Download Dr. Spring`s Lecture Geography 1African landscapes and their

Dr. Spring’s Lecture Geography 1African landscapes and their formation
Size of Africa
• The United States, China, Europe, India, Argentina, New Zealand fit within Africa’s
shores with room for a number of smaller countries.
One country, Democratic Republic of Congo (Zaire), is as large as half of the continental
United States
Government institutions are located in cities, far from rural areas
70%-80% of the population lives in
rural areas where infrastructure
is not developed
Africa is truly tropical: More area between Tropics of Cancer and Capricorn than other
areas
Two implications
• More crop and animal diseases and pests
• Limitations on agricultural production
High agricultural potential
• 12 month growing season
• not restricted by low temperatures
No single line continental divide
• Continent is a flat plateau
• Few dramatic areas
• Atlas mountains to the North
• Ethiopian Masif and East African Rift Valley to the East
• Cape ranges in extreme south
High plateau landscape as in Zimbabwe, -- lone and level plain stretches for miles.
Altitude: the major part is
> 300 meters (shaded area)
• Areas of more than 1000 meters are illustrated in yellow.
• Penguin in Antarctica
Africa also has the lowest proportion of its land area lying at sea level
• Rapid decent to the ocean
• Called the Great Escarpment e.g., coast of Sierra Leone, Namibia and Eritrea
• The Great Escarpment creates an enormous obstacle for communications and
transportation
• Roads and railroads must ascend sharply from the coast inland creating both costs and
engineering problems.
• North and West Africa are known as Low Africa
• South and East Africa, are known as High Africa.
High Africa includes the two major outstanding areas of the continent
• The Ethiopian Massif, where elevations > 4000 meters
• The Rift Valley Systems of east Africa seen here as a "gully" running from the Red
Sea in the North to Southern Africa.
Mount Kilimanjaro in Tanzania
• Is a dormant volcano
• Africa's highest point, exceeding 5880 meters above sea level
• Snow-capped
Mt. Kilimanjaro located very close to the equator
Allows examination of an important feature of the African landscapes-• The effect of altitude on climate, vegetation and farming systems.
With every 100 meters of elevation
• Temperatures decrease 0.6 degrees
Centigrade or 1.1 degree Fahrenheit.
• This means that from sea level to the top of Mount Kilimanjaro.
Great shifts in vegetation types
• Analogous to what could be observed in a trip from the equator to the north or south
pole.
• Vegetation types range from tropical savanna in the foreground to tundra vegetation at
the top.
Satellite image of Mount Kilimanjaro
• Concentric vegetation belts can be easily detected
• Desert landscapes tropical forests are no farther than 100 kilometers away from huge
glaciers
Major parts of East and South Africa are > 1000 meters
• Africa is less tropical given its location astride the equator.
Plateau areas feature a very pleasant climate and farming systems
• Unlike those usually found in tropical low-lands.
• In the Ethiopian Massif, moderate temperatures of 16 degrees Celsius (61° F) prevail
year round
• Wheat growing is not an uncommon phenomena
• The Irish potato, a crop also associated with temperature climates, was successfully
introduced in Malawi (part of High Africa)
Geological Timescale of Africa
• Much of Africa's rocks are counted in billions of years and come close to the earth's
estimated age of 4.5 billion years.
The rocks are old, weathered, and leached
• Lack many essential plant nutrients
• Soils may form a serious constraint to farming
• The world's most productive soils are younger soils ones near rivers.
Africa's political boundaries, were drawn in colonial times
• Seldom follow physiographic features
• Largely ignore ethnic configurations
• Have serious implications for the development of many regions
Africa's rivers and coastline
This line represents Africa's continental divide.
• All rivers and streams originating east of this line deposit their contents in the Indian
Ocean.
• All rivers west of this line flow into the Atlantic Ocean.
Three of the world's ten longest rivers are in Africa
• The Nile is the world's longest river, surpassing both the Amazon and the Mississippi.
• The Zaire (Congo) river ranks 8th
• The Niger ranks 10th.
In volume of total discharge
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The Nile is third
The Niger second
The Congo (Zaire) is first.
The Congo (Zaire) discharges 16 times more water per year than the Nile.
The majority of Africa's rivers outside the equatorial zone have great seasonal variety in
volume.
Africa's rivers reflect the affects of distinct dry and wet seasons.
• The rivers are nearly completely dry for much of the year, as is this one
• They are flooded during the rainy season.
The Niger river
• Africa's second largest river
• Discharges at least 25 times more water during the rainy season than during the dry
season, when water is most needed.
The African farmer
• Has developed generally well adapted farming systems to match these seasonal
fluctuations
• Grows millet and sorghum that are adapted to the alternating dry and wet conditions.
Maize / corn
• Does not have these properties, and is more susceptible to wilting.
• Maize from the New World was introduced on a large scale even in the drier areas of
Africa, because it may give higher yields.
Another feature of Africa's rivers is related to Africa's plateau
character and the
presence of the Great Escarpment
Many rivers interrupted
by rapids and falls
• Such rivers provide poor access to the interior of the continent because they are
unavailable at vital locations.
• This is one of the reasons for Africa's relatively long isolation in the past.
However, African rivers possess
great hydroelectric potential
Continental Shelf is narrow
• The ocean floor often drops to a great depth near the coastline.
• Developing a commercial fishing industry has been slow since it lacks shallow waters
favorable to fish breeding and growing.
Africa's huge size, its tropical location, its plateau-like relief and extreme age, and
peculiar rivers
• Make Africa unique among the continents.
• Africa's physical characteristics to facilitate our discussion of Africa's climate,
vegetation, soils and
economic studies.
African Landscapes and Their Formation
Mountains, valleys and volcanos in Africa.
• Caused by
–Faulting
–Volcanism
–Folding
Warping resulted in depressions or basins
• Lake Victoria, Africa's largest and the world's third largest lake is a broad, shallow
basin
• Other basins are the Djout, Chad and Sudan basin, Congo (Zaire) basin, and Kalahari
Basin.
Faulting caused the spectacular East African Rift Valley
• The world's most extensive rift valley system.
• Most spectacular of all of Africa's surface features.
The African plateau stops suddenly, drops, and the Rift Valley is created.
• The Rift Valley floor and the plateau possesses climatic and vegetative characteristics
quite unlike the plateau above.
• The floor is often much drier and the vegetation much sparser.
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The second process related to Continental Drift is volcanism.
Volcanic and seismatic activity is relatively heavy in East Africa
Many volcanoes are found in the area
Volcanic activity
Africa's largest active volcano, Mount Cameroon, 4,000 meters high
It erupted four times this century.
Soils derived from volcanic rock are among the most productive soils, and are
generally associated with intensive farming.
Folding formed Africa's Cape Ranges and Atlas Mountains.
• Rocks bend not break alongside a fault, under the influence of colliding land masses,
resulting in typical mountain chains such as the Atlas Mountains and Cape Ranges.