Mountain Ranges, Deserts and Landforms of Colombia

Geography

South America occupies the southern portion of the Americas. The continent is generally delimited on the northwest by the Darién watershed along the Colombia–Panama border, although some may consider the border instead to be the Panama Canal. Geopolitically and geographically, all of Panama – including the segment east of the Panama Canal in the isthmus – is typically included in North America alone and among the countries of Central America. Almost all of mainland South America sits on the South American Plate.

History

South America is thought to have been first inhabited by humans when people were crossing the Bering Land Bridge (now the Bering Strait) at least 15,000 years ago from the territory that is present-day Russia. They migrated south through North America, and eventually reached South America through the Isthmus of Panama.

Amongst the oldest evidence for human presence in South America is the Monte Verde II site in Chile, suggested to date to around 14,500 years ago. From around 13,000 years ago, the Fishtail projectile point style became widespread across South America, with its disappearance around 11,000 years ago coincident with the disappearance of South America's megafauna.

Economy

Since 1930, the continent has experienced growth and diversification in most economic sectors. Most agricultural and livestock products are destined for the domestic market and local consumption. However, the export of agricultural products is essential for the balance of trade in most countries.

The main agrarian crops are export crops, such as soy and wheat. The production of staple foods such as vegetables, corn or beans is large, but focused on domestic consumption. Livestock raising for meat exports is significant in Argentina, Paraguay, Uruguay and Colombia. In tropical regions the most important crops are coffee, cocoa and bananas, mainly in Brazil, Colombia and Ecuador.

Geography

The Llanos occupy a lowland that extends mostly east and west. The Llanos are bounded on the west and northwest by the Andes, and on the north by the Venezuelan Coastal Range. The Guiana Highlands are to the southeast, and the Negro-Branco moist forests are to the southwest. To the east the Orinoco wetlands and Orinoco Delta swamp forests occupy the Orinoco Delta. The Llanos' main river is the Orinoco, which runs from west to east through the ecoregion and forms part of the Colombia–Venezuela border. The Orinoco is the major river system of Venezuela.

A 2017 assessment found that 105,323 km², or 28%, of the ecoregion, is in protected areas.

Climate

The ecoregion has a tropical savanna climate that grades into a tropical monsoon climate in the Colombian Llanos. Rainfall is seasonal, with a rainy season from April to November, and a dry season between December and March. The wettest months are typically June and July. Rainfall varies across the ecoregion, from up to 3,000 millimetres (120 in) per year in the southwest, 1,200 to 1,600 millimetres (47 to 63 in) in Apure State, and 800 to 1,200 millimetres (31 to 47 in) per year in Monagas State in the northeast. Mean annual temperature is 27 °C or 80.6 °F, and the average monthly temperature varies little throughout the year; the lowest-temperature months (June, July, December, and January) are only 2 °C or 3.6 °F cooler than the hottest months.

Economy

The primary economic activity since the Spanish colonial era is the herding of millions of cattle. An 1856 watercolor by Manuel María Paz depicts sparsely populated open grazing lands with cattle and palm trees. The term llanero ("plainsman") became synonymous with the cowhands that took care of the herds and had some cultural similarities with the gauchos of the Pampas or the vaqueros of Spanish and Mexican Texas. Decades of extensive cattle raising has altered the ecology of the Llanos. Grasslands and savannas are frequently burned to make them more suitable for grazing and eliminate trees and shrubs. Non-native grasses have been introduced for cattle fodder, including the African grass Melinis minutiflora, and now cover large areas.

Geology

The oldest rocks in the shield consist of Archean Imataca Complex, composed of a quartz-feldspar gneiss and subordinate mafic gneiss. The Guri Fault marks the southern boundary of the complex. South of that fault are Early Proterozoic rocks consisting of the metavolcanic Pastora Supergroup and the granitic plutonic Supamo Complex. The Cuchivero Group consists of ash flow tuff and granitic plutonic rocks. The Early to Middle Proterozoic Roraima Group consists of continental clastic sedimentary rocks. These Precambrian sediments include quartz sandstones, quartzites, and conglomerates presumed to be 1.8 to 1.4 Ga in age.

Ecology

The Guiana Shield is one of the world's most biodiverse regions, and has many endemic species. The region houses over 3000 vertebrate species: 1168 fresh water fish, 269 amphibians (54% endemics), 295 reptiles (29%), 1004 birds (7.7%), and 282 mammals (11%). Diversity of invertebrates remains largely undocumented, but there are several species of endemic butterflies and dung beetles.

Plant life is equally rich and 13,367 species of vascular plants have been found, approximately 40% of which is considered endemic. The shield is overlain by the largest expanse of tropical forest on any Precambrian shield area in the world.