Chapter 20 review: life in the sahara and the sahel: adapting to a desert region
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.
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
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.
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.
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.
The Harsh Desert Climate Temperatures can vary greatly: Night time below freezing and daytime over 100⁰F. Sandstorms Unpredictable rain flash floods Plant adaptations
Adaptations to Desert Life The Wandering Tuareg “Blue Men of the Desert” Nomads Trade for food Camel Caravans
Technology Makes Life Easier Satellite phones Creation of oases Better transportation Trucks vs. camels Planes between oases
The Oasis Environment Islands of Water Surrounded by Desert Natural creations Some man-made Large and Small Centers of Life Various plants and animals
Adaptations to Life in the Oases The Traditional 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.
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
The Sahel Environment Includes portions of: Niger Gambia Senegal Mauritania Mali Burkina Faso Nigeria Chad Sudan
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
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
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.
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.
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?