynaputina lies in Southern Perus Moquegua Region,80 kilometres southeast of Arequipa, the volcano is part of the Central Volcanic Zone, the segment of the Andes running through Peru and Chile. It is north of at least one more complex with a resurgent dome. Despite the volcanos listed elevation of 4,800 metres, Huaynaputina has very little prominence, the mountain resides within a horseshoe-shaped crater 2.5 kilometres in width, and includes three 100-metre deep cones which formed from ash fallout of the 1600 eruption. Another external vent formed a maar just outside the caldera, before the Spanish colonization of the Americas, not much is known of the regions history. It is likely natives made human sacrifices ritualistically to the volcano, also sacrificing animals, father Alonso Ruiz of Arequipa predicted a hit from heaven in 1599, at which time activity may have begun at the volcano. This subduction process has resulted in the formation of the Peru–Chile Trench and it also produced the Andean Volcanic Belt and the rest of the Andes. Ticsani, Ubinas and Huaynaputina sit on a volcanic lineament slightly oblique to the volcanic front. Because the crust of the Central Volcanic Zone is unusually thick, Huaynaputina is rich in andesitic and dacitic rocks, which form a calc-alkalic suite high in potassium.8 mya, respectively. The history of the Huaynaputina region is marked by silicic volcanism, records of silicic eruptions begin with remnants from the Barroso formation, from the Miocene. A few days before the eruption, someone reported booming noise from the volcano, navarro tells of local wizards scrambling to appease the volcano, preparing girls, pets, and flowers for sacrifice, and of the volcano ejecting ash during the sacrifice ceremony. By February 15, the activity had increased, as earthquakes began to occur. By February 18, seismic activity occurred as frequently as three or four times every fifteen minutes, some tremors powerful enough to wake those sleeping, at 5 P. M. on February 19, Huaynaputina erupted violently, sending volcanic ash into the atmosphere. Observers described the event as a big explosion with cannonball-like explosions that had the appearance of an enormous fire, river-like pyroclastic flows flowed down the mountain, the flows on the southern side mixed with water from the Rio Tambo to create lahars. One hour after the eruption, ash began to fall from the sky, intermittent eruptions occurred for a little less than a month, concluding on March 5
Huaynaputina
–
Ash falling on the city of Arequipa in 1600
Huaynaputina
–
Huaynaputina
32.
Magmas
–
Besides molten rock, magma may also contain suspended crystals, dissolved gas and sometimes gas bubbles. Magma often collects in magma chambers that may feed a volcano or solidify underground to form an intrusion, magma is capable of intruding into adjacent rocks, extrusion onto the surface as lava, and explosive ejection as tephra to form pyroclastic rock. Magma is a complex high-temperature fluid substance, temperatures of most magmas are in the range 700 °C to 1300 °C, but very rare carbonatite magmas may be as cool as 600 °C, and komatiite magmas may have been as hot as 1600 °C. Environments of magma formation and compositions are commonly correlated, environments include subduction zones, continental rift zones, mid-ocean ridges and hotspots. Despite being found in such locales, the bulk of the Earths crust. Except for the outer core, most of the Earth takes the form of a rheid. Magma, as liquid, preferentially forms in high temperature, low pressure environments within several kilometers of the Earths surface, magma compositions may evolve after formation by fractional crystallization, contamination, and magma mixing. By definition rock formed of solidified magma is called igneous rock, melting of solid rocks to form magma is controlled by three physical parameters, temperature, pressure, and composition. Mechanisms are discussed in the entry for igneous rock, as a rock melts, its volume changes. When enough rock is melted, the small globules of melt link up, under pressure within the earth, as little as a fraction of a percent partial melting may be sufficient to cause melt to be squeezed from its source. The degree of melting is critical for determining what type of magma is produced. The degree of partial melting required to form a melt can be estimated by considering the relative enrichment of incompatible elements versus compatible elements, incompatible elements commonly include potassium, barium, cesium, and rubidium. Rock types produced by small degrees of melting in the Earths mantle are typically alkaline. Typically, primitive melts of this composition form lamprophyre, lamproite, kimberlite and sometimes nepheline-bearing mafic rocks such as alkali basalts, pegmatite may be produced by low degrees of partial melting of the crust. Some granite-composition magmas are eutectic melts, and they may be produced by low to high degrees of melting of the crust. At high degrees of melting of the crust, granitoids such as tonalite, granodiorite and monzonite can be produced. Being only the time in recorded history that magma had been reached, IDDP decided to invest in the hole. A cemented steel case was constructed in the hole with a perforation at the close to the magma
Magmas
–
Lava flow on
Hawaii. Lava is the
extrusive equivalent of magma.
33.
Mafic
–
Mafic is an adjective describing a silicate mineral or igneous rock that is rich in magnesium and iron, and is thus a portmanteau of magnesium and ferric. Most mafic minerals are dark in color, and common rock-forming mafic minerals include olivine, pyroxene, amphibole, common mafic rocks include basalt, dolerite and gabbro. Mafic rocks often also contain calcium-rich varieties of plagioclase feldspar, chemically, mafic rocks are on the other side of the rock spectrum from the felsic rocks. The term roughly corresponds to the basic rock class. Mafic lava, before cooling, has a low viscosity, in comparison to felsic lava, water and other volatiles can more easily and gradually escape from mafic lava. As a result, eruptions of volcanoes made of mafic lavas are less violent than felsic-lava eruptions. Most mafic-lava volcanoes are shield volcanoes, like those in Hawaii, QAPF diagram List of minerals List of rock types
Mafic
–
Basalt
34.
Fumaroles
–
A fumarole is an opening in a planets crust, often in areas surrounding volcanoes, which emits steam and gases such as carbon dioxide, sulfur dioxide, hydrogen chloride, and hydrogen sulfide. The steam forms when superheated water vaporizes as its pressure drops when it emerges from the ground, the name solfatara, from the Italian solfo, sulfur, is given to fumaroles that emit sulfurous gases. Fumaroles may occur along tiny cracks or long fissures, in clusters or fields. A fumarole field is an area of springs and gas vents where magma or hot igneous rocks at shallow depth release gases or interact with groundwater. From the perspective of groundwater, a fumarole could be described as a hot spring that boils off all its water before the water reaches the surface. Fumaroles may persist for decades or centuries if located above a persistent heat source, the Valley of Ten Thousand Smokes, for example, was formed during the 1912 eruption of Novarupta in Alaska. Initially, thousands of fumaroles occurred in the ash from the eruption. An estimated four thousand fumaroles exist within the boundaries of Yellowstone National Park in the United States, in April 2006 fumarole emissions killed three ski-patrol workers east of Chair 3 at Mammoth Mountain Ski Area in California. The workers were overpowered by toxic fumes that had accumulated in a crevasse they had fallen into, another example is an array of fumaroles in the Valley of Desolation in Morne Trois Pitons National Park in Dominica. Boiling Lake Mazuku Mofetta Mudpot Mud volcano USGS Photo Glossary, Fumarole Sulfur Mining on Gunung Welirang Volcano Chisholm, Hugh, ed. Fumarole
Fumaroles
–
Fumaroles on
Mount Redoubt in Alaska
Fumaroles
Fumaroles
–
Fumarole at Námafjall,
Iceland
Fumaroles
–
Sampling gases at a fumarole on
Mount Baker in
Washington, United States
35.
Ash plume
–
An eruption column is a cloud of hot volcanic ash suspended in volcanic gas emitted during an explosive volcanic eruption. The ash forms a column that may rise many kilometres into the air above the vent of the volcano, in the most explosive eruptions, the eruption column may rise over 40 km, penetrating the stratosphere. Stratospheric injection of aerosols by volcanoes is a cause of short-term climate change. A common occurrence in explosive eruptions is for column collapse to occur, in this case, the eruption column is too dense to be lifted high into the air by air convection, and instead falls down the flanks of the volcano to form a pyroclastic flow or surge. On some occasions, if ash isnt dense enough to fall, eruption columns form in explosive volcanic activity, when the high concentration of volatile materials in the rising magma causes it to be disrupted into fine volcanic ash and coarser tephra. The ash and tephra are ejected at speeds of several hundred metres per second, eruption columns may be transient, if formed by a discrete explosion, or sustained, if produced by a continuous eruption or closely spaced discrete explosions. The gas expands because the pressure of rock above it rapidly reduces as it approaches the surface and this region is called the gas thrust region and typically reaches to only one or two kilometres above the vent. The convective thrust region covers most of the height of the column, the gas thrust region is very turbulent and surrounding air becomes mixed into it and heated. The air expands, reducing its density and rising, the rising air carries the solid and liquid material from the eruption entrained in it upwards. As the column rises into less dense surrounding air, it will reach an altitude where the hot. In this neutral buoyancy region, the material will then no longer rise through convection. This is called the region, and is usually marked by the column spreading out sideways. The eruptive material and the cool air has the same density at the base of the umbrella region. Because the speeds are low or negligible in this region it is often distorted by stratospheric winds. The column will stop rising once it attains an altitude where it is no longer less dense than the surrounding air, several factors control the height that an eruption column can reach. Intrinsic factors include the diameter of the vent, the gas content of the magma. Extrinsic factors can be important, with winds sometimes limiting the height of the column, the atmospheric temperature in the troposphere normally decreases by about 6-7 K/km, but small changes in this gradient can have a large effect on the final column height. Theoretically, the maximum column height is thought to be about 55 km
Ash plume
–
Eruption column over
Mount Pinatubo in the
Philippines
Ash plume
–
Eruption column rising over
Redoubt Volcano, Alaska
Ash plume
–
Volcano types
36.
State of emergency
–
A government or division of government may declare that their area is in a state of emergency. This means that the government can suspend and/or change some functions of the executive and it alerts citizens to change their normal behavior and orders government agencies to implement emergency plans. Justitium is its equivalent in Roman law, where Senate could put forward senatus consultum ultimum and it can also be used as a rationale for suspending rights and freedoms guaranteed under a countrys constitution or basic law. The procedure for and legality of doing so varies by country, under international law, rights and freedoms may be suspended during a state of emergency, for example, a government can detain persons and hold them without trial. All rights that can be derogated from are listed in the International Covenant for Civil, non-derogable rights are listed in Article 4 of the ICCPR, they include the rights to freedom from arbitrary deprivation of liberty and to freedom from torture and/or ill-treatment. Constitutions are contracts between the government and the individuals of that country. The International Covenant for Civil and Political Rights is an international law document signed by states, therefore, the Covenant only applies to persons acting in an official capacity, not private individuals. However, signatories to the Covenant are expected to integrate it into national legislation, although this is common protocol stipulated by the ICCPR often this is not strictly followed, enforcement is better regulated by European Convention of human rights. In some situations, martial law is declared, allowing the military greater authority to act. In other situations, emergency is not declared and de facto measures taken or decree-law adopted by the government. Ms. Nicole Questiaux and Mr. Article 4 to the International Covenant on Civil, the European Convention on Human Rights and American Convention on Human Rights have similar derogatory provisions. No derogation is permitted to the International Labour Conventions, some political theorists, such as Carl Schmitt, have argued that the power to decide the initiation of the state of emergency defines sovereignty itself. The state of emergency can, and often has been, abused by being invoked, an example would be to allow a state to suppress internal opposition without having to respect human rights. An example was the August 1991 attempted coup in the Soviet Union where the coup leaders invoked a state of emergency and this provision was much abused during dictatorships, with long-lasting states of siege giving the government a free hand to suppress opposition. State-of-emergency legislation differs in each state of Australia, in Victoria, the premier can declare a state of emergency if there is a threat to employment, safety or public order. The declaration expires after 30 days, and a resolution of either the upper or lower House of Parliament may revoke it earlier, under the Public Safety Preservation Act, a declared state of emergency allows the premier to immediately make any desired regulations to secure public order and safety. However, these regulations expire if Parliament does not agree to them within 7 days. Also, under the Essential Services Act, the premier may operate or prohibit operation of, as desired, a State of Emergency does not apply to the whole state, but rather districts or shires, where essential services may have been disrupted
State of emergency
–
After natural disasters such as this earthquake in El Salvador, some governments declare a state of emergency.
37.
List of volcanoes in Peru
–
This is a list of active and extinct volcanoes in Peru. Siebert L, Simkin T. Volcanoes of the World, an Illustrated Catalog of Holocene Volcanoes, smithsonian Institution, Global Volcanism Program Digital Information Series, GVP-3. John Seach, Volcano Live, Volcanoes of Peru, Retrieved December 27,2007 Peakware World Mountain Encyclopedia, Peruvian Andes, Retrieved December 27,2007
List of volcanoes in Peru
–
Chachani and Misti
List of volcanoes in Peru
–
Coropuna
List of volcanoes in Peru
–
Sabancaya
38.
Pukasaya (Moquegua)
–
Puka Saya is a 5,320 metres high mountain in the Andes of Peru. It is situated southeast of the lake named Salinas. The mountain is located in the Moquegua Region, General Sánchez Cerro Province, Matalaque District, puka Saya lies on the southern border of the buffer zone of the Salinas and Aguada Blanca National Reservation
Pukasaya (Moquegua)
–
Satellite image of the volcano
Ubinas (on the left) and Pukasaya (lower left)
39.
Global Volcanism Program
–
The Smithsonian Institutions Global Volcanism Program documents Earths volcanoes and their eruptive history over the past 10,000 years. The GVP reports on current eruptions from around the world as well as maintaining a repository on active volcanoes. In this way, a context for the planets active volcanism is presented. Smithsonian reporting on current volcanic activity dates back to 1968, with the Center for Short-Lived Phenomena, the GVP is housed in the Department of Mineral Sciences, part of the National Museum of Natural History, on the National Mall in Washington, D. C. During the early stages of an eruption, the GVP acts as a clearinghouse of reports, data, the Weekly Volcanic Activity Report is a cooperative project between the Smithsonians Global Volcanism Program and the United States Geological Surveys Volcano Hazards Program. Notices of volcanic activity posted on the Report website are preliminary, detailed reports on various volcanoes are published monthly in the Bulletin of the Global Volcanism Network The GVP also documents the last 10,000 years of Earths volcanism. The historic activity can guide perspectives on future events and on volcanoes showing activity. GVPs volcano and eruption databases constitute a foundation for all statements concerning locations, frequencies. Two editions of Volcanoes of the World, a regional directory, and were published based on the GVP data and interpretations
Global Volcanism Program
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1995 eruption of
Mount Rinjani in
Indonesia.
40.
Smithsonian Institution
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The Smithsonian Institution, established in 1846 for the increase and diffusion of knowledge, is a group of museums and research centers administered by the Government of the United States. Originally organized as the United States National Museum, that ceased to exist as an administrative entity in 1967. Additional facilities are located in Arizona, Maryland, Massachusetts, New York City, Texas, Virginia, more than 200 institutions and museums in 45 states, Puerto Rico, and Panama are Smithsonian Affiliates. The Institutions thirty million annual visitors are admitted without charge and its annual budget is around $1.2 billion with 2/3 coming from annual federal appropriations. Other funding comes from the Institutions endowment, private and corporate contributions, membership dues, and earned retail, concession, Institution publications include Smithsonian and Air & Space magazines. The British scientist James Smithson left most of his wealth to his nephew Henry James Hungerford, Congress officially accepted the legacy bequeathed to the nation, and pledged the faith of the United States to the charitable trust on July 1,1836. The American diplomat Richard Rush was dispatched to England by President Andrew Jackson to collect the bequest, Rush returned in August 1838 with 105 sacks containing 104,960 gold sovereigns. Once the money was in hand, eight years of Congressional haggling ensued over how to interpret Smithsons rather vague mandate for the increase, unfortunately, the money was invested by the US Treasury in bonds issued by the state of Arkansas which soon defaulted. The United States Exploring Expedition by the U. S. Navy circumnavigated the globe between 1838 and 1842, in 1846, the regents developed a plan for weather observation, in 1847, money was appropriated for meteorological research. The Institution became a magnet for young scientists from 1857 to 1866, the Smithsonian played a critical role as the U. S. partner institution in early bilateral scientific exchanges with the Academy of Sciences of Cuba. The Smithsonian Institution Building began construction in 1849, designed by architect James Renwick Jr. its interiors were completed by general contract Gilbert Cameron and the building opened in 1855. The Smithsonians first expansion came with construction of the Arts and Industries Building in 1881, Congress had promised to build a new structure for the museum if the 1876 Philadelphia Centennial Exposition generated enough income. It did, and the building was designed by architects Adolf Cluss and Paul Schulze, meigs of the United States Army Corps of Engineers. The National Zoological Park opened in 1889 to accommodate the Smithsonians Department of Living Animals and this structure was designed by the D. C. architectural firm of Hornblower & Marshall. More than 40 years would pass before the museum, the Museum of History. It was designed by the firm of McKim, Mead & White. That same year, the Smithsonian signed an agreement to take over the Cooper Union Museum for the Arts of Decoration, the National Portrait Gallery and the Smithsonian American Art Museum opened in the Old Patent Office Building on October 7,1968. The first new building to open since the National Museum of Natural History was the Hirshhorn Museum and Sculpture Garden
Smithsonian Institution
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The
"Castle" (1847), the Institution's first building and still its headquarters
Smithsonian Institution
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Smithsonian Institution Logo of the Smithsonian Institution
Smithsonian Institution
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Aircraft on display at the
National Air and Space Museum, including a
Ford Trimotor and
Douglas DC-3 (top and second from top)
Smithsonian Institution
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The Smithsonian Castle doorway
41.
International Standard Book Number
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The International Standard Book Number is a unique numeric commercial book identifier. An ISBN is assigned to each edition and variation of a book, for example, an e-book, a paperback and a hardcover edition of the same book would each have a different ISBN. The ISBN is 13 digits long if assigned on or after 1 January 2007, the method of assigning an ISBN is nation-based and varies from country to country, often depending on how large the publishing industry is within a country. The initial ISBN configuration of recognition was generated in 1967 based upon the 9-digit Standard Book Numbering created in 1966, the 10-digit ISBN format was developed by the International Organization for Standardization and was published in 1970 as international standard ISO2108. Occasionally, a book may appear without a printed ISBN if it is printed privately or the author does not follow the usual ISBN procedure, however, this can be rectified later. Another identifier, the International Standard Serial Number, identifies periodical publications such as magazines, the ISBN configuration of recognition was generated in 1967 in the United Kingdom by David Whitaker and in 1968 in the US by Emery Koltay. The 10-digit ISBN format was developed by the International Organization for Standardization and was published in 1970 as international standard ISO2108, the United Kingdom continued to use the 9-digit SBN code until 1974. The ISO on-line facility only refers back to 1978, an SBN may be converted to an ISBN by prefixing the digit 0. For example, the edition of Mr. J. G. Reeder Returns, published by Hodder in 1965, has SBN340013818 -340 indicating the publisher,01381 their serial number. This can be converted to ISBN 0-340-01381-8, the check digit does not need to be re-calculated, since 1 January 2007, ISBNs have contained 13 digits, a format that is compatible with Bookland European Article Number EAN-13s. An ISBN is assigned to each edition and variation of a book, for example, an ebook, a paperback, and a hardcover edition of the same book would each have a different ISBN. The ISBN is 13 digits long if assigned on or after 1 January 2007, a 13-digit ISBN can be separated into its parts, and when this is done it is customary to separate the parts with hyphens or spaces. Separating the parts of a 10-digit ISBN is also done with either hyphens or spaces, figuring out how to correctly separate a given ISBN number is complicated, because most of the parts do not use a fixed number of digits. ISBN issuance is country-specific, in that ISBNs are issued by the ISBN registration agency that is responsible for country or territory regardless of the publication language. Some ISBN registration agencies are based in national libraries or within ministries of culture, in other cases, the ISBN registration service is provided by organisations such as bibliographic data providers that are not government funded. In Canada, ISBNs are issued at no cost with the purpose of encouraging Canadian culture. In the United Kingdom, United States, and some countries, where the service is provided by non-government-funded organisations. Australia, ISBNs are issued by the library services agency Thorpe-Bowker
International Standard Book Number
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A 13-digit ISBN, 978-3-16-148410-0, as represented by an
EAN-13 bar code
42.
BBC
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The British Broadcasting Corporation is a British public service broadcaster headquartered at Broadcasting House in London, England. The total number of staff is 35,402 when part-time, flexible, the BBC is established under a Royal Charter and operates under its Agreement with the Secretary of State for Culture, Media and Sport. The fee is set by the British Government, agreed by Parliament, and used to fund the BBCs radio, TV, britains first live public broadcast from the Marconi factory in Chelmsford took place in June 1920. It was sponsored by the Daily Mails Lord Northcliffe and featured the famous Australian Soprano Dame Nellie Melba, the Melba broadcast caught the peoples imagination and marked a turning point in the British publics attitude to radio. However, this public enthusiasm was not shared in official circles where such broadcasts were held to interfere with important military and civil communications. By late 1920, pressure from these quarters and uneasiness among the staff of the licensing authority, the General Post Office, was sufficient to lead to a ban on further Chelmsford broadcasts. But by 1922, the GPO had received nearly 100 broadcast licence requests, John Reith, a Scottish Calvinist, was appointed its General Manager in December 1922 a few weeks after the company made its first official broadcast. The company was to be financed by a royalty on the sale of BBC wireless receiving sets from approved manufacturers, to this day, the BBC aims to follow the Reithian directive to inform, educate and entertain. The financial arrangements soon proved inadequate, set sales were disappointing as amateurs made their own receivers and listeners bought rival unlicensed sets. By mid-1923, discussions between the GPO and the BBC had become deadlocked and the Postmaster-General commissioned a review of broadcasting by the Sykes Committee and this was to be followed by a simple 10 shillings licence fee with no royalty once the wireless manufactures protection expired. The BBCs broadcasting monopoly was made explicit for the duration of its current broadcast licence, the BBC was also banned from presenting news bulletins before 19.00, and required to source all news from external wire services. Mid-1925 found the future of broadcasting under further consideration, this time by the Crawford committee, by now the BBC under Reiths leadership had forged a consensus favouring a continuation of the unified broadcasting service, but more money was still required to finance rapid expansion. Wireless manufacturers were anxious to exit the loss making consortium with Reith keen that the BBC be seen as a service rather than a commercial enterprise. The recommendations of the Crawford Committee were published in March the following year and were still under consideration by the GPO when the 1926 general strike broke out in May. The strike temporarily interrupted newspaper production and with restrictions on news bulletins waived the BBC suddenly became the source of news for the duration of the crisis. The crisis placed the BBC in a delicate position, the Government was divided on how to handle the BBC but ended up trusting Reith, whose opposition to the strike mirrored the PMs own. Thus the BBC was granted sufficient leeway to pursue the Governments objectives largely in a manner of its own choosing, supporters of the strike nicknamed the BBC the BFC for British Falsehood Company. Reith personally announced the end of the strike which he marked by reciting from Blakes Jerusalem signifying that England had been saved, Reith argued that trust gained by authentic impartial news could then be used
BBC
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BBC Television Centre at
White City, West London, which opened in 1960 and closed in 2013
BBC
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BBC Pacific Quay in
Glasgow, which was opened in 2007
BBC
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BBC New Broadcasting House, London which came into use during 2012–13.
BBC
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The headquarters of the BBC at
Broadcasting House in
Portland Place, London, England. This section of the building is called 'Old Broadcasting House'.
43.
Andean Volcanic Belt
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The Andean Volcanic Belt is a major volcanic belt along the Andean cordillera in Argentina, Bolivia, Chile, Colombia, Ecuador and Peru. It formed as a result of subduction of the Nazca Plate, the belt is subdivided into four main volcanic zones that are separated from each other by volcanic gaps. The volcanoes of the belt are diverse in terms of activity style, products, while some differences can be explained by which volcanic zone a volcano belongs to, there are significant differences within volcanic zones and even between neighboring volcanoes. Romeral in Colombia is the northernmost member of the Andean Volcanic Belt, South of latitude 49° S within the Austral Volcanic Zone volcanic activity decreases with the southernmost volcano Fueguino in Tierra del Fuego archipelago. The Andean Volcanic Belt is segmented into four areas of active volcanism. The Northern Volcanic Zone extends from Colombia to Ecuador and includes all volcanoes on the mainland of these countries. Of the zones volcanoes,55 are located in Ecuador while 19 are in Colombia, in Ecuador the volcanoes are located in the Cordillera Occidental and Cordillera Real while in Colombia they are located in Cordillera Central. The volcanic arc has formed due to subduction of the Nazca Plate under western South America, some volcanoes of the Northern Volcanic Zone, such as Galeras and Nevado del Ruiz that lie in densely populated highland areas, are major sources of hazards. It has been estimated that crustal thickness beneath this region varies from around 40 to perhaps more than 55 km, sangay is the southernmost volcano of the Northern Volcanic Zone. The Central Volcanic Zone is an arc in western South America. It is one of the four zones of the Andes. The Central Volcanic Zone extends from Peru to Chile and forms the boundary of the Altiplano plateau. The volcanic arc has formed due to subduction of the Nazca Plate under western South America along the Peru–Chile Trench, the CVZ is characterized by a continental crust that reaches a thickness of approximately 70 km. Within this zone there are 44 major and 18 minor volcanic centers that are considered to be active, other silicic systems are Los Frailes ignimbrite plateau in Bolivia, and the caldera complexes of Incapillo and Cerro Galán in Argentina. The South Volcanic Zone extends roughly from Central Chiles Andes at the latitude of Santiago, 33°S, to Cerro Arenales in Aysén Region at ca. 46°S, a distance of well over 870 mi, the arc has formed due to subduction of the Nazca Plate under the South American Plate along the Peru–Chile Trench. The southern end of the SVZ is marked by the Chile Triple Junction where the Chile Rise subducts under South America at the Taitao Peninsula giving origin to the Patagonian Volcanic Gap, further south lies the Austral Volcanic Zone. During the Pliocene the SVZ south of 38°S consisted of a volcanic arc
Andean Volcanic Belt
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Map of the volcanic arcs in the
Andes, and
subducted structures affecting volcanism
Andean Volcanic Belt
–
Nevados de Chillán (2003)
44.
Nevado del Ruiz
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It is a stratovolcano, composed of many layers of lava alternating with hardened volcanic ash and other pyroclastic rocks. Nevado del Ruiz has been active for two million years, since the early Pleistocene or late Pliocene epoch, with three major eruptive periods. The current volcanic cone formed during the present eruptive period, which began 150 thousand years ago, the volcano usually generates Plinian eruptions, which produce swift-moving currents of hot gas and rock called pyroclastic flows. These eruptions often cause massive lahars, which pose a threat to human life, the impact of such an eruption is increased as the hot gas and lava melt the mountains snowcap, adding large quantities of water to the flow. On November 13,1985, a small eruption produced an enormous lahar that buried and destroyed the town of Armero in Tolima and this event later became known as the Armero tragedy—the deadliest lahar in recorded history. Similar but less deadly incidents occurred in 1595 and 1845, consisting of an explosive eruption followed by a large lahar. The volcano is part of Los Nevados National Natural Park, which contains several other volcanoes. The summit of Nevado del Ruiz is covered by large glaciers, the volcano continues to pose a threat to the nearby towns and villages, and it is estimated that up to 500,000 people could be at risk from lahars from future eruptions. Nevado del Ruiz, which lies about 129 kilometers west of Bogotá, is part of the Andes mountain range, the volcano is part of the Ruiz–Tolima volcanic massif, a group of five ice-capped volcanoes which includes the Tolima, Santa Isabel, Quindio and Machin volcanoes. The massif is located at the intersection of four faults, some of which still are active, Nevado del Ruiz lies within the Pacific Ring of Fire, a region that encircles the Pacific Ocean and contains some of the worlds most active volcanoes. It is the third most northerly of the lying in the North Volcanic Zone of the Andean Volcanic Belt. The Andean Volcanic Belt is produced by the subduction of the oceanic Nazca Plate beneath the South American continental plate. Like many other Andean volcanoes, Nevado del Ruiz is a stratovolcano and its lavas are andesitic–dacitic in composition. It covers an area of more than 200 square kilometers, stretching 65 kilometers from east to west, the mountains broad summit includes the Arenas crater, which is one kilometer in diameter and 240 meters deep. The summit of the volcano has steep slopes inclining from 20 to 30 degrees, at lower elevations, the slopes become less steep, their inclination is about 10 degrees. From there on, foothills stretch almost to the edge of the Magdalena River north of the volcano, on the two major sides of the summit, headwalls show where past rock avalanches occurred. At times, ice on the summit has melted, generating devastating lahars, on the volcanos southwest flank is the pyroclastic cone La Olleta, which is not currently active, but may have erupted in historical times. The summit of Nevado del Ruiz is covered by glaciers, which formed many thousands of years
Nevado del Ruiz
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Steam on the mountain in July 2007
Nevado del Ruiz
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Satellite radar image of Nevado del Ruiz, with the deep Arenas crater visible near the summit
Nevado del Ruiz
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The volcano’s summit and upper flanks are covered by several glaciers that appear as a white mass surrounding the Arenas crater.
45.
Nevado del Tolima
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Nevado del Tolima is a stratovolcano located in Tolima Department, Colombia, south of Nevado del Ruiz volcano. The steep-sided, glacier-clad Nevado del Tolima volcano contrasts with the profile of Nevado del Ruiz volcano to the north. The andesitic-dacitic younger Tolima volcano formed during the past 40,000 years, rising above, the summit contains a funnel-shaped crater 200–300 m deep. This crater is quite recent and was not present in December 1926, <El Grafico 19 February 1927 no.819 page 714 first column at the bottom> Holocene activity has included explosive eruptions ranging in size from moderate to plinian. The last major eruption took place about 3600 years ago, lava dome growth has produced block-and-ash flows that traveled primarily to the NE and SE. Minor explosive eruptions have been recorded from Tolima in the 19th and 20th centuries
Nevado del Tolima
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Nevado del Tolima in 1985
46.
Nevado del Huila
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Nevado del Huila at 5,364 metres, is the highest volcano in Colombia located in Huila Department, Tolima and Cauca Departments. It is visible from the city of Cali, after being dormant for more than 500 years, the volcano showed heavy signs of activity in 2007 and 2008. As of February 20,2007, there were more than 7000 minor seismic events, the volcano erupted twice in April 2007, once in April 2008 and again in November 2008. On April 18,2007, the volcano erupted twice causing avalanches into the Paez River, more than 4,000 people were evacuated with no casualties reported. Nevado del Huila became active again in March 2008, after a multitude of earthquakes inside the volcano, Colombian authorities declared a state of yellow alert on March 18. The state of alert was increased to orange on March 29, on April 14,2008 at 11,08 pm, an ash eruption took place, prompting the government to issue a red alert and evacuate 13,000 to 15,000 people from around the mountain. The state of red alert was again lowered to orange on April 16, on November 20,2008, the volcano erupted at 02,45 GMT according to Colombian Institute of Geology and Mining. An immediate mass-scale evacuation was put in motion by the Colombian authorities, there were no injured reported at the time. The eruption had triggered an avalanche of earth and debris that damaged houses, bridges, the three small towns of Paicol, La Plata and Belalcázar along the Paez River were affected by this eruption. President Álvaro Uribe ordered the Air Force of Colombia to create an air bridge to provide supplies for cut off towns along the Paez River, global Volcanism Program Nevado del Huila Volcano Observatory
Nevado del Huila
–
Nevado del Huila
47.
Galeras
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Galeras Volcano, Galeras is an Andean stratovolcano in the Colombian department of Nariño, near the departmental capital Pasto. Its summit rises 4,276 metres above sea level and it has erupted frequently since the Spanish conquest, with its first historical eruption being recorded on December 7,1580. It is currently the most active volcano in Colombia, Galeras has been an active volcano for at least a million years, with andesite as the dominant product. Two major caldera-forming eruptions have occurred, the first about 560,000 years ago in an eruption which expelled about 15 cubic kilometres of material. The second some time between 40,000 and 150,000 years ago, in a smaller but still sizable eruption of 2 cubic kilometres of material, Galeras is considered the most active volcano in Colombia, followed by Nevado del Ruiz. Its earliest activity during the Holocene has been dated at 7050 BC ±1000 years through radiocarbon dating. Other eruptions similar to this event include those in 3150 BC ±200 years,2580 BC ±500 years,1160 BC ±300 years,490 BC ±100 years, and in 890 AD ±200 years. Typically these eruptions consist of a central vent explosion, conducive to an explosive eruption causing pyroclastic flows and/or lahars, reported incidents with no official proof occurred in 1836,1930,1933, and 1973. Galeras became active again in 1988 after 10 years of dormancy, a Decade Volcano conference in the city of Pasto, in 1993, ended in disaster when several of the scientists present mounted an impromptu expedition on 14 January to the crater of Galeras. An eruption occurred unexpectedly while they were at the summit, resulting in the deaths of six scientists, elements in the media made the event controversial by suggesting the expedition leader, geologist Stanley Williams, who survived along with four others, had ignored safety procedures. A prediction had been three days before the eruption based on B-Type activity seen on a seismograph. Seismic B-types had been used successfully to predict eruptions on other volcanoes, activity at a low level has continued at Galeras, with small explosions occasionally dusting nearby villages and towns with ash. The volcano has continued to be studied, and predictions of eruptions at the volcano have improved. One phenomenon, which seems to be a precursor to eruptive activity, is a low-frequency seismic event known as a tornillo event. These have occurred before about four-fifths of the explosions at Galeras, more than 100 minor tremors were felt during a major eruption in April 2002, although no damage or injury was reported. An eruption in November 2005 forced an evacuation of the area surrounding the volcano. The city of Pasto, about 9 kilometres from the volcano, was blanketed by a layer of ash after the explosion, forcing the residents to don goggles. Numerous minor tremors and ash emissions since March 2006 culminated on 12 July 2006 in three explosive eruptions, producing an ash and gas column reaching an altitude of 8 kilometres
Galeras
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Galeras, December 2005
Galeras
–
Space radar image of Galeras Volcano. City of Pasto at bottom
48.
Cayambe (volcano)
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Cayambe is the name of a volcano located in the Cordillera Central, a range of the Ecuadorian Andes. It is located in Pichincha province some 70 km northeast of Quito and it is the third highest mountain in Ecuador. Cayambe, which has a permanent snow cap, is a Holocene compound volcano which last erupted in March 1786, at 4,690 metres on its south slope is the highest point in the world crossed by the Equator and the only point on the Equator with snow cover. The volcano and most of its slopes are within the Cayambe Coca Ecological Reserve, Cayambe was first climbed by British adventurer Edward Whymper and his two Italian guides and companions Juan Antonio and Luis Carrel in 1880, and it is a favourite of mountain climbers today. Lists of volcanoes List of volcanoes in Ecuador Cayambe, Instituto Geofísico de la Escuela Politécnica Nacional Cayambe, Etymology Photographs of the Andes Climbing Trip Report
Cayambe (volcano)
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Cayambe
Cayambe (volcano)
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Cayambe Volcano
49.
Reventador
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Reventador is an active stratovolcano which lies in the eastern Andes of Ecuador. It lies in a area of the national park of the same name. Since 1541 it has erupted over 25 times, although its isolated location means that many of its eruptions have gone unreported and its most recent eruption was in 2009, but the largest historical eruption occurred in 2002. During that eruption the plume from the reached a height of 17 km. On March 30,2007, the mountain ejected ash again, the ash reached a height of about two miles. No injuries or damages have been reported, the volcanos main peak lies inside a U-shaped caldera which is open towards the Amazon basin to the east
Reventador
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Cone of Reventador in 2012 (V. Scherrer)
