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Chapter 20 review
1. CHAPTER 20 REVIEW: LIFE IN
THE SAHARA AND THE SAHEL:
ADAPTING TO A DESERT REGION
2. Introduction
Oasis: An isolated spot where water is found
in the desert.
Drought: Long periods with very little or no
rain.
Physical Features: Mountains, lakes, rivers,
etc.
Climate:The average temperature of a given
place.
3. The Geographic Setting
Sahara covers about 3.5 million square miles
Bordered by the Red Sea on the east and the
Atlantic Ocean on the west
Atlas Mountains in the north
Merges with the semiarid Sahel
Sahara and Sahel cover all or parts of 15
countries
4. The World’s Largest Desert
Used to have a wetter
climate, but 6,000 years
ago the climate changed.
Trade winds:Winds that
begin in the northern
latitudes and blow south
towards the Equator.
5. The Sahel: On the Sahara’s
Edge
Marginal land: Land that is not well suited for
farming.
Pastoral nomads: Groups of herders who
move with their animals from place to place
in search of pasture and water.
Desertification:The process during which an
area of land becomes increasingly dry.
6. The Desert Environment
Ergs: Great seas of sand with tall sand dunes.
Regs: Gravel-covered plains.
Hammadas: High, rock-covered flatlands.
Wadis: Dry riverbeds that can turn into
raging rivers after a rain.
7. The Harsh Desert Climate
Temperatures can vary greatly: Night time
below freezing and daytime over 100⁰F.
Sandstorms
Unpredictable rain flash floods
Plant adaptations
8. Adaptations to Desert Life
TheWanderingTuareg
“Blue Men of the
Desert”
Nomads
Trade for food
Camel Caravans
9. Technology Makes Life Easier
Satellite phones
Creation of oases
Better transportation
Trucks vs. camels
Planes between oases
10. The Oasis Environment
Islands of Water
Surrounded by Desert
Natural creations
Some man-made
Large and Small
Centers of Life
Various plants and
animals
11. Adaptations to Life in the
Oases
TheTraditional Ways of Oasis Settlers
Cash crops: Dates, wheat, barley, vegetables.
Trade for goods
Homes made of mud bricks
Work done in the evening
Windbreaks:A wall or hedge that breaks the force
of the wind.
12. Water Problems Limit the
Growth of Oasis Towns
Mostly small villages
Why people move here
Jobs at factories
Pasture for animals
Refuge from drought or wars
Kinds of water problems
How to get water during expansion
Water shortages
13. The Sahel Environment
Includes portions of:
Niger
Gambia
Senegal
Mauritania
Mali
Burkina Faso
Nigeria
Chad
Sudan
14. A Landscape Threatened by
Drought and Desertification
Natural vegetation: grasslands, acacia trees,
baobab trees, small bushes.
Not fertile soil
Water is scarce most of the year
Farther south=rain more plentiful
Varied vegetation
15. Adaptation to Life in the
Sahel
Most people are farmers or herders
Plant crops : grains like millet and sorghum
Shifting agriculture: Plant some crops on a
plot of land for a year or two, then planted a
different field.
Herders use a similar system to feed the animals
16. Human Causes of
Desertification
Cash crops
Overgrazing of cattle
Deforestation: Cutting
down trees for various
uses.
Erosion:The process of
wearing down a piece
of land.
17. Beginning to Think Globally
1/3 of Earth’s land is
arid or semiarid
Some desert regions
expanding
China
Sandstorms
Desertification
A sandstorm in China.
18. Global Connections
Are the world’s deserts
growing or shrinking?
What human activities
contribute to
desertification?
How might people
adapt to living in areas
threatened by
desertification?