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Chile Geography
 Chile has a unique and curious shape. A long and narrow country, it extends 4,270 kilometres north to south, an extensive latitudinal range (17°30'S South to Cape Horn at 56°30'S) and yet it only averages 177 kilometres east to west. It stretches from the driest desert in the world in the north, to eternal snow and ice-fields in the south, and if Chilean claims to areas of Antarctica are included Chile's territory would extend to the South Pole. Chile borders to the north with Peru, north-east with Bolivia and to the east with Argentina, and to the west with the cold Pacific Ocean. Chile's continental surface area is 756,096 km2. Dominated throughout by the mighty Andes - Chile is home to many of the highest mountains in South America - and fringed by the Pacific Ocean coastline, with its surf-swept headlands battered by the cold waters of the Humboldt Current, Chile's rugged landscape runs through valleys and gorges, forests, mountains, volcanoes, rivers, lakes, islands, gullies and glaciers. It is no exaggeration to state that Chile offers incredible opportunities for the wilderness explorer. Three morphological features characterize the Chilean landscape: the Cordillera de los Andes or Andes Mountains to the east, the Coastal Mountains to the west , and the intermediate depression or longitudinal valley located between the two mountain systems. In the northern region, almost entirely desert, the temperatures are moderate due to the Humboldt Current. The central region is characterized as presenting a template Mediterranean climate with precipitations concentrated in the winter months and which do not surpass 400 mm. The rains increase in the meridian direction, coinciding with a colder climate, principally in the extreme south, where annual precipitations can surpass 5000 mm. In general, Chile has increasing precipitation from north to south and from west to east. However, topographic variations in the west-east direction distort the effects of the dominant westerly winds. In central-south Chile (32°-43°S), the Coastal Cordillera rarely exceeds 1,000 m in elevation, and on average has c. 600 m. To the east is the Andes Cordillera, with and average of 3,000 m in elevation in the central-south region and 1,000 in Tierra del Fuego. In between there is the central valley depression which is in a rain-shadow, as well as the eastern slopes of the Coastal Cordillera. The Coastal Cordillera is formed of old Palaeozoic and Precambrian rocks, and soils have developed in situ from metamorphic materials (granite and schist). It was not affected by the last glaciation. In the Andean Cordillera, soils have originated from andesitic and basaltic volcanic deposits of lava and ash. South of 35°S the foothills are formed by moraines from the last glaciation and fluvial and lacustrine sediments. Presently, the Andean Cordillera is covered with andesitic volcanic deposits of recent origin. The central depression, which was glaciated south of 38°S, is filled with quaternary glacial, fluvio-glacial, aeolian, and alluvial deposits and volcanic ash. Volcanic materials cover the Andean Cordillera, the Central Depression and up to 400-500 m asl in the eastern slopes of the Coastal Cordilleras. These soils are in general more fertile than those of the upper and western slopes of the Coastal Cordillera, which are usually shallower, more acidic, and highly leached. The northern two-thirds of Chile lie on top of the Nazca Plate, which is forcing its way under the continental plate of South America, moving eastward at an estimated ten centimetres a year. This movement results in the subduction of the ocean plate under the continental plate, and the formation of a deep oceanic trench, lying off the northern two-thirds of the coast. The trench is about 150 kilometres wide and averages about 5,000 meters in depth. At its deepest point, just north of the port of Antofagasta, it plunges to 8,066 meters. Although the ocean's surface obscures this fact, most of Chile literally lies at the 'edge of the world'. The same plate tectonic movements that form the Peru-Chile oceanic trench make the country highly prone to earthquakes and volcanic activity. The clash between the earth's surface plates has also generated the Andes, a geologically young mountain range that, in Chilean territory alone, includes about 620 volcanoes, many of them active. Chile has in the region of 150 identified active volcanoes, 10% of globally active peaks. All are located in the Andes mountain chain. Almost sixty of these had erupted in the twentieth century by the early 1990s. More than half of Chile's land surface is volcanic in origin. During the twentieth century, Chile has been struck by twenty-eight major earthquakes, all with a force greater than 6.9 on the Richter scale. The strongest of these occurred in 1906 (registering an estimated 8.4 on the Richter scale) and in Valdivia 1960 (reaching 9.5). This latter earthquake occurred on May 22, the day after another major quake measuring 7.25 on the Richter scale, and covered an extensive section of south-central Chile. It caused a tsunami that decimated several fishing villages in the south and raised or lowered sections of the coast as much as two meters. Chilean territory extends across the Pacific Ocean as far west as Easter Island (Isla de Pascua, also known by its Polynesian name of Rapa Nui), located 3,600 kilometres west of Chile's mainland port of Caldera, just below the Tropic of Capricorn. The Juan Fernández Islands, located 587 kilometres west of Valparaíso, are the locale of a small fishing communities. One of the islands, Robinson Crusoe Island, is where Alexander Selkirk was marooned for about four years, becoming the inspiration for Daniel Defoe's novel after which the island is now named. Cordillera de Los Andes The Andean Mountain Range or Cordillera de los Andes, a volcanic mountain chain, began forming approximately 65 million years ago - a process that continues today. The mountains create a continuous highland range along the western coast of South America, and are again related to the plate tectonic processes which form the oceanic trench, and not only dominate the physical geography of the continent but also its weather patterns and ecology. It is over 7,000 km long, approximately 200-300 km wide throughout its length (widest between 18° to 20°S latitude in the 'Bolivian flexure' where it is up to 640km wide), and of an average height of about 4,000 metres. In the South American tropics mountain glaciers are generally found above 4,800 meters. The snowline descends southwards, and is about 2,400m in Central Chile (35'S), and less than 1,000m in southern Patagonia, where mountain glaciers may descend to sea level in the fiords of southern Chile. The Andes mountain range is the highest mountain range outside Asia, with its highest peak, Aconcagua, rising to 6,962 m above sea level, the highest in the Western Hemisphere, and the second highest, the volcano Ojos del Salado at 6,891 masl, is the highest active volcano in the world. Both are located on the Chile-Argentina border region. As a point of interest, the summit of Mount Chimborazo in the Ecuadorean Andes is the point on the Earth's surface most distant from its centre, as a result of the global 'equatorial bulge' in the earth. 'Relief' (or orographic) rainfall is caused when masses of air pushed by wind are forced up the side of elevated land formations, such as the Andes mountains. The pushing of air from the Pacific Ocean up the eastern side of the mountain chain results in temperature related adiabatic cooling, and the condensation of water vapour it holds, ultimately resulting in precipitation. Therefore a more moist climate usually dominates on the western windward side of a mountain than on the eastern leeward (downwind) side. Moisture is removed by orographic lift, leaving drier air on the descending leeward side where a rain shadow is created. This can be clearly seen in Central Chile, where the Andes mountain range blocks Pacific moisture that arrives, resulting in higher rainfall on the eastern slopes of the Andes, and a desert climate across the Andes in western Argentina. The southern Valdivian forests depend on this rainfall, which in the south can extend over the Andes and onto the eastern Argentinean slopes. Whilst the Andes provide an ever-present backdrop to much of the country, there are other mountains chains as well, forming transverse and parallel coastal ranges within the country. The former extend from the Andes to the ocean, creating valleys with an east-west directions, and the latter run parallel to the Andes and are evident mainly in the centre of the country, creating the Coastal Cordillera and Valle Central. In the south, the Central Valley runs into the ocean's waters, and the Isle de Chiloe remains as evidence of the Coastal Cordillera. Further south the higher elevations of the coastal range become a multiplicity of islands, forming an intricate labyrinth of channels and fjords that have formed an enduring challenge to maritime navigators. The country usually is divided by geographers into five natural regions on the basis which CORFO divided continental Chile in 1950. The five regions: the far north, the near north, central Chile, the south, and the far south. Each has its own characteristic vegetation, fauna, climate, and, despite the omnipresence of both the Andes and the Pacific, its own distinct topography.
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