Cordillera Oriental

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Cordillera Oriental

 

(also Eastern Cordillera of the Andes), mountain ranges which form the eastern fringes of the Andes mountain system.

In the Central Andean countries the term “Cordillera Oriental” has been applied to several mountain ranges, resulting in different readings on maps and in literature; it has been most firmly established as the name of mountains in the Andes of Colombia and Ecuador. Orographically the Cordillera Oriental is not a single mountain range, but structurally, along with the Cordillera Central, it does form a unified system of anticlinoria with Hercynian cores.

The Cordillera Oriental of Colombia extends from 1° 30’ to 9° N latitude as a large mountain range reaching an altitude of 5,493 m (Ritacuva). It declines sharply in the east to the level of the plains of the Orinoco River and the western edge of the Guiana Highlands and in the west to the basin of the Magdalena River. Extensive intermontane plains and hollows at altitudes of 2,500 to 3,500 m are characteristic of the central section (which is the broadest, with widths extending to 270 km). The range abruptly narrows and descends in the north (where it is called the Sierra de Perijá) and the south, where it becomes part of the Cordillera Central. It continues into Ecuador, where it is called the Cordillera Oriental or the Cordillera Real. In separate spurs and massifs the Cordillera Oriental of Ecuador descends in the east to the Amazon Basin; in front of the western slopes lie the high intermontane “basins,” or depressions. Extinct and active volcanoes that have formed peaks as high as 5,897 m (the Cotopaxi volcano) are built up along the fracture lines. In the south, between 4° and 6° S latitude, the Cordillera Oriental is not orographically expressed. Its structures continue further into the Cordillera Central of northern Peru, the Cordilleras of southeastern Peru, and the Cordillera Real of Bolivia.

In northern Peru the term Cordillera Oriental is also applied to the Sub-Andean Cordilleras, folded mountain ranges of moderate altitude that frame the western Amazon Basin (5°-10° S latitude) and the eastern chains of Bolivia, which border upon the plains of Beni-Mamore (15°-19° S latitude) at an elevation to 4,051 m.

Throughout their entire length the eastern slopes of the Cordillera Oriental face the wind (with precipitation ranging from 4,000 to 5,000 mm annually) and are deeply dissected by rivers and covered by evergreen forests (mountain tropical) with precisely delineated altitude zones. Only on the more arid northern and southern extremities and the western slopes are there mixed deciduous and evergreen forests and thin-forest areas. The snow line is located at an altitude of 4,400 to 5,000 m.

E. N. LUKASHOVA

References in periodicals archive ?
Cloetingh, 2006, Mesozoic transtensional basin history of the Eastern Cordillera, Colombian Andes: Inferences from tectonic models: Journal of South American Earth Sciences, v.
4[degrees]N and beneath the Western, Central and Eastern cordilleras (Figure 1, inset map).
The Paipa volcano is located at the central part of the Eastern Cordillera of Colombia (EC), in the Department of Boyaca (Figure 1).
Thus, there are always more species of Ericaceae on the wet than on the dry sides of mountains (see Table III; although only the numbers of endemic species found in the wet Western Cordillera and the much drier Eastern Cordillera or Sierra Nevada de Santa Marta in Colombia are compared, those numbers are representative of the Vaccinieae as a whole).
Between latitudes 5[degrees]40'28"N and 5[degrees]45'20"N, and longitudes 73[degrees]9'4"W and 73[degrees]3'39"W, in the central part of the Eastern Cordillera (EC) of Colombia (Figure 1), the Paipa volcano was recognized during the INGEOMINAS (Colombian Geological Survey) Geothermal Research Project.
Contrary to this view and based on the results of this study we propose that the reddish brown paleosols that are very widespread in the "Altiplano" of the Eastern Cordillera of Colombia developed in Early Pliocene before the Uplift of the Cordillera.
A number of bonanza gold skarn deposits occur in the Eastern Cordillera of
has signed with the National Hydrocarbon Agency of Colombia (ANH) a new Exploration and Production Contract (Muisca) in the Eastern Cordillera Region, approximately 100 km north-east of Bogota.
The Company has also been granted the 11,850 hectare La Mireya concession in the Miches area of the eastern Cordillera.
The crucial defining features (high levels of endemism, overlap of northern and southern groups) of the zone are not restricted to the western slope: There may be a wider area of overlap in the Eastern Cordillera than in the Western Cordillera, which is partly explained by presence of the Rio Maranon, which runs south to north, and may also reflect the more gradual climatic changes on the eastern slope and the less-dissected nature of its habitats.
Bucaramanga Organic is grown in the eastern Cordillera of the Andes Mountains and meets the shade grown coffee criteria developed by the Smithsonian Migratory Bird Center.
Samper will be aided by the oil bonanza he inherits from the Cusiana oil field on the edge of the Eastern Cordillera hills.

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