135-491: Viedma Glacier is a large glacier that is part of the huge Southern Patagonian Ice Field , located at the southern end of mainland South America . Viedma Glacier is a valley glacier and its moraine -rich terminus flows into the western end of Lake Viedma , which is fed primarily by its melting ice. Viedma Glacier is located in the undefined part of the limit between Chile and Argentina , in Argentinian legislature it
270-468: A de jure sovereignty over the area. In 1669, the district around Puerto Deseado was explored by John Davis and was claimed in 1670 by Sir John Narborough for King Charles II of England , but the English made no attempt to establish settlements or explore the interior. The first European explorers of Patagonia observed that the indigenous people in the region were taller than the average Europeans of
405-424: A cirque landform (alternatively known as a corrie or as a cwm ) – a typically armchair-shaped geological feature (such as a depression between mountains enclosed by arêtes ) – which collects and compresses through gravity the snow that falls into it. This snow accumulates and the weight of the snow falling above compacts it, forming névé (granular snow). Further crushing of the individual snowflakes and squeezing
540-813: A dissected topography . The Antarctic Plate started to subduct beneath South America 14 million years ago in the Miocene, forming the Chile Triple Junction . At first, the Antarctic Plate subducted only in the southernmost tip of Patagonia, meaning that the Chile Triple Junction was located near the Strait of Magellan . As the southern part of the Nazca Plate and the Chile Rise became consumed by subduction,
675-513: A Patagonian landscape; the presence of austral parakeets ( Enicognathus ferrugineus ) as far south as the shores of the strait attracted the attention of the earlier navigators, and green-backed firecrowns ( Sephanoides sephaniodes ), a species of hummingbird , may be seen flying amid the snowfall. One of the largest birds in the world, the Andean condor ( Vultur gryphus ) can be seen in Patagonia. Of
810-419: A derivation meaning "land of the big feet". However, this etymology is questionable. The term is most likely derived from an actual character name, "Patagón", a savage creature confronted by Primaleón of Greece, the hero in the homonymous Spanish chivalry novel (or knight-errantry tale ) by Francisco Vázquez. This book, published in 1512, was the sequel of the romance Palmerín de Oliva ;it was much in vogue at
945-549: A difficult winter at what he named Puerto San Julián before resuming its voyage further south on 21 August 1520. During this time, it encountered the local inhabitants, likely to be Tehuelche people , described by his reporter, Antonio Pigafetta, as giants called Patagons . The territory became the Spanish colony of the Governorate of New Léon, granted in 1529 to Governor Simón de Alcazaba y Sotomayor [ es ] , part of
1080-511: A glacier is usually assessed by determining the glacier mass balance or observing terminus behavior. Healthy glaciers have large accumulation zones, more than 60% of their area is snow-covered at the end of the melt season, and they have a terminus with a vigorous flow. Following the Little Ice Age 's end around 1850, glaciers around the Earth have retreated substantially . A slight cooling led to
1215-411: A glacier via moulins . Streams within or beneath a glacier flow in englacial or sub-glacial tunnels. These tunnels sometimes reemerge at the glacier's surface. Most of the important processes controlling glacial motion occur in the ice-bed contact—even though it is only a few meters thick. The bed's temperature, roughness and softness define basal shear stress, which in turn defines whether movement of
1350-758: A horseriding lifestyle. While the interest of the Spanish Empire had been chiefly to keep other European powers away from Patagonia, independent Chile and Argentina began to colonize the territory slowly over the course of the 19th and early 20th centuries. This process brought a decline of the indigenous populations, whose lives and habitats were disrupted, while at the same time thousands of Europeans, Argentines, Chilotes and mainland Chileans settled in Patagonia. The contemporary economy of eastern Patagonia revolves around sheep farming and oil and gas extraction, while in western Patagonia fishing , salmon aquaculture , and tourism dominate. The name Patagonia comes from
1485-629: A hunter-gathered lifestyle. The indigenous peoples of the region included the Tehuelches , whose numbers and society were reduced to near extinction not long after the first contacts with Europeans. Tehuelches included the Gununa'kena to the north, Mecharnuekenk in south-central Patagonia, and the Aonikenk or Southern Tehuelche in the far south, north of the Magellan strait. On Isla Grande de Tierra del Fuego ,
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#17328545880601620-408: A kilometer per year. Eventually, the ice will be surging fast enough that it begins to thin, as accumulation cannot keep up with the transport. This thinning will increase the conductive heat loss, slowing the glacier and causing freezing. This freezing will slow the glacier further, often until it is stationary, whence the cycle can begin again. The flow of water under the glacial surface can have
1755-404: A large effect on the motion of the glacier itself. Subglacial lakes contain significant amounts of water, which can move fast: cubic kilometers can be transported between lakes over the course of a couple of years. This motion is thought to occur in two main modes: pipe flow involves liquid water moving through pipe-like conduits, like a sub-glacial river; sheet flow involves motion of water in
1890-460: A lower heat conductance, meaning that the basal temperature is also likely to be higher. Bed temperature tends to vary in a cyclic fashion. A cool bed has a high strength, reducing the speed of the glacier. This increases the rate of accumulation, since newly fallen snow is not transported away. Consequently, the glacier thickens, with three consequences: firstly, the bed is better insulated, allowing greater retention of geothermal heat. Secondly,
2025-586: A part of the Los Lagos Region , is also located within Patagonia. By some definitions, Chiloé Archipelago, the rest of the Los Lagos Region, and part of the Los Ríos Region are also part of Patagonia. Patagonia's climate is mostly cool and dry year round. The east coast is warmer than the west, especially in summer, as a branch of the southern equatorial current reaches its shores, whereas the west coast
2160-422: A region of steppe -like plains, rising in a succession of 13 abrupt terraces about 100 m (330 ft) at a time, and covered with an enormous bed of shingle almost bare of vegetation. In the hollows of the plains are ponds or lakes of fresh and brackish water. Towards Chilean territory, the shingle gives way to porphyry , granite , and basalt lavas, and animal life becomes more abundant. Vegetation
2295-754: A site for the conservation of marine mammals . The Patagonian freshwater fish fauna is relatively restricted compared to other similar Southern Hemisphere regions. The Argentine part is home to a total of 29 freshwater fish species, 18 of which are native. The introduced are several species of trout , common carp , and various species that originated in more northerly parts of South America. The natives are osmeriforms ( Aplochiton and Galaxias ), temperate perches ( Percichthys ), catfish ( Diplomystes , Hatcheria and Trichomycterus ), Neotropical silversides ( Odontesthes ) and characiforms ( Astyanax , Cheirodon , Gymnocharacinus , and Oligosarcus ). Other Patagonian freshwater fauna include
2430-467: A temperature of −25 °C has been recorded in Bariloche, and most places can often have temperatures between −12 and −15 °C and highs staying around 0 °C for a few days. Directly east of these areas, the weather becomes much harsher; precipitation drops to between 150 and 300 mm, the mountains no longer protect the cities from the wind, and temperatures become more extreme. Maquinchao
2565-484: A thin layer. A switch between the two flow conditions may be associated with surging behavior. Indeed, the loss of sub-glacial water supply has been linked with the shut-down of ice movement in the Kamb ice stream. The subglacial motion of water is expressed in the surface topography of ice sheets, which slump down into vacated subglacial lakes. The speed of glacial displacement is partly determined by friction . Friction makes
2700-410: 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 climate change than other glaciers. Thermally, a temperate glacier is at a melting point throughout the year, from its surface to its base. The ice of a polar glacier is always below the freezing threshold from the surface to its base, although
2835-636: Is a unitary state , its first-level administrative divisions—the regions—enjoy far less autonomy than analogous Argentine provinces. Argentine provinces have elected governors and legislatures, while Chilean regions had government-appointed intendants prior to the adoption of elected governors from 2021. The Patagonian Provinces of Argentina are Neuquén , Río Negro , Chubut , Santa Cruz , and Tierra del Fuego . The southernmost part of Buenos Aires Province can also be considered part of Patagonia. The two Chilean regions undisputedly located entirely within Patagonia are Aysén and Magallanes . Palena Province ,
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#17328545880602970-478: Is a few hundred kilometers east of Bariloche, at the same altitude on a plateau, and summer daytime temperatures are usually about 5 °C warmer, rising up to 35 °C sometimes, but winter temperatures are much more extreme: the record is −35 °C, and some nights not uncommonly reach 10 °C colder than Bariloche. The plateaus in Santa Cruz province and parts of Chubut usually have snow cover through
3105-457: Is about 2 kilometres (1.2 mi) wide at the point it enters Lake Viedma. Chunks of ice fall off the terminus and float off into the lake, eventually melting. Glacial moraines are glacial debris of soil and rock that collect in front of, and along the sides of, the glacier as it flows across the land. The dark parallel lines inside the white central mass of the Viedma Glacier show where
3240-456: Is above or at freezing at the interface and is able to slide at this contact. This contrast is thought to a large extent to govern the ability of a glacier to effectively erode its bed , as sliding ice promotes plucking at rock from the surface below. Glaciers which are partly cold-based and partly warm-based are known as polythermal . Glaciers form where the accumulation of snow and ice exceeds ablation . A glacier usually originates from
3375-407: Is affected by factors such as slope, ice thickness, snowfall, longitudinal confinement, basal temperature, meltwater production, and bed hardness. A few glaciers have periods of very rapid advancement called surges . These glaciers exhibit normal movement until suddenly they accelerate, then return to their previous movement state. These surges may be caused by the failure of the underlying bedrock,
3510-411: Is because these peaks are located near or in the hyperarid Atacama Desert . Glaciers erode terrain through two principal processes: plucking and abrasion . As glaciers flow over bedrock, they soften and lift blocks of rock into the ice. This process, called plucking, is caused by subglacial water that penetrates fractures in the bedrock and subsequently freezes and expands. This expansion causes
3645-406: Is by basal sliding, where meltwater forms between the ice and the bed itself. Whether a bed is hard or soft depends on the porosity and pore pressure; higher porosity decreases the sediment strength (thus increases the shear stress τ B ). Porosity may vary through a range of methods. Bed softness may vary in space or time, and changes dramatically from glacier to glacier. An important factor
3780-434: Is called glaciology . Glaciers are important components of the global cryosphere . Glaciers are categorized by their morphology, thermal characteristics, and behavior. Alpine glaciers form on the crests and 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
3915-416: Is called rock flour and is made up of rock grains between 0.002 and 0.00625 mm in size. Abrasion leads to steeper valley walls and mountain slopes in alpine settings, which can cause avalanches and rock slides, which add even more material to the glacier. Glacial abrasion is commonly characterized by glacial striations . Glaciers produce these when they contain large boulders that carve long scratches in
4050-497: Is called "Camwy" in Patagonian Welsh. Chupat, Chubut and Camwy have the same meaning and are used to talk about the river and the province. Welsh settlers and placenames are associated with one of the projects of the country of Wales, Project Hiraeth. Due to the language, culture and location, many Patagonians do not consider themselves Latinos and proudly call themselves Patagonians instead. People from Y Wladfa, Laurie Island,
4185-492: Is caused principally by the sudden melting and retreat of ice aided by tectonic changes, has scooped out a deep longitudinal depression, best in evidence where in contact with folded Cretaceous rocks, which are lifted up by the Cenozoic granite. It generally separates the plateau from the first lofty hills, whose ridges are generally called the pre-Cordillera. To the west of these, a similar longitudinal depression extends all along
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4320-528: Is 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 (also known as "continental glaciers") in the polar regions , but glaciers may be found in mountain ranges on every continent other than the Australian mainland, including Oceania's high-latitude oceanic island countries such as New Zealand . Between latitudes 35°N and 35°S, glaciers occur only in
4455-442: Is greater) and the relatively fast moving ice at the glacier's center. On the southwestern side of the glacier terminus, calving of ice is visible. The glacier terminus ends in a cliff. Glacier A glacier ( US : / ˈ ɡ l eɪ ʃ ər / ; UK : / ˈ ɡ l æ s i ər , ˈ ɡ l eɪ s i ər / ) is a persistent body of dense ice that is constantly moving downhill under its own weight. A glacier forms where
4590-628: Is higher, and the mountains above 5,000 m (16,400 ft) usually have permanent snow. Even at high latitudes, glacier formation is not inevitable. Areas of the Arctic , such as Banks Island , and the McMurdo Dry Valleys in Antarctica are considered polar deserts where glaciers cannot form because they receive little snowfall despite the bitter cold. Cold air, unlike warm air, is unable to transport much water vapor. Even during glacial periods of
4725-655: Is in Los Glaciares National Park which was declared a World Heritage Site in 1981. in Chilean legislature part of it is in Bernardo O'Higgins National Park . The Southern Patagonian Ice Field is 13,000 square kilometres (5,000 sq mi); Viedma Glacier is one of the Ice Field's 48 outlet glaciers that have more than 20 square kilometres (7.7 sq mi) of ice field area each. Viedma Glacier's glacier terminus
4860-481: Is more luxuriant, consisting principally of southern beech and conifers . The high rainfall against the western Andes ( Wet Andes ) and the low sea-surface temperatures offshore give rise to cold and humid air masses, contributing to the ice fields and glaciers , the largest ice fields in the Southern Hemisphere outside of Antarctica. Among the depressions by which the plateau is intersected transversely,
4995-897: Is termed an ice cap or ice field . Ice caps have an area less than 50,000 km (19,000 sq mi) by definition. Glacial bodies larger than 50,000 km (19,000 sq mi) are called ice sheets or continental glaciers . Several kilometers deep, they obscure the underlying topography. Only nunataks protrude from their surfaces. The only extant ice sheets are the two that cover most of Antarctica and Greenland. They contain vast quantities of freshwater, enough that if both melted, global sea levels would rise by over 70 m (230 ft). Portions of an ice sheet or cap that extend into water are called ice shelves ; they tend to be thin with limited slopes and reduced velocities. 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
5130-413: Is the region where there is a net loss in glacier mass. The upper part of a glacier, where accumulation exceeds ablation, is called the accumulation zone . The equilibrium line separates the ablation zone and the accumulation zone; it is the contour where the amount of new snow gained by accumulation is equal to the amount of ice lost through ablation. In general, the accumulation zone accounts for 60–70% of
5265-402: Is the underlying geology; glacial speeds tend to differ more when they change bedrock than when the gradient changes. Further, bed roughness can also act to slow glacial motion. The roughness of the bed is a measure of how many boulders and obstacles protrude into the overlying ice. Ice flows around these obstacles by melting under the high pressure on their stoss side ; the resultant meltwater
5400-552: Is then forced into the cavity arising in their lee side , where it re-freezes. As well as affecting the sediment stress, fluid pressure (p w ) can affect the friction between the glacier and the bed. High fluid pressure provides a buoyancy force upwards on the glacier, reducing the friction at its base. The fluid pressure is compared to the ice overburden pressure, p i , given by ρgh. Under fast-flowing ice streams, these two pressures will be approximately equal, with an effective pressure (p i – p w ) of 30 kPa; i.e. all of
5535-637: Is very scarce. The weather only gets a bit colder further south in Chubut, and the city of Comodoro Rivadavia has summer temperatures of 24 to 28 °C, nights of 12 to 16 °C, and winters with days around 10 °C and nights around 3 °C, and less than 250 mm of rain. However, a drastic drop occurs as one moves south to Santa Cruz; Rio Gallegos, in the south of the province, has summer temps of 17 to 21 °C, (nights between 6 and 10 °C) and winter temperatures of 2 to 6 °C, with nights between −5 and 0 °C, despite being right on
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5670-454: Is washed by a cold current. However, winters are colder on the inland plateaus east of the slopes and further down the coast on the southeast end of the Patagonian region. For example, at Puerto Montt , on the inlet behind Chiloé Island, the mean annual temperature is 11 °C (52 °F) and the average extremes are 25.5 and −1.5 °C (77.9 and 29.3 °F), whereas at Bahía Blanca near
5805-952: The Andes , the Himalayas , the Rocky Mountains , the Caucasus , Scandinavian Mountains , and the Alps . Snezhnika glacier in Pirin Mountain, Bulgaria with a latitude of 41°46′09″ N is the southernmost glacial mass in Europe. Mainland Australia currently contains no glaciers, although a small glacier on Mount Kosciuszko was present in the last glacial period . In New Guinea, small, rapidly diminishing, glaciers are located on Puncak Jaya . Africa has glaciers on Mount Kilimanjaro in Tanzania, on Mount Kenya , and in
5940-560: The Cuncos (also known as Veliches) settled in Chiloé Island in Pre-Hispanic times as a consequence of a push from more northern Huilliches who in turn were being displaced by Mapuches . While being outside traditional Huilliche territory the western Patagonian volcanoes Michimahuida , Hornopirén and Chaitén have Huilliche etymologies. In Chubut Province modern toponymy comes from
6075-769: The Early Holocene (c. 9000 years BP ) much in the same way that Riesco Island was back then. A Selk'nam tradition recorded by the Salesian missionary Giuseppe María Beauvoir relate that the Selk'nam arrived in Tierra del Fuego by land, and that the Selk'nam were later unable to return north as the sea had flooded their crossing. Agriculture was practised in Pre-Hispanic Argentina as far south as southern Mendoza Province . Agriculture
6210-636: The Faroe and Crozet Islands were completely glaciated. The permanent snow cover necessary for glacier formation is affected by factors such as the degree of slope on the land, amount of snowfall and the winds. Glaciers can be found in all latitudes except from 20° to 27° north and south of the equator where the presence of the descending limb of the Hadley circulation lowers precipitation so much that with high insolation snow lines reach above 6,500 m (21,330 ft). Between 19˚N and 19˚S, however, precipitation
6345-642: The Governorates of the Spanish Empire of the Americas. The territory was redefined in 1534 and consisted of the southernmost part of the South American continent and the islands towards Antarctica. Rodrigo de Isla , sent inland in 1535 from San Matías by Simón de Alcazaba y Sotomayor (on whom western Patagonia had been conferred by Charles I of Spain , is presumed to have been the first European to have traversed
6480-750: The Himalayas , Andes , and a few high mountains in East Africa, Mexico, New Guinea and on Zard-Kuh in Iran. With more than 7,000 known glaciers, Pakistan has more glacial ice than any other country outside the polar regions. Glaciers cover about 10% of Earth's land surface. Continental glaciers cover nearly 13 million km (5 million sq mi) or about 98% of Antarctica 's 13.2 million km (5.1 million sq mi), with an average thickness of ice 2,100 m (7,000 ft). Greenland and Patagonia also have huge expanses of continental glaciers. The volume of glaciers, not including
6615-511: The Patagonian mara ( Dolichotis patagonum ) are also characteristic of the steppe and the pampas to the north. The fauna of Patagonia was heavily decimated by the end-Pleistocene extinction event around 12-10,000 years ago that resulted in the extinction of most large ( megafaunal ) animal species native to the region (as well as across the Americas). Species formerly present in the region include
6750-551: The Quaternary , Manchuria , lowland Siberia , and central and northern Alaska , though extraordinarily cold, had such light snowfall that glaciers could not form. In addition to the dry, unglaciated polar regions, some mountains and volcanoes in Bolivia, Chile and Argentina are high (4,500 to 6,900 m or 14,800 to 22,600 ft) and cold, but the relative lack of precipitation prevents snow from accumulating into glaciers. This
6885-521: The Rwenzori Mountains . Oceanic islands with glaciers include Iceland, several of the islands off the coast of Norway including Svalbard and Jan Mayen to the far north, New Zealand and the subantarctic islands of Marion , Heard , Grande Terre (Kerguelen) and Bouvet . During glacial periods of the Quaternary, Taiwan , Hawaii on Mauna Kea and Tenerife also had large alpine glaciers, while
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#17328545880607020-497: The Selk'nam (Ona) and Haush (Manek'enk) lived in the north and southeast, respectively. In the archipelagos to the south of Tierra del Fuego were Yámana, with the Kawéskar (Alakaluf) in the coastal areas and islands in western Tierra del Fuego and the southwest of the mainland. In the Patagonian archipelagoes north of Taitao Peninsula lived the Chonos . These groups were encountered in
7155-719: The Strait of Magellan , the Beagle Channel , and the Drake Passage to the south. The Colorado and Barrancas rivers, which run from the Andes to the Atlantic, are commonly considered the northern limit of Argentine Patagonia. The archipelago of Tierra del Fuego is sometimes included as part of Patagonia. Most geographers and historians locate the northern limit of Chilean Patagonia at Huincul Fault , in Araucanía Region . At
7290-571: The Yagagtoo , Musters , and Colhue Huapi , and others situated to the south of Puerto Deseado in the center of the country. Across much of Patagonia east of the Andes, volcanic eruptions have created formation of basaltic lava plateaus during the Cenozoic . The plateaus are of different ages with the older –of Neogene and Paleogene age– being located at higher elevations than Pleistocene and Holocene lava plateaus and outcrops. Erosion, which
7425-555: The patagon personage in the chivalric romances Primaleon printed in 1512, ten years before Magellan arrived in these southern lands. This hypothesis was published in a 2011 New Review of Spanish Philology report. There are various placenames in the Chiloé Archipelago with Chono etymologies despite the main indigenous language of the archipelago at the arrival of the Spanish being Mapudungun . A theory postulated by chronicler José Pérez García explains this holding that
7560-448: The 1990s and 2000s. In a study using data from January 1993 through October 2005, more events were detected every year since 2002, and twice as many events were recorded in 2005 as there were in any other year. Ogives or Forbes bands are alternating wave crests and valleys that appear as dark and light bands of ice on glacier surfaces. They are linked to seasonal motion of glaciers; the width of one dark and one light band generally equals
7695-606: The 40th parallel, they found a "land" or a "point extending into the sea", and further south, a gulf. The expedition is said to have rounded the gulf for nearly 300 km (186 mi) and sighted the continent on the southern side of the gulf. The Atlantic coast of Patagonia was first fully explored in 1520 by the Spanish expedition led by Ferdinand Magellan , who on his passage along the coast named many of its more striking features – San Matías Gulf, Cape of 11,000 Virgins (now simply Cape Virgenes ), and others. Magellan's fleet spent
7830-549: The Atlantic Islands, Antarctica (including the Chilean town in Antarctica, "The Stars Village", and the Argentine civilian settlement, "Hope Base"), other non-latin speaking areas use this term as a patriotic and inclusive demonym. A Patagonian is a person that is part of the Patagonia region, language and culture. That person could be a citizen from Chilean Patagonia, Argentine Patagonia, or of native communities that existed before
7965-431: The Atlantic coast and just outside the northern confines of Patagonia, the annual temperature is 15 °C (59 °F) and the range much greater, as temperatures above 35 °C and below −5 °C are recorded every year. At Punta Arenas, in the extreme south, the mean temperature is 6 °C (43 °F) and the average extremes are 24.5 and −2 °C (76.1 and 28.4 °F). The prevailing winds are westerly, and
8100-473: The Atlantic coast of Patagonia. The geological limit of Patagonia has been proposed to be Huincul Fault , which forms a major discontinuity. The fault truncates various structures including the Pampean orogen found further north. The ages of base rocks change abruptly across the fault. Discrepancies have been mentioned among geologists on the origin of the Patagonian landmass. Víctor Ramos has proposed that
8235-450: The Atlantic coast, through the Strait of Magellan and northward along the Pacific coast, was memorable, yet the descriptions of the geography of Patagonia owe much more to the Spanish explorer Pedro Sarmiento de Gamboa (1579–1580), who, devoting himself especially to the south-west region, made careful and accurate surveys. The settlements that he founded at Nombre de Jesús and San Felipe
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#17328545880608370-542: The Patagonian landmass originated as an allochthonous terrane that separated from Antarctica and docked in South America 250 to 270 Mya in the Permian period. A 2014 study by R.J. Pankhurst and coworkers rejects any idea of a far-traveled Patagonia, claiming it is likely of parautochtonous (nearby) origin. The Mesozoic and Cenozoic deposits have revealed a most interesting vertebrate fauna. This, together with
8505-422: The Patagonian plains. The Patagonian steppe is one of the last strongholds of the guanaco and Darwin's rheas ( Rhea pennata ), which had been hunted for their skins by the Tehuelches , on foot using boleadoras , before the diffusion of firearms and horses ; they were formerly the chief means of subsistence for the natives, who hunted them on horseback with dogs and bolas . Vizcachas ( Lagidum spp.) and
8640-422: The accumulation of snow exceeds its ablation over many years, often centuries . It acquires distinguishing features, such as crevasses and seracs , as it slowly flows and deforms under stresses induced by its weight. As it moves, it abrades rock and debris from its substrate to create landforms such as cirques , moraines , or fjords . Although a glacier may flow into a body of water, it forms only on land and
8775-412: The advance of many alpine glaciers between 1950 and 1985, but since 1985 glacier retreat and mass loss has become larger and increasingly ubiquitous. Glaciers move downhill by the force of gravity and the internal deformation of ice. At the molecular level, ice consists of stacked layers of molecules with relatively weak bonds between layers. When the amount of strain (deformation) is proportional to
8910-520: The air from the snow turns it into "glacial ice". This glacial ice will fill the cirque until it "overflows" through a geological weakness or vacancy, such as a gap between two mountains. When the mass of snow and ice reaches sufficient thickness, it begins to move by a combination of surface slope, gravity, and pressure. On steeper slopes, this can occur with as little as 15 m (49 ft) of snow-ice. In temperate glaciers, snow repeatedly freezes and thaws, changing into granular ice called firn . Under
9045-430: The amount of melting at surface of the glacier, the faster the ice will flow. Basal sliding is dominant in temperate or warm-based glaciers. The presence of basal meltwater depends on both bed temperature and other factors. For instance, the melting point of water decreases under pressure, meaning that water melts at a lower temperature under thicker glaciers. This acts as a "double whammy", because thicker glaciers have
9180-713: The annual movement of the glacier. Ogives are formed when ice from an icefall is severely broken up, increasing ablation surface area during summer. This creates a swale and space for snow accumulation in the winter, which in turn creates a ridge. Sometimes ogives consist only of undulations or color bands and are described as wave ogives or band ogives. Glaciers are present on every continent and in approximately fifty countries, excluding those (Australia, South Africa) that have glaciers only on distant subantarctic island territories. Extensive glaciers are found in Antarctica, Argentina, Chile, Canada, Pakistan, Alaska, Greenland and Iceland. Mountain glaciers are widespread, especially in
9315-432: The bedrock has frequent fractures on the surface, glacial erosion rates tend to increase as plucking is the main erosive force on the surface; when the bedrock has wide gaps between sporadic fractures, however, abrasion tends to be the dominant erosive form and glacial erosion rates become slow. Glaciers in lower latitudes tend to be much more erosive than glaciers in higher latitudes, because they have more meltwater reaching
9450-445: The bedrock. By mapping the direction of the striations, researchers can determine the direction of the glacier's movement. Similar to striations are chatter marks , lines of crescent-shape depressions in the rock underlying a glacier. They are formed by abrasion when boulders in the glacier are repeatedly caught and released as they are dragged along the bedrock. The rate of glacier erosion varies. Six factors control erosion rate: When
9585-771: The border with Chile, receives up to 434 mm of rain and snow in May, 297 mm in June, and 273 in July, compared to 80 in February and 72 in March. The total for the city is 2074 mm, making it one of the rainiest in Argentina. Further west, some areas receive up to 4,000 mm and more, especially on the Chilean side. In the northeast, the seasons for rain are reversed; most rain falls from occasional summer thunderstorms but totals barely reach 500 mm in
9720-592: The coast in the north but happens more often in the south, and frost is usually not very intense. Immediately east from the coast are the Andes, cut by deep fjords in the south and by deep lakes in the north, and with varying temperatures according to the altitude. The tree line ranges from close to 2,000 m on the northern side (except for the Andes in northern Neuquén in Argentina, where sunnier and dryer conditions allow trees to grow up to close to 3,000 m), and diminishes southward to only 600–800 m in Tierra del Fuego. Precipitation changes dramatically from one spot to
9855-420: The coast. Snowfall is common despite the dryness, and temperatures are known to fall to under −18 °C and to remain below freezing for several days in a row. Rio Gallegos is also among the windiest places on Earth, with winds reaching 100 km/h occasionally. Tierra del Fuego is extremely wet in the west, relatively damp in the south, and dry in the north and east. Summers are cool (13 to 18 °C in
9990-596: The coastline of Patagonia is possibly mentioned in a Portuguese voyage in 1511–1512, traditionally attributed to captain Diogo Ribeiro, who after his death was replaced by Estevão de Frois, and was guided by the pilot and cosmographer João de Lisboa ). The explorers, after reaching Rio de la Plata (which they would explore on the return voyage, contacting the Charrúa and other peoples) eventually reached San Matias Gulf , at 42°S. The expedition reported that after going south of
10125-559: The created ice's density. 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 , and ultimately Latin glaciēs , meaning "ice". The processes and features caused by or related to glaciers are referred to as glacial. The process of glacier establishment, growth and flow is called glaciation . The corresponding area of study
10260-410: The debris-filled moraines have become entwined within the center of the new glacial ice mass as it forms. At right angles to the glacial moraines in the middle, crevasses , large, canyon-sized cracks, are apparent in the grey-brown ice that can be seen along the sides of the glacier. These cracks are formed from the stress arising between ice along the valley walls (that is slower moving as the friction
10395-467: The deep profile of fjords , which can reach a kilometer in depth as ice is topographically steered into them. The extension of fjords inland increases the rate of ice sheet thinning since they are the principal conduits for draining ice sheets. It also makes the ice sheets more sensitive to changes in climate and the ocean. Although evidence in favor of glacial flow was known by the early 19th century, other theories of glacial motion were advanced, such as
10530-483: The deformation to become a plastic flow rather than elastic. Then, the glacier will begin to deform under its own weight and flow across the landscape. According to the Glen–Nye flow law , the relationship between stress and strain, and thus the rate of internal flow, can be modeled as follows: where: The lowest velocities are near the base of the glacier and along valley sides where friction acts against flow, causing
10665-591: The details of which are as yet poorly understood. Several sites have been excavated, notably caves such as Cueva del Milodon in Última Esperanza in southern Patagonia, and Tres Arroyos on Tierra del Fuego, that support this date. Hearths, stone scrapers, and animal remains dated to 9400–9200 BC have been found east of the Andes. At the close of the Pleistocene around 12-11,000 years ago (10,000-9,000 BC) Fishtail projectile points (a type of knapped stone spear point) were widespread across Patagonia (along with much of
10800-572: The discovery of the perfect cranium of a turtle ( chelonian ) of the genus Niolamia , which is almost identical to Ninjemys oweni of the Pleistocene age in Queensland , forms an evident proof of the connection between the Australian and South American continents. The Patagonian Niolamia belongs to the Sarmienti Formation. Fossils of the mid-Cretaceous Argentinosaurus , which may be
10935-418: The essentially correct explanation in the 1840s, although it was several decades before it was fully accepted. The top 50 m (160 ft) of a glacier are rigid because they are under low pressure . This upper section is known as the fracture zone and moves mostly as a single unit over the plastic-flowing lower section. When a glacier moves through irregular terrain, cracks called crevasses develop in
11070-399: The first periods of European contact with different lifestyles, body decoration, and language, although it is unclear when this configuration emerged. Towards the end of the 16th century, Mapuche -speaking agriculturalists penetrated the western Andes and from there across into the eastern plains and down to the far south. Through confrontation and technological ability, they came to dominate
11205-461: The foot of the snowy Andean Cordillera. This latter depression contains the richest, most fertile land of Patagonia. Lake basins along the Cordillera were also gradually excavated by ice streams, including Lake Argentino and Lake Fagnano , as well as coastal bays such as Bahía Inútil . The establishment of dams near the Andes in Argentina in the 20th century has led to a sediment shortage along
11340-475: The fracture zone. Crevasses form because of differences in glacier velocity. If two rigid sections of a glacier move at different speeds or directions, shear forces cause them to break apart, opening a crevasse. Crevasses are seldom more than 46 m (150 ft) deep but, in some cases, can be at least 300 m (1,000 ft) deep. Beneath this point, the plasticity of the ice prevents the formation of cracks. Intersecting crevasses can create isolated peaks in
11475-411: The glacial base and facilitate sediment production and transport under the same moving speed and amount of ice. Material that becomes incorporated in a glacier is typically carried as far as the zone of ablation before being deposited. Glacial deposits are of two distinct types: Patagonia Patagonia ( Spanish pronunciation: [pataˈɣonja] ) is a geographical region that encompasses
11610-453: The glacier to melt, creating a water source that is especially important for plants, animals and human uses when other sources may be scant. However, within high-altitude and Antarctic environments, the seasonal temperature difference is often not sufficient to release meltwater. Since glacial mass is affected by long-term climatic changes, e.g., precipitation , mean temperature , and cloud cover , glacial mass changes are considered among
11745-428: The glacier will be accommodated by motion in the sediments, or if it'll be able to slide. A soft bed, with high porosity and low pore fluid pressure, allows the glacier to move by sediment sliding: the base of the glacier may even remain frozen to the bed, where the underlying sediment slips underneath it like a tube of toothpaste. A hard bed cannot deform in this way; therefore the only way for hard-based glaciers to move
11880-504: The glacier's surface area, more if the glacier calves icebergs. Ice in the accumulation zone is deep enough to exert a downward force that erodes underlying rock. After a glacier melts, it often leaves behind a bowl- or amphitheater-shaped depression that ranges in size from large basins like the Great Lakes to smaller mountain depressions known as cirques . The accumulation zone can be subdivided based on its melt conditions. The health of
12015-449: The great Patagonian plain. If the men under his charge had not mutinied, he might have crossed the Andes to reach the Pacific coast. Pedro de Mendoza , on whom the country was next bestowed, founded Buenos Aires , but did not venture south. Alonso de Camargo [ es ] (1539), Juan Ladrilleros (1557), and Hurtado de Mendoza (1558) helped to make known the Pacific coasts, and while Sir Francis Drake 's voyage in 1577 down
12150-739: The highly unusual aeglid crustaceans. Human habitation of the region dates back thousands of years, with some early archaeological findings in the area dated to at least the 13th millennium BC , although later dates around the 10th millennium BC are more securely recognized. Evidence exists of human activity at Monte Verde in Llanquihue Province , Chile, dated to around 14,500 years Before Present (~12,500 BC). The glacial-period ice fields and subsequent large meltwater streams would have made settlement difficult at that time. The region seems to have been inhabited continuously since 10,000 BC by various cultures and alternating waves of migration,
12285-614: The ice at the bottom of the glacier move more slowly than ice at the top. In alpine glaciers, friction is also generated at the valley's sidewalls, which slows the edges relative to the center. Mean glacial speed varies greatly but is typically around 1 m (3 ft) per day. There may be no motion in stagnant areas; for example, in parts of Alaska, trees can establish themselves on surface sediment deposits. In other cases, glaciers can move as fast as 20–30 m (70–100 ft) per day, such as in Greenland's Jakobshavn Isbræ . Glacial speed
12420-420: The ice sheets of Antarctica and Greenland, has been estimated at 170,000 km . Glacial ice is the largest reservoir of fresh water on Earth, holding with ice sheets about 69 percent of the world's freshwater. Many glaciers from temperate , alpine and seasonal polar climates store water as ice during the colder seasons and release it later in the form of meltwater as warmer summer temperatures cause
12555-544: The ice to act as a lever that loosens the rock by lifting it. Thus, sediments of all sizes become part of the glacier's load. If a retreating glacier gains enough debris, it may become a rock glacier , like the Timpanogos Glacier in Utah. Abrasion occurs when the ice and its load of rock fragments slide over bedrock and function as sandpaper, smoothing and polishing the bedrock below. The pulverized rock this process produces
12690-488: The ice, called seracs . Crevasses can form in several different ways. Transverse crevasses are transverse to flow and form where steeper slopes cause a glacier to accelerate. Longitudinal crevasses form semi-parallel to flow where a glacier expands laterally. Marginal crevasses form near the edge of the glacier, caused by the reduction in speed caused by friction of the valley walls. Marginal crevasses are largely transverse to flow. Moving glacier ice can sometimes separate from
12825-411: The idea that meltwater, refreezing inside glaciers, caused the glacier to dilate and extend its length. As it became clear that glaciers behaved to some degree as if the ice were a viscous fluid, it was argued that "regelation", or the melting and refreezing of ice at a temperature lowered by the pressure on the ice inside the glacier, was what allowed the ice to deform and flow. James Forbes came up with
12960-418: The increased pressure can facilitate melting. Most importantly, τ D is increased. These factors will combine to accelerate the glacier. As friction increases with the square of velocity, faster motion will greatly increase frictional heating, with ensuing melting – which causes a positive feedback, increasing ice speed to a faster flow rate still: west Antarctic glaciers are known to reach velocities of up to
13095-423: The infrared OH stretching mode of the water molecule. (Liquid water appears blue for the same reason. The blue of glacier ice is sometimes misattributed to Rayleigh scattering of bubbles in the ice.) A glacier originates at a location called its glacier head and terminates at its glacier foot, snout, or terminus . Glaciers are broken into zones based on surface snowpack and melt conditions. The ablation zone
13230-460: The land was divided by The Boundary Treaty of 1881 . Patagonia is divided between Western Patagonia (Chile) and Eastern Patagonia (Argentina) and several territories are still under dispute and claiming their rights. Mapuche people came from the Chilean Andes and voted to remain in different sides of Patagonia. Welsh settlers came from Wales and North America and voted to remain in Patagonia; when
13365-488: The large cow-sized ground sloth Mylodon , the large camel-like ungulate Macrauchenia , indigenous equines belonging to the genus Hippidion , the giant short-faced bear Arctotherium , and the large sabertooth cat Smilodon . The extinct fox Dusicyon avus (a close relative of the Falkland Islands wolf ) also formerly inhabited the region, until apparently becoming extinct around 500-400 years ago. Patagonia
13500-513: The largest of all dinosaurs, have been found in Patagonia, and a model of the mid- Jurassic Piatnitzkysaurus graces the concourse of the Trelew airport (the skeleton is in the Trelew paleontological museum; the museum's staff has also announced the discovery of a species of dinosaur even bigger than Argentinosaurus ). Of more than paleontological interest, the middle Jurassic Los Molles Formation and
13635-542: The many kinds of waterfowl the Chilean flamingo ( Phoenicopterus chilensis ), the upland goose ( Chloephaga picta ), and in the strait, the remarkable steamer ducks are found. Signature marine fauna include the southern right whale , the Magellanic penguin ( Spheniscus magellanicus ), the killer whale , and elephant seals . The Valdés Peninsula is a UNESCO World Heritage Site , designated for its global significance as
13770-875: The more northerly regions of the Antarctic Plate began to subduct beneath Patagonia so that the Chile Triple Junction advanced to the north over time. The asthenospheric window associated to the triple junction disturbed previous patterns of mantle convection beneath Patagonia inducing an uplift of c. 1 km that reversed the Miocene transgression. At a state level, Patagonia visually occupies an area within two countries: approximately 10% in Chile and approximately 90% in Argentina . Both countries have organized their Patagonian territories into nonequivalent administrative subdivisions: provinces and departments in Argentina, as well as regions , provinces , and communes in Chile. As Chile
13905-679: The most deformation. Velocity increases inward toward the center line and upward, as the amount of deformation decreases. The highest flow velocities are found at the surface, representing the sum of the velocities of all the layers below. Because ice can flow faster where it is thicker, the rate of glacier-induced erosion is directly proportional to the thickness of overlying ice. Consequently, pre-glacial low hollows will be deepened and pre-existing topography will be amplified by glacial action, while nunataks , which protrude above ice sheets, barely erode at all – erosion has been estimated as 5 m per 1.2 million years. This explains, for example,
14040-445: 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 , because water molecules absorb other colors more efficiently than blue. 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
14175-448: The north, 12 to 16 °C in the south, with nights generally between 3 and 8 °C), cloudy in the south, and very windy. Winters are dark and cold, but without the extreme temperatures in the south and west ( Ushuaia rarely reaches −10 °C, but hovers around 0 °C for several months, and snow can be heavy). In the east and north, winters are much more severe, with cold snaps bringing temperatures down to −20 °C all
14310-411: The northeast corner, and rapidly decrease to less than 300 mm. The Patagonian west coast, which belongs exclusively to Chile, has a cool oceanic climate, with summer maximum temperatures ranging from 14 °C in the south to 19 °C in the north (and nights between 5 and 11 °C) and very high precipitation, from 2,000 to more than 7,000 mm in local microclimates. Snow is uncommon at
14445-476: The other and diminishes very quickly eastward. An example of this is Laguna Frías, in Argentina, which receives 4,400 mm yearly. The city of Bariloche, about 40 km further east, receives about 1,000 mm, and the airport, another 15 km east, receives less than 600 mm. The easterly slopes of the Andes are home to several Argentine cities: San Martín de los Andes , Bariloche, El Bolsón , Esquel , and El Calafate . Temperatures there are milder in
14580-532: The other peoples of the region in a short period of time, and are the principal indigenous community today. Navigators such as Gonçalo Coelho and Amerigo Vespucci possibly had reached the area (his own account of 1502 has it that they reached the latitude 52°S), but Vespucci's failure to accurately describe the main geographical features of the region such as the Río de la Plata casts doubts on whether they really did so. The first or more detailed description of part of
14715-674: The pooling of meltwater at the base of the glacier — perhaps delivered from a supraglacial lake — or the simple accumulation of mass beyond a critical "tipping point". Temporary rates up to 90 m (300 ft) per day have occurred when increased temperature or overlying pressure caused bottom ice to melt and water to accumulate beneath a glacier. In glaciated areas where the glacier moves faster than one km per year, glacial earthquakes occur. These are large scale earthquakes that have seismic magnitudes as high as 6.1. The number of glacial earthquakes in Greenland peaks every year in July, August, and September and increased rapidly in
14850-410: The pressure of the layers of ice and snow above it, this granular ice fuses into denser firn. Over a period of years, layers of firn undergo further compaction and become glacial ice. Glacier ice is slightly more dense than ice formed from frozen water because glacier ice contains fewer trapped air bubbles. Glacial ice has a distinctive blue tint because it absorbs some red light due to an overtone of
14985-801: The principal ones are the Gualichu , south of the Río Negro , the Maquinchao and Valcheta (through which previously flowed the waters of Nahuel Huapi Lake , which now feed the Limay River), the Senguerr (spelled Senguer on most Argentine maps and within the corresponding region), and the Deseado River . Besides these transverse depressions (some of them marking lines of ancient interoceanic communication), others were occupied by either more or less extensive lakes, such as
15120-458: The region, apparently hunting of guanaco, and to a lesser extent rhea ( ñandú ), were the primary food sources of tribes living on the eastern plains. It is also not clear if domestic dogs were part of early human activity. Bolas are commonly found and were used to catch guanaco and rhea . A maritime tradition existed along the Pacific coast, whose latest exponents were the Yaghan (Yámana) to
15255-451: The rest of South America). At several sites these points have been found associated with extinct megafauna, including the large ground sloth Mylodon and the native equine Hippidion . The Cueva de las Manos is a famous site in Santa Cruz, Argentina. This cave at the foot of a cliff is covered in wall paintings, particularly the negative images of hundreds of hands, believed to date from around 8000 BC. Based on artifacts found in
15390-558: The sea, often with an ice tongue , like Mertz Glacier . Tidewater glaciers are glaciers that terminate in the sea, including most glaciers flowing from Greenland, Antarctica, Baffin , Devon , and Ellesmere Islands in Canada, Southeast Alaska , and the Northern and Southern Patagonian Ice Fields . As the ice reaches the sea, pieces break off or calve, forming icebergs . Most tidewater glaciers calve above sea level, which often results in
15525-679: The singular mammal Pyrotherium , also of very large dimensions. In the Cenozoic marine formation, considerable numbers of cetaceans have been discovered. During the Oligocene and early Miocene , large swathes of Patagonia were subject to a marine transgression , which might have temporarily linked the Pacific and Atlantic Oceans, as inferred from the findings of marine invertebrate fossils of both Atlantic and Pacific affinity in La Cascada Formation . Connection would have occurred through narrow epicontinental seaways that formed channels in
15660-560: The south of Tierra del Fuego, the Kaweshqar between Taitao Peninsula and Tierra del Fuego, and the Chono people in the Chonos Archipelago . The Selk'nam , Haush , and Tehuelche are generally thought to be culturally and linguistically related peoples physically distinct from the sea-faring peoples. It is possible that Isla Grande de Tierra del Fuego was connected to the mainland in
15795-581: The southern end of South America , governed by Argentina and Chile . The region comprises the southern section of the Andes Mountains with lakes, fjords , temperate rainforests , and glaciers in the west and deserts , tablelands , and steppes to the east. Patagonia is bounded by the Pacific Ocean on the west, the Atlantic Ocean to the east, and many bodies of water that connect them, such as
15930-409: The stagnant ice above, forming a bergschrund . Bergschrunds resemble crevasses but are singular features at a glacier's margins. Crevasses make travel over glaciers hazardous, especially when they are hidden by fragile snow bridges . Below the equilibrium line, glacial meltwater is concentrated in stream channels. Meltwater can pool in proglacial lakes on top of a glacier or descend into the depths of
16065-674: The still richer late Jurassic ( Tithonian ) and early Cretaceous ( Berriasian ) Vaca Muerta formation above it in the Neuquén basin are reported to contain huge hydrocarbon reserves (mostly gas in Los Molles, both gas and oil in Vaca Muerta) partly accessible through hydraulic fracturing . Other specimens of the interesting fauna of Patagonia, belonging to the Middle Cenozoic, are the gigantic wingless birds, exceeding in size any hitherto known, and
16200-423: The stress being applied, ice will act as an elastic solid. Ice needs to be at least 30 m (98 ft) thick to even start flowing, but once its thickness exceeds about 50 m (160 ft) (160 ft), stress on the layer above will exceeds the inter-layer binding strength, and then it'll move faster than the layer below. This means that small amounts of stress can result in a large amount of strain, causing
16335-494: The summer (in the north, between 20 and 24 °C, with cold nights between 4 and 9 °C; in the south, summers are between 16 and 20 °C, at night temperatures are similar to the north) and much colder in the winter, with frequent snowfall (although snow cover rarely lasts very long). Daytime highs range from 3 to 9 °C in the north, and from 0 to 7 °C in the south, whereas nights range from −5 to 2 °C everywhere. Cold waves can bring much colder values;
16470-438: The surface snowpack may experience seasonal melting. A subpolar glacier includes both temperate and polar ice, depending on the depth beneath the surface and position along the length of the glacier. In a similar way, the thermal regime of a glacier is often described by its basal temperature. A cold-based glacier is below freezing at the ice-ground interface and is thus frozen to the underlying substrate. A warm-based glacier
16605-419: The time of the Spanish arrival , Patagonia was inhabited by multiple indigenous tribes. In a small portion of northwestern Patagonia, indigenous peoples practiced agriculture, while in the remaining territory, peoples lived as hunter-gatherers, traveling by foot in eastern Patagonia or by dugout canoe and dalca in the fjords and channels . In colonial times indigenous peoples of northeastern Patagonia adopted
16740-569: The time, and a favorite reading of Magellan. Magellan's perception of the natives, dressed in skins, and eating raw meat, clearly recalled the uncivilized Patagón in Vázquez's book. Novelist and travel writer Bruce Chatwin suggests etymological roots of both Patagon and Patagonia in his book, In Patagonia , noting the similarity between "Patagon" and the Greek word παταγος, which means "a roaring" or "gnashing of teeth" (in his chronicle, Pigafetta describes
16875-446: The time, prompting some of them to believe that Patagonians were giants. According to Antonio Pigafetta, one of the Magellan expedition's few survivors and its published chronicler, Magellan bestowed the name Patagão (or Patagón ) on the inhabitants they encountered there, and the name "Patagonia" for the region. Although Pigafetta's account does not describe how this name came about, subsequent popular interpretations gave credence to
17010-469: The treaty was signed, they voted for culture and administration to be apart from the country keeping the settlement, language, schools, traditions, regional dates, flag, anthems, and celebrations. Patagonians also live abroad in settlements like Saltcoats, Saskatchewan , Canada; New South Wales , Australia; South Africa; the Falkland Islands; and North America. Argentine Patagonia is for the most part
17145-463: The way to the Rio Grande on the Atlantic coast. Snow can fall even in the summer in most areas, as well. The guanaco ( Lama guanicoe ), South American cougar ( Puma concolor concolor ), the Patagonian fox ( Lycalopex griseus ), Patagonian hog-nosed skunk ( Conepatus humboldtii ), and Magellanic tuco-tuco ( Ctenomys magellanicus ; a subterranean rodent ) are the most characteristic mammals of
17280-417: The weight of the ice is supported by the underlying water, and the glacier is afloat. Glaciers may also move by basal sliding , where the base of the glacier is lubricated by the presence of liquid water, reducing basal shear stress and allowing the glacier to slide over the terrain on which it sits. Meltwater may be produced by pressure-induced melting, friction or geothermal heat . The more variable
17415-440: The westward slope has a much heavier precipitation than the eastern in a rainshadow effect; the western islands close to Torres del Paine receive an annual precipitation of 4,000 to 7,000 mm, whilst the eastern hills are less than 800 mm and the plains may be as low as 200 mm annual precipitation. Precipitation is highly seasonal in northwestern Patagonia. For example, Villa La Angostura in Argentina, close to
17550-615: The winter, and often experience very cold temperatures. In Chile, the city of Balmaceda is known for being situated in this region (which is otherwise almost exclusively in Argentina), and for being the coldest place in Chile. In 2017, temperatures even dropped down to −20 °C in the region. The northern Atlantic coast has warm summers (28 to 32 °C, but with relatively cool nights at 15 °C) and mild winters, with highs around 12 °C and lows about 2–3 °C. Occasionally, temperatures reach −10 or 40 °C, and rainfall
17685-550: The word patagón . Magellan used this term in 1520 to describe the native tribes of the region, whom his expedition thought to be giants. The people he called the Patagons are now believed to have been the Tehuelche , who tended to be taller than Europeans of the time. Argentine researcher Miguel Doura observed that the name Patagonia possibly derives from the ancient Greek region of modern Turkey called Paphlagonia , possible home of
17820-466: The word "chupat" belonging to a transitional language between the southern and northern Tehuelche ethnic groups that were located in that region called Tewsün or Teushen. The word means transparency and is related to the clarity and purity of the river that bears that name and runs through the province. It is also related to the origin of the Welsh pronunciation of the word "chupat" which later became "Chubut". It
17955-411: Was at times practised beyond this limit in nearby areas of Patagonia but populations reverted at times to non-agricultural lifestyles. By the time of the Spanish arrival to the area (1550s) there is no record of agriculture being practised in northern Patagonia. The extensive Patagonian grasslands and an associated abundance of guanaco game may have contributed for the indigenous populations to favour
18090-408: Was formerly inhabited by the jaguar subspecies Panthera onca mesembrina (which is considerably larger than living jaguars) during the Pleistocene, with jaguars continuing to inhabit Patagonia into historic times (until the late 19th century), but are now extirpated from the region. Bird life is often abundant. The crested caracara ( Caracara plancus ) is one of the characteristic aspects of
18225-541: Was neglected by the Spanish government, the latter being abandoned before Thomas Cavendish visited it in 1587 during his circumnavigation , and so desolate that he called it Port Famine . After the discovery of the route around Cape Horn, the Spanish Crown lost interest in southern Patagonia until the 18th century, when the coastal settlements Carmen de Patagones, San José, Puerto Deseado, and Nueva Colonia Floridablanca were established, although it maintained its claim of
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