Transcript Notes, Chapter 20

Chapter 20
Physical Geography of Africa South of the Sahara
1. The Land
 Known for extraordinary physical geography
 Very diverse
Landforms
 MI: Africa south of Sahara is a region of plateaus, mountains
and rift valley in east
 Massive region covers 9.5 million square miles
The Great Rift Valley
 Runs from Syria in SWA to Mozambique in SE Africa
 Rift valley – large depression in Earth’s surface, formed by
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tectonic plate movement
Volcanic mountains at it’s edges, deep lakes
Includes Mt. Kilimanjaro, one of largest mtns. in world
Lake Tanganyika, one of deepest and longest freshwater lakes in
world, lies on western branch of GRV
Lake Malawi, more than 2300 ft deep
Mountains and Plateaus
 Series of plateaus, rise in elevation from coast inland
 Plateaus range in elevation from 500 ft to 8000 ft
 Edges lined by escarpments, steep jagged cliffs, and cataracts, or
waterfalls
 Largest mountains include Kilimanjaro and Mt. Kenya
Water Systems
 MI: Landforms and physical processes have influenced the
regions water systems (lakes, waterfalls, rivers)
 Lakes/rivers, located in basins, formed by tectonic activity
 Rivers start at high elevations, make their way to the sea
Land of Lakes
 Most lakes near Great Rift Valley, E Africa
 Lake Victoria, largest freshwater lake in Africa, second
largest in world behind Lake Superior
 Lake Chad, W. Africa, shrinking due to irrigation,
desertification, global warming
 Desertification – long periods of drought and land use
destroy vegetation
Human Made Lake
 Lake Volta, W. Africa (Ghana), among largest HM lake in the
world
 Created in 1960’s by damming Volta River
 Dam built for hydroelectric power in Ghana
River Basins
 Niger River, main river in W. Africa
 2600 miles long
 Important for agriculture and transportation in region
 Forms Niger Delta upon entering Atlantic Ocean, 200
miles wide
 Delta – a triangular section of land formed by sand and silt
carried downriver
River Basins
 Zambezi River, S. Central Africa
 2200 miles long
 Headwater near the Zambia-Angola border, flows to Indian
Ocean
 At border of Zambia and Zimbabwe, Zambezi falls 355 feet,
forming Victoria Falls
River Basins
 Congo River, Central Africa
 About 2,900 miles long
 Reaches sea through an estuary, or passage where freshwater
meets seawater
Natural Resources
 MI: Mineral resources and water are among the region’s
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most abundant natural resources
Oil – Nigeria, Angola, Gabon, Congo and Cameroon
4 percent of world oil in Sub-Saharan Africa
South Africa – half of worlds gold
Uranium – South Africa, Botswana
Water is abundant, but irregular and unpredictable,
difficult to control for irrigation and hydroelectric power
2. Climate and Vegetation
 MI: Rain helps determine:
 climate
 vegetation growth
Tropical Climates
 Causes of variation in climate and vegetation:
 rainfall
 ocean currents
 prevailing winds
 elevation
 latitude
Tropical Wet
Map of p. 516
TW Zone located near equator
More than 60 inches of rain per year
Produces variety of vegetation
Rainforest levels:
Low: ferns, moss, shrubs
Mid: Trees, palms
Canopy: leafy trees, max height of 150 ft
Soil not fertile
Heavy rains leach, or dissolve and carry away, nutrients
from soil
 Crops grown: bananas, pineapples, cocoa, tea, coffee,
timber, cotton
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Tropical Dry
 Savanna, or grassland with scattered trees, covers half of
Africa
 Alternating wet and dry seasons
 35-45 inches annual rainfall
 Hot, dry air from Sahara, called harmattan, affects
TDZone
 Cool, humid air from SW affect TDZone
 Combination at times forms tornadoes
 Animals: zebras, gazelles, hyenas, lions, giraffes and
cheetahs
Dry Climates
 MI: Dry climates of Sub-Saharan Africa located in the north
and south, away from the equator
Steppe
 Transition zone between tropical dry savanna and desert
 Northern steppe called the Sahel, from Senegal to Sudan
 4-8 inches annual rainfall
Desertification
 Sahel, undergone desertification over past 50 years
 May be caused by climate change
 May be caused by human activities, animal grazing, logging,
farming, etc.
Desert
 Namib Desert, Atlantic coast of Namibia
 Kalahari, eastern Namibia, Botswana and part of South Africa
 Daily temps in Kalahari vary widely, from 50 dg., night, to
120 dg., day
Midlatitude
 Coastal areas of South Africa, humid subtropical climates
 Highland East Africa, moderate climates, adequate rainfall for
farming, some snow at high elevations