Patagonia 2
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2022-08-19 14:54:28
Patagonia 2
In 1519, the Italian scholar Antonio Pigafetta, who traveled around the world with Magellan and arrived at today's Commodore City of Rivadavia, saw the local aboriginal people, the Patagonians, wearing fat and bulky animal leather shoes. Leaving huge footprints on the beach, it was named Patagonia. Magellan, who was born in a Portuguese family of knights, was named after the knight's name Patagon (Patagon was the protagonist of a famous knight novel in the 16th century), and "Patagon" in Spanish also means a person with big feet. Patagonia, which is 2,000 kilometers long from north to south, is the Big Foot of America, extending at the southernmost tip of South America. It is located between the Colorado River and Cape Horn, the southern tip of the American continent, covering an area of 900,000 square kilometers. It borders the indifferent ice of Antarctica to the south, and to the north is the Papans grassland where the grass is tall and the cowboy runs. Patagonia hides in it, its vast melancholy. Even not so long ago, this place was like the land of legends, this vast and sparsely populated area was synonymous with remoteness - "finis terrae" (Spanish), which means the final end of the earth， sports fitness .
At the end of the 16th century, the Spaniards wanted to colonize the Patagonian coast to clear the English pirates, but their plans to establish a Jesuit colony in the bay of San Matias failed. In 1778, when the British attempted to colonize the aforementioned bay, the Spanish responded by establishing two first cities in Patagonia: San Jose and Viedma. From 1780 to 1807, the Spaniards established a colony in Puerto Deseado, but three years later there were no European colonies in this area.
After Argentina's independence, Patagonia remained almost unnoticed by white immigrants until the Indians were conquered in the 1870s through the "Conquest of the Desert." The Argentine government has since planned to emigrate to the region and make it an integral part of the country. Although people come to settle here for various reasons, such as developing economic resources, enjoying religious and political freedom, etc., immigration is still not very active. The local underground wealth is particularly attractive to Chilean immigrants, who now make up the largest portion of the population, looking for temporary employment rather than long-term settlement. With the exception of Commodore Rivadavia and the towns along the upper Negro River valley, which have larger population centers, Patagonia is sparsely populated, mainly in the countryside.
Patagonia has a unique hydrological situation. Although the desert is vast, the inflow area is small, and the inflow area is limited to the narrow area between the Negro and Chubut rivers. The rivers in the rest of the region have become out-stream rivers due to the supply of meltwater from mountain snow and ice or glacial lakes. However, due to the arid climate, only the Colorado River, the Negro River and the Chubut River have abundant water for shipping, irrigation and power generation. It has become a valley plain base for the development of agriculture, animal husbandry and forestry in Patagonia.
On the eastern side of the eastern foothills of the Andes Mountains, glacial lakes and moraine lakes are widely distributed. There are more than 300 large and small lakes, which constitute an important lake group in southern Argentina.
hydrology
The valley is deep and wide with cliffs on both sides, cutting into the mesa from west to east. These river valleys are all the riverbeds of rivers that flowed from the Andes to the Atlantic in the past, and only a few rivers originating in the Andes have perennial flow (such as the Colorado River, the Negro River, the Chubut). Chubut, Senguerr, Chico, Santa Cruz, etc.).
Most river valleys either have intermittent flows - such as the Coig and Gallegos rivers originating in the Andes, or dry rivers where all or part of the river has completely dried up, such as the Deseado The (Deseado) River, due to the influence of wind and sand, has changed beyond recognition, and it is impossible to see from the surface that the river once flowed in the past. There are other rivers, such as the Perdido River, which flow into shallow salt flats and salt ponds and stop. The bottom of the gorge is very deep, mostly alluvial coarse sand and gravel, which acts as an underground reservoir to make up for the lack of surface water.
The intermediate zone between the Patagonian Mesa and the Patagonian Andes is a series of lakes in glacial troughs or ice craters that are covered with layers of moraine or loose, unlayered moraine, etc. Other formations of glaciers are blocked to form lakes. To the north of Lake Nahuel Huapi, all lakes except Lacar flow into the Atlantic Ocean; to the south of Lake Nahuel Huapi, except Lake Viedma and Lake Argentina, all lakes pass through deep and narrow The valleys flow into the Pacific Ocean, and these narrow canyons are formed by erosion of the Cordillera from top to bottom, cutting off in an east-west direction.
In Patagonia, the soils north of the Negro River are of the best quality, especially those formed by volcanic rocks. Towards the south the soil gradually becomes barren and rocky, often with large patches of pebbles on the ground.
Patagonia's east coast has the Falkland Current running north along its coast.
climate
Patagonia is affected by the westerly winds of the South Pacific, which bring moist air from the ocean to the mainland. Westerly winds blow over the west coast of South America and the Andes Mountains, reducing humidity due to cooling and condensation, and the air is already dry by the time it enters Patagonia. Patagonia can be divided into two climatic regions, south and north. The dividing line starts from the Andes at about 39° south latitude and ends at about 43° south latitude due south of the Valdes peninsula.
The northern area is a semi-arid area, with an annual average temperature of about 12 to 20°C (54 to 68°F), the highest recorded temperature of about 41 to 45°C (106 to 113°F), and the lowest temperature of -11 to -5°C. (12-23°F). The sunshine time is the shortest along the coast, and the most abundant in the inland to the northwest. The annual rainfall is about 90 to 430 mm (3.5 to 17 inches). Dry, cold and strong southwesterly winds prevail.
The climate in the South is very different from the wet weather in the Andesco Dillera to the west. The northern part of the southern region is practically unaffected by the Atlantic Ocean—perhaps because of the higher elevations along its coast, reaching 274 to 548 m (900 to 1,800 ft) around the Bay of San Jorge—though the Pacific Ocean is cold. The westerly winds and the frigid Falkland Current off the Atlantic have some influence. In the south, with increasing latitude, the terrain becomes more and more peninsular, with some influence from the Atlantic Ocean. The climate in the southern region is cold and dry, with warmer coastal temperatures than inland areas and strong westerly winds. The annual average temperature is 4 to 13°C (40 to 55°F), the highest temperature is about 34°C (93°F), and the lowest temperature is -9 to -33°C (16° to 27°F). There are heavy snowfalls in winter and frosts throughout the year, and spring and autumn are only short transition periods between summer and winter. The average annual precipitation is about 127 to 203 mm (5 to 8 inches), but there have been records as high as 483 mm (19 inches). The central dry area has less precipitation, but has longer sunshine hours than the coast and the Antique Diller.
plant
The narrow strip on the western edge of Patagonia has vegetation similar to the adjacent Cordillera, mainly deciduous and coniferous. The vast plateau area is divided into southern and northern areas, each with its own distinct vegetation.
The larger steppe in the north extends southward to near latitude 46°S. Drought-tolerant shrubland vegetation in the north gradually transforms into open thickets in the south, which can reach a height of 1 to 2 m (3 to 7 ft). Grasses thrive in sandy areas, while salt-tolerant grasses and shrubs predominate on saline flats. The areas south of latitude 46°S are more drier, with low, apparently sparse vegetation that requires little water.
animal
Among Patagonian birds are herons and other waders; carnivorous birds include shield eagles, sparrowhawks, and insectivorous caracalla hawks; and the nearly extinct jellyfish. The typical marsupial in this area is the possum (a species of mustelidae). There are various bats, including a long-eared variant. Also found are armadillos, South American armadillos (armadillos), foxes, ferrets, North American skunks, bobcats and mountain lions, as well as Patagonian guinea pigs and various introduced rodents such as rabbits Rat and Cutter.
Patagonia's tectonic foundation is the Patagonian land platform, and between the Negro and Buchut rivers are widely exposed ancient granite, crystalline slate, gneiss, banyan and other crystalline rocks The other parts are overlying the Mesozoic and Cenozoic sedimentary rock series, and there are still Tertiary basalts in some areas. Trace elements and isotopic compositions of Sr, Nd, Pb and O of Pliocene-Quaternary alkaline basalts in the Patagonian Plateau lava at the southern tip of South America.
The Patagonian Plateau lava at the southern tip of South America was formed by volcanic activity that began in the Late Baili or early Cenozoic and periodically continued into the Holocene. The bottom of the plateau lava is the sub-alkaline basalt with an older age and a wider distribution range, and the overlying rocks are an important part of the lava, mainly the Pliocene-Quaternary alkaline basalt with a narrow distribution range. Basalt.
The Pliocene-Quaternary alkaline basalts in the Patagonian Plateau at the southern tip of South America can be divided into two categories: "craton" basalts and "transition" basalts. The "craton" basalt is distributed in the Cenozoic plateau volcanic activity area and continental sedimentary rock distribution area, and its isotopic composition varies greatly: the ratio of ~(87)Sr/~(86)Sr is 0.70316-0.70512; ε_(Nd) is 0-+ 5.5; The ratios of ~(206)Pb/~(204)Pb\~(207)Pb/~(204)Pb and ~(208)Pb/~(204)Pb are 18.26－19.38, 15.53－15.68 and 38.30－ 39.23. These isotopic values of "craton" basalts, as well as the Ba/La, Ba/Nb, La/Nb, K/Rb and Cs/Rb ratios, all fall within the range of sea-island basalts. The "transitional" basalts are distributed in the western margin of the Pliocene-Quaternary plateau lava outcrop zone, which was originally the volcanic activity area of the Andean orogenic arc in the early Cenozoic. In contrast to the "craton" basalts, the "transition" basalts have a much smaller variation in the isotopic composition: the ~(87)Sr/~(86)Sr ratio is 0.7039 ± 0.0004; ε_
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