Patagonian Desert

Patagonian Desert

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The Patagonian Desert, also known as the Patagonia Desert or the Patagonian Steppe, is the largest desert in Argentina and is the 7th largest desert in the world by area, occupying 673,000 square kilometers (260,000 mi²). It is located primarily in Argentina with small parts in Chile
Chile
Chile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...

 and is bounded by the Andes
Andes
The Andes is the world's longest continental mountain range. It is a continual range of highlands along the western coast of South America. This range is about long, about to wide , and of an average height of about .Along its length, the Andes is split into several ranges, which are separated...

, to its west, and the Atlantic Ocean
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...

 to its east, in the region of Patagonia
Patagonia
Patagonia is a region located in Argentina and Chile, integrating the southernmost section of the Andes mountains to the southwest towards the Pacific ocean and from the east of the cordillera to the valleys it follows south through Colorado River towards Carmen de Patagones in the Atlantic Ocean...

, southern Argentina
Argentina
Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...

. To the north the desert grades into the semi-arid Cuyo Region
Cuyo (Argentina)
Cuyo is the name given to the wine-producing, mountainous area of central-west Argentina. Historically it comprised the provinces of San Juan, San Luis and Mendoza. The term New Cuyo is a modern one, which indicates both Cuyo proper and the province of La Rioja...

 and the Dry and Humid Pampa
Humid Pampa
The Humid Pampa is an extensive region of flat, fertile grassland of loessic origin in Argentina. It has a precipitation average of 900 mm per year, in contrast with the Dry Pampas to the west, which average less than 700 mm.-Setting:...

s. The central parts of the steppe are dominated by shrub
Shrub
A shrub or bush is distinguished from a tree by its multiple stems and shorter height, usually under 5–6 m tall. A large number of plants may become either shrubs or trees, depending on the growing conditions they experience...

by and herbaceous
Herbaceous
A herbaceous plant is a plant that has leaves and stems that die down at the end of the growing season to the soil level. They have no persistent woody stem above ground...

 plant species albeit to the west, where precipitation is higher, bushes are replaced by grass
Grass
Grasses, or more technically graminoids, are monocotyledonous, usually herbaceous plants with narrow leaves growing from the base. They include the "true grasses", of the Poaceae family, as well as the sedges and the rushes . The true grasses include cereals, bamboo and the grasses of lawns ...

es. Topographically the deserts consist of alternating tablelands and massifs dissected by river valleys and canyons. The more western parts of the steppe host lakes of glacial origin and grades into barren mountains or cold temperate forests along valleys.

Inhabited by hunter-gatherer
Hunter-gatherer
A hunter-gatherer or forage society is one in which most or all food is obtained from wild plants and animals, in contrast to agricultural societies which rely mainly on domesticated species. Hunting and gathering was the ancestral subsistence mode of Homo, and all modern humans were...

s since Pre-Hispanic times the desert faced in the 19th century migration of Mapuche
Mapuche
The Mapuche are a group of indigenous inhabitants of south-central Chile and southwestern Argentina. They constitute a wide-ranging ethnicity composed of various groups who shared a common social, religious and economic structure, as well as a common linguistic heritage. Their influence extended...

s, Chilean
Chilean people
Chilean people, or simply Chileans, are the native citizens and long-term immigrants of Chile. Chileans are mainly of Spanish and Amerindian descent, with small but significant traces of 19th and 20th century European immigrant origin...

s, Argentines, Welsh
Welsh people
The Welsh people are an ethnic group and nation associated with Wales and the Welsh language.John Davies argues that the origin of the "Welsh nation" can be traced to the late 4th and early 5th centuries, following the Roman departure from Britain, although Brythonic Celtic languages seem to have...

s and other European peoples transforming it from a conflictive borderland zone
Conquest of the Desert
The Conquest of the Desert was a military campaign directed mainly by General Julio Argentino Roca in the 1870s, which established Argentine dominance over Patagonia, which was inhabited by indigenous peoples...

 to an integral part of Argentina with cattle, sheep and horse husbandry being the primary land use
Land use
Land use is the human use of land. Land use involves the management and modification of natural environment or wilderness into built environment such as fields, pastures, and settlements. It has also been defined as "the arrangements, activities and inputs people undertake in a certain land cover...

.

Geography and climate


The Patagonian Desert is the largest continental landmass of the 40° parallel and is a large cold winter desert, where the temperature rarely exceeds 12°C and averages just 3°C. The region experiences about seven months of winter and five months of summer. Frost is not uncommon in the desert but, due to the very dry condition year round, snow is. The Andes, to the desert's west, are the primary reason for the Patagonian desert status as they inhibit the westerly flow of moisture from the southern Pacific from reaching inland. This creates a rain shadow
Rain shadow
A rain shadow is a dry area on the lee side of a mountainous area. The mountains block the passage of rain-producing weather systems, casting a "shadow" of dryness behind them. As shown by the diagram to the right, the warm moist air is "pulled" by the prevailing winds over a mountain...

 that accounts for the formation of the desert and is why, despite approximately half of the desert being only about 200 miles from the ocean, such a large desert is found in the region. The cold Falkland Current
Falkland Current
The Falkland Current is a cold water current that flows northward along the Atlantic coast of Patagonia as far north as the mouth of the Río de la Plata. This current results from the movement of water from the West Wind Drift as it rounds Cape Horn. It takes its name from the Falkland Islands....

 off the Atlantic coast of South America also contributes to the area's aridity.

Different climates can be distinguished: the coast north of the 45th parallel is much milder because of the warm currents from Brazil, and the entire northern half of the region is significantly warmer in the summer, when sunny weather predominates. Daily temperatures in the summer reach 31°C in the Rio Colorado region, a general 26°C to 29°C in the northern coast, and 24°C to 28°C in the northern plain, with nights around 12°C to 15°C in the coast and between 7°C and 10°C in the steppe.
In the south, summer temperatures decrease from 22°C to only 16°C along the coast, and from 24°C to 17°C along the steppes, while nights go from 8°C to 11°C on the coast, and from 6°C to 10°C in the steppe.

During the winter, the proximity to the coast and the altitude are the main factors: while northern coastal areas have mild winters, from 2°C at night to about 11°C during the day, southern Santa Cruz ranges from -2°C to 5°C, and Tierra del Fuego, from -3°C to 3°C, for a mean of 0°C.
Inland, the northern areas range from 0°C to 10°C in low areas, and from -5°C to 5°C on the plateaus (again, mean around 0°C), while in the south, low areas range from -3°C to 4°C, and higher areas are clearly below 0°C. The coldest spots usually register temperatures between -20°C and -25°C during cold waves, and the official record is -33.9°C in Chubut province. However, some towns claim to have had records of around -35°C.

Summer frost is common everywhere except for the northern coast, and even sleet and light snow can fall during the warm season. Winds are constant and very strong, from the west in most cases.


Before the Andes were formed, the region was likely covered by temperate forests. However, after the formation of the Andes, ash from nearby volcanoes covered the forests and mineral-saturated waters seeped into the logs, thus fossilizing the trees and creating one of the world's best preserved petrified forests in the desert's center. The Patagonian is mainly composed of gravel plains and plateaus with sandstone canyons and clay shapes dotting the landscape, sculpted by the desert wind. The region encompassing the desert, however, has many diverse features. Ephemeral rivers, lakes, and drainage deposits from the Andes' spring melt form annually, hosting a variety of waterfowl
Waterfowl
Waterfowl are certain wildfowl of the order Anseriformes, especially members of the family Anatidae, which includes ducks, geese, and swans....

 and aquatic grasses. A variety of glacial, fluvial, and volcanic deposits are also found in the region and have significantly affected the desert's climate over time, especially contributing to the gravel sediments covering parts of the Patagonian.

The desert is quite windy as well, a result of the rain shadow effect and descending cool mountain air. This wind helps make the Patagonian one of the largest, if not the largest, sources of dust over the South Atlantic Ocean.

On the west the Patagonian grasslands portion of the Patagonian Desert are bounded by nothofagus
Nothofagus
Nothofagus, also known as the southern beeches, is a genus of 35 species of trees and shrubs native to the temperate oceanic to tropical Southern Hemisphere in southern South America and Australasia...

 forests of the Magellanic subpolar forests
Magellanic subpolar forests
The Magellanic subpolar forests are a terrestrial ecoregion of southernmost South America, covering parts of southern Chile and Argentina, and is part of the Neotropic ecozone...

.

Volcanic rocks covers more than 120,000 km2 of the Patagonian Desert, mainly in the Somun Cura Massif (i.e. North Patagonian Massif) and the Deseado Massif. Some other volcanic areas include the Pali-Aike Volcanic Field
Pali-Aike Volcanic Field
Pali-Aike Volcanic Field is a Pleistocene-to-Holocene volcanic field in Patagonia on the Argentina–Chile border, located north of the Straits of Magellan about 150 km northeast of Punta Arenas, Chile. The volcanic field contains lake-filled maars, along with basaltic scoria cones and spatter...

 near the Strait of Magellan
Strait of Magellan
The Strait of Magellan comprises a navigable sea route immediately south of mainland South America and north of Tierra del Fuego...

. The volcanic rocks are the result of back-arc volcanism
Back-arc basin
Back-arc basins are geologic features, submarine basins associated with island arcs and subduction zones.They are found at some convergent plate boundaries, presently concentrated in the Western Pacific ocean. Most of them result from tensional forces caused by oceanic trench rollback and the...

 distributed mainly in two episodes: one in the Eocene
Eocene
The Eocene Epoch, lasting from about 56 to 34 million years ago , is a major division of the geologic timescale and the second epoch of the Paleogene Period in the Cenozoic Era. The Eocene spans the time from the end of the Palaeocene Epoch to the beginning of the Oligocene Epoch. The start of the...

 and Miocene
Miocene
The Miocene is a geological epoch of the Neogene Period and extends from about . The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words and and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene...

 and the other from Late Miocene to Pleistocene
Pleistocene
The Pleistocene is the epoch from 2,588,000 to 11,700 years BP that spans the world's recent period of repeated glaciations. The name pleistocene is derived from the Greek and ....

.

Fauna and Flora


Despite the harsh desert environment, a number of animals venture into and live in the Patagonian. Some only live on the more habitable and geographically-varied outskirts of the desert, where food is more abundant and the environment less hostile, but all are found within the region encompassing the Patagonian. The burrowing owl
Burrowing Owl
The Burrowing Owl is a tiny but long-legged owl found throughout open landscapes of North and South America. Burrowing Owls can be found in grasslands, rangelands, agricultural areas, deserts, or any other open dry area with low vegetation. They nest and roost in burrows, such as those excavated...

, lesser rhea, guanaco, tuco-tuco
Tuco-tuco
The tuco-tucos are members of a group of rodents that belong to the family Ctenomyidae. The tuco-tucos belong to a single genus: Ctenomys, but they include some 60 different species. The relationships among the species are debated by taxonomists. Their closest relatives are degus and other...

, mara
Mara (mammal)
The maras are a genus of the cavy family. They are the sole representatives of the subfamily Dolichotinae. These large relatives of guinea pigs are common in the Patagonian steppes of Argentina but live in other areas of South America as well such as Paraguay...

, pygmy armadillo
Armadillo
Armadillos are New World placental mammals, known for having a leathery armor shell. Dasypodidae is the only surviving family in the order Cingulata, part of the superorder Xenarthra along with the anteaters and sloths. The word armadillo is Spanish for "little armored one"...

, Patagonian weasel
Patagonian Weasel
The Patagonian Weasel is a small mustelid that is the only member of the genus Lyncodon. Its geographic range is the Pampas of western Argentina and sections of Chile...

, puma, Patagonian gray fox, desert iguana
Desert iguana
The desert iguana is one of the most common lizards of the Sonoran and Mojave deserts of the southwestern United States and northwestern Mexico...

, Jumping Cow Spider, and various species of eagle and hawk are a few of the variety of animals living in the region.

The flora of the region is quite common for its climate and includes several species of desert shrubs like Acantholippia and Benthamiella and tuft grasses like Stipa
Stipa
This article is about a type of grass.For Speech Transmission Index for Public Address Systems, see Speech transmission index.For the Italian aircraft designer, see Luigi Stipa...

and Poa
Poa
Poa is a genus of about 500 species of grasses, native to the temperate regions of both hemispheres. Common names include meadow-grass , bluegrass , tussock , and speargrass. "Poa" is Greek for fodder...

. Aquatic grasses and larger flora exist on the outskirts of the desert and around the ephemeral lakes that form from the Andes' runoff.

Human land use



The desert has hosted various indigenous peoples
Indigenous peoples
Indigenous peoples are ethnic groups that are defined as indigenous according to one of the various definitions of the term, there is no universally accepted definition but most of which carry connotations of being the "original inhabitants" of a territory....

 in its past, as evidenced by cave painting
Cave painting
Cave paintings are paintings on cave walls and ceilings, and the term is used especially for those dating to prehistoric times. The earliest European cave paintings date to the Aurignacian, some 32,000 years ago. The purpose of the paleolithic cave paintings is not known...

s in the area. The earliest inhabitants of the desert known by name are those of the Tehuelche complex. Tehuelches lived as hunter-gatherer
Hunter-gatherer
A hunter-gatherer or forage society is one in which most or all food is obtained from wild plants and animals, in contrast to agricultural societies which rely mainly on domesticated species. Hunting and gathering was the ancestral subsistence mode of Homo, and all modern humans were...

s and did not practise agriculture in lush valleys found in the desert. In the 18 and 19th century the northern part of the desert came under Mapuche
Mapuche
The Mapuche are a group of indigenous inhabitants of south-central Chile and southwestern Argentina. They constitute a wide-ranging ethnicity composed of various groups who shared a common social, religious and economic structure, as well as a common linguistic heritage. Their influence extended...

 influence during a process of Araucanization
Araucanization
The Araucanization of Patagonia was the process of expansion of Mapuche culture, influence and language from Araucanía into the Patagonic plains. Historians disagree in the time of the expansion but it would have occurred sometime between 1550 and 1850. Amerindian peoples such as the Puelches and...

. Mapuches came to practise horse husbandry in the northern part of the Patagonian steppe. Mapuche tribes came to control trade across the desert and traded with the cities of southern Chile as well as Buenos Aires
Buenos Aires
Buenos Aires is the capital and largest city of Argentina, and the second-largest metropolitan area in South America, after São Paulo. It is located on the western shore of the estuary of the Río de la Plata, on the southeastern coast of the South American continent...

 and the Cuyo Region
Cuyo
Cuyo means "whose" in Spanish, but may also refer to:*Cuyo *Cuyo Province, historic, Argentina*Cuyo, Palawan, Philippines*Cuyo Airport, Philippines*Guinea pig dish eaten usually by Ecuadorian and Peruvian peoples....

.

From the mid-19th century on several settlements, some of them sporadic, appeared at the edges of the desert. The most important was established at Chubut River
Chubut River
The Chubut River is located in the Patagonia region of southern Argentina. Its name comes from the Tehuelche word chupat, which means "transparent". The Argentine Chubut Province, through which the river flows, is named after it...

's outflow by Welsh immigrants in 1860. Perito Moreno explored the desert in the 1870s. In the 1870s the Argentine army undertook the Conquest of the Desert
Conquest of the Desert
The Conquest of the Desert was a military campaign directed mainly by General Julio Argentino Roca in the 1870s, which established Argentine dominance over Patagonia, which was inhabited by indigenous peoples...

 campaign, massively defeating Mapuche warlords. The Conquest of the Desert was followed by a sharp decline in the indigenous population of the desert; some were chased into Chile and peripheral areas in the Andes. It is estimated that the Conquest of the Desert caused the death of about 1,000 Native Americans
Indigenous peoples of the Americas
The indigenous peoples of the Americas are the pre-Columbian inhabitants of North and South America, their descendants and other ethnic groups who are identified with those peoples. Indigenous peoples are known in Canada as Aboriginal peoples, and in the United States as Native Americans...

. Additionally 10,000 Native Americans were taken prisoner of whom 3,000 ended up in Buenos Aires separated by sexes to avoid their procreation. The boundary treaty of 1881 between Chile and Argentina bought most of the desert under definitive Argentine sovereignty, previously Chile had claimed varying now Argentine areas under claims of inherited colonial titles
Uti possidetis
Uti possidetis is a principle in international law that territory and other property remains with its possessor at the end of a conflict, unless otherwise provided for by treaty; if such a treaty doesn't include conditions regarding the possession of property and territory taken during the war,...

.

In the few decades before and after 1900 the less dry parts of the Patagonian steppe experienced a sheep farming boom, transforming the region into one of the world's greatest exporters of ovine products.

The area is sparsely populated today and those that do live here survive mainly by the raising of livestock such as sheep and goats. Resource mining, especially of oil, gas, and coal in parts of the region, is another way humans interact with and influence the desert environment. Humans can also interact with the environment by hunting or poaching animals.

See also

  • Patagonia
    Patagonia
    Patagonia is a region located in Argentina and Chile, integrating the southernmost section of the Andes mountains to the southwest towards the Pacific ocean and from the east of the cordillera to the valleys it follows south through Colorado River towards Carmen de Patagones in the Atlantic Ocean...

  • Desert
    Desert
    A desert is a landscape or region that receives an extremely low amount of precipitation, less than enough to support growth of most plants. Most deserts have an average annual precipitation of less than...

  • Rio Negro
  • Chubut
    Chubut Province
    Chubut a province in the southern part of Argentina situated between the 42nd parallel south and the 46th parallel south , the Andes range separating Argentina from Chile, and the Atlantic ocean...

  • Santa Cruz
    Santa Cruz Province (Argentina)
    Santa Cruz is a province of Argentina, located in the southern part of the country, in Patagonia. It borders Chubut province to the north, and Chile to the west and south. To the east is the Atlantic Ocean...