Andes: World’s Longest
Mountain Range
Kim Ann Zimmermann, LiveScience
The south face of Aconcagua, the highest peak in South
America, at 22,841 feet (6,962 meters) above sea level.
The Andes is the longest mountain range in the
world and boasts some of the highest peaks. The
range is also known for its volcanoes, ruins of longago civilizations and the source of a malaria treatment.
The origin of the name Andes has not been definitively determined; most agree that it comes from the
Quechua word anti, which translates to "high crest." A minority argue that it comes from Anti Suyu, which is
one of the four regions of the Incas who once inhabited the range.
Located along the entire western coast of South America, the Andes mountain range is about 4,500 miles
(7,242 kilometers) long. The mountain range spans seven countries — Venezuela, Colombia, Ecuador, Peru,
Bolivia, Chile and Argentina — and can be found between 10 degrees north and 57 degrees south latitudes
and 70 degrees to 80 degrees west longitude. It is up to 500 miles (804 km) wide.
The only mountains that are taller than the Andes are the Himalaya Mountains and their adjacent ranges,
including the Hindu Kush. The average elevation in the Andes is about 13,000 feet (3,962 meters). The highest
elevation in the Andes is Mount Aconcagua in Argentina, which is 22,841 feet (6,962 m) above sea level.
The Andes are dotted with a number of depressions that separate the length of the range into several
segments.
Climate of the Andes: Because the Andes act as a large wall between the Pacific Ocean and the continent,
they have a tremendous impact on climate in the region. The northern part of the Andes is typically rainy and
warm, and the weather is also wet in the eastern part of central Andes, and the area to the southwest. To the
west, the dry climate is dominated by the Atacama Desert in northern Chile. The mountains form a rain cover
over the eastern plains of Argentina, which have extremely dry weather.
The Andes Mountains of South America are home to 99 percent of tropical glaciers — permanent rivers of ice
at high enough elevations not to be affected by the types of balmy temperatures usually associated with the
tropics.
The Andes are also home to the world’s highest volcano when measured above sea level, Ojos del Salado on
the Chile-Argentina border, which reaches 22,615 feet (6,893 m), and more than 50 volcanoes that reach
19,685 feet (6,000 m).
1. What is the name of the highest mountain peak in South America?
2. How is the climate to the east of the Andes different from the climate to the west?
The Eight Most Important Things to Know About the Amazon River
By Matt Rosenberg
The Rio Negro tributary of the
Amazon River in Brazil.
Jose de Paula Machado/Getty Images
The Amazon River in South America is
an amazing and important river for the
planet and therefore, you need to know
about it. Here are the eight most
important things you need to know
about the Amazon River:
1. The Amazon River carries more
water than any other river in the world.
In fact, the Amazon River is responsible
for about one-fifth (twenty percent) of
the fresh water that flows into the
world's oceans.
2. The Amazon River is the second longest river in the world
(the Nile River in Africa is the longest) and is about 4,000 miles
(6400 km) long. (In July 2007 a group of scientists reportedly
determined that the Amazon River might just be the longest river in
the world, taking that title from the Nile River. It will take further
studies to substantiate the claim and for the Amazon River to be
recognized as the longest.)
3. The Amazon River has the largest watershed (area of land that
flows into the river) and more tributaries (streams that flow into it)
than any other river in the world. The Amazon River has more than
200 tributaries.
4. Streams that begin in the Andes Mountains are the starting
sources for the Amazon River.
5. Most of the runoff of Brazil flows into the Amazon River along
with runoff from four other countries: Peru, Bolivia, Colombia, and
Ecuador.
6. Due to the vast amount of water as well as sediment that are deposited where the Amazon River meets the
Atlantic Ocean, the color and salinity of the Atlantic Ocean are modified for nearly 200 miles (320 km) from the
delta.
7. For much of its path, the Amazon River can be as much as one to six miles wide! During flood seasons, the
Amazon River can be much, much wider; some report it is more than 20 miles wide (32 km) in certain places.
8. The Amazon River taken different routes since it began to carry water. Some scientists have determined that
the Amazon River even flowed west at one time or more, into the Pacific Ocean.
1. Where does the Amazon River originate? Where does the River end?
2. How does the Amazon River affect the color and salinity of the Atlantic Ocean?
Driest Place: Atacama Desert, Chile
Even the Driest Place on Earth has Water
Dry mountains in the Atacama Desert see an average of less than .004 inches/.01cm of rain per year. Many
times this area will go without rainfall at all for years. Some places in the Atacama Desert have not had rainfall
for over 400 years. The Atacama desert is found along the coast of Chile, South America – right next to the
Pacific Ocean – the biggest body of water in the world. Much of the desert extends up into the Andes
mountains and is very high in elevation. Unlike more familiar deserts, like the Sahara desert in Africa and the
Mojave in California, the Atacama is actually a pretty cold place, with average daily temperatures ranging
between 32 and 80°F. The annual rainfall (or lack of it) defines a desert, but that doesn’t mean that it never
rains in Atacama. Every so often a warming effect over the Pacific Ocean around the equator changes the
weather the world over and even places like the driest desert in the world can become doused with drenching
storms. Even though Atacama gets almost no rainfall, there is water in this arid place and you’ll find it in the
following places:
Salt Lakes: During years of heavy rainfall in the distant past, enough water accumulated in basins found
throughout the Andes to create lakes. Some of the lakes got
their water from melting glaciers at the end of the last ice age.
But in some lakes in the Andes mountains, such as Atacama,
more water is lost through evaporation than is replaced by
rainfall so the lakes are drying up. As the water evaporates, the
mineral salts in the water become more concentrated, creating
very salty water.
Snow: In the higher elevations when precipitation comes to
Atacama snow falls instead of rain. There are small patches of
unmelted snow in the mountain tops where it never gets warm enough to melt the snow.
Underground: Anywhere you go in the world, regardless of how much or little it rains, there is always water
underground. After it rains, some of the rainwater evaporates back into the air, but much of it trickles down into
the ground and stays there – even in the desert. How much water and where depends on a number of things;
soil composition, air and soil surface temperature, amount and frequency of rainfall/precipitation, and drainage.
Since the Andes is a volcanically active mountain range, the magma beneath the ground will heat the
groundwater in certain places causing geysers to erupt.
Fog and Dew: Most of the precipitation that comes to the Atacama is in the form of fog that blows in from the
Pacific. Fog is essentially very low clouds, consisting of water vapor cooling and beginning to condense. If
you’ve ever been in fog you know that it can leave you a little moist. When the air temperature reaches dew
point the water vapor in the air condenses to leave little droplets of water behind. The few things that are able
to survive in the Atacama live on the combined moisture from fog and dew.
1. How is the Atacama different from other deserts like the Mojave and Sahara?
2. Oh no! You just got stranded in the Atacama Desert. How would you get drinking water?
Driest Place: Atacama Desert, Chile
The Atacama Desert is the driest hot desert on the planet, but does anything live there?
Does Anything Live There?
Many people have the view that deserts are places forsaken by Mother Nature and that no living thing
would possibly want to set up camp in a place so dry. Although it is tough to find anything living in the
Atacama there are isolated pockets and small patches of plants, which support life for animals and
insects. Some plant species have adapted well to this dry environment by developing tap roots that run
very deep into the ground gathering water from below. There are flocks of flamingos that live in and
around the salt lakes feeding on red algae that grows in the waters. There are even people living in the
Atacama.
There is a town called Calama in the desert which is complete with motels, restaurants and shops, but it is
definitely not the norm. For the most part, Atacama is a pretty lonely place. Humans have lived in the Atacama
for many thousands of years, based on the cultural relics and artifacts that archaeologists have found. The
South American Indians who have set up
housekeeping in the desert over the millennia
have left relics from their culture and even
themselves. Because the Atacama is so bonedry, the bodies of the buried indians have dried
perfectly preserved turning them into mummies.
Some of the oldest mummies found anywhere on
earth have come from the Atacama Desert and
have been dated to be 9,000 years old!
What Causes Deserts? One reason is that the
high atmospheric pressure in this region over the
Andes can cause dry, cold air from the upper
altitudes to compress and come down to earth. This dry air has almost no water vapor so it can be easily
heated by the sun, causing high ground temperatures with very low humidity.
Another reason that the Atacama doesn't get enough rainfall is because of a phenomenon called rainshadow.
The warm, moist tropical air that blows on the tradewinds from the east, which douse the South American
rainforest, get hung-up on the east side of the Andes. The mountains are so high in altitude that the air cools,
condenses and rains (or snows) on the mountains. As the air descends the other side of the mountain range it
warms, holding in its moisture preventing rain from falling on to the ground below.
This is one of the reasons why the Amazon basin and river are the largest anywhere in the world. The
mountains that cause the Amazon to be the largest river from collecting all the rainfall are also responsible for
preventing the Atacama from ever receiving any rainfall. The driest and one of the wettest places in the world
are right next to each other!
1. What types of life are found in the Atacama Desert?
2. Why does the Atacama not get enough rainfall?
The Amazon Rainforest: The World’s Lungs
The Amazon rainforest, also known as Amazonia, is one of the world’s greatest natural resources. Because its
vegetation continuously recycles carbon dioxide into oxygen, it has been described as the “Lungs of our
Planet”. About 20% of earth’s oxygen is produced by the Amazon
rainforest.
The Amazon rainforest gets its name from the Amazon River, the life
force of the rainforest. The Amazon River begins in the Peruvian
Andes, and winds its way east over the northern half of South America.
It meets the Atlantic Ocean at Belem, Brazil. The main river is about
4,080 miles long. Its drainage basin covers 2,722,000 million square
miles, and lies in the countries of Brazil, Columbia, Peru, Venezuela,
Ecuador, Bolivia, and the three Guyanas. Sixteen percent of all the
world’s river water flows through the Amazon delta. Twenty eight billion gallons of water flow into the Atlantic
every minute, diluting the salinity of the ocean for more than 100 miles offshore. The Amazon rainforest
watershed is home to the world’s highest level of biodiversity.
Amazonia receives about 9 feet of rain every year. Fifty percent of this returns to the atmosphere through the
foliage of trees. Most of the Amazon River’s water comes from the annual snowmelt high in the Peruvian
Andes. Between June and October, the water level rises by 30 to 45 feet. Tens of millions of acres of rainforest
are covered by water as the flood advances, reaching as far inland from the main channel as 12 miles.
Some 15 million years ago, the Amazon River flowed westward into the Pacific Ocean. When the South
American plate moved into another tectonic plate, the Andes
Mountains slowly rose up and blocked the flow of the river.
As the river system backed up, freshwater lakes were
formed, and the environment of the Amazon basin changed
drastically. Then about 10 million years ago the river found
its way eastward towards the Atlantic.
Today, more than 20% of the Amazon rainforest has been
destroyed and is gone forever. The land is being cleared for
cattle ranches, mining operations, logging, and subsistence
agriculture. Some forests are being burned to make charcoal
to power industrial plants. More than half of the world’s
rainforests have been destroyed by fire and logging in the last 50 years. Over 200,000 acres are burned every
day around the world, or over 150 acres every minute. Experts also estimate that 130 species of plants,
animals, and insects are lost every day. At the current rate of destruction, it is estimated that the last remaining
rainforests could be destroyed in less than 40 years.
Native peoples of the Amazon rainforest have used different plants for centuries as cures and potions for their
health and survival. Scientists are now discovering that many of the plants are sources for new drugs for AIDS,
cancer, diabetes, arthritis, and Alzheimer’s. Quinine, muscle relaxants, steroids, and caner drugs have already
been discovered. Today 121 prescription drugs sold around the world come from plant-derived sources.
Although 25% of all drugs are derived from rainforest ingredients, scientists have tested only 1% of tropical
plants.
Another concern for Amazonia is the fate of it indigenous people. An estimated 10 million Indians were living in
Amazonia about five hundred years ago. Today there are less than 200,000 indigenous peoples left in
Amazonia. remaining are 70 years old or more. With them goes a wealth of knowledge of medicinal species of
plants and organisms.
1. What caused the Amazon River to begin flowing east towards the Atlantic instead of west towards the
Pacific?
2. Why is the rainforest being cleared?
The Pampas: South America’s Grassland
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 64° F. 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.
Several interesting mammals can be found
in the pampas. The Geoffroy's Cat, for
example, with its gray coat and black stripped
legs, is almost invisible in the mesquite and
bunchgrass. The Maned Wolf has very long
legs so it can see over the tall grasses. Also,
one can find a llama-like Guanaco that lingers
among the ponds. It is important to note that at
least fifteen mammal species, twenty bird
species, and fifteen plant species are at
serious risk of extinction in the Pampas.
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. Unfortunately, domestic
livestock and farming have severely affected the
pampas. Fertilizers and overgrazing are a
serious threat to the pampas. There are only a
very few pristine remnants of the legendary
"ocean of grass" that was the Pampas. It is
considered to be one of the most endangered
habitats on earth.
by Claire L. 2002,
http://www.blueplanetbiomes.org/pampas.htm
1. In what ways has the wildlife of the pampas evolved to survive in their environment?
2. What are the threats to the pampas today?