Chile Geology and Morphology

Chile Geology and Morphology

As a whole, Chile, an essentially mountainous country, consists of the western side of the Andes, a series of secondary reliefs parallel to the coast and a series of longitudinal furrows between the latter and the Andes. A first division, based on the climatic characteristics, which will be discussed later, allows us to distinguish: northern Chile with very little rainfall and sometimes presenting a desert aspect; Central Chile, a land of temperate crops, and southern Chile, cold and humid, covered with dense forests.

In northern Chile, from the border with Peru up to about a latitude of 23 °, the morphology of the country has the following characteristics: a coastal plateau, formed by very ancient rocks (Cordillera de la Costa), to the east of which the Pampa del Tamarugal, 25 to 30 km wide, at a height of 900-1200 m, which faces the sea in the northern region; around noon the pampas continue in the Llano de la Paciencia.

Towards the east rises the Andean mountain range, deeply engraved by erosion on the edge of the pampas.

Proceeding southwards, the morphology becomes more complicated: the Atacama desert (see) follows eastwards at the Cordillera de la Costa, oriented from the SW. to the NE., limited to the east by the Cordillera de Domeyko: there is a sinking pit to the east, always oriented in the direction of the meridians, which extends for hundreds of km. from the Salar de Atacama through the Salar de Punta Negra to the Salar de Pedernales; it forms the western limit of the Puna proper. Large volcanoes, over 6000 meters, dominate this morphological landscape.

According to itypeusa, this section of Chile includes the provinces of Atacama, Antofagasta, Tarapacá and the department of Arica: these are the provinces of desert Chile, where the rains are nil or very scarce, where consequently life centers in the oases, or in the points where it is a little irrigation possible; they are still the provinces of saltpetre, which owe their economic development precisely to the presence of the precious deposits. Through a transition zone, which extends between 30 ° and 33 ° south latitude, interesting the provinces of Coquimbo and Antofagasta, in which we note the presence of numerous trunks of chains with a direction perpendicular to the coastal area (Cordillera de la Punilla), detached from the Andean Cordillera, we enter central Chile, characterized by another large longitudinal groove extending from Santiago to Puerto Montt,

The coastal region is always mountainous, engraved by the streams coming from the inland area, broken into many trunks of various heights, which exceed 2000 m. at the latitude of Santiago, they go down to 1500 m. in the Cordillera de Nahuelbuta between the Bío-Bío and the Río Imperial, 800 m. on the island of Chiloé.

The central plain is the most densely populated region in Chile: closed to the north by the Chacabuco chain (Río Aconcagua), it varies in width and is intersected by the numerous rivers that flow down from the Cordillera; shows a progressive decrease from its level: 520 m. in Santiago; 500 in Rancagua; 330 to S. Fernando; 157 in Linares; 114 in Chillán. Towards the gulf of Ancud (Puerto Montt) the plain does not end with a regular slope, but by means of a series of terraces. Fluvial and glacial deposits have contributed to the superficial formation of this plain.

The structure of the Andes of central Chile does not differ much from that of the Andes of northern Chile: however, there is a greater development of erosion in relation to the more abundant precipitation and with the progressive lowering of the limit of permanent snow, which at latitude of Santiago is maintained around 4000 m., and gradually descends to reach 1500 m. south of 40 ° (latitude of Valdivia). It is the section of the sublime peaks, between 6000 and 7000 m. (Mercedario, m. 6670; Aconcagua, m. 6960, Tupungato, m. 6550; Marmolejo, m. 6100). Volcanism is widespread above all starting from the latitude of Santiago: towards the south the series of volcanic cones is detached from the axis of the Cordillera, and more precisely to the west, where it forms a second chain, less regular, but higher (Longavi m 3230; Antuco, m. 3380; Laima, m. 3060, etc.). Proceeding south also the glacial manifestations become more intense.

The third section of Chile begins in S. del Golfo di Ancud, with a very tormented morphology. The central plain continues towards the S. in the gulfs of Chacao and Corcovado up to the isthmus of Ofqui, which joins the mainland to the Taitao peninsula.

The Patagonian Cordillera is divided into a series of massifs, isolated by a system of longitudinal and transverse depressions. Between 41 ° and 46 ° lat. S. the height of the Cordillera is between 200 and 2500 m., Surpassed only by the Tronador (3470 m.); between 46 ° and 56 ° it becomes more sensitive (between 3000 and 4000); in Tierra del Fuego it is just over 2000 m. (M. Sarmiento, d. 2235). The limit of permanent snow is 1200 m. east of the Golfo de Peñas, 700 m. in Tierra del Fuego.

Coastal glaciers drop to 500-300m. between 42 ° and 44 ° of lat. S .; starting from 44 ° 30 ′ the front of the glaciers touches the sea. It is the area of ​​very abundant rainfall and the great forest of the temperate and subarctic regions (see Andes).

The Chylene coasts have a very different morphology in the different sections. North of the Canal de Chacao (42 ° parallel south) the coast is uniform on the whole, interrupted only by some promontory that identifies more or less pronounced gulfs and inlets. Thus we will remember the Bahía de Mejillones del Sur, the Bahía Jorje on which Antofagasta was built; the Bahía Salada, those of Coquimbo and Tongoi, of Valparaiso, of Concepción, of Arauco, very important for the rise on their coasts of numerous centers, which sometimes benefit from the presence of river estuaries. South of the Canal de Chacao begins the troubled section of the Chilean coasts, rich in inlets, gulfs, promontories, peninsulas, dotted on the ocean by an interrupted fringe of islands and rocks. The deep, branching creeks, closed between steep walls, they closely resemble the Norwegian fjords. The series of archipelagos is interrupted by the peninsula of Taitao, joined to the continent by the isthmus of Ofqui; further south are the Muñoz Gamero and Brunswick peninsulas; in Tierra del Fuego the great peninsula of the Darwin mountain range extends westwards, visited and described by De Agostini.

South of the 42nd parallel the island groups are very numerous: the Chiloé Archipelago is made up of 26 main islands and a large number of minor islands: the most important is the homonymous island, which measures 8350 sq km; south of the Corcovado Gulf is the Archipelago de los Chonos. Magellan’s territory includes a large number of islands and archipelagos, including the Guaitecas Islands and Wellington Island; the archipelago of Tierra del Fuego is made up of a series of islands, of which the most important are: Desolación, Santa Ines, Clarence, Dawson, Tierra del Fuego, the largest, which has 48,000 sq km. of surface. Some islands far from the coast still belong to Chile, such as the islands of S. Felice and S. Ambrogio and the Juan Fernández islands, the Mas a Tierra (93 sq km), 670 km away. from the mainland and Mas Afuera (84 sq km), 160 km. west of the previous one; in the middle of the Pacific, Chile also has the islands of Easter and Sala-y-Gómez.

Chile Geology

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