explorers and settlers.
Rock musicians Lenny Kravitz (left) and
Mick Jagger perform together at an awards
ceremony.
78 Rocky Mountains BRITANNICA STUDENT ENCYCLOPEDIA
The Rockies are more than 3,000 miles
(4,800 kilometers) long. They cover
parts of the U.S. states of Montana,
Idaho, Washington, Wyoming, Utah,
Colorado, and New Mexico. In
Canada, they extend into British
Columbia, Alberta, and the Yukon and
Northwest Territories. Sometimes
Alaska’s mountains are called part of the
Rockies, too. Mount Elbert, in
Colorado, is the highest peak. It is
14,433 feet (4,399 meters) high.
Rocky Mountain forests include aspen,
white pine, Douglas fir, western hemlock,
and western red cedar trees. The
animals of the Rockies include bighorn
sheep, mountain goats, mountain lions,
American elk (wapiti), reindeer, and
grizzly bears. Bald eagles, golden eagles,
peregrine falcons, and other large birds
soar above the mountains.
The spectacular scenery of the Rockies
attracts many tourists. National parks of
the region include Yellowstone, Jasper,
Banff, Yoho, and Kootenay. The Rockies
are also rich in minerals. Mines provide
copper, gold, silver, lead, and zinc. There
are also supplies of oil, natural gas, and
coal.
Native Americans may have lived in the
Rocky Mountain region as early as
12,000 years ago. The groups of the
northern mountains included the
Kootenai, the Shoshone, the Coeur
d’Alene, and the Flathead. The Ute, the
Navajo, the Hopi, and the Pueblo lived
farther south.
The Rockies were one of the last parts of
North America to be explored by Europeans.
The rough terrain and harsh
weather made exploration difficult. In
1793 the Scottish explorer Alexander
Mackenzie crossed the Canadian Rockies.
The Lewis and Clark Expedition
The climate in the Rocky Mountains varies
widely. In summer only a short distance
may separate warm foothills from frosty
peaks.
BRITANNICA STUDENT ENCYCLOPEDIA Rocky Mountains 79
crossed the Rockies in what are now
Montana and Idaho in 1805.
#More to explore
Mountain • North America
Rodent
Rodents are mammals with long, sharp
front teeth that they use for gnawing.
They are found almost everywhere in
the world. More than half the mammals
on Earth are rodents. Rats, mice, squirrels,
chipmunks, gerbils, hamsters, lemmings,
beavers, guinea pigs, and
porcupines are all rodents.
Most rodents are small. Some mice and
dormice are only 3 inches (8 centimeters)
long and weigh as little as 0.7
ounce (20 grams). The largest rodent by
far is the capybara of South America. It
can be 4 feet (1.3 meters) long and
weigh more than 100 pounds (45 kilograms).
Rodents are different from other mammals
because they have teeth that keep
growing throughout their lives. They
have one upper pair and one lower pair
of these teeth, which are called incisors.
Rodents spend much of their time
gnawing, or nibbling at, hard objects to
wear their incisors down. If the incisors
grow too long, the rodent cannot eat.
The incisors can even grow back into
the skull and kill the animal.
Rodents can be pests. They can ruin
farmers’ crops and stored grains. Their
gnawing can damage boards in houses,
barns, or even metal telephone cables.
Some rodents carry diseases that may
infect people.
But some rodents are valuable to people.
People use the fur of nutrias and chinchillas
to make clothing. They keep
hamsters, guinea pigs, and gerbils as
pets. Mice, rats, and other rodents are
useful in scientific research.
#More to explore
Beaver • Chipmunk • Gerbil • Guinea
Pig • Hamster • Lemming • Mammal
• Mouse • Porcupine • Rat • Squirrel
Roller Skating
Roller skating is a fun pastime and a
competitive sport. Roller skaters wear
shoes or boots with small wheels on the
bottom. They skate outdoors on sidewalks
and other paved areas. They also
skate indoors in buildings called rinks.
Roller-skating sports include hockey,
speed skating, figure skating, and danc-
The capybara of South America is the largest
rodent.
80 Rodent BRITANNICA STUDENT ENCYCLOPEDIA
ing competitions. These are similar to
traditional ice-skating sports. Today
roller skaters also compete in “extreme”
sports such as vertical skating. Vertical
skaters jump from ramps and perform
tricks in the air.
Roller skates were invented in the 1760s.
Early skates were modeled on the ice
skate. They had an in-line arrangement
of wheels. This means that the wheels
formed a single straight line along the
bottom of the skate, where the blade is
on an ice skate. Skaters found it hard to
turn or stop while using these early
skates.
In 1863 James Plimpton of the United
States designed the first roller skates that
were widely used. Plimpton’s skates had
four wheels arranged in a rectangular
pattern. This design made it easier for
skaters to turn. Other changes in the late
1800s helped in braking and created a
smoother ride.
The improved skates helped to make
roller skating very popular in the early
1900s. In the 1960s plastic wheels
began to replace metal ones. The plastic
wheels gripped the skating surface
better. A new type of in-line skates,
often called Rollerblades, became
popular in the 1980s.
#More to explore
Ice Skating • Skating
Rom
