other. The sun and the Moon both pull
on Earth, but the Moon has a greater
influence because it is closer to Earth
than the sun. As the Moon pulls on
Earth it makes the water move. On the
side of Earth near the Moon, the water
builds up in a wave. Another wave
forms on the other side of Earth. This
is because the Moon is pulling Earth
away from the water on that side. These
waves result in high tide. As Earth
rotates and the Moon moves around
Earth, the tides change as well. Because
the Moon moves around Earth in a
regular path, the cycle of the tides
follows a regular pattern.
#More to explore
Earth • Gravity • Moon • Sun
Tierra del Fuego
Tierra del Fuego is a group of islands at
the southern tip of South America.
About two thirds of the islands are in
Chile, and the rest are in Argentina.
The name Tierra del Fuego is Spanish
for “land of fire.” The explorer Ferdinand
Magellan named the islands.
When he sailed around the tip of South
America in the 1500s, he saw many fires
built by Indians along the coast.
A waterway called the Strait of
Magellan separates the islands from
mainland South America. The main
island, called Tierra del Fuego, is
triangular. The southern and western
parts of the islands are mountainous.
Both the sun and the Moon pull on Earth’s
ocean water with a natural force called
gravity. This pull creates tides. As the sun,
Moon, and Earth move in space, they
sometimes form a straight line, shown at
top. This arrangement creates high tides
that are higher than usual. It also creates
low tides that are lower than usual. At other
times the sun, Earth, and Moon are positioned
like the corner of a square, shown at
bottom. This arrangement evens out the
tides more. It creates high tides that are less
high than usual and low tides that are less
low than usual.
64 Tierra del Fuego BRITANNICA STUDENT ENCYCLOPEDIA
Forests of beech trees grow in the
middle of the main island.
Chile’s only oil field is in the northern
part of Tierra del Fuego. The islands
have some textile and electronics companies.
There is some logging in the forests.
Tourism is a valuable industry, too.
The first people to live on the islands
were the Ona, Yahgan, and Alacaluf
Indians. Magellan sailed past the islands
in 1520. Gold was discovered on Tierra
del Fuego in the 1880s. Then people
from Argentina and Chile started moving
to the islands. Oil was found in the
area in 1945.
#More to explore
Argentina • Chile • Magellan, Ferdinand
Tiger
The tiger is the largest of the cats. Like
lions, tigers are very strong and fierce
hunters.Tigers are found in the wild only
in parts of Russia, China, and South and
Southeast Asia. They live in forests,
grasslands, and swamps. The scientific
name of the tiger is Panthera tigris.
Physical Features
Male tigers can grow to more than 3 feet
(1 meter) high and 10 feet (3 meters)
long, including the tail. They usually
weigh between 350 and 640 pounds
(160 to 290 kilograms). Their fur can
range from light yellow on the belly to
deep yellow or orange on the back. Dark
stripes cover the head, body, and legs.
There are also black rings on the tail.
There are five different kinds of tiger.
The best known is the Bengal tiger,
found mainly in India. The rare Siberian
tiger is larger and has longer, softer fur.
The Bengal and Siberian tigers are the
kinds most often seen in zoos.
Behavior
Tigers hunt alone at night. They prey on
animals such as deer and wild hogs.
Tigers generally avoid large animals such
as elephants and bears. They also try to
stay away from people. But sometimes
they attack people to save themselves or
because they cannot find other food.
A tiger crouches in the grass and watches
its prey before attacking it. It grabs the
prey with its paws and bites the animal’s
neck. Then the tiger drags the dead animal
to a safe place and eats it over several
days.
Siberian tiger
BRITANNICA STUDENT ENCYCLOPEDIA Tiger 65
Life Cycle
Tigers normally come together only to
mate. About three months after mating,
the female has two or three cubs. She
looks after them for about two years and
teaches them to hunt. Tigers live about
11 years.
Tigers and Humans
Tigers are endangered, or in danger of
dying out. People have moved onto land
where tigers once lived, destroying their
homes. Plus, people hunt tigers for sport
and for their skin. Many countries now
have laws to protect tigers.
#More to explore
Cat • Lion
Tigris River
The Tigris River of southwest Asia is
1,180 miles (1,900 kilometers) long. It
begins in the mountains of eastern Turkey.
It then touches the northeastern
border of Syria and crosses Iraq. In
southeastern Iraq the Tigris joins the
Euphrates River. The two rivers together
form the Shatt Al-!Arab. That waterway
empties into the Persian Gulf.
The land that the Tigris flows through
gets little rainfall. It is also very hot. But
farmers are still able to grow crops there.
They water their crops using water from
the Tigris and the Euphrates. The watering
methods they use are called irrigation.
Some of the earliest known civilizations
began on the land between the Tigris
and the Euphrates. The ancient Greeks
