South America: Physical Geography (2024)

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.

South America’s physical geography, environment and resources, and human geography can be considered separately.

South America can be divided into three physical regions: mountains and highlands, river basins, and coastal plains.

Mountains

and

coastal plains generally run in a north-south direction, while highlands and river

basins

generally run in an east-west direction.

South America’s extreme geographic variation contributes to the

continent

’s large number of biomes. A

biome

is a community of animals and plants that spreads over an area with a relatively uniform climate.

Within a few hundred kilometers, South America’s

coastal

plains

’ dry desert

biome

rises to the rugged alpine

biome

of the Andes

mountains

. One of the

continent

’s river

basins

(the Amazon) is defined by dense, tropical rain forest, while the other (Paraná) is made up of vast grasslands.

With an unparalleled number of plant and animal species, South America’s rich biodiversity is unique among the world’s

continents

.

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.

Most plants in the

alpine

biome

are small, and their leaves are stiff and strong to protect them from frost and drought. The largest herb in the world, Puya raimondii, is known as the Queen of the Andes. A Puya raimondii can live for 100 years and can grow to more than 9 meters (30 feet) tall. The leaves of this endangered species all grow from one woody

stem

, allowing moisture to run down the leaves to the base of the plant.

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.

River Basins

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 diversity of animal life in the Amazon rain forest is unsurpassed in the rest of the world. The rain forest is perfectly suited for arboreal, or tree-living, animals. More than 2 million species of insects are native to the

region

, including hundreds of spiders and butterflies. Primates are abundant—howler monkeys, spider monkeys, and capuchin monkeys—along with sloths, snakes, and iguanas. Thousands of native birds include brightly colored macaws, parrots, toucans, and parakeets.

The Orinoco River flows north of the Amazon. The Orinoco flows in a giant arc for more than 2,736 kilometers (1,700 miles), 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

.

Coastal Plains

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.

Very few plants grow in this

desert

. Even bacteria, insects, and fungi are sc

arce

. Larger animal species are also rare, and include the grey fox, a type of deer called the huemul, and the viscacha—the largest member of the chinchilla family. Ocean birds, such as penguins, cormorants, and pelicans, are found on the

desert

coast. While Atacama lacks flora and fauna, it is a rich source of copper and a chief source of revenue for the Chilean economy.

South America: Physical Geography (2024)
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