The Chimehuin River is a river in the northwest of the Patagonic Province of Neuquén, Argentina. Its origin is at Lake Huechulafquen and it passes by the city of Junín de los Andes. After a course of about 53 km, it merges with the Aluminé River to form the Collón Curá River; the Chimehuin is considered a prime spot for fly fishing. It is known for its two introduced species of the brown trout and the rainbow trout; the area around first part of the river's course is a protected nature reserve
A glacier is a persistent body of dense ice, moving under its own weight. Glaciers deform and flow due to stresses induced by their weight, creating crevasses and other distinguishing features, they abrade rock and debris from their substrate to create landforms such as cirques and moraines. Glaciers form only on land and are distinct from the much thinner sea ice and lake ice that form on the surface of bodies of water. On Earth, 99% of glacial ice is contained within vast ice sheets in the polar regions, but glaciers may be found in mountain ranges on every continent including Oceania's high-latitude oceanic island countries such as New Zealand and Papua New Guinea. Between 35°N and 35°S, glaciers occur only in the Himalayas, Rocky Mountains, a few high mountains in East Africa, New Guinea and on Zard Kuh in Iran. Glaciers cover about 10 percent of Earth's land surface. Continental glaciers cover nearly 13 million km2 or about 98 percent of Antarctica's 13.2 million km2, with an average thickness of 2,100 m.
Greenland and Patagonia have huge expanses of continental glaciers. Glacial ice is the largest reservoir of fresh water on Earth. Many glaciers from temperate and seasonal polar climates store water as ice during the colder seasons and release it in the form of meltwater as warmer summer temperatures cause the glacier to melt, creating a water source, important for plants and human uses when other sources may be scant. Within high-altitude and Antarctic environments, the seasonal temperature difference is not sufficient to release meltwater. Since glacial mass is affected by long-term climatic changes, e.g. precipitation, mean temperature, cloud cover, glacial mass changes are considered among the most sensitive indicators of climate change and are a major source of variations in sea level. A large piece of compressed ice, or a glacier, appears blue, as large quantities of water appear blue; this is. The other reason for the blue color of glaciers is the lack of air bubbles. Air bubbles, which give a white color to ice, are squeezed out by pressure increasing the density of the created ice.
The word glacier is a loanword from French and goes back, via Franco-Provençal, to the Vulgar Latin glaciārium, derived from the Late Latin glacia, Latin glaciēs, meaning "ice". The processes and features caused by or related to glaciers are referred to as glacial; the process of glacier establishment and flow is called glaciation. The corresponding area of study is called glaciology. Glaciers are important components of the global cryosphere. Glaciers are categorized by their morphology, thermal characteristics, behavior. Cirque glaciers form on the slopes of mountains. A glacier that fills a valley is called a valley glacier, or alternatively an alpine glacier or mountain glacier. A large body of glacial ice astride a mountain, mountain range, or volcano is termed an ice cap or ice field. Ice caps have an area less than 50,000 km2 by definition. Glacial bodies larger than 50,000 km2 are called continental glaciers. Several kilometers deep, they obscure the underlying topography. Only nunataks protrude from their surfaces.
The only extant ice sheets are the two that cover most of Greenland. They contain vast quantities of fresh water, enough that if both melted, global sea levels would rise by over 70 m. Portions of an ice sheet or cap that extend into water are called ice shelves. Narrow, fast-moving sections of an ice sheet are called ice streams. In Antarctica, many ice streams drain into large ice shelves; some drain directly into the sea with an ice tongue, like Mertz Glacier. Tidewater glaciers are glaciers that terminate in the sea, including most glaciers flowing from Greenland, Antarctica and Ellesmere Islands in Canada, Southeast Alaska, the Northern and Southern Patagonian Ice Fields; as the ice reaches the sea, pieces break off, or calve. Most tidewater glaciers calve above sea level, which results in a tremendous impact as the iceberg strikes the water. Tidewater glaciers undergo centuries-long cycles of advance and retreat that are much less affected by the climate change than those of other glaciers.
Thermally, a temperate glacier is at melting point throughout the year, from its surface to its base. The ice of a polar glacier is always below the freezing point from the surface to its base, although the surface snowpack may experience seasonal melting. A sub-polar glacier includes both temperate and polar ice, depending on depth beneath the surface and position along the length of the glacier. In a similar way, the thermal regime of a glacier is described by its basal temperature. A cold-based glacier is below freezing at the ice-ground interface, is thus frozen to the underlying substrate. A warm-based glacier is above or at freezing at the interface, is able to slide at this contact; this contrast is thought to a large extent to govern the ability of a glacier to erode its bed, as sliding ice promotes plucking at rock from the surface below. Glaciers which are cold-based and warm-based are known as polythermal. Glaciers form where the accumulation of ice exceeds ablation. A glacier originates from a landform called'cirque' – a armchair-shaped geological feature (such as a depressio
The Andes or Andean Mountains are the longest continental mountain range in the world, forming a continuous highland along the western edge of South America. This range is about 7,000 km long, about 200 to 700 km wide, of an average height of about 4,000 m; the Andes extend from north to south through seven South American countries: Venezuela, Ecuador, Bolivia and Argentina. Along their length, the Andes are split into several ranges, separated by intermediate depressions; the Andes are the location of several high plateaus – some of which host major cities such as Quito, Bogotá, Medellín, Sucre, Mérida and La Paz. The Altiplano plateau is the world's second-highest after the Tibetan plateau; these ranges are in turn grouped into three major divisions based on climate: the Tropical Andes, the Dry Andes, the Wet Andes. The Andes Mountains are the world's highest mountain range outside Asia; the highest mountain outside Asia, Argentina's Mount Aconcagua, rises to an elevation of about 6,961 m above sea level.
The peak of Chimborazo in the Ecuadorian Andes is farther from the Earth's center than any other location on the Earth's surface, due to the equatorial bulge resulting from the Earth's rotation. The world's highest volcanoes are in the Andes, including Ojos del Salado on the Chile-Argentina border, which rises to 6,893 m; the Andes are part of the American Cordillera, a chain of mountain ranges that consists of an continuous sequence of mountain ranges that form the western "backbone" of North America, Central America, South America and Antarctica. 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. The Andes can be divided into three sections: The Southern Andes in Chile. 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 Leeward Antilles islands Aruba and Curaçao, which lie in the Caribbean Sea off the coast of Venezuela, were thought to represent the submerged peaks of the extreme northern edge of the Andes range, but ongoing geological studies indicate that such a simplification does not do justice to the complex tectonic boundary between the South American and Caribbean plates; the Andes are a Mesozoic–Tertiary orogenic belt of mountains along the Pacific Ring of Fire, a zone of volcanic activity that encompasses the Pacific rim of the Americas as well as the Asia-Pacific region. The Andes are the result of tectonic plate processes, caused by the subduction of oceanic crust beneath the South American Plate, it is the result of a convergent plate boundary between the Nazca Plate and the South American Plate The main cause of the rise of the Andes is the compression of the western rim of the South American Plate due to the subduction of the Nazca Plate and the Antarctic Plate.
To the east, the Andes range is bounded by several sedimentary basins, such as Orinoco, Amazon Basin, Madre de Dios and Gran Chaco, that separate the Andes from the ancient cratons in eastern South America. In the south, the Andes share a long boundary with the former Patagonia Terrane. To the west, the Andes end at the Pacific Ocean, although the Peru-Chile trench can be considered their ultimate western limit. 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 contain large quantities of iron ore located in many mountains within the range. The Andean orogen has a series of 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 and Argentina; 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 and according to Isacks the orocline is related to crustal shortening. The specific point at 18° S where the coastline bends is known as the "Arica Elbow". Further south lies the Maipo Orocline or Maipo Transition Zone located between 30° S and 38°S with a break in trend at 33° S. Near the southern tip of the Andes lies the Patagonian orocline; the western rim of the South American Plate has been the place of several pre-Andean orogenies since at least the late Proterozoic and early Paleozoic, when several terranes and microcontinents collided and amalgamated with the ancient cratons of eastern South America, by the South American part of Gondwana. The formation of the modern Andes began with the events of the Triassic when Pangaea began the break up that resulted in developing several rifts; the development continued through the Jurassic Period. It was during the Cretaceous Period that the Andes began to take their present form, by the uplifting and folding of sedimentary and metamorphic rocks of the ancient cratons to the east.
The rise of the Andes has not been constant, as different regions have had different degrees of tectonic stress and erosion. Tectonic forces above the subduction zone al
A glacial lake is a body of water with origins from glacier activity. They are formed when a glacier erodes the land, melts, filling the depression created by the glacier. Near the end of the last glacial period 10,000 years ago, glaciers began to retreat. A retreating glacier left behind large deposits of ice in hollows between drumlins or hills; as the ice age ended, these melted to create lakes. This is apparent in the Lake District in Northwestern England where post-glacial sediments are between 4 and 6 metres deep; these lakes are surrounded by drumlins, along with other evidence of the glacier such as moraines and erosional features such as striations and chatter marks. These lakes are visible in aerial photos of landforms in regions that were glaciated during the last ice age; the coastlines near these areas are very irregular, reflecting the same geological process. By contrast, other areas have fewer lakes that appear attached to rivers, their coastlines are smoother. These areas were carved more by water erosion.
The formation and characteristics of glacial lakes vary between location and can be classified into glacial erosion lake, ice-blocked lake, moraine-dammed lake, other glacial lake, supraglacial lake, subglacial lake. Since the deglaciation of the little ice age Earth has lost more than 50% of its glaciers; this along with the current increase in retreating glaciers caused by climate change has created a shift from frozen to liquid water, increasing the extent and volume of glacial lakes around the world. Most glacial lakes present today can be found in Asia and North America; the area which will see the greatest increase in lake formation is the Southern Tibetan Plateau region from debris covered glaciers. This increase in glacial lake formation indicates an increase in occurrence of glacial lake outburst flood events caused by damming and subsequent breaking of moraine and ice; the amount of sediment found in glacial lakes varies from four to six meters in depth, has a general stratigraphic sequence of.
Over time the glacial lake sediments are subjected to change. As seen in the English Lake District, the layers of the sediments at the bottom of the lakes contain evidence of the rate of erosion; the elemental make up of the sediments are not associated with the lakes themselves, but by the migration of the elements within the soil, such as iron and manganese. The distribution of these elements, within the lake bed, are attributed to the condition of the drainage basin and the chemical composition of the water. Sediment deposition can be influenced by animal activity; the amount of halogens and boron found in the sediments accompanies a change in erosional activity. The rate of deposition reflects the amount of boron in the deposited sediments; the scouring action of the glaciers pulverizes minerals in the rock. These pulverized minerals become sediment at the bottom of the lake, some of the rock flour becomes suspended in the water column; these suspended minerals support a large population of algae.
Biodiversity and productivity tend to be lower in glacial lakes as only cold-tolerant and cold-adapted species can withstand their harsh conditions. Glacial rock flour and low nutrient levels create an oligotrophic environment where few species of plankton and benthic organisms reside. Before becoming a lake the first stages of glacial recession melt enough freshwater to form a shallow lagoon. In the case of Iceland's Jökulsárlón glacial lagoon located on the edge of the Atlantic Ocean, tides bring in an array of fish species to the edge of the glacier; these fish attract an abundance of predators from birds to marine mammals, that are searching for food. These predators include fauna such as, arctic terns and arctic skua. Glacial lakes that have been formed for a long period of time have a more diverse ecosystem of fauna originating form neighboring tributaries or other glacial refugia. For example, many native species of the great lakes basin entered via the Mississippi basin refugia within the past 14,000 years.
Glacial lakes act as fresh water storage for the replenishing of a regions water supply and serve as potential electricity producers from hydropower. Glacial lakes aesthetic nature stimulates economic activity through the attraction of the tourism industry. Thousands of tourists visit the Jökulsárlón glacial lagoon in Iceland annually to take part in commercial boat tours and every two to four years thousands visit the Argentino glacial lake in Argentina to witness the collapse of the cyclically formed arch of ice from the Perito Moreno glacier, making it one of the largest travel destinations in Patagonia. Great Lakes of North America Glacial history of Minnesota Proglacial lake Moraine-dammed lake Subglacial lake Zungenbecken
Neuquén is a province of Argentina, located in the west of the country, at the northern end of Patagonia. It borders Mendoza Province to the north, Rio Negro Province to the southeast, Chile to the west, it meets La Pampa Province at its northeast corner. The Neuquén Province receives its name from the Neuquén River; the term "Neuquén" derives from the Mapudungun word "Nehuenken" meaning drafty, which the aborigines used for the river. The word is a palindrome. Lácar Department in Neuquén Province has the southernmost known remains of maize before the diffusion of associated with the Inca Empire; the site where maize remains were found Melinquina lies at 40°19' S the maize being found in Melinquina, the maize being found inside pottery datet to 730 ±80 BP and 920 ±60 BP. This maize was brought across the Andes from Chile. In that location maize remains were found inside pottery date to 730 ±80 BP and 920 ±60 BP; this maize was brought across the Andes from Chile. Inhabited by Tehuelches and Pehuenche, the territory was explored by conquistadores coming from Chile.
In 1670 a Jesuit priest established in Chiloé Archipelago, Nicolás Mascardi, founded the Jesuit mission Nuestra Senora de Nahuel Huapi. The Jesuit missions lasted few years and the last mission in Neuquén was destroyed in 1717; the suppression of the Society of Jesus in 1767 halted further missionary activity. The Neuquén area came under Argentine influence after explorer Perito Francisco Moreno made several trips to Patagonia and made accurate descriptions of the area in his book "Viaje al Pais de las Manzanas", reaching Nahuel Huapi lake in 1875. In 1879 Julio Argentino Roca started the Conquest of the Desert that broke the aboriginal resistance. In 1884 Patagonia's political divisions were restructured and the Territory of Neuquén acquired its current boundaries; the capital of the province moved several times to Norquín, Campana Mahuida, Chos Malal, Confluencia known as Neuquén. At the beginning of the 20th century the railway reached the city of Neuquén, a new irrigation system was finished, facilitating the production and transportation of crops.
Petroleum was found in Plaza Huincul in 1918. Local politics have long been dominated by a single political party, the MPN or Movimiento Popular Neuquino founded by Elias Sapag, a prosperous businessman born in Lebanon. Migrating to Argentina, the Sapag family arrived in Neuquén Territory around 1910 with the railroad making their home in Zapala, whose dry, fertile mountain valleys and orchards were reminiscent of their native Lebanon. Neuquén is rich in natural resources such as natural gas, virgin forests and water resources suitable for electric power and tourism alike; these resources were managed by the central National Government, which resulted in little local benefit at the time. Because of social unrest, Elias Sapag and two younger brothers and Amado, started the MPN, an active political movement rooted in federalism and greater local rights over the territory and its resources; the territory was made a province on June 15, 1955, its constitution promulgated on November 28, 1957. Felipe Sapag soon became politically prominent.
Although he was elected governor in 1962 representing the Movimiento Popular Neuquino, a coup against progressive President Arturo Frondizi that March prevented Sapag from taking office. Becoming governor in 1963-66 and 1973–76, he presided over one of Argentina's fastest-growing provinces; the national government established the University of Neuquén in 1964 incorporated into the new National University of Comahue in 1971. Removed as governor following the violent March 1976 coup against Isabel Perón, Felipe Sapag was returned to office in 1983-87 and 1995-99, his emphasis on public works and political independence from Buenos Aires have helped him and his successors with the MPN win every province-wide election since. His brother Elias Sapag became senator in 1963-66, 1973–76 and from 1983 until his death in 1993, becoming the longest-serving senator in national history; the MPN elected Governors Pedro Salvatori, Jorge Sobisch and current Governor Jorge Sapag. Neuquén has, since 1955, become a prosperous province with a high impact on the national energy supply and, as a growing tourist destination, outperforming most other provinces in the Patagonia region and in Argentina.
The province's limits are the Colorado River to the northeast, separating it from the Mendoza Province, the Limay River to the southeast toward the Río Negro Province, the Andes mountains to the west, separating it from Chile. There are two main distinctive landscapes; the lacustrine system includes other less-important rivers such as the Aluminé River, the Malleo, the Picún Leufú River, a series of lakes including Nahuel Huapi Lake, shared with Río Negro Province, Aluminé Lake, Lácar Lake, Huechulaufquen Lake, Lolog Lake, Hermoso, Quillén, Ñorquinco and Falkner. The province is home to the magnificent Arrayanes forest at the Los Arrayanes National Park. Other National parks include Lanín National Park and the Lanín extinct volcano, the Nahuel Huapí National Park shared with Río Negro Province, the Laguna Blanca National Park. Neuquén Province, being far away from both the Atlantic coast and the Pacific ocean by the Andes mountai
Lanín National Park
Lanín National Park is a national park of Argentina, located in the Neuquén Province, with forests of diverse tree varieties Fagaceae and conifers such as the lenga and the Araucaria, many species of which are not found elsewhere in Argentina. The park contains Lanín volcano, Huechulafquen, Aluminé, Lácar lakes among others. In them, the numerous rivers and streams, sport fishing of salmon and trout is practiced; the animal life of the park is similar to the southern Nahuel Huapi National Park. The city of San Martín de los Andes on the shore of Lake Lácar serves as hub for tourists visiting the park, as well as to skiers visiting the nearby Chapelco ski centre; the park has a moist temperate climate. Mean temperatures range from 4 °C in winter to 20 °C in summer. Mean annual precipitation is around 1,800 mm. Most of the precipitation is concentrated from May to August while snowfall can fall anytime from May to October. Official site Parque Nacional Lanín