Honors Humanities

Notes-Physical Geography of Sub-Saharan Africa

Africa is a region of great extremes containing some of the earth’s driest land and some of the wettest. It has the world’s longest river (the Nile), the largest desert (the Sahara), and is rich in natural resources.

Africa’s place in the theory of continental drift: it was at the center of the huge landmass known as Gondwana. Other continents broke off of Africa (which actually moved little). This situation explains why Africa has a rather smooth coastline with few harbors, bays, or peninsulas. It also explains why the continent has no high mountain ranges (no tectonic plates crashing into each other pushing up high mountains).

Landforms

Plateau

South of the Sahara, Africa is mostly a huge, relatively high lying plateau that slopes gently downward from east to west. Near the coast the land drops off sharply in a series of cliffs called escarpments, the plateaus and highlands have a number of significant basins, valleys, and river systems.

Plains

Between the escarpments and the oceans a narrow band of low coastal plains encircles the region.

The Great Rift Valley

Located in east Africa, this valley is a 40mile wide zone where two tectonic plates are pulling apart creating a long line of valleys, seas, and narrow lakes known as rift lakes.

Mountains

Remember, there are few major mountain regions in Sub-Saharan Africa. An exception to this general rule of thumb is the region of the Great Rift Valley, which contains the Ethiopian highlands and Mt. Kilimanjaro (on the Kenya/Tanzania border)—both products of volcanic activity in this region.

Rivers

The Nile-in Sudan, Egypt, and Ethiopia. The two main branches, the White Nile (from Sudan) and the Blue Nile (from Ethiopia) come together at Khartoum, Sudan and flow north to the Mediterranean Sea. Determining the source of the Nile was the goal of many of the European explorers in the 19th century. The White Nile originates in the highlands of the rift valley in east central Africa. As the White Nile descends from the highlands and reaches the Nile Basin (in southern Sudan), it breaks into hundreds of small branches that constantly shift course creating a swampy region known as the Sudd.

The Congo-(formerly known as the Zaire) - in Congo and D.R. Congo. This huge river system dominates the CongoBasin in the heart of Africa with many tributaries flowing through the deepest of the African rainforests.

The Niger-in Nigeria, Niger, Benin, Mali, and Guinea. It originates around Guinea and Senegal flowing NE into the dry regions of the Sahel then turns southward flowing into the Gulf of Guinea.

The Zambezi-in Mozambique, Zimbabwe, Zambia, and Botswana. The river was dammed to create LakeKariba, which provides important hydroelectric power to the region. Also Victoria Falls is located on the Zambezi.

Other important rivers include the Orange in South Africa and the Volta in Burkina Faso and Ghana.

All these rivers flow to the coast. When they hit the escarpments near the coast, they flow over a series of cataracts and waterfalls. As a result they are not navigable. (This situation actually created problems for early European explorers who were trying to reach the interior, since rivers were their highways of transportation).

Climates and Ecosystems

Africa is the most tropical continent—much lies between the Tropics of Cancer and Capricorn—yet it’s relatively high lying location moderates the temperatures somewhat. The continent experiences a wide range of rainfall—some areas are extremely dry while others are extremely wet. The climates and vegetation regions include:

Rainforest

Rainforests are found in much of equatorial Africa from Guinea to the Great Rift Valley. This region has no seasonal variation. Instead it is always hot and rainy (the climate here is the tropical wet type) receiving up to 100 inches of rain per year. The vegetation features tall, dense trees that often block out the sun at the ground level and thousands of species (of animals in addition to vegetation). The shrinking of the African rainforest (as with other rainforests around the world) due to clearing for farms and other development has been well documented.

Savanna

Found in much of Africa to the north and south of the rainforests, the climate here is tropical wet and dry (hot year round with a distinct rainy season and a distinct dry season). As a result, this region is characterized by its tall, thick grasslands and scattered trees. Much of the wildlife associated with Africa is found here in places like the Serengeti Plain (of Kenya and Tanzania).

Steppe

Found in the areas to the north and south of the savanna, this region features a semiarid climate, which forms a transitional zone between the deserts and the wetter parts of the continent. Rainfall in these areas is too limited and unpredictable to sustain dense vegetation. Instead, short grasses interspersed with shrubs/bushes cover these lands, and trees are virtually non-existent. Along the southern border of the Sahara, the African steppe is known as the Sahel (an Arabic word meaning “shore”—as in the shore of the desert—or “border”). This region including the countries of Sudan, Chad, Mali, Burkina Faso, Niger (and even Ethiopia on the eastern edge) is prone to drought, and the land suffers from overuse by the subsistence farmers who are part of Africa’s fast growing population. Their attempts to make a living in increasingly crowded but marginally useful farmland has contributed to the occurrence of a process called desertification, the spread of desert-like conditions into semiarid areas.

Desert

These regions with arid climates are found in both northern (the Sahara) and southern (the Namib and Kalahari deserts).

Subtropical Regions

These regions are found in the relatively small areas of Africa that are located outside the tropics. Obviously, they are dominated by temperate climates (such as Mediterranean and Humid Subtropical). These are some of the most densely populated regions of the continent. WHY?

Resources

Africa is rich in natural resources; however these resources are unevenly distributed. Africa is rich in gold, diamonds, copper, platinum and cobalt. Nigeria, Angola, Libya, Algeria and Gabon all have oil deposits. Some African nations lack the money to cultivate these resources so they turn to foreign companies to invest in their development. As a result the profits from these resources flow out of Africa.