The geography of South America contains many diverse regions and climates. Geographically, South America is generally considered a continent forming the southern portion of the landmass of the Americas, south and east of the Colombia–Panama border by most authorities, or south and east of the Panama Canal by some. South and North America are sometimes considered a single continent or supercontinent, while constituent regions are infrequently considered subcontinents.
South America became attached to North America only recently (geologically speaking) with the formation of the Isthmus of Panama some 3 million years ago, which resulted in the Great American Interchange. The Andes, likewise a comparatively young and seismically restless mountain range, runs down the western edge of the continent; the land to the east of the northern Andes is largely tropical rainforest, the vast Amazon River basin. The continent also contains drier regions such as eastern Patagonia and the extremely arid Atacama Desert.
The South American continent also includes various islands, most of which belong to countries on the continent. The Caribbean territories are grouped with North America. The South American nations that border the Caribbean Sea — Colombia and Venezuela —are also known as the Caribbean South America.
Topography and geology The geographical structure of South America is deceptively simple for a continent-sized landmass. The continent's topography is often likened to a huge bowl owing to its flat interior almost ringed by tall mountains. With the exception of narrow coastal plains on the Pacific and Atlantic oceans, there are three main topographic features: the Andes, a central lowland, and the extensive Brazilian and Guiana Highlands in the east.
The Andes are a Cenozoic mountain range formed (and still forming) Altiplano and a number of major valleys such as the Rio Magdalena. These contain three of the world's highest capitals: Bogotá, Quito and highest of all, La Paz. The southernmost Andes hosts the Southern Patagonian Ice Field are lower and narrower. There are a number of large glaciers in the northern part, but from latitude 19°S to 28°S the climate is so arid that no permanent ice can form even on the highest peaks. Permafrost, however, is widespread in this section of the Altiplano and continuous above .
The very fertile soils from the erosion of the Andes formed the basis for the continent's only pre-Columbian state civilizations: those of the Inca Empire and its predecessors (Chavín, Nazca, Mochica, etc.). The area is still a major agricultural region. The Altiplano contains many rare minerals such as copper, tin, mercury ore. The Atacama is mined for its nitrates. Peru east of the Andes is regarded as the most important biodiversity hotspot in the world with its unique forests that form the western edge of the world's largest rainforest, the Amazon rainforest.
East of the Andes is a large lowland drained by a small number of rivers, including the two largest in the world by drainage area—the Amazon River and the more southerly Paraná River. The other major river of this central lowland is the Orinoco River, which has a natural channel linking it with the Amazon.South America physical map Most of this central lowland is sparsely populated because the soils are heavily leached, but in the south is the very fertile pampas of Argentina—one of the world's major food-producing regions where wheat and beef cattle are pre-eminent. The natural vegetation of the northern lowlands are either savanna in the northern Llanos and southern campos, or tropical rainforest throughout most of the Amazon basin. Efforts to develop agriculture, outside of fertile floodplains of rivers descending from the Andes, have been largely failures because of the soils. Cattle have long been raised in the llanos of northern Colombia and Venezuela, but petroleum is now the dominant industry in the northern lowlands, making Venezuela the richest country in the continent.
The eastern highlands are areas of Earth's crust that are much older than the Andes, being pre-Cambrian in origin, but are still rugged in places, especially in the wet tepuis of Venezuela, Guyana and Roraima. The Amazon River has cut a large valley through a former highland, and to the east is a relatively low plateau comprising the Northeast and Southeast regions of Brazil. In the north of this region is the arid sertão, a poor region consistently affected by extremely erratic rainfall, and the humid Zona da Mata, once the home of the unique Atlantic Rainforest with many species not found in the Amazon, and now a center for sugarcane. Further south, the mainland use is coffee, while São Paulo is the economic heart of the continent with its industry.
South of about Santa Catarina, the highlands fade out to low plains in Uruguay.
East of the Andes in Argentina, there are a number of rugged, generally arid to semi-arid isolated mountain chains called Sierras Pampeanas, the highest of which is the Sierra de Córdoba near the city of the same name. Eastern Patagonia is characterized by containing a series of stepped plateaus of lava. South America and North America
Territories The largest country in South America by far, in both area and population, is Brazil. Regions in South America include the Andean States, the Guianas and the Southern Cone.
Name of territory,with flag Area(km2) Population(July 2021 est.Except for the figures on the Falkland Islands (which are from October 2016) and French Guiana (January 2018).) Population density (per km2) Capital ArgentinaCIA - The World Factbook - Argentina 2,766,890 45,864,941 16.6 Buenos Aires BoliviaCIA - The World Factbook - Bolivia 1,098,580 11,758,869 10.7 La Paz, SucreLa Paz is the administrative capital of Bolivia; Sucre is the judicial seat. BrazilCIA - The World Factbook - Brazil 8,511,965 213,445,417 25.1 Brasília ChileCIA - The World Factbook - ChileIncludes Easter Island in the Pacific Ocean, a Chilean territory frequently reckoned in Oceania. Santiago is the administrative capital of Chile; Valparaíso is the site of legislative meetings. 756,950 18,307,925 24.2 Santiago ColombiaCIA - The World Factbook - Colombia 1,138,910 50,355,650 44.2 Bogotá EcuadorCIA - The World Factbook - Ecuador 283,560 17,093,159 60.3 Quito Falkland Islands (UK)CIA - The World Factbook - Falkland IslandsClaimed by Argentina. 12,173 3,198 0.26 Stanley French Guiana (France) 83,534BBC NEWS | Americas | Country profiles | Regions and territories: French Guiana 283,539 3.4 Cayenne GuyanaCIA - The World Factbook - Guyana 214,970 787,971 3.7 Georgetown ParaguayCIA - The World Factbook - Paraguay 406,750 7,272,639 17.9 Asunción PeruCIA - The World Factbook - Peru 1,285,220 32,201,224 25.1 Lima South Georgia andSouth Sandwich Islands (UK)CIA - The World Factbook - South Georgia and the South Sandwich IslandsAlso claimed by Argentina, the South Georgia and the South Sandwich Islands in the South Atlantic Ocean are commonly associated with Antarctica (due to proximity) and have no permanent population, only hosting a periodic contingent of about 100 researchers and visitors. 3,903 0 0 Grytviken SurinameCIA - The World Factbook - Suriname 163,270 614,749 3.8 Paramaribo UruguayCIA - The World Factbook - Uruguay 176,220 3,398,239 19.3 Montevideo VenezuelaCIA - The World Factbook - Venezuela 912,050 29,069,153 31.9 Caracas
Climate
As part of the Hadley model of atmospheric circulation, the equator is characterised by the ascending branches of separate meridional cells, driven by intense insolation.Sylvestre, F. (2009). Moisture Pattern During the Last Glacial Maximum in South America. Past Climate Variability in South America and Surrounding Regions: From the Last Glacial Maximum to the Holocene. F. Vimeux, F. Sylvestre and M. Khodri. 14.Grodsky, S. A. and J. A. Carton (2003). "The intertropical convergence zone in the South Atlantic and the equatorial cold tongue". Journal of Climate 16(4): 723–733. The vertical convection draws in air from the surrounding atmosphere, known as the trade winds. As these inward flows of air converge they reduce horizontal wind speed, and as they rise, they form precipitation. The vertical convection also results in a net export of heat and freshwater from the lower atmosphere into the troposphereOliver, J. E. (2005). Encyclopedia of World Climatology, Springer. This system is known as the ITCZ. The location of the ITCZ is centred on the areas of highest insolation, although it is more stationary over the oceans than landmasses.
In the Atlantic region, the ITCZ is clearly developed, and the spatial extent of the ITCZ reaches a minimum close to the equator during the boreal spring (March–May), while extending to a maximum of 10°–15°N in late boreal summer (August). No comprehensive theory for ITCZ formation and spatial variation has been validated, although several hypotheses have been proposed. Some studies advance ideas that describe one or more atmospheric cells over the equator,Hastenrath, S. L. (1968). "On mean meridional circulations in the tropics". Journal of the Atmospheric Sciences 25: 979–983. while others state that the position of the ITCZ depends on Ekman pumping efficiency and moisture availability.Charney, J. G. (1971). "Dynamical theory of formation of cloud bands in tropical oceans". Bulletin of the American Meteorological Society 52(8): 778. Whichever hypothesis best represents the natural system, it is clear that the dynamics of the ITCZ are influenced by several other external climate systems. These include continental convection and equatorially asymmetric sea surface temperature (SST) distribution. This asymmetry is evident in the northward bias of the ITCZ's location, which is maintained by a positive feedback between wind speed, evaporation and SST.Xie, S. P. and Y. Tanimoto (1998). "A pan-Atlantic decadal climate oscillation". Geophysical Research Letters 25(12): 2185–2188.
Whereas the ITCZ has a global extent, South America is subject to its own unique climate patterns. which have been organised into the South American monsoon system (SAMS). As an integrated component in the global climate system, the SAMS is influenced the Atlantic sector of the ITCZ, variability in the adjacent Pacific and Atlantic Oceans, the Andean and central-east Brazil topography, complex land surface processes and relations with land use change, and interactions involving topography and soil moisture.Marengo, J. A., B. Liebmann, et al. (2010). "Recent developments on the South American monsoon system". International Journal of Climatology: n/a–n/a. The SAMS framework comprises several distinct subcomponents, which are discussed below:
The Pacific and Atlantic subtropical high: These are semi-permanent high pressure systems caused by descending sectors of the equatorial Hadley cells. The air masses are relatively warm and dry, and move in an anticyclonic circulation pattern over the sub-tropical oceans. The Pacific High is generally stable, whereas the Atlantic High moves throughout the year. During the summer, it covers most of the midlatitude and subtropical Atlantic Ocean. During winter, it is smaller and moves to the east.