AFRICA'S UNIQUE PHYSICAL GEOGRAPHY

Size
Unique Features
Why is it unique?
Africa's Isolation

Size

The continent of Africa makes up one fifth of the world's land surface. This comes as a surprise to many students since on a common map used in many schools, called the Mercator Projection, Africa appears smaller than it really is. This is because all maps distort (see appendix A in your textbook.). Maps distort because they try to portray the curved surface of the earth on a flat (map) surface. The Mercator projection enlarges areas near the north and south poles and shrinks areas near the equator. (It does this so that north and south will always be directly up and down on the map.) For example, the island of Greenland is about the same size as the country of Mexico [wwmexgln]. Africa therefore, which sits on the equator appears smaller. Another map projection, the Peters Projection distorts the shapes of the continents, but preserves their relative sizes (see Greenland and Mexico [wwpetmex]. On this map you can see the true size of Africa in comparison to the other continents.

For more on the Peters Projection go to the following website and "Go Forward" through the ten short pages: http://www.webcom.com/~bright/petermap.html

Africa stretches 4,800 miles north to south and 4,500 miles east to west. It is larger than the United States, Europe, India, China, Argentina, and New Zealand combined!

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Unique Features

Africa has a very unique physical geography. You should study these six unique features:

1. no major mountain chain [Mountains]
   All continents, except Africa, have continental mountain ranges. Africa does have scattered volcanic mountains, the old and worn Atlas mountains in the northwest, and the Ethiopian highlands [afelevpc]. None of these compares to the Rockies of North America, the Sierra mountains of Middle America, the Andes of South America, the Alps of Europe, or the Himalayas of Asia.
   
2. elongated lakes [Lakes]
   Note the long narrow lakes of eastern and southeastern Africa. Beginning with Lake Turkana in northern Kenya and Lake Albert in western Uganda and extending south with Lake Tanganyika and Lake Malawi. Below, we will discuss why these lakes have this peculiar shape.
   
3. erratic river courses [Rivers]
   Note the erratic courses of the continent's major rivers. The Niger River in West Africa begins flowing in a northeasterly direction and enters the Atlantic ocean in Nigeria flowing in the opposite direction (southwest). The Zambezi and the Nile both have large "S" shaped curves. And the large Congo (Zaire) river begins flowing to the north and east, makes a broad curve to the east and enters the Atlantic Ocean flowing in a southeasterly direction.
   
4. plateau continent with escarpments and rift valleys [afelevpc] [Escarp] [naelevpc] [wwelevpc]
   Africa is often characterized as a plateau continent. A plateau is an "upland" or "tableland" [afelevpc] . An area of relatively high elevation. The elevation of Chicago [naelevpc], which is located near the center of the North American landmass is about 600 feet. Most of Africa is well above 3000 feet. If fact, within just a 100 or so mile of the coast of the southern third of the continent, the land rises steeply to this elevation. These long, steep, almost cliff like or mountain like, changes in relief are called "escarpments" [Escarp]. We will study the cause of these escarpments later.
   
   Along the western part of the continent this, plateau is cut by rift valleys; large, elongated, "trenches" about 20 to 60 miles wide. These valleys have a total length of more than 6000 miles and they stretch from the Red Sea south to Mozambique. The elongated lakes discussed above lie within these rift valleys. [Lakes]
   
   You can clearly see these rift valleys on these elevation maps of Kenya [kenelev] (see lower elevations through the center of the country) and Malawi [malaelev] (see low elevations along the western border of the country).
   
5. climate and vegetation symmetrical about the equator [afsymcli] [Climate] [afsymveg] [Veget]
   Africa is the only continent that is centered on the equator [reliefeq]. As a result, the climates and vegetation of Africa are symmetrical about the equator. No other continent has such a pattern [wwclimat]
   
6. major deserts [Deserts] [afprec]
   Africa is often thought of as the continent of jungles and herds of wild animals on vast savannas. But it is also a continent of vast deserts [Deserts]. The Sahara, the world's largest desert, covers an area ofd 3,500,000 square miles. Just slightly smaller than the United States (3,787,400 square miles) [afus]. Note the Kalahari desert in southern Africa and the deserts along the coasts.

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Why is it unique? [Phys]

Above we discussed the WHERE question. Here we will discuss the WHY THERE?

The unique physical geography of Africa can be explained by the theory of plate tectonics that we studied in the introduction.

The world's major mountain chains have been created by the collision of the earth's crustal plates. The plate on which Africa sits has been relatively stationary while other plates have moved away from it [Drift]. Therefore, there has been no collisions, and no mountain chain formed.

Africa high elevation [Plateau] and the escarpments along it coast [Escarp] are also a result of plate tectonics. As South America [wrldphys] broke away from Africa it left an escarpment along the southwest coast of Africa AND along the southeast coast of South America. As India [india] broke away from Africa it left an escarpment along the southeast coast of Africa AND along the southwest coast of India. (This escarpment is the "Western Ghats" mountains.)

Currently, East Africa [Escarp] is breaking away from the rest of Africa creating the rift valleys that extend from the Red Sea in Eritrea through Kenya, Zaire, and Malawi. Part of these rift valleys have filled with water forming Africa's characteristic elongated lakes.

The erratic river courses are also the result Africa's plateau characteristic with few mountains and a relatively level surface.

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Africa's Isolation

WHY DO WE CARE? Africa's physical geography helps explain Africa's isolation from the rest of the world until the 19th century. (Remember, Columbus came to America at the end of the 15th century, 300 years earlier.) Except for a few coastal ports, Europeans knew little of Africa before then. Why? A quick look at the map will help us [Isolation].

Note the deserts, escarpments and waterfalls along much of Africa's coast. Furthermore, there are few good harbors. These features, along with Africa's great size and the existence of diseases, prevented the easy exploration of Africa's interior.

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