Patagonian Ice Sheet

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Map showing the extent of the Patagonian Ice Sheet in the Strait of Magellan area during the last glacial period. Selected modern settlements are shown with yellow dots. Sea level was much lower than shown here. Magellanglaciacion.jpg
Map showing the extent of the Patagonian Ice Sheet in the Strait of Magellan area during the last glacial period. Selected modern settlements are shown with yellow dots. Sea level was much lower than shown here.
During the last ice age the Patagonian Ice Sheet created the elongated and forested drumlins seen south of Puerto Williams, Chile. Puerto Williams, Chili.JPG
During the last ice age the Patagonian Ice Sheet created the elongated and forested drumlins seen south of Puerto Williams, Chile.

The Patagonian Ice Sheet was a large elongated and narrow ice sheet centered in the southern Andes that existed during the Llanquihue glaciation. The ice sheet covered all of Chile south of Puerto Montt plus the western fringes of Argentine Patagonia.

The ice sheet extended beyond the crest of the Andes into Argentina, but because of the dryness of the climate it did not reach beyond present-day lakes such as the Yagagtoo, Musters, and Colhue Huapi. At its peak (about 18,000 to 17,500 years ago), the Patagonian Ice Sheet covered about 480,000 km2 of land with an estimated ice-volume of more than 500,000 km3, [1] of which about 4% remains glaciated today in two separated portions known as the Northern and Southern Patagonian Ice Fields.

The ice-volume reduction contributed to a global sea level rise of about 1.2 meters. [1] However, during the first glacial period at the beginning of the Pleistocene ice extended to the present-day Argentine coast. With each successive glaciation it is known that the ice has stopped further and further to the west, with aridity always serving as the decisive factor halting glacier spread: it is believed that the east-west precipitation gradients during glacial periods were even steeper than the extremely steep ones of present-day Patagonia.

Unlike the Laurentide Ice Sheet or the ice sheets of Northern Europe, the Patagonian Ice Sheet did not cause major extinctions or loss of biodiversity. This is because the flora remaining to the north of the ice were isolated by the Atacama Desert and were able to speciate easily wherever suitable microclimates occurred. In fact, most of the original Antarctic flora survives today on land occupied by the ice sheet. However, there are indications that during the last deglaciation (17,500 years ago), the rapid melting of the northernmost extension of the Patagonian Ice Sheet resulted in a dramatic release of freshwater to the adjacent ocean, decreasing its salinity [2] and altering its circulation, resulting in significant ecological changes both locally and remotely. [3]

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<span class="mw-page-title-main">Andes</span> Mountain range in South America

The Andes, Andes Mountains or Andean Mountain Range are the longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range is 8,900 km (5,530 mi) long, 200 to 700 km wide, and has an average height of about 4,000 m (13,123 ft). The Andes extend from north to south through seven South American countries: Venezuela, Colombia, Ecuador, Peru, Bolivia, Chile and Argentina.

<span class="mw-page-title-main">Patagonia</span> Geographical region in South America

Patagonia is a geographical region that encompasses 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 the Strait of Magellan, the Beagle Channel, and the Drake Passage to the south.

<span class="mw-page-title-main">Valdivian temperate forests</span> Temperate forest ecoregion in Chile and Argentina

The Valdivian temperate forests (NT0404) is an ecoregion on the west coast of southern South America, in Chile and Argentina. It is part of the Neotropical realm. The forests are named after the city of Valdivia. The Valdivian temperate rainforests are characterized by their dense understories of bamboos, ferns, and for being mostly dominated by evergreen angiosperm trees with some deciduous specimens, though conifer trees are also common.

<span class="mw-page-title-main">Last Glacial Period</span> Period of major glaciations of the Northern Hemisphere (115,000–12,000 years ago)

The Last Glacial Period (LGP), also known colloquially as the Last Ice Age or simply Ice Age, occurred from the end of the Last Interglacial to the end of the Younger Dryas, encompassing the period c. 115,000 – c. 11,700 years ago.

Viedma is a subglacial volcano whose existence is questionable. It is supposedly located below the ice of the Southern Patagonian Ice Field, an area disputed between Argentina and Chile. The 1988 eruption deposited ash and pumice on the ice field and produced a mudflow that reached Viedma Lake. The exact position of the edifice is unclear, both owing to the ice cover and because the candidate position, the "Viedma Nunatak", does not clearly appear to be of volcanic nature.

<span class="mw-page-title-main">Tronador</span> Mountain in Argentina and Chile

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<span class="mw-page-title-main">Viedma Lake</span> Lake in Santa Cruz province, Argentina

Viedma Lake is a Patagonian lake in the province of Santa Cruz, Argentina, situated near its border with Chile. Measuring approximately 50 miles in length, it is a major elongated trough lake formed from melting glacial ice. Viedma Lake is the second largest perennial lake located entirely within Argentina.

<span class="mw-page-title-main">Northern Patagonian Ice Field</span> A series of interconnected glaciers in Chile

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<span class="mw-page-title-main">Lautaro (volcano)</span> Mountain in Chile

Lautaro is an active subglacial stratovolcano located in Chilean Patagonia, in the northern part of the Southern Patagonian Ice Field. Its summit rises roughly 2,400 m (7,900 ft) above the average surface of the ice cap plateau.

<span class="mw-page-title-main">Última Esperanza Sound</span> Inlet in the Chilean region of Magallanes

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<span class="mw-page-title-main">Patagonian Desert</span> Largest desert in Argentina

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<span class="mw-page-title-main">Geology of Chile</span>

The geology of Chile is a characterized by processes linked to subduction, such as volcanism, earthquakes, and orogeny. The building blocks of Chile's geology were assembled during the Paleozoic Era when Chile was the southwestern margin of the supercontinent Gondwana. In the Jurassic, Gondwana began to split, and the ongoing period of crustal deformation and mountain building known as the Andean orogeny began. In the Late Cenozoic, Chile definitely separated from Antarctica, and the Andes experienced a significant rise accompanied by a cooling climate and the onset of glaciations.

<span class="mw-page-title-main">Tortel</span> Commune in Aisén, Chile

Tortel is a Chilean commune located at the outflow of the Baker River and Pascua River to the Pacific Ocean. It lies between the Northern and Southern Patagonian Ice Field in the Capitán Prat Province in the Aysén Region. The commune is administered by the municipality in Caleta Tortel, the principal settlement.

<span class="mw-page-title-main">Reclus (volcano)</span> Volcano located in the Patagonia Ice Field, Chile

Reclus, also written as Reclús, is a volcano located in the Southern Patagonian Ice Field, Chile. Part of the Austral Volcanic Zone of the Andes, its summit rises 1,000 metres (3,300 ft) above sea level and is capped by a crater about 1 kilometre (0.62 mi) wide. Close to the volcano lies the Amalia Glacier, which is actively eroding Reclus.

<span class="mw-page-title-main">Viedma Glacier</span>

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 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.

The northern and southern hemispheres of the earth have a dynamic history of advancing and retreating ice sheets. The glacial and interglacial periods are linked to regular eccentricities in the Earth's orbit and correspond to approximately 100 kyr cycles. The advancing, or glacial periods can cause a massive displacement of flora and fauna as it drives them away from the poles, with the most recent glacial maximum having occurred about 20,000 years ago.,

<span class="mw-page-title-main">Arid Diagonal</span>

The Arid Diagonal is a contiguous zone of arid and semi-arid climate that traverses South America from coastal Peru in the Northwest to Argentine Patagonia in Southeast including large swathes of Bolivia and Chile. The Arid Diagonal encompasses a number of deserts, for example: Sechura, Atacama, Monte and the Patagonian Desert.

<span class="mw-page-title-main">Llanquihue glaciation</span> Last glacial period in southern Chile

The last glacial period and its associated glaciation is known in southern Chile as the Llanquihue glaciation. Its type area lies west of Llanquihue Lake where various drifts or end moraine systems belonging to the last glacial period have been identified. The glaciation is the last episode of existence of the Patagonian Ice Sheet. Around Nahuel Huapi Lake the equivalent glaciation is known as the Nahuel Huapi Drift.

Fueguino is a volcanic field in Chile. The southernmost volcano in the Andes, it lies on Tierra del Fuego's Cook Island and also extends over nearby Londonderry Island. The field is formed by lava domes, pyroclastic cones, and a crater lake.

References

  1. 1 2 Hulton, N.R.J., R.S. Purvesa, R.D. McCullocha, D.E. Sugdena, M.J. Bentleyb. 2002. The Last Glacial Maximum and eglaciation in southern South America. Quaternary Science Reviews , vol. 21, 233–241
  2. Lamy, F., J. Kaiser, U. Ninnemann, D. Hebbeln, H. W. Arz, J. Stoner. 2004. Antarctic Timing of Surface Water Changes off Chile and Patagonian Ice Sheet Response. Science, vol. 304, 1959-1962
  3. De Pol-Holz, R., O. Ulloa, L. Dezileau, J. Kaiser, F. Lamy and D. Hebbeln. 2006. Melting of the Patagonian Ice Sheet and deglacial perturbations of the nitrogen cycle in the eastern South Pacific. Geophysical Research Letters, vol. 33, L04704, doi : 10.1029/2005GL024477

See also

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