Patagonian steppe
The Patagonian Steppe , also known as the Patagonian Desert , is an arid landscape in southern South America .
Location and climate
The Patagonian steppe occupies the south of the American mainland including the north of the Isla Grande de Tierra del Fuego island and some islands in the eastern part of the Tierra del Fuego archipelago. The Río Colorado is considered to be the northern limit of this area , the forest zone on the eastern slope of the Andes forms the western limit, the Atlantic coast the eastern limit of the area. A large part of the Patagonian Desert is located in the 5 southernmost provinces of the Republic of Argentina ( Tierra del Fuego, Antartida e Islas de Atlantico Sur ; Santa Cruz ; Chubut ; Rio Negro ; Neuquén ), in addition, the part of the south of the Rio Colorado also counts Province of Buenos Aires ( Partido Patagones ) to the Patagonian steppe. The share of the Republic of Chile in the Patagonian steppe is limited to a few valleys in regions X, XI and XII on the narrow coastal strip along the Strait of Magellan east of Punta Arenas . With an area of around 673,000 km², the Patagonian steppe is the most extensive dry area in America.
The year-round westerly air currents south of the fortieth parallel leads to the fact that the clouds formed over the South Pacific mostly rain down on the western slopes of the Andes, and the ice fields of Campo de Hielo Sur and Campo de Hielo Norte also have a further negative effect. The cold Falkland Current in the southern Atlantic prevents cloud formation over the Atlantic. The southern location leads to extended, cold winters in which frost is not uncommon. Snowfalls are known but rare. The average annual temperature is around 12 ° C.
The seasonal distribution of precipitation shows no extremes, the maxima are usually in the months of January to April. The geographical distribution shows a clear west-east and a less pronounced north-south gradient, the maximum values of around 300 mm of precipitation per year are reached in the northeast of the area around Viedma , in the extreme rain shadow areas on the eastern slope of the Andes in some years less than 100 mm of precipitation can be recorded. The continuous westerly wind contributes to the extreme drought by drying out the soil.
geology
Geomorphologically, the area is characterized by the hilly country called meseta and wide plains along the Atlantic Ocean, table mountains often appear , which are often only broken down by the valleys of periodically flowing watercourses. The soils are largely formed by coarse, nutrient-poor sediments , fine-grained materials and organic substances are only found in areas with little air movement.
Characteristic are the numerous occurrences of petrified wood, which can be explained by the penetration of mineral-rich liquids (mostly rich in silica ) into sediment-covered, dead tree trunks in the course of the formation of the Andes. Some sites - such as the Monumento Natural Bosques Petrificado - have meanwhile been placed under protection. In addition to these obvious evidence of increased forest cover, various raw material deposits - such as coal near Rio Turbio and oil near Comodoro Rivadavia - as well as the remains of herbivorous sauropods on the Río Limay speak for a dramatic change in vegetation more than 50 million years ago.
Flora and fauna
The natural flora of the area consists mainly of grasses of the genera of spring grasses and the bluegrasses , isolated to stocks indicate shrubs of the genera Benthamiella (family Solanaceae family ) and Acantholippia (Family vervain family ). Species that need more moisture can also be found along the rivers and lakes on the eastern slopes of the Andes.
Agriculture and forestry are irrelevant, the poplars that are frequently encountered are used exclusively for wind protection.
In addition to the farm animals kept as part of extensive livestock farming - mainly sheep , horses and donkeys - diverse populations of wild animals have been preserved, but the number of animals is relatively low due to the climatic conditions. Typical bird species are Darwin's rhea and rabbit owl , and various species of birds of prey are also striking. The mammals are represented by various species from the genus of the crested rats , pampas rabbits , guanacos and dwarf armadillos ; Predators are the Patagonian weasel , the Argentine battle fox and the puma .
history
Sites like the Cueva de las Manos document the settlement of this area for at least 9,000 years. Since the climatic conditions at that time should not have differed significantly from those of today, it can be assumed that the settlers at that time lived nomadically. The coast of Patagonia was first visited in 1520 by Ferdinand Magellan , who spent the southern winter of 1520 near what is now Puerto San Julián . Participants of the expedition met members of indigenous peoples, whom Antonio Pigafetta called Patagonians because of their height . Sir Francis Drake reached this bay in 1578 . Settlement of the area south of the Rio Colorado did not begin until the second half of the 19th century, and many localities were not founded until the 20th century.
Web links
Coordinates: 41 ° 19 ′ S , 69 ° 19 ′ W