Cuscatlán is a department of El Salvador, located in the center of the country. With a surface area of 756.19 square kilometres, it is El Salvador's smallest department. It is inhabited by over 252,000 people. Cuscatlán or Cuzcatlán was the name the original inhabitants of the Western part of the country gave to most of the territory, now El Salvador. In their language it means "land of precious jewels", it was created on 22 May 1835. Suchitoto was the first capital of the department but on 12 November 1861, Cojutepeque was made the capital, it is known in producing fruits, sugar cane, coffee among other items. The department is famous for its chorizos from the city of Cojutepeque. Candelaria Cojutepeque El Carmen El Rosario Monte San Juan Oratorio de Concepción San Bartolomé Perulapía San Cristóbal San José Guayabal San Pedro Perulapán San Rafael Cedros San Ramón Santa Cruz Analquito Santa Cruz Michapa Suchitoto Tenancingo El Salvador at GeoHive
In volcanology, a lava dome or volcanic dome is a circular mound-shaped protrusion resulting from the slow extrusion of viscous lava from a volcano. Dome-building eruptions are common in convergent plate boundary settings. Around 6% of eruptions on earth are lava dome forming; the geochemistry of lava domes can vary from basalt to rhyolite although the majority are of intermediate composition The characteristic dome shape is attributed to high viscosity that prevents the lava from flowing far. This high viscosity can be obtained in two ways: by high levels of silica in the magma, or by degassing of fluid magma. Since viscous basaltic and andesitic domes weather fast and break apart by further input of fluid lava, most of the preserved domes have high silica content and consist of rhyolite or dacite. Existence of lava domes has been suggested for some domed structures on the Moon and Mars, e.g. the Martian surface in the western part of Arcadia Planitia and within Terra Sirenum. Lava domes evolve unpredictably, due to non-linear dynamics caused by crystallization and outgassing of the viscous lava in the dome's conduit.
Domes undergo various processes such as growth, collapse and erosion. Lava domes grow by exogenic dome growth; the former implies the enlargement of a lava dome due to the influx of magma into the dome interior, the latter refers to discrete lobes of lava emplaced upon the surface of the dome. It is the high viscosity of the lava that prevents it from flowing far from the vent from which it extrudes, creating a dome-like shape of sticky lava that cools in-situ. Spines and lava flows are common extrusive products of lava domes. Domes may reach heights of several hundred meters, can grow and for months, years, or centuries; the sides of these structures are composed of unstable rock debris. Due to the intermittent buildup of gas pressure, erupting domes can experience episodes of explosive eruption over time. If part of a lava dome collapses and exposes pressurized magma, pyroclastic flows can be produced. Other hazards associated with lava domes are the destruction of property from lava flows, forest fires, lahars triggered from re-mobilization of loose ash and debris.
Lava domes are one of the principal structural features of many stratovolcanoes worldwide. Lava domes are prone to unusually dangerous explosions since they can contain rhyolitic silica-rich lava. Characteristics of lava dome eruptions include shallow, long-period and hybrid seismicity, attributed to excess fluid pressures in the contributing vent chamber. Other characteristics of lava domes include their hemispherical dome shape, cycles of dome growth over long periods, sudden onsets of violent explosive activity; the average rate of dome growth may be used as a rough indicator of magma supply, but it shows no systematic relationship to the timing or characteristics of lava dome explosions. Gravitational collapse of a lava dome can produce a ash flow. A cryptodome is a dome-shaped structure created by accumulation of viscous magma at a shallow depth. One example of a cryptodome was in the May 1980 eruption of Mount St. Helens, where the explosive eruption began after a landslide caused the side of the volcano to fall, leading to explosive decompression of the subterranean cryptodome.
Coulées are lava domes that have experienced some flow away from their original position, thus resembling both lava domes and lava flows. The world's largest known dacite flow is the Chao dacite dome complex, a huge coulée flow-dome between two volcanoes in northern Chile; this flow is over 14 kilometres long, has obvious flow features like pressure ridges, a flow front 400 metres tall. There is another prominent coulée flow on the flank of Llullaillaco volcano, in Argentina, other examples in the Andes. Global Volcanism Program: Lava Domes USGS Photo glossary of volcano terms: Lava dome
1980 eruption of Mount St. Helens
On May 18, 1980, a major volcanic eruption occurred at Mount St. Helens, a volcano located in Skamania County, in the U. S. state of Washington. The eruption was the most significant volcanic eruption to occur in the contiguous 48 U. S. states since the much smaller 1915 eruption of Lassen Peak in California. It has been declared the most disastrous volcanic eruption in U. S. history. The eruption was preceded by a two-month series of earthquakes and steam-venting episodes, caused by an injection of magma at shallow depth below the volcano that created a large bulge and a fracture system on the mountain's north slope. An earthquake at 8:32:17 a.m. PDT on Sunday, May 18, 1980, caused the entire weakened north face to slide away, creating the largest landslide recorded; this allowed the molten, high-pressure gas- and steam-rich rock in the volcano to explode northwards toward Spirit Lake in a hot mix of lava and pulverized older rock, overtaking the avalanching face. An eruption column rose 80,000 feet into the atmosphere and deposited ash in 11 U.
S. states. At the same time, snow and several entire glaciers on the volcano melted, forming a series of large lahars that reached as far as the Columbia River, nearly 50 miles to the southwest. Less severe outbursts continued into the next day, only to be followed by other large, but not as destructive, eruptions that year. Thermal energy released during the eruption was equal to 26 megatons. 57 people were killed directly, including innkeeper Harry R. Truman, photographers Reid Blackburn and Robert Landsburg, geologist David A. Johnston. Hundreds of square miles were reduced to wasteland, causing over $1 billion in damage, thousands of animals were killed, Mount St. Helens was left with a crater on its north side. At the time of the eruption, the summit of the volcano was owned by the Burlington Northern Railroad, but afterward the land passed to the United States Forest Service; the area was preserved, as it was, in the Mount St. Helens National Volcanic Monument. Mount St. Helens remained dormant from its last period of activity in the 1840s and 1850s until March 1980.
Several small earthquakes, beginning on March 15, indicated that magma may have begun moving below the volcano. On March 20, at 3:45 p.m. Pacific Standard Time, a shallow magnitude 4.2 earthquake centered below the volcano's north flank, signaled the volcano's violent return from 123 years of hibernation. A building earthquake swarm saturated area seismographs and started to climax at about noon on March 25, reaching peak levels in the next two days, including an earthquake registering 5.1 on the Richter scale. A total of 174 shocks of magnitude 2.6 or greater were recorded during those two days. Shocks of magnitude 3.2 or greater occurred at a increasing rate during April and May with five earthquakes of magnitude 4 or above per day in early April, eight per day the week before May 18. There was no direct sign of eruption, but small earthquake-induced avalanches of snow and ice were reported from aerial observations. At 12:36 p.m. on March 27, phreatic eruptions ejected and smashed rock from within the old summit crater, excavating a new crater 250 feet wide, sending an ash column about 7,000 feet into the air.
By this date a 16,000-foot-long eastward-trending fracture system had developed across the summit area. This was followed by more earthquake swarms and a series of steam explosions that sent ash 10,000 to 11,000 feet above their vent. Most of this ash fell between three and twelve miles from its vent, but some was carried 150 miles south to Bend, Oregon, or 285 miles east to Spokane, Washington. A second, new crater and a blue flame were observed on March 29; the flame was visibly emitted from both craters and was created by burning gases. Static electricity generated from ash clouds rolling down the volcano sent out lightning bolts that were up to two miles long. Ninety-three separate outbursts were reported on March 30, strong harmonic tremors were first detected on April 1, alarming geologists and prompting Governor Dixy Lee Ray to declare a state of emergency on April 3. Governor Ray issued an executive order on April 30 creating a "red zone" around the volcano; this precluded many cabin owners from visiting their property.
By April 7, the combined crater was 500 feet deep. A USGS team determined in the last week of April that a 1.5-mile-diameter section of St. Helens' north face was displaced outward by at least 270 feet. For the rest of April and early May this bulge grew by five to six feet per day, by mid-May it extended more than 400 feet north; as the bulge moved northward, the summit area behind it progressively sank, forming a complex, down-dropped block called a graben. Geologists announced on April 30 that sliding of the bulge area was the greatest immediate danger and that such a landslide might spark an eruption; these changes in the volcano's shape were related to the overall deformation that increased the volume of the volcano by 0.03 cubic miles by mid-May. This volume increase corresponded to the volume of magma that pushed into the volcano and deformed its surface; because the intruded magma remained below ground and was not directly visible, it was called a cryptodome, in contrast to a true lava dome exposed at t
San Salvador (volcano)
The San Salvador Volcano is a stratovolcano situated northwest to the city of San Salvador. The crater has been nearly filled with a newer edifice, the Boquerón volcano. San Salvador is adjacent to the volcano and the western section of the city lies among its slopes. Due to this close proximity, any geological activity of the volcano, whether eruptive or not, has the potential to result in catastrophic destruction and death to the city. Despite this, the volcano is iconic of the city, several TV and radio antennas are situated on the El Picacho peaks and the crater of Boqueron. El Picacho, the prominent peak is the highest elevation; the Boquerón edifice formed between 1,000 years ago, filling up the G-1 eruption crater. The lavas of the Boquerón edifice contain more alkali element and iron oxide than the lavas of the san salvador edifice, allowing for a clear chemical distinction. Around 800 years ago, the present day crater was formed in a violent explosion; the crater, which gives it the present name is 1.5 km in diameter and 500m deep.
Within the crater around the upper walls, crops are cultivated by the locals who live on the volcano. The magma chamber which the volcano sits upon contains a number of fissures which protrude along the flanks and sides of the volcano; the northwest fissure has been the most active with such significant eruptive events, such as the Loma Caldera eruption which buried the ancient village of Ceren and the eruption of El Playon which buried the town of Nexapa. The citizens relocated to Nejapa and nowadays the eruption is celebrated annually; the most recent eruption in 1917 caused a flank eruption on the volcano along the N40W fissure. During this eruption, the crater lake inside the Boqueron evaporated and a cinder cone appeared, christened'Boqueroncito'. List of volcanoes in El Salvador "San Salvador". Global Volcanism Program. Smithsonian Institution. Williams, H. and Meyer-Abich, H. 1955 Volcanisim in the southern part of El Salvador: University of California Publication in geological Sciences v. 32 pp1–64 Sofield.
D. Eruptive history and volcanic hazards of Volcan San Salvador, in Rose W. I. et al. Natural Hazards in El Salvador: Bolder, Geological Society of America Special Paper 375, pp 147–158. Fairbrothers G E. Carr M J. and Mayfield F G. Temporal Magmatic Variation at Boqueron Volcano, El Salvador. Contrib. Mineral. Petrol. V 67, pp 1–9 Topographical hazard zonation maps regarding the volcano and the city
Body of water
A body of water or waterbody is any significant accumulation of water on a planet's surface. The term most refers to oceans and lakes, but it includes smaller pools of water such as ponds, wetlands, or more puddles. A body of water contained. Most are occurring geographical features, but some are artificial. There are types. For example, most reservoirs are created by engineering dams, but some natural lakes are used as reservoirs. Most harbors are occurring bays, but some harbors have been created through construction. Bodies of water that are navigable are known as waterways; some bodies of water collect and move water, such as rivers and streams, others hold water, such as lakes and oceans. The term body of water can refer to a reservoir of water held by a plant, technically known as a phytotelma. Bodies of water are affected by gravity, what creates the tidal effects on Earth. Note that there are some geographical features involving water that are not bodies of water, for example waterfalls and rapids.
Arm of the sea – sea arm, used to describe a sea loch. Arroyo – a dry creek bed or gulch that temporarily fills with water after a heavy rain, or seasonally. See wadi. Artificial lake or artificial pond – see Reservoir. Barachois – a lagoon separated from the ocean by a sand bar. Bay – an area of water bordered by land on three sides, similar to, but smaller than a gulf. Bayou – a slow-moving stream or a marshy lake. Beck – a small stream. Bight – a large and only receding bay, or a bend in any geographical feature. Billabong – an oxbow lake in Australia. Boil – see Seep Brook – a small stream. Burn – a small stream. Canal – an artificial waterway connected to existing lakes, rivers, or oceans. Channel – the physical confine of a river, slough or ocean strait consisting of a bed and banks. See stream bed and strait. Cove – a coastal landform. Earth scientists use the term to describe a circular or round inlet with a narrow entrance, though colloquially the term is sometimes used to describe any sheltered bay.
Creek – a small stream. Creek – an inlet of the sea, narrower than a cove. Delta – the location where a river flows into an ocean, estuary, lake, or reservoir. Distributary or distributary channel – a stream that branches off and flows away from a main stream channel. Drainage basin – a region of land where water from rain or snowmelt drains downhill into another body of water, such as a river, lake, or reservoir. Draw – a dry creek bed or gulch that temporarily fills with water after a heavy rain, or seasonally. See wadi. Estuary – a semi-enclosed coastal body of water with one or more rivers or streams flowing into it, with a free connection to the open sea Firth – a regional term of Scotland used to denote various coastal waters, such as large sea bays, estuaries and straits. Fjord – a narrow inlet of the sea between cliffs or steep slopes. Glacier – a large collection of ice or a frozen river that moves down a mountain. Glacial pothole – a kettle Gulf – a part of a lake or ocean that extends so that it is surrounded by land on three sides, similar to, but larger than a bay.
Headland – an area of water bordered by land on three sides. Harbor – an artificial or occurring body of water where ships are stored or may shelter from the ocean's weather and currents. Impoundment – an artificially-created body of water, by damming a source. Used for flood control, as a drinking water supply, ornamentation, or other purpose or combination of purposes. Note that the process of creating an "impoundment" of water is itself called "impoundment." Inlet – a body of water seawater, which has characteristics of one or more of the following: bay, estuary, fjord, sea loch, or sound. Kettle – a shallow, sediment-filled body of water formed by retreating glaciers or draining floodwaters. Kill – used in areas of Dutch influence in New York, New Jersey and other areas of the former New Netherland colony of Dutch America to describe a strait, river, or arm of the sea. Lagoon – a body of comparatively shallow salt or brackish water separated from the deeper sea by a shallow or exposed sandbank, coral reef, or similar feature.
Lake – a body of water freshwater, of large size contained on a body of land. Lick — a small watercourse or an ephemeral stream Loch – a body of water such as a lake, sea inlet, fjord, estuary or bay. Mangrove swamp – Saline coastal habitat of mangrove trees and shrubs. Marsh – a wetland featuring grasses, reeds, typhas and other herbaceous plants in a context of shallow water. See Salt marsh. Mediterranean sea – a enclosed sea that has limited exchange of deep water with outer oceans and where the water circulation is dominated by salinity and temperature differences rather than winds Mere – a lake or body of water, broad in relation to its depth. Mill pond – a reservoir built to provide flowing water to a watermill Moat – a deep, broad trench, either dry or filled with water and protecting a structure, installation, or town. Ocean – a major body of salty water that, in totality, covers about 71% of the Earth's surface. Oxbow lake – a U-shaped lake formed when a wide meander from the mainstem of a riv
The Pleistocene is the geological epoch which lasted from about 2,588,000 to 11,700 years ago, spanning the world's most recent period of repeated glaciations. The end of the Pleistocene corresponds with the end of the last glacial period and with the end of the Paleolithic age used in archaeology; 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, the Gelasian, Middle Pleistocene and Upper Pleistocene. In addition to this international subdivision, various regional subdivisions are used. Before a change confirmed in 2009 by the International Union of Geological Sciences, the time boundary between the Pleistocene and the preceding Pliocene was regarded as being at 1.806 million years Before Present, as opposed to the accepted 2.588 million years BP: publications from the preceding years may use either definition of the period. 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.
This distinguished it from the older Pliocene epoch, which Lyell had thought to be the youngest fossil rock layer. He constructed the name "Pleistocene" from the Greek πλεῖστος, pleīstos, "most", καινός, kainós, "new"; the Pleistocene has been dated from 2.588 million to 11,700 years BP with the end date expressed in radiocarbon years as 10,000 carbon-14 years BP. 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 end of the Younger Dryas is the official start of the current Holocene Epoch. Although it is considered an epoch, the Holocene is not different from previous interglacial intervals within the Pleistocene, it was not until after the development of radiocarbon dating, that Pleistocene archaeological excavations shifted to stratified caves and rock-shelters as opposed to open-air river-terrace sites. In 2009 the International Union of Geological Sciences confirmed a change in time period for the Pleistocene, changing the start date from 1.806 to 2.588 million years BP, accepted the base of the Gelasian as the base of the Pleistocene, namely the base of the Monte San Nicola GSSP.
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 and Discoaster surculus; 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 start date of the Pleistocene to 2.58 Ma, results in the inclusion of all the recent repeated glaciations within the Pleistocene. The modern continents were at their present positions during the Pleistocene, the plates upon which they sit having moved no more than 100 km relative to each other since the beginning of the period.
According to Mark Lynas, the Pleistocene's overall climate could be characterized as a continuous El Niño with trade winds in the south Pacific weakening or heading east, warm air rising near Peru, warm water spreading from the west Pacific and the Indian Ocean to the east Pacific, other El Niño markers. Pleistocene climate was marked by repeated glacial cycles in which continental glaciers pushed to the 40th parallel in some places, it is estimated. In addition, a zone of permafrost stretched southward from the edge of the glacial sheet, a few hundred kilometres in North America, several hundred in Eurasia; the mean annual temperature at the edge of the ice was −6 °C. Each glacial advance tied up huge volumes of water in continental ice sheets 1,500 to 3,000 metres thick, resulting in temporary sea-level drops of 100 metres or more over the entire surface of the Earth. 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 Tasmania; the current decaying glaciers of Mount Kenya, Mount Kilimanjaro, the Ruwenzori Range in east and central Africa were larger. Glaciers existed 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 Fenno-Scandian ice sheet rested including much of Great Britain. Scattered domes stretched across Siberi
El Salvador the Republic of El Salvador, is the smallest and the most densely populated country in Central America. It is bordered on the northeast by Honduras, on the northwest by Guatemala, on the south by the Pacific Ocean. El Salvador's capital and largest city is San Salvador; as of 2016, the country had a population of 6.34 million. El Salvador was for centuries inhabited by several Mesoamerican nations the Cuzcatlecs, as well as the Lenca and Maya. In the early 16th century, the Spanish Empire conquered the territory, incorporating it into the Viceroyalty of New Spain ruled from Mexico City; however the Viceroyalty of Mexico had little or no influence in the daily affairs of the Central American isthmus, which would be colonized in 1524. In 1609 the area became the Captaincy General of Guatemala, from which El Salvador was part of until its independence from Spain, which took place in 1821, as part of the First Mexican Empire further seceded, as part of the Federal Republic of Central America, in 1823.
When the Republic dissolved in 1841, El Salvador became a sovereign nation formed a short-lived union with Honduras and Nicaragua called the Greater Republic of Central America, which lasted from 1895 to 1898. From the late 19th to the mid-20th century, El Salvador endured chronic political and economic instability characterized by coups, a succession of authoritarian rulers. Persistent socioeconomic inequality and civil unrest culminated in the devastating Salvadoran Civil War, fought between the military-led government and a coalition of left-wing guerrilla groups; the conflict ended with the Chapultepec Peace Accords. This negotiated settlement established a multiparty constitutional republic, which remains in place to this day. El Salvador's economy has been dominated by agriculture, beginning with the indigo plant, the most important crop during the colonial period, followed thereafter by coffee, which by the early 20th century accounted for 90 percent of export earnings. El Salvador has since reduced its dependence on coffee and embarked on diversifying the economy by opening up trade and financial links and expanding the manufacturing sector.
The colón, the official currency of El Salvador since 1892, was replaced by the U. S. dollar in 2001. As of 2010, El Salvador ranks 12th among Latin American countries in terms of the Human Development Index and fourth in Central America due in part to ongoing rapid industrialisation. However, the country continues to struggle with high rates of poverty and crime. Conquistador Pedro de Alvarado named the new province for Jesus Christ – El Salvador; the full name was "Provincia De Nuestro Señor Jesus Cristo, El Salvador Del Mundo", subsequently abbreviated to "El Salvador". Tomayate is a paleontological site located on the banks of the river of the same name in the municipality of Apopa; the site has produced abundant Salvadoran megafauna fossils belonging to the Pleistocene epoch. The paleontological site was discovered accidentally in 2000, in the following year, an excavation by the Museum of Natural History of El Salvador revealed not only several remnants of Cuvieronius, but several other species of vertebrates.
In the Tomayate site, they have recovered at least 19 species of vertebrates, including giant tortoises, Glyptodon, extinct horses, paleo-llamas and a large number of skeletal remains of proboscis genus Cuvieronius. The Tomayate site stands out from most Central American Pleistocene deposits, being more ancient and much richer, which provides valuable information of the Great American Interchange, in which the Central American isthmus landbridge played the title primordial role. At the same time, it is considered the richest vertebrate paleontological site in Central America and one of the largest accumulations of proboscideans in the Americas. Sophisticated civilization in El Salvador dates to its settlement by the indigenous Lenca people; the Lenca were succeeded by the Olmecs, who also disappeared, leaving their monumental architecture in the form of the pyramids still extant in western El Salvador. The Maya arrived and settled in place of the Olmecs, but their numbers were diminished when the Ilopango supervolcano eruption caused a massive Mayan exodus out of what is now El Salvador.
Centuries they themselves were replaced by the Pipil people, Nahua speaking groups who migrated from Mexico in the centuries before the European conquest and occupied the central and western regions. The Pipil were the last indigenous people to arrive in El Salvador, they called their territory Kuskatan, a Pipil word meaning The Place of Precious Jewels, backformed into Classical Nahuatl Cōzcatlān, Hispanicized as Cuzcatlán. The people of El Salvador today are referred to as Salvadoran, while the term Cuzcatleco is used to identify someone of Salvadoran heritage. In pre-Columbian times, the country was inhabited by various other indigenous peoples, including the Lenca, a Chilanga Lencan-speaking group who settled in the eastern highlands. Cuzcatlan was the larger domain until the Spanish conquest. Since El Salvador resided on the eastern edge of the Maya Civilization, the origins of many of El Salvador's ruins are controversial. However, it is agreed that Mayas occupied the areas around Lago de Guija and Cihuatán.
Other ruins such as Tazumal, Joya de Cerén and San Andrés may have been