South America, the fourth-largest continent, extends from the Gulf of Darién in the northwest to the archipelago of Tierra del Fuego in the south.
• It is also known as ‘Continent of Birds’.
• South America is bounded by the Atlantic Ocean in the east, the Pacific Ocean in the west and the Caribbean Sea in the north-
• The Andes Mountains, which lies parallel to the western side of the continent, forms the largest mountain chain in the world.
• The Amazon River occupies a large depression in the Earth’s Crust, formed by the uplift of the Andes.
• The Amazon Basin in the largest area of the tropical evergreen forests in the world. These tropical evergreen forests are known as ‘Selvas’.
• Amazon and its tributaries, Parana, Orinoco and Sao Francisco, are the main rivers of South America.
• The immense Brazilian Shield underlies more than one-third of South America. It is pitted with numerous volcanic intrusions and a large basaltic plateau exists between the Parana River and the Atlantic Ocean.
• It includes the Easter Islands, the Falkland Islands, the Galapagos Islands and the Tierra del Fuego.
• Tropical conditions are found across over half of South America, when both rainfall and temperatures are high, hot humid rainforest prevail.
South America can be divided into three physical regions: mountains and highlands, river basins, and coastal plains.
Mountains & Highlands
South America’s primary mountain system, the Andes, is also the world’s longest. The range covers about 8,850 kilometers (5,500 miles). Situated on the far western edge of the continent, the Andes stretch from the southern tip to the northernmost coast of South America. There are hundreds of peaks more than 4,500 meters (15,000 feet) tall, many of which are volcanic.
The highest peak in the Andes, Aconcagua, stands at 6,962 meters (22,841 feet) and straddles the Argentina-Chile border. Aconcagua is the tallest mountain outside Asia.
High plateaus are also a feature of the Andes. The altiplano of Peru and Bolivia, for example, has an elevation of about 3,700 meters (12,300 feet). The Patagonia region of Argentina and Chile consists of lower-elevation plateaus and rugged glaciers.
Outside the Andes, South America has two principal highland areas: the Brazilian Highlands and the Guiana Highlands. Located south of the Amazon River in Brazil, the Brazilian Highlands are made up of low mountains and plateaus that rise to an average elevation of 1,006 meters (3,300 feet). The Guiana Highlands are located between the Amazon and Orinoco Rivers. The heavily forested plateau of the Guiana Highlands covers southern Venezuela, French Guiana, Guyana, northern Brazil, and a portion of southeastern Colombia.
South America has three important river basins: the Amazon, Orinoco, and Paraguay/Paraná.
The Amazon River basin has an area of almost 7 million square kilometers (2.7 million square miles), making it the largest watershed in the world. The basin, which covers most of northern South America, is fed by tributaries from the glaciers of the Andes. Every second, the Amazon River empties 209,000 cubic meters (7,381,000 cubic feet) of freshwater into the Atlantic Ocean.
The Amazon River is the life force of the equally vast Amazon rain forest, which makes up about half of the rain forest of the entire planet. This tropical biome has as many as 100 different tree species on a single acre, including the rubber tree, silk cotton tree, and Brazil nut tree. Other important plant species include palms, ferns, and ropelike vines known as lianas that network throughout the rain forest’s dense canopy.
The Orinoco River flows north of the Amazon. The Orinoco flows in a giant arc for more than 2,736 kilometers (1,700miles), originating in the Guiana Highlands of northern Brazil and discharging in the Atlantic Ocean in Venezuela. The Orinoco River basin covers an area of about 948,000 square kilometers (366,000 square miles) and encompasses approximately 80 percent of Venezuela and 25 percent of Colombia.
A vast savanna or grassland region, known as the Llanos, is the primary biome of the Orinoco River basin. The Llanos is primarily made up of grasses. Swamp grasses, sedges, and bunchgrass are found in wet, low-lying areas. Carpet grass is found in the higher and drier elevations.
Like most grassland biomes, the Llanos is the perfect habitat for many bird species, including the scarlet ibis, bellbird, and umbrellabird. Important river species include the piranha, electric eel, and the Orinoco crocodile, which can reach a length of more than 6 meters (20 feet).
The Paraguay/Paraná River basin covers almost 2.8 million square kilometers (1,081,000 square miles), which is much of southeastern Brazil and Bolivia, Paraguay, and northern Argentina. The Paraná River includes Iguazu Falls, a massive series of waterfalls that extend for 2.7 kilometers (1.7 miles).
Along with the Uruguay River, the Paraná River empties into the Rio de la Plata estuary between Argentina and Uruguay. The Rio de la Plata is the most populated region of both countries. The capital cities of Buenos Aires, Argentina, and Montevideo, Uruguay, practically face each other across the estuary.
The Paraguay/Paraná River basin supplies water to the plains biome, or Pampas, of South America. The Pampas have rich, fertile soil and predictable rainfall patterns. They are the most important grazing and cropland areas on the continent.
A coastal plain is an area of low, flat land next to a seacoast. South American coastal plains are found on the northeastern coast of Brazil, on the Atlantic Ocean, and the western, Pacific coast of Peru and Chile. The coastal plains of northeastern Brazil are extremely dry. The Brazilian Highlands act as a wedge that pushes moist sea winds away from the coastal plains.
The western coastal plains are also extremely dry. They are trapped between the cold Peru Current to the west and the Andes Mountains to the east. The Peru Current brings cold water to the Pacific coast of Peru and Chile. This cold surface water results in thermal inversion: cold air at sea level and stable, warmer air higher up. Thermal inversion produces a thick layer of clouds at low altitudes. These low-lying clouds blanket much of the Pacific coast of South America. They do not allow precipitation to form.
The Atacama Desert is part of the western coastal plain. The Atacama is considered the driest region in the world. The average rainfall is about 1 millimeter (0.04 inches) a year, and some parts of the Atacama have never had rain in recorded history.
Climate of South America
The Climate of South America influenced by the geographical location. Away from the equator to the north and south, there is a greater contrast in temperature between summer and winter in the tropical region. Winters are cooler and summers are less hot.
The Equatorial region: The Highlands of Brazil and Guiana receives moderate annual rainfall and summer is the rainy season. The Equatorial region receives high rainfall throughout the year. There is no dry season in the Equatorial region.
Pampas: In the Pampas lowlands of South America winters are cooler and summers are less hot. Rainfall is moderate and is maximum in summer. The rain-shadow region of the Andes ranges is the Plateau of Patagonia. It is a temperate desert and gets a low rainfall.
Chile: The southernmost region of Chile has marine or oceanic type of climate. This region receives high rainfall throughout the year. Central Chile region has warm summers and mild winters with rainfall in winter only.
Atacama desert: The Atacama desert has the hot desert type of climate, which is found in the Northern Chile and Southern Peru. The Andes mountains region climate changes according to height above the sealevel. The lower slopes have tropical climate, the middle slopes have temperate conditions and above 6000 metres permanent cover of snow.
Deserts of South America
• La Guajira Desert – a desert in northern Colombia,
• Patagonian Desert – the largest desert by area in the Americas, located in Argentina and Chile,
• Atacama – a desert in Chile and Peru, the driest place on Earth,
• Sechura Desert – a desert located along a portion of the northwestern coast in Peru, South America,
• Monte Desert – in Argentina, a smaller desert above the Patagonian
• Peruvian Desert- in Peru and Chile
The Pampas of South America are a grassland biome. They are flat, fertile plains that covers an area of 300,000 sq. miles or 777,000 square kilometers, from the Atlantic Ocean to the Andes Mountains. It is found primarily in Argentina and extends into Uruguay.
The word Pampas comes from the Guarani Indian word for level plain. The Argentinean Pampas are the home of the ‘Gaucho’, the original South American cowboy. The pampas is located just below Buenos Aires, between 34° and 30° south latitude, and 57° and 63° west latitude.
The average temperature in the Pampas is 18° C. The pampas has a ‘high sun’ or dry season in the summer, which in the Southern Hemisphere is in December. The wind blows most of the time. The climate in the pampas is humid and warm.
There are many kinds of animal and plant life in the Pampas. Native plants and animals on the Pampas have made adaptations to living in a windy grassland. There are not very many trees because fires frequently occur in the pampas. The fires do not kill the grasses, which regenerate from their root crowns, but destroy the trees, which have shallow root systems. The exception is the Ombu, which has made adaptations to protect itself from fires.
The humid Pampas ecosystem is one of the richest grazing areas in the world. Because of its temperate climate and rich, deep soil, most of the Pampas has been cultivated and turned into croplands.